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Course title: Introduction to Engineering

Table of Contents: Basic bibliography .................................................................................................................................................. 2 Additional bibliography .......................................................................................................................................... 2 Lectures................................................................................................................................................................... 3

Lecture no. 1 Basics concepts in engineering ..................................................................................................... 3 Lecture no. 2 Outline of the history of engineering............................................................................................ 6 Lecture no. 3 Friction in engineering .................................................................................................................. 8 Lecture no. 4 Material features, criteria class and properties............................................................................ 11 Lecture no. 5 Metals and alloys used in engineering........................................................................................ 14 Lecture no. 6 Other materials used in engineering............................................................................................ 17 Lecture no. 7 Metalworking, forging and its main features .............................................................................. 20 Lecture no. 8 Other metalworking methods...................................................................................................... 23 Lecture no. 9 Thermo and chemical treatment.................................................................................................. 27 Lecture no. 10 Metal casting.............................................................................................................................31 Lecture no. 11 Material removal processes - chip-forming machining............................................................. 33 Lecture no. 12 Abrasive, erosive and concentrated energy beam machining.................................................... 37 Lecture no. 13 Joints and connections - inseparable......................................................................................... 40 Lecture no. 14 Joints and connections - separable ............................................................................................ 46 Lecture no. 15 Basic mechanisms in engineering - Simple Machines .............................................................. 51

Exercises ............................................................................................................................................................... 58 Exercise no. 1 Basic units used in engineering ................................................................................................. 58 Exercise no. 2 Friction in engineering............................................................................................................... 60 Exercise no. 3 Conservation of energy in engineering...................................................................................... 62 Exercise no. 4 Basic units used in engineering ................................................................................................. 65 Exercise no. 5 Accumulation of energy in engineering..................................................................................... 68 Exercise no. 6 Use of liquids in engineering..................................................................................................... 70 Exercise no. 7&8 Simple machines designing and material features................................................................ 72

Basic bibliography 1. Wprowadzenie do techniki (Introduction to Technology) - Tytyk Edwin, Butlewski

Marcin, Wyd. Politechniki Poznańskiej, Poznań, 2009 2. Wprowadzenie do techniki - materiały do ćwiczeń i wykładów (Introduction to

technology- materials for lectures and exercises), Tomaszewski Zbigniew, Wyd. Politechniki Poznańskiej, Poznań, 2002

3. Physics: Principles with Applications – Giancoli Douglas, Addison-Wesley, 2009 4. Encyklopedia technik wytwarzania stosowanych w przemyśle maszynowym

(Encyclopedia of production techniques in industry), Volume I - Erbel Jerzy, Oficyna Wydawnicza Politechniki Warszawskiej, Warszawa, 2001

5. Encyklopedia technik wytwarzania stosowanych w przemyśle maszynowym (Encyclopedia of production techniques in industry), Volume II - Erbel Jerzy, Oficyna Wydawnicza Politechniki Warszawskiej, Warszawa, 2001

Additional bibliography 1. Technologia maszyn (Technology of machines) - Okoniewski Stefan, WSiP,

Warszawa, 1999 2. Dawne wynalazki (Past inventions) - James Peter, Thorpe Nick, Świat Książki,

Warszawa, 1997 3. Powszechna historia techniki (Contemporary history of technology) - Bolesław

Orłowski, Oficyna Wydawnicza „Mówią Wieki”, Warszawa, 2010

DESCRIPTION OF THE VARIOUS FORMS OF SUBJECTS

Lectures

Lecture no. 1 Basics concepts in engineering Keywords:

1. Philosophy of technology

2. Praxeology rules

3. Machine, apparatus and useful machinery features

4. Phases of development of technical devices

5. Production process and its phases

Basic definitions:

1. Technology - (1) the overall knowledge of a particular method of production of some

good or of achieving a specific industrial or service effect; (2) all material resources

that support human action, that is - simple tools and more complex technical

equipment, such as machinery, apparatus and aggregators, (3) ability to perform a

particular task,

2. Machine is a set of interconnected parts and components, of which at least one is

movable, with the appropriate working parts/actuators, control systems, power supply,

etc. are connected together for the execution of specific activities, particularly for

processing, treatment, moving, or packaging of materials1

3. Machine tools - technological machines designated to change the shape, dimensions,

and surface roughness of metal objects or others by removing excess material in the

form of chips,

4. Mechanization is the replacement of human effort with the work of machines,

5. Automation is the use of process control devices (e.g. technological) without or with

little human participation (from Greek: automatos – automatic),

6. Robotics – is the use of devices intended for automatic manipulation with the ability to

perform programmable motions along a number of axes, equipped with grippers or

technological tools,

Description of contents:

Lecture is related to the basic concepts used in engineering. There were defined

concepts such as machinery, apparatus and aggregators. During the course is discussed 1 Machinery Directive 2006/42/EC

Technology model by Bunge2 (C,S,D,G,F,B,P,K,A,M,V) which is composed of components

such as: professional community, social context, domain, general outlook and philosophy,

formal background, background knowledge, problems, fund of knowledge, set of aims,

methods, values.

Technology is shown as social experimentation, because a laboratory experiment using

technical solutions cannot be carried out on a massive scale. There are shown such a

components as:

• ensuring the safety of the offered technological works,

• anticipation of the possible side effects of the proposed solutions

• expression of sufficient concern for the tracking of side effects of solutions and the

consequences of using these solutions on a large scale,

• reliable information about dangers,

• constantly considering the experimental nature of each project,

• taking into account social acceptance for the creation, production, and dissemination

of technical solutions

• willingness to take responsibility for the results of the undertaken projects.

There are shown three stages of technology development:

• Primitive technology - based on common sense

• Craftsmanship technology -based on experience

• Engineering technology - based on scientific knowledge

During lecture praxeology is defined and its basic rules:

• condition for achieving the objective is to take action,

• sequence of action,

• activity leading to success is an activity, in which the person is usually aware of the

purpose of his effort. If the goal is distant, it is not always possible to achieve it by a

direct route and sometimes we resort to shortcuts,

• reflection before action,

• reflection replaces unnecessary physical effort,

• mere reflection (planning) is not enough if implementation does not occur afterwards,

• method of action is an important element in a successful operation,

• unintended effects of action often have a beneficial effect,

During lecture are discussed traditional and modern machine models and types of machines:

2 Bunge M., 1985, Treatise on Basic Philosophy, Reidel Vol. 7:2, p. 231,

• technological, used to perform operations associated with the change of shape,

physical-chemical properties, or states of the worked on materials or objects (such as

machine tools, metallurgical machinery, agricultural machinery),

• energetic, used for the processing of one type of energy into another (e.g. engines,

turbines, generators),

• transport, used to move people and goods

• others: cybernetic, logical, steering-controlling

Lecture contains information about machine tools (general purpose, specialized and special

machine tools) and their features (power, efficiency coefficient, structural layout, nominal

parameters). Performance indicators are defined: volume performance index, surface

performance index and unit performance index. Student will understand what influences the

accuracy of machines (geometric, kinematic, control, measurement accuracy).

During lecture the general structure of production process is given (research and development,

manufacturing process, trade and service process). Manufacturing process is discussed and is

divided into: technological process, control process, transport process, and storage process.

Preparation of production is defined and its phases are described, which are:

• preliminary design,

• structural design,

• construction and prototype testing,

• technological design,

• execution of instrumentation,

• organizational design,

• execution of a trial run and a start-up series.

The production phase of a product’s life cycle is described as the following stages:

• preparation (cooperation agreements, delivery - parts, resources, materials, energy,

storage processes, preparatory processes, foundry processes, plastic working

processes)

• processing (excess machining processes, thermal and thermo-chemical processes,

surface machining processes, other machining and finishing processes)

• assembly (initial assembly processes, end of assembly processes, trials and tests,

maintenance and packaging, storage with manufacturer)

At the end of the lecture final phase of a product life cycle is indicated (dismantling,

segregation and regeneration of parts, recycling of materials, utilization and storage of waste).

Issues for discussion and increasing knowledge of students

1. Technology principles

2. Engineering as a knowledge of praxeology

3. Impact of the factors of production on human

Lecture no. 2 Outline of the history of engineering Keywords:

1. Work and technology in primitive societies

2. Work and technology in the Medieval period

3. Work and technology of the Renaissance and Enlightenment

4. Age of Steam

5. Industrial Revolution

Basic definitions:

1. An invention - a unique or novel device, method, composition or process.

2. The craftsmanship style of production is based on an idea that the product is made

from start to finish by the same group of people, one of which - the master -

determines the manufacturing process and all the features of the product. The product

has individual characteristics and can be identified with a specific style, characteristic

of the manufacturer.

3. Mass production is the production of large amounts of standardized products,

including and especially on assembly lines.

4. Standardization is the process of developing and implementing technical standards for

commoditization, compatibility, interoperability, safety, repeatability, and quality.


Lecture is related to the basic concepts used in engineering. There are described most

important inventions in the history of human kind:

• first tools – 2.5 mln years ago,

• thrown tools – 400 000 BC,

• flute – 40 000 BC,

• rope – 13 000 BC,

• string drill - 8000 BC,

• sledge on roller and wheel - 5000 BC,

• smelting of copper ore - 4000 BC,

• casting - 3700 BC,

• wheeled carriage - 3700 BC,

• pulley - 700 BC,

• watermill - 80 BC,

• windmill - 105 AD,

• ship rudder - 1250 AD,

• lathe - 1350 AD,

• pig iron - 1400 AD,

• printing machine – 1447 AD,

• Besson’s threading lathe – 1568 AD,

• the first steam machine equipped with a piston and cylinder by Papin – 1690,

• Newcomen’s steam engine -1712 AD,

• smelting of iron on coke -1717 AD,

• Watt's steam engine - 1776 AD,

• milling machine by Whitney – 1818 AD,

• planer - 1820 AD,

• water turbine -1827 AD,

• turret lathe - 1845 AD,

• Bessemer steel - 1856 AD,

• gas engine (two stroke) by Etienne Lenoir – 1860 AD,

• automatic lathe - 1870 AD,

• four-stroke engine with a mixture of compressed by Nicolaus August Otto – 1876 AD,

• Steam turbine - 1884 AD,

• car by Carl Benz – 1886 AD,

• piston engine compression ignition by Rudolf Diesel - 1893,

• high-speed tool steel - 1898 AD,

• airplane - 1903 AD,

• conveyor belt mass production - 1913 AD,

There are discussed some of the forgotten polish inventors who overtook their times on

example of: aircraft by Możajski (1882) and 16-bit minicomputer K-202 by Karpinski (1973).


1. Why many ancient inventions were forgotten and again invented during the medieval

period?

2. Why is there a large influence of small inventions?

3. From where comes the need to make inventions?

4. Why is inventiveness variable in time?

5. What is the impact of natural disasters, such as the plague, on technical development?

Lecture no. 3 Friction in engineering Keywords:

1. Static & Dynamic friction

2. Rolling & Sliding friction

3. Lubrication

4. Bearing

Basic definitions:

1. Friction - Friction results from relative motion between objects. Frictional forces are

forces that resist or oppose motion.

2. Lubrication is the act of applying lubricants and lubrication substances which are

capable of reducing friction between moving mechanical parts.

3. Adhesion is the property of a lubricant that causes it to stick or adhere to the parts

lubricated.

4. Cohesion is the property which holds a lubricant together and resist a breakdown of

the lubricant under pressure.

Description of contents: Friction is in all processes and machines. All surfaces, no matter how smooth they may

appear to the unaided eye, when sufficiently magnified are rough and uneven. This

unevenness is known as asperities. Friction always consumes power and produces heat. Any

fluid when placed between two surfaces tends to keep them apart and change sliding friction

into fluid friction, thus they are said to be lubricated. The extent to which lubrication reduces

the friction between two surfaces is governed by two factors: 1) The selection of the fluid

which has the best proportion of cohesive and adhesive properties. 2) The amount of pressure

between the two surfaces. To insure lubrication, the layer of fluid must be kept intact, the

greater the pressure the more difficult this becomes. Friction and heat cause the destruction of

asperities resulting in metal particles interrupting the oil film between two surfaces generating

more particles. These particles react with moisture, impurities and lubricant additives creating

corrosive acids that further pit the surface creating new asperities. These acids oxidize the

lubricant, accelerate wear and rapidly deteriorate the functions of the lubricant resulting in the

3-common wears in the fluid system. That’s why the 5 functions of the lubricant are:

1. Friction reduction

2. Sealing

3. Heat removal

4. Cleansing

5. Absorbing Shock

A good lubricant must reduce particulate wear from the interaction of metal-metal contact.

Even the best lubricants degrade over time, as a result of friction and chemical in the additive

package reacting with particulate, moisture, heat and oxygen resulting in acidic properties.

These acids react with the metal surface causing micro-pitting (asperities) and the vicious

cycle begins anew. The very anti-wear additive package designed to protect metal-metal

contact, turns acidic and become part of the problem. The typical downfall of a lubricant

occurs as a result of an imperfect, temporary and sacrificial boundary layer between surfaces

allowing asperity-asperity contact thus introducing particulate into the lubricant. Heat,

moisture, air, and metal particulates combined with certain additives interact creating acids

which micro-pit the surfaces and oxidize the oil. The efficiency and longevity of a lubricant

dramatically increases as the asperity-asperity contact decreases. The goal is to reduce friction

through a solid and permanent boundary layer on the surfaces. Bad condition of friction

lubricants is followed by:

• loss of power

• loss of fuel economy

• frequent oil drains due to degradation

• component wear

• increased emissions

• rising maintenance cost

• rising labour cost

The way to reduce friction in technology are bearings. There are used not only to fight against

friction but also to carry loads and guide moving parts.

Fig. 1 Component parts of a ball bearing

Fig. 2 Component parts of a ball bearing

The main factors of bearing selection are: available space, misalignment, speed, life,

load/direction, operating conditions (vibration, temperature) – Fig. 3.

Fig. 3 Bearing Selection Factors


1. The role of friction in engineering.

2. The possibility of reducing friction and its importance to the economy.

3. Energy losses due to friction.

Lecture no. 4 Material features, criteria class and properties Keywords:

1. Material groups

2. Mechanical properties

3. Hardness

Basic definitions:

1. Density (volumetric mass density) of a substance is its mass per unit volume,

2. Elastic modulus (known as Young's Modulus) - the normal stress divided by linear

strain 3. Elastic modulus is the measure of resistance to elastic deformation.

3. Hardness is a measure of how resistant solid matter is to various kinds of permanent

shape change when a force is applied. Hardness is the property of a material that

enables it to resist plastic deformation, penetration, indentation, and scratching.

4. Hookes Law - if a metal is lightly stressed, a temporary deformation, presumably

permitted by an elastic displacement of the atoms in the space lattice, takes place.

Removal of the stress results in a gradual return of the metal to its original shape and

dimensions. 4

5. Malleability is the ability of a metal to exhibit large deformation or plastic response

when being subjected to compressive force. 5

6. Poisson's ratio - the ratio of the lateral to longitudinal strain is Poisson's ratio.

Poisson's ratio is a dimensionless constant used for stress and deflection analysis of

structures such as beams, plates, shells and rotating discs.6

7. Toughness – energy required to deform one cubic inch of metal until it fractures,

Toughness describes the way a material reacts under sudden impacts.

8. Yield strength - point at which material exceeds the elastic limit and will not return to

its origin shape or length if the stress is removed. This value is determined by

evaluating a stress-strain diagram produced during a tensile test.


3 IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. 4 http://www.engineersedge.com/material_science/hookes_law.htm 5 http://www.engineersedge.com/material_science/malleability.htm 6 http://www.engineersedge.com/strength_of_materials.htm

Lecture is related to the basic technical materials groups and their properties. Materials

were divided into: metallic, nonmetallic, and composite. In the metallic group the following

can be distinguished: iron alloys and non-ferrous metals. Iron alloys were divided into:

• cast iron: white, gray, ductile/nodular/spheroidal,

• cast steel

• steel: low-carbon, medium-carbon, high-carbon (spring steel), alloy steel: tool,

tempered, heat-resistant, acid-resistant, stainless

Main material features definitions are discussed as:

• relative cost

• density

• elastic modulus

• strength resistance to cracking

• indicator of fatigue

• thermal conductivity

• diffusivity

• heat capacity

• melting temperature

• glass transition temperature

• coefficient of thermal expansion

• resistance to thermal shock

• resistance to creep

• consumption indicator

• corrosion indicator

During lecture is discussed hardness and its tests (Brinell, Rockwell, Vickers, Knoop,

Grodzinski, Poldi, Shore). As a conclusion of the discussion:

• the Brinell method, which does not allow diamond penetrators, cannot be used for

hardened steel.

• the Rockwell method is more universal, because it allows for the use of diamond cone

and steel ball penetrators.

• the Vickers method, which only allows for a diamond pyramid penetrator, can be

employed in the entire hardness range. However, it is most suitable for tests in

laboratories compared to tests in workshops.

Fig. 4 Schematic of measurement of hardness of metals by the Brinell method

When considering materials economically we find the following applications for specific

materials:

• for big and simple structures is used wood, cement, construction steel which costs

$60–550 per ton

• for medium and small structures (planes, cars, instruments) are used metals, alloys,

and polymers, which costs $550–5500 per ton

• for special conditions working materials such as turbine blades are used: alloys,

special modern composite materials (CFRP BFRP) which cost up to $200x103 per ton

• for special machine parts (bearings) or in electro technology (electrical contacts,

microprocessor circuits) are used: sapphire, silver, gold which costs up to $2x106 per

ton

• for cutting and polishing tools are used industrial diamonds which costs up to $9x108

per ton

Another very important feature is the ability to recycle materials. For example, recovery of

aluminium uses only 5 to 10% of the energy needed to manufacture new aluminium. But to

produce 1 kg of pure aluminium it takes about 300 MJ (6 times more than steel) and about 4.6

kilograms of bauxite – the obtained product is aluminium oxide (1.9 kg), and the residue -

(2.7 kg), commonly known as 'red mud.’


1. Engineering criteria for materials and their significance

2. The impact of environmental requirements on technique

3. The criteria groups for materials and the relationship between them

Lecture no. 5 Metals and alloys used in engineering Keywords:

1. iron alloys

2. steel

3. cast steel

4. cast iron

5. brass, bronze

Basic definitions:

1. brass – copper-zinc alloy (Cu + Zn) up to 38% Zn - easily cut, used for casting and

machining, the manufacture of valves for the water supply system, hardware

construction, electrical engineering, sliding bearings and propellers.

2. bronze – copper-tin alloy (Cu + Sn) - resistant to chemically aggressive environment,

abrasion and corrosion, used for casting and metal cutting (obróbka skrawaniem).

With the different types of bronzes (lead, silicon, aluminium, beryllium) created are

sliding bearings, springs, chemical fittings, measuring instruments,

3. cast iron - iron casting alloy with carbon, silicon, manganese, phosphorus, sulphur and

other ingredients, containing from 2 to 3.6% C

4. cast steel is carbon or alloy steel obtained in the process of steelmaking carried out in

for ex. an electric furnace and cast into molds. Cast steel has better strength properties

than cast iron (even ductility) and therefore it is used for machine parts with complex

shapes and which are heavily loaded.

5. ductile (nodular/spheroidal) iron is obtained similarly to gray iron, but with the

introduction of additives into the liquid metal such as magnesium (Mg) and silicon

(Si), during the slow solidification the carbon excess is excreted in the form of nodules

of graphite, creating so-called “spheroids”. Thanks to this, ductile iron is much less

brittle than gray iron and is suitable for casting parts for internal combustion engines,

pipes, valve bodies, and other parts of machines.

6. duralumin – alloys of Al + Cu + Mg + Mn + Si – very durable, lightweight, cured,

used in aerospace structures, vehicles bodies, and in many different industries

7. gray cast iron is a cast alloy of iron and coal (about 2% C) and small amounts of

silicon (Si), phosphorus (P), manganese (Mn), nickel (Ni). Thanks to slow cooling, the

excess carbon in the solidifying alloy is released in the form of graphite flakes.

8. gray pig iron – created during slow cooling, as a result of which excess carbon is

released in the form of small flakes or graphite rosettes.

9. malleable iron is cast iron alloy with carbon (more than 2% C). After casting solidifies

as white iron, but as a result of prolonged annealing the cast gains malleability and

workability (excess of carbon is released in the form of “flakes”, (also known as

carbon filaments). Malleable cast iron is used for pipe connectors, brake drums,

exhaust pipes.

10. monel alloy – alloy of Ni + Cu + Fe + Mn – ductile, durable, resistant to corrosion and

aggressive chemical agents; used for machine parts and systems exposed to aggressive

agents.

11. silumin – Al + Si alloys (containing 4-13% Si) or Al + Mg or Al + Cu - are used in

internal combustion engines pistons, engine head castings and other machinery parts,

marine fittings, tableware gallantry,

12. special steels - most are alloy steels for special applications: stainless steel (12-14%

Cr), acid-resistant (17-20% Cr + 8-14% Ni), heat-withstanding and heat-resistant (Cr

+ Ni + Mo + W), for magnets, for transformer and generator plates (Si).

13. steel - an alloy of iron and carbon, machined and heat treatable with a carbon content

not exceeding overall 2%

14. structural steels - contain up to 0.5% carbon (sometimes even up to 0.9%) and are used

for sheets, plates and sections, load-bearing elements of building structures, many

parts of machines and other technical devices, sometimes heavily loaded, such as

shafts, springs, bearings. Some types are used for heat and thermo-chemical treatment

(carburizing, nitriding, tempering, hardening).

15. tool steels - contain up to 1.3% of carbon as well as alloying elements (W, Cr, V, Mn,

Ni, Mo). They are used for making tools, heavily loaded parts of machines, measuring

instruments. They are characterized by high hardness after hardening, resistance to

abrasion and impact, and resistance to elevated temperature.

16. white cast iron is produced by rapid cooling of the iron alloy with carbon and a

slightly higher content of manganese. Due to the exceptional hardness sometimes a

“whitened layer” is applied in the casting of gray iron in the places which should be

firm and resistant to abrasion (for example, road rollers).

17. white pig iron – created during fast cooling, as a result of which the carbon doesn’t

have time to separate and remains in a supercooled, homogeneous solution, binding

with the iron into the hard structure of cementite (Fe3C);

Description of contents: Lecture is related to the basic materials used in engineering. There are discussed

material properties and ways of obtaining them for cast iron, steel and non-ferrous metals.

Discussed is the history of the production of steel (Bessemer's pear) and modern techniques in

this field (fig. 5)

Fig. 5 Blast furnace

Steel type are discussed and defined. For cast iron are given the following characteristics:

1) ease of casting of complex shapes

2) possibility of reducing metal cutting to a minimum and good machinability,

3) good strength (similar to low or medium-carbon steel),

4) high capacity to dampen vibrations,

5) high resistance to abrasion,

6) low thermal expansion (features 5 and 6 led to widespread use of cast iron in the

automotive industry for cylinders, pistons, sliding rings),

7) low cost of manufacture.

During lecture are explained differences between cast steel and cast iron (shown in table 1)

Table 1. Comparison of features of cast steel and cast iron

Cast Steel Cast Iron

- carbon content up to 2,1 % - carbon content from 2,1% to 4%

- contains a eutectic - does not contain a eutectic

- large casting shrinkage - small casting shrinkage

- good castability - bad castability

There are discussed main metal materials as:

• copper (Cu), which is used primarily for electrical wiring (due to the low resistivity),

for manufacture of chemical apparatus and equipment for the food industry, for

roofing, making gutters, and the production of electroplating coating

• copper alloys, bronzes (e.g. aluminium bronzes, beryllium bronzes, silicon bronzes,

manganese bronzes), brass

• aluminium (Al) - which is difficult to cast, it is ductile and machinable (though with

some difficulty due to the accumulation of hardened layers of Al on the edge of the

tool). It is used for heat exchangers, vessels, drums, beverage cans, tubes, foils (for

packaging food products, and capacitors), the electrical wires, cladding for buildings,

sections.

• aluminium alloys duralumin and silumin

• nickel (Ni) – which is highly resistant to chemically aggressive environmental

influences: the atmosphere, sea water, and organic acids; it is used to construct the

apparatus in the chemical and food industries and in the galvanic-technics to make

protective and decorative coatings,


1. Ecological aspect of the production of ferro-alloys, aluminium, copper alloys

2. Titanium alloys and their applications in technology

3. Development of steel production techniques - continuous casting of steel lines

Lecture no. 6 Other materials used in engineering Keywords:

1. Ceramics

2. Polymers

3. Composites

Basic definitions:

1. Ceramics - a wide-ranging group of materials whose ingredients are clays, sand and

felspar.

2. Polymers are large organic molecules with a molecular weight from 104 to 106 g/mol.

3. duroplasts - thermo- and chemosetting plastomers - under the action of heat or

chemical agents irreversibly harden and keep the shape given to them, and reheating

causes chemical decomposition of the plastic, characterized by cross-linked structure,

4. elastomers (vulcanizing plastics) - characterized by a change in the cross-linked chain

structure during processing because the atoms of additives (such as sulphur) form

transverse bridges binding the neighbouring chains – for ex. rubber

5. thermosoftening plastomers (thermoplastic) - soften whenever heated and can be

easily shaped when hot, while after cooling, they harden and retain the shape given to

them, are characterized by a straight chain structure,

6. composite material (or composite) – material with a heterogeneous structure,

consisting of 2 or more components with different properties.


Lecture is related to materials used in engineering other then metal. Three main groups

are discussed: ceramics, polymers and composites. At the beginning ceramics material are

described and divided into: glass, clay products, refractories, abrasives, cements and advanced

ceramics like cermetals for turbine blades. The main features of ceramics are given:

• high hardness and brittleness

• electrical and thermal insulation,

• resistance to the environment

• considerable resistance to corrosion

• poor technological properties – limited machining abilities

• mechanical strength does not change with increasing temperature up to 1800°C

(silicon carbide)

• excellent resistance to abrasion - sander

• very good chemical resistance, even at high temperatures

Next group are polymers which are lightweight, non-conducting of the electric current

running through a material, characterized by resistance to corrosion, but are not very strong,

especially at high temperature (from 100°C). During lecture are presented some issues of

history of artificial polymers which began in 1862 – by Alexander Parkes of Birmingham

which showed everyday objects madeof material not previously known. This material, the

inventor received from the combination of nitrocellulose, camphor and alcohol. Next main

types of polymers are given with their appliance:

• polyethylene used for packaging foil, bottles, buckets, bowls, canisters, insulation,

bags, pipes, fittings; softening temperature: 150°C

• polypropylene used for packaging, tanks, parts for electrical and electronic equipment,

toys, casing; softening temp: 165°C

• polyamide used for tanks for fuel oil and gasoline, synthetic fibers, pipes, valves,

gears; softening temp: 165 - 265°C

• polyurethane used for machinery parts, paints, sealants, insulation, leather, products

made of foam

• polyacetal resin used for parts of pumps, springs, bearings, gears, screws, nuts, valves

• acrylic glass (poly-methyl methacrylate) used for windows, advertising boards, sinks,

lenses, goggles

• polystyrene used for packaging of food, housing, buckets, in the form of foam:

acoustic and thermal insulation, pots

• polyvinyl chloride used for facade cladding, pipes, floor coverings, foils, packaging

materials, rollers, pumps, gaskets, hoses, leather

• polyester used for storage tanks, large containers, boat hulls, foils, road signs, bolts,

rollers, chains, artificial fibers

At the end there are discussed composites which main general issues are:

• superior stiffness and durability parameters,

• excellent mechanical properties,

• low specific gravity,

• creation of a material with specified properties.

Composites are divided into:

• particles (large or with secretions)

• reinforced fiber (continuous or discontinuous)

• structural (laminates or layers)

Currently, the most important from the point of view of high technology are composites

reinforced with fibers. Fiber structure provides high rigidity and strength, which is many

times greater than the corresponding characteristics of the material in bulk form (e.g. tensile

strength of steel is typically 0.2-0.7 GPa, while the strength of thin steel fibers is about 4

GPa). There are also given and discussed most disadvantages of composites:

• complex manufacturing and machining

• difficult to assemble components (composite cannot be welded or sealed)

• general composite unrepairability

• minimal toughness and usually occurring brittleness

• the relatively high price

During lecture are also given and discussed sample composites of everyday use, such as

concrete or plywood.


1. The principles of the leading material (stone, bronze, iron, steel age),

2. The role of composites in everyday life.

3. Nanocomposites and their application

Lecture no. 7 Metalworking, forging and its main features Keywords:

1. Metalworking

2. Forging

3. Plastic deformation

Basic definitions:

1. Forging – a type of metalworking in which the shape of the worked on material is

altered by impact or pressure from tools, with one, on the top usually moving, and the

second (usually on the bottom) is stationary. The method of forging depends on the

design of the tools used. Forging is also called the material being forged (final product

of forging procedure).


Lecture is related to the metalworking of materials, which aims at changing the shape

and properties of the material without changing the volume. For plastic deformation to occur,

the stresses caused by external forces (compressive, tensile, bending, twisting) must exceed a

certain value called the yield strength/elastic limit (Re). The Re for structural steels is 1000-

1500 MPa, but for ex. steel for piano wire is able to withstand stress up to 5000 MPa.

Metalworking may be cold or hot, what is connected with the ability of materials to undergo

plastic deformation at a temperature lower than the material’s recrystallization temperature.

Main advantages of metalworking are discussed:

• material saving,

• labour saving,

• tool saving,

• higher quality of the material and improving its mechanical properties

• the ability to create complex shapes, which in other technologies is difficult or

impossible to achieve

There are discussed differences between open-die forging, semi-open-die forging, closed-die

forging (fig. 6 and table 2).

Fig. 6 Types of forging (from left: open-die forging, semi-open-die forging, closed-die

forging)

Table 2. Comparison of features of forging types

Main hammers for forging are shown, described and discussed (fig. 7). Typical structure

of die is given, which is a tool consisting of two parts, in which “negatives” of the external

shape of the product are reproduced. Closed forging die components are: bottom and top die,

hammer ram, bottom die mount, wedges fastening the dies, inlets fixing the position of the

dies, anvil.

Fig. 7 Types of hammers (from left: Steam-air hammer, Counter hammer, Board hammer,

Belted hammer, Compressor hammer, Lever hammer)

At the end there are discussed special ways of forging as:

• sectional dies reducing the strength of forging

• Marciniak’s oscillating die reduces the strength of pressing

• TR (Tadeusz Rut) forging method

TR forging method is given as an example of an innovative method which involves the use of

an articulated system of conversion of the press pressure to forces which automatically clamp

the rod (workpiece) and the forces shaping the forging. Simultaneous upsetting, bending and

cranking gives advantages: material saving by decreased labour intensity and

higher quality of the product (for ex. proper course of the fibers). This method gives also the

ability to forge crankshafts for large presses with relatively low pressures.


1. Forging methods.

2. The effect of metal forming (plastic deformation) on the mechanical properties of

metals.

3. Technological excess of materials in forgings.

Lecture no. 8 Other metalworking methods Keywords:

1. Rolling

2. Extrusion

3. Drawing

4. Stamping

5. Spinning

Basic definitions:

1. Brandishing is an operation which results in the increased diameter of the hole cut in

the bottom of the previously performed metal stampings, followed by eversion of the

collar around the hole. In this way, you can also get a larger volume of the cylindrical

part of the stamping.

2. Crimping is the reduction of the lateral dimensions of the stamping or pipes in a

section of its length, often - in the final stretch. In this way, a bottle shape is created

(in cylinders for compressed gases, ammo shells, flared end of the hydraulic pipes,

etc.)

3. Extrusion - the technological process of extrusion based on putting pressure on the

material through a stamp.

4. Rolling - type of metalworking consisting of forming a deformation in metals and their

alloys as a result of pressure exerted by the rotating rollers or moving the jaw, as a

result of rolling.

5. Spinning is the shaping of a rotating disc sheet or other semi-product by the local

pressure of the tool in the form of a disc, roller, or presser sliding over the surface of

the plate.

6. Stamping is an operation in which the input materials are sheets, plates or foils -

objects of small thickness compared to other dimensions.

7. Stretching is the enhancing of the depth of stampings by reducing the thickness of the

sidewall, during which the inner diameter of the stamping decreases slightly.

Description of contents: Lecture is related to the basic methods of metalworking for block forming as: rolling,

stamping, drawing, extrusion. There are also discussed sheet metalworking and cutting.

Rolling is the deformation of the material between two driven rotating rollers or discs

which could be made in 2-high (duo), 3-high (trio), 4-high (quatro) or more systems.

Fig. 8 Plate rolling 2-high (duo)

On the lecture the principles of rolling is presented: linear velocity: v1 < v2 [m/s], change in

volume: Ủ1 = Ủ2 [m3/s]. The differences between methods of rolling are discussed, for ex. in

4-high (quatro) when rolling the material it is deformed between rollers of small diameter

which allows for achieving a high pressure for deformation (the ratio of force to the contact

surface), and the work rolls are stiffened by pressure from rigid resistance rolls of large

diameter (fig. 9).

Fig. 9 Plate rolling 4-high (quatro)

The main procedures for products obtained from rolling are discussed:

• slabs - thick and thin sheet metal in forms (sheets of tapes and ribbons),

• slabs of a square cross-section - large profiles, rods and pipes and train tracks or billets

destined to be rolled into medium or small profiles and bars, tubes and wire rods and

hoops,

• sheet bars - thick slabs for rolling sheet metal into sheet form,

• wagon wheels, wheel rims, gears (fig. 10), elements with screw threads, beads, and

semi-finished products for forging in the form of rods of variable cross section,

• manufactures from metal powders, including bi- or tri-metallic tapes

Fig. 10 Principles of rolling of gear wheels

Procedures of extrusion (fig. 11) are discussed and explained (plasticized material flows out

in the same direction as the stamp by an appropriately shaped calibration hole in the die

(concurrent extrusion) or squeezes through the gap between the stamp and the die shape

(countercurrent extrusion, cavity). Main advantages of extrusion are explained which are:

• high dimensional accuracy and surface smoothness

• high strength properties, especially after cold extrusion

Fig. 11 Principles of extrusion

As a next metalworking procedure drawing is defined as a way of metalworking done

predominantly in the cold involving dragging a charged material through a die with

die

stamp

dimensions smaller than the cross-sectional dimension of the material. As a result of

deformation, the shape and cross-sectional dimensions of the material change and it increases

in length. Products obtained here have a high dimensional accuracy and a clean surface;

strength and hardness are also increased. By drawing there are obtained: wire, pipes, strings.

Fig. 11 Principles of drawing

Next, stamping operation is explained where the output materials (products) are thin-walled

objects with an unwindable surface (ones which can not stretch out on the straight plane),

called stampings (fig. 12).

Fig. 12 Principles of stamping of sheet metal

Spinning is discussed, where the tool presses the plate to the spinning stencil sheet with

the plate and deforms it, gradually giving it the shape of the stencil. Sheet thickness in this

operation does not change. This way you can get shapes difficult or impossible to obtain by

other techniques. On the other hand is given rotary compression which is similar to spinning,

but the difference is that the pressure of the tool causes a large thinning of the walls of the

shaped article due to their rotating rolling. These operations are performed on machines called

spinners. A characteristic feature of the objects obtained by the rotary compression operations

is that their bottoms are much thicker than the side walls.

Forces used in cutting and blanking are discussed – where it’s required to separate the

material depends on the size of the cross-sectional area S and the shear strength of the

material to shear Rt. In practice, strength 30% higher is used, which results from the need to

overcome friction between the material and tool. Some goals of cutting and blanking are

discussed as:

• division of input material, in the form of sheets, plates, profiles, and tubes, into smaller

fragments (cutting);

• obtaining the output material (product) of the desired shape (blanking of sheet metal or

plate);

• separation of material from the rest of the article without total loss of cohesion

(incision).


1. Multi-stage drawing machine

2. Explosive stamping

3. Cutting and blanking methods

Lecture no. 9 Thermo and chemical treatment Keywords:

1. Quenching

Basic definitions:

1. Annealing - operation of heat treatment consisting of heating steel to a certain

temperature, maintaining this temperature, and cooling in order to obtain the structure

close to the equilibrium state.

2. Austenite, also known as gamma phase iron (γ-Fe), is a metallic, non-magnetic

allotrope of iron or a solid solution of iron, exists above the critical eutectoid

temperature of 730 °C

3. Heat treatment - a technological procedure, or a combination of several procedures,

intended to induce the desired structural changes influencing the mechanical, physical,

(but not chemical) properties of materials.

4. Tempering procedure which consists of heating the previously quenched steel to a

temperature below the eutectoid transformation temperature (austenite to pearlite) and

cooling to the temperature of the surroundings.


Lecture is related to heat treatment and thermo-chemical treatment. There are discussed

main goals of heat treating:

• increase in hardness and for ex. resistance to stretching

• decrease in hardness and improved ductility

• improvement in technological properties

• change in other properties by changing the structure

The scheme of heat treating procedures is presented:

1. Heating – constantly or gradually increasing the temperature of the heat treated

workpiece,

2. Maintaining temperature – keeping the heat treated workpiece at the target or

intermediate temperature,

3. Cooling – constantly or gradually decreasing the temperature of the workpiece.

The main features of quenching are discussed as:

• temperature of warming - above the specified temperature of austenite, around 800 -

1000°C,

• maintaining temperature and then rapidly cooling in water, oil, or polymer solutions,

• speed of cooling - some high-alloy steels quench during cooling in air (these are

martensitic steels, commonly referred to as self-quenching steels),

• mandatory operations made after quenching of steel - tempering operations

(unstressing)

There are also discussed defects after quenching for ex.:

• insufficient hardness (underheated, low cooling rate)

• surface carbonizing and oxidation (oxidizing environment)

• so called "soft spots"

• excessive brittleness (overheating)

• cracks in workpiece (quenching stresses)

There are discussed tempering type and their applications:

• Low tempering is carried out in the temperature range of 150-250°C in order to

remove quenching stresses, while maintaining the high hardness and wear resistance.

Used primarily for tool steels.

• Medium tempering is carried out in the temperature range of 250-500°C in order to

obtain the steel high strength and elasticity. Hardness is significantly reduced. Used

for springs, dies, engine parts, cars, etc.

• High tempering is carried out in the temperature range above 500°C and below Ac1. –

possibly the highest impact strength of steel - almost complete removal of the stress

generated during quenching. High tempering is applied to the majority of structural

steels.

There are discussed annealing type and their applications:

• Solution annealing - heating the steel to a temperature of 1050 - 1200°C, maintaining

this temperature range for a long time, and then cooling. Time approximately 12-15 h.

The purpose of this operation, which is mainly used for steel ingots, is to reduce the

heterogeneity of their chemical composition, due to microsegregation.

• Stress relief annealing consists of heating steel to a temperature below the

transformation temperature of pearlite to austenite - Ac1, maintaining this

temperature, and subsequent slow cooling of it together with the furnace,

• Normalizing annealing, which consists of: steel heated to a temperature of

transformation of ferrite into austenite, maintaining this temperature, and next cooling

in still air. This operation is designed to obtain a homogeneous fine-grained structure,

thereby improving the mechanical properties of steel. It is used for non-alloy

construction steels and cast steel - often before further heat treatment - in order to

unify the structure.

• Full annealing, used for alloy steels, consists of heating steel, maintaining the

temperature, and next very slow cooling, for ex. in a furnace, in the temperature range

between apprx. 1200 -700oC. Further cooling can take place in the air.

• Spheroidizing annealing, also called softening, consists of: heating steel to a

temperature close to Ac1 (aust-pearl), maintaining this temperature, very slow cooling

to a temperature around 600°C and then any type of cooling to the temperature of the

surroundings. As a result of spheroidizing annealing operations the structure of steel

consists of ball cementite, so called sferoidite, in a ferrite matrix. This structure

provides a low hardness, good machinability, and good susceptibility to plastic

deformation during cold working.

• Recrystallizing annealing which consists of: heating the metal, previously plastically

deformed during cold work, to a temperature above the recrystallization temperature,

maintaining this temperature and cooling of at any speed. Recrystallizing annealing,

often used as an intermediate during rolling or cold drawing of metal, removes

crushing strengthening (umocnienie zgniotowe), resulting in reduced hardness and

strength, and increased plastic properties of metal, which enables further cold working

There are also discussed examples of thermo-chemical treatment procedures:

• Carburizing is the process which involves diffusion hardening of the top layer of the

material with carbon during heating (typically 900 ÷ 950°C) in a medium containing

carbon in atomic form. Layer thickness (0.2 ÷ 2mm) depends mainly on the processing

time and the carbon potential of the medium atmosphere. The purpose of hardening

the top layer of the alloy with carbon is to increase hardness (hardness of the quenched

material depends on the amount of carbon which it contains), increase resistance to

fatigue and abrasive wear while maintaining the flexibility of the core. Carburizing

can be carried out in these mediums: solid, liquid, gas, vacuum, plasma, or in a

fluidized bed.

• Nitriding is a type of thermo-chemical treatment, which consists of diffusion

hardening of the surface layer of material with nitrogen. Thickness of the layers

obtained generally does not exceed 0.5 mm and its hardness is close to 1000HV.

Nitrides formed in the diffusion layer increase the hardness of the material and its

resistance to wear. Nitriding is a final treatment, this means that after it quenching or

tempering treatments are not applied. After nitriding steel has better mechanical

properties than after carburizing.

• Nitrocarburizing is a process which is a modification of carburizing. It consists of

simultaneous hardening of the surface layer with carbon and nitrogen atoms. The

temperature at which this process is carried out is lower than in the case of carburizing

and varies from 775 to 900°C. The layer obtained in this way usually has a thickness

of 0.05 ÷ 0.8 mm and the process is used to increase the wear resistance of machine

parts

• Aluminizing is a process of saturating the top layer of steel products with aluminium.

It allows for obtaining a surface layer resistant to high temperature and oxidation.

Aluminizing is carried out in aluminium powder, aluminium oxide, and ammonium

chloride at temperatures around 900°C for 24 h, resulting in a layer about 1 mm thick,

containing about 50% Al. Aluminizing is used in the production of elements highly

vulnerable to corrosion.


1. Surface treatments methods (induction, flame, bath, laser)

2. Austenite transformation

3. Heat treatment of non-ferrous alloys

Lecture no. 10 Metal casting Keywords:

1. Casting is a technique of manufacturing metal objects with a required shape and

dimensions by filling properly prepared casting molds with molten metal

Basic definitions:

1. Casting is a technique of manufacturing metal objects with a required shape and

dimensions by filling properly prepared casting molds with molten metal


Lecture is related to the basic concept and methods of metal casting. There are discussed

main features, considered during choosing material for casting as:

• fluidity - the ability to fill the form and reproduce the exact shape

• solidification shrinkage - percent reduction in size of the casting compared to the

corresponding dimensions of the pattern

• tendency to form shrinkage cavities - due to a decrease in the volume of metal during

cooling in the liquid state and during solidification

• tendency to create internal stresses in castings - caused by uneven abilities of free

shrinking of metal inside the forms

For casting are used mainly (in parentheses are the applied temperature range):

• Silumin (700°C –730°C)

• Tin and phosphate bronzes (1050°C –1150°C)

• Carbon cast steel (1420°C –1470°C)

• High-alloy cast steel (1440°C –1480°C)

• Gray cast iron (1250°C –1350°C)

The general procedure of casting is shown and described (fig 12.)

Fig. 13 General procedure of casting

The decisions when constructing models are discussed which regards:

• position of division planes of the pattern

• size and arrangement of excess material necessary because of the shrinkage of the

solidifying metal;

• size and arrangement of the so-called casting slope - the convergence of the vertical

walls of the model (and casting) - usually around 1%;

• size and arrangement of excess material on subsequent mechanical treatment of

selected parts of the casting (in sand molds, depending on casting size: 2-20 mm);

• size and arrangement of risers compensating for the loss in volume of the metal during

solidification (shrinkage cavity).

Main casting method are distinguish the and discussed:

• Sand casting

• Permanent (metal) mold casting

• Investment (lost wax) casting

• Die - pressure casting (used especially for aluminium alloy products used especially

for aluminium alloy products)

• Centrifugal casting (fig. 14)

Fig. 14 Principles of centrifugal casting


1. Advantages of gravity permanent casting

2. Casting in metal molds

3. Investment (lost wax) casting

Lecture no. 11 Material removal processes - chip-forming machining Keywords:

1. turning

2. drilling

3. broaching

4. milling

5. threading

Basic definitions:

1. Turning process consists of collecting unnecessary material in the form of swarf,

removed from the surface (external or internal) of a rotating workpiece.

2. Machining centers – CNC (Computerized Numerical Control) machining units capable

of many different chip-forming machining operations and mass production of objects

with complex shapes and repeatable dimensions.

3. Shaping involves removing layers of material excess from a flat surface or on making

linear grooves with different cross sectional shapes (e.g. rectangular, V-shaped, T-

shaped)

4. Sawing is an operation of dividing the material with a multi-edged tool called a saw.

This operation can be performed manually or by a machine. Working part of the saw

mold

is called a blade and the groove in the material, made during sawing with the blade, is

called the saw cut

5. Drilling is an operation conducted with the use of drill bits, aimed at making an open

hole in the material (through the entire thickness of the material) or a blind hole (with

a length less than the thickness of the material).

6. Threading is cutting screw grooves manually or by a machine on cylinders (external

threads) and in holes (internal threads).


Lecture is related to the removal processes. There are discussed: range of application of

tool materials, classification and designation of chip shapes according to PN-ISO 3685

(Ribbon, Tubular, Spiral, Open screw, Closed screw, Bow, Element and Needle chips).

Turning process are discussed (fig. 15) and different types of turning operations for example

boring (fig. 16).

Fig. 15 Principles of turning

Fig. 16 Principles of boring

Constriction of lathe (fig. 17) is discussed and its different types: center lathes, disc lathe,

carousel lathe, multi-knife lathe, turret lathes, semi-automatic and automatic lathes

1 - headstock, 2 - feed selector, 3 - tool post, 4 - apron, 5 - tailstock assembly, 6 - ways, 7, 8 -

bed base, 9 - chip pan, 10 - lead screw (the pinion), 11 - the rack, 12 - feed rod

Fig. 17 Center lathe

Milling (fig. 18) is defined as a material removal machining with a rotating multi-edged

cutting tool called a milling cutter. A characteristic feature of milling is the rotary motion of

the cutting tool (perpendicular to the axis of the feed) with simultaneous sliding movement of

the workpiece relative to the cutter or the cutter relative to the workpiece.

Fig. 18 Plain milling – down cut

engine

Shaping procedures (fig 19) and the application are discussed. There are also discussed

shaping with simple knife which is used for cutting of uneven depth, and shaping with bent

knife, cutting with constant depth.

Fig. 19 The principles of shaping

Next broaching and pushing is discussed, which are chip-forming machining processes

commonly used to form differently shaped holes, such as square shaped, with a keyway,

grooved (fig. 20) or multi-grooved (for splined connections), and less frequently - for shaping

the external surface.

Fig. 20 The principles of grooves broaching

There are discussed sawing issues like the thickness of the blade as the saw teeth are bent to

the side - the aim of this is to reduce the friction of the material on the sides of the blade.

There are discussed drilling types (spot drilling, final drilling reaming, roller drilling, tapered

drilling) and construction of different tools for drilling.

inclined surface shaping

groove shaping cutting

keyway slotting


1. Dependence of the hardness of the basic tool materials on temperature

2. Performance of modern machining processes

3. Computer Numerical Controlled CNC machines and their applications

Lecture no. 12 Abrasive, erosive and concentrated energy beam machining Keywords:

1. Grinding

2. Honing

3. Electropolishing

4. Laser beam machining

5. Plasma cutting

Basic definitions:

1. Grinding – material removal process in which waste is created not as chips but as dust

– particles of the processed material and the ground material of the grinding wheel –

of not determined in advance shapes and sizes.

2. Electropolishing is an electrochemical process that removes material from a metallic

workpiece.

Description of contents: Lecture is dedicated to abrasive, erosive and concentrated energy beam machining.

Abrasive materials are discussed such as natural diamond, aluminium oxide, quartz and

synthetic: synthetic diamond, regular boron nitride, silicon carbide, elektrokorund. Griding is

discussed and its layer thickness from a few millimeters up to 0,005 mm during final grinding.

Dressing the grinding wheel is aimed at restoring its ability to cut while keeping a certain

shape of the work surface. For dressing of grinding wheels we use diamond dressers or

carborund discs. As an example of a variation of the grinding technology is machining by

honing: smoothing is presented (fig. 21).

Fig. 21 The principles of honing

The abrasive blasting is used to remove oxide layers after heat treatment or

metalworking is abrasive blasting which uses silicon carbide SiC or electrorund Al2O3 with

gas or liquid under high speed - up to 300 m/s (fig. 22)

Fig. 22 The principles of abrasive blasting

Electropolishing it is used to polish, passivate, and deburr metal parts. It is often described as

the reverse of electroplating. Advantages of electrochemical polishing:

• allows for excellent anti-corrosive properties,

• cheaper than mechanical polishing,

1- honed element 2- honed surface 3- honing stones

• is more aesthetic – shine and uniformity of color similar to the surface of polished

chrome,

• facilitates and improves the efficiency of cleaning and helps to clean the objects

subjected to polishing by shortening the washing time to 50% (micro-grooves and

micro-peaks of the unpolished surface are the perfect anchor for the deposits of salt,

dirt, bacteria, fungi, molds, etc.).

Plasma cutting is discussed, where stream speed close to the speed of sound. Arc ignition in

plasma cutting is done by current pulse of high intensity. The plasma is sufficiently hot to

melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut.

Plasma cutting can be use to cut all metals, because they are electrically conductive.

Fig. 23 The principles of plasma machining 7

Laser beam machining (LBM) is discussed as en example of unconventional machining

process in which a beam of highly coherent light called a laser is directed towards the work

piece for machining. Since the rays of a laser beam are monochromatic and parallel it can be

focused to a very small diameter and can produce energy as high as 100 MW of energy for a

square millimeter of area.

7 Hogan J.A. and Lewis J.B., "Plasma Processes of Cutting and Welding". (Project Report by Bethlehem Steel Corporation in cooperation with U.S. Maritime Administration 1976) http://www.sppusa.com/reference/white_paper/wp_pc.html.

Fig. 24 The principles of Laser beam machining

The main features of laser beam machining are:

• precise machining

• can be used for almost all materials: metals, composites, plastics, ceramics, paper, etc.

does not require electrical conductivity,

• good quality of edges

• rapid process

• a small zone of thermal influence


1. The energy efficiency of different machining processes

2. Abrasives and abrasive materials

3. Electrical Discharge Machining

Lecture no. 13 Joints and connections - inseparable Keywords:

1. riveted joint

2. soldered joint

3. adhering joint

4. welded joint

5. wrapped joint

Basic definitions:

1. Welding - heating the both connected materials to melting state and then hardening

with or without the addition of a filler material

2. Weld face - external surface of the weld on the side of its deposition

3. Weld root - external surface opposite to the face, where the weld begins at the

intersection of the joined plates, occurs in one-sided welds

4. Weld bead - a part or whole weld deposited in a single pass of the weld filler material

5. Weld layer - one or more weld beads deposited in a single layer with respect to the

root layer


Lecture is related to the basic inseparable connections used in engineering. A riveted

connection (fig. 25) is characterized by a high preload, a significant pliancy, and a relatively

low temperature during technical process. In this connection there are no residual stresses,

which allows for the combination of different materials. Disadvantages of riveted connection:

inseparability, weakening of combined elements by drilling holes, construction difficulties,

difficulties in obtaining sealing and workload. Types of rivet heads are discussed (fig. 26):

round, round-top countersunk, flat-top countersunk, pan.

Fig. 25 The principles of riveted connection

Fig. 26 Types of rivet heads a) round, b) round-top countersunk, c) flat-top countersunk, d)

pan

Welding connection is discussed. As a result of welding a connection is formed, in which we

can distinguish three areas:

1. the weld or fusion zone (melted metal with the structure of a casting)

2. heat-affected zone (combined material with an altered structure due to thermal effects)

3. base material also known as native (with a structure unaffected by the welding process).

Fig. 27 The principles of welded connection

The width and properties of the heat-affected zone depend on the type of base material

and filler material, the dimensions (particularly thickness) or the welded workpiece, as well as

the welding conditions. Sometimes the heterogeneity of the structure and mechanical

properties is so great that the created connection in the raw state after welding is unsuitable

for use, therefore heat treatment is required. Especially dangerous – during variable and

impact loads – is a significant increase in hardness in the heat-affected zone resulting in the

so-called structural notch. In addition, thermal processes and changes in the structure are the

cause of the appearance of residual stresses, and sometimes significantly worsen the

performance properties of the connection, and even lead to the formation of cracks.

During electric welding the heat source may be an electric arc (arc welding), resistance

(electric resistance welding), electron beam energy (electron beam welding), or light energy

(laser welding).

Arc welding [Spawanie łukowe] uses an electric arc between an electrode and the base

material to melt the metals at the welding point. A consumable electrode will melt and thus

give the filler material; if it is non-consumable it is necessary to add a filler. Welding with a

consumable electrode can be done manually, by submerged arc welding (SAW), by gas metal

arc welding (GMAW) with an inactive shielding gas protecting the weld site (Metal Inert Gas

MIG method), or with an active gas (Metal Active Gas MAG method). During welding with

non-consumable electrodes we use an inert shielding gas (Tungsten Inert Gas TIG method) or

an ionized gas (plasma welding).

Arc welding is discussed and its advantages:

• possibility to use the same equipment for welding of steel, cast steel, cast iron, and

non-ferrous metals,

• ability to create welds in all positions and in areas difficult to access,

• lower requirements regarding the preparation of the edges of joined elements.

There where given also arc welding disadvantages:

• low productivity, dependence of the weld quality on the welder’s qualifications and

thoroughness

• difficult working conditions for the welder (toxic gas, blinding effect from the arc).

Shielded Metal Arc Welding SMAW is discussed (fig. 28) where the electrode is coated in a

flux (chemical cleaning agent) which during welding disintegrates giving off vapors that serve

as a shielding gas and provide a layer of slag, both of which protect the weld area from

atmospheric contamination.

Fig. 28 The principles of Shielded Metal Arc Welding SMAW

Preparation of elements for welding is discussed where are included activities: ·

• chamfering

• cleaning the edges,

• assembling connectors,

• tacking the edges of the sheets.

The next welding method is electroslag welding ESW which is melting the wire

electrode in liquid slag. Connecting the elements is performed in an upright position or close

to it, and the weld is formed in a single pass from bottom to top. This welding method is

mainly used for connecting elements of large thicknesses (up to 2000 mm) in heavy

constructions made from carbon steel and low and medium-alloy steels.

Gas metal arc welding (GMAW) features include: ability to perform welds in all

positions, significant performance and possibility of mechanization of the process, and low

deformation and stress. This welding method is used for connecting carbon steels, but also

alloy, aluminium, and copper steels. Gas metal arc welding can be divided into MIG Metal

Inert Gas (in a shield of inert gases Ar, He) and MAG Metal Active Gas (in a shield of active

gas such as CO2 and other mixtures).

TIG - Tungsten Inert Gas (also known as GTAW – Gas Tungsten Arc Welding) is a

method with non-consumable tungsten electrode shielded by inert gases such as argon,

helium, or a mixture of them. It is most commonly used for welding aluminium alloys and

stainless steel, where uniformity of connection is critical.

Oxyfuel/gas welding a manual process in which the metal surfaces to be joined are

melted progressively by heat from a gas flame, with or without filler metal, and are caused to

flow together and solidify without the application of pressure to the parts being joined. The

most important source of heat for OFW is the oxyacetylene welding (OAW) torch.

Fig. 29 The principles of oxyacetylene welding (OAW)

Resistive spot welding (fig. 30), known as RSW is a process in which contacting metal

surfaces are joined by the heat obtained from resistance to electric current. Typically the

sheets are in the 0.5 to 3 mm thickness range. The process uses two shaped copper alloy

electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the

sheets together.

Fig. 30 The principles of oxyacetylene welding (OAW)

Soldering involves combining metals with a solder (filler) from a metal or alloy which

melts more easily than the metal that is to be combined. It’s different from welding because

connected material is not melted. There are two basic types of soldering:

• soft - melting point below 350 °C (originally used a tin-lead alloy);

• hard (brazing) - melting point of 600-1400 °C (solder from metals such as copper,

bronze, brass, nickel, silver).

Pressure connection (for long considered as a inseparable technology) is a connection in

which the immobilization of the parts is provided by the friction between their surfaces. In a

pressure connection the elements undergo deformation and the elastic forces of the materials

connected with this ensure adequate pressure. The rule of the shaft is bigger than the opening

in the hub.

Fig. 31 The principles of pressure connection


1. Upset Welding

2. Flash welding

3. Friction stir welding

4. Additional materials used in soldering and welding

Lecture no. 14 Joints and connections - separable Keywords:

1. Threads

2. Splines

3. Keys

4. Dowels

5. Pins

Basic definitions:

1. Separable connections can be joint and disjoint several times, and even repeatedly

assembled and disassembled using the same elements, so that every time you fit for

requirements.


Lecture is related to the basic separable - shape conections used in technology. A

characteristic of shape connections is that the connection of elements is due to the special

shape of their surface (threads, splines) or the use of connectors (keys, dowels, pins, wedges).

Shape connections can be direct (for ex. splined) or indirect (for ex. keyed, dowel, wedge,

clevis).

Wedge connections are indirect, separable connections, in which the connector is a

wedge (fig. 32). In wedge connections there must be self-stopping conditions. Wedge

connections can be one sided or double sided, symmetrical or asymmetrical.

Fig. 32 The principles of wedge connection

Dowel connections/joints (fig. 33) uses metal connectors (dowels), which prevent

movement of the elements relative to each other.

Fig. 33 The principles of dowel connection

Dowel connections can be divided onto:

• fixing, because of fixing one element relative to another without any possibility of

movement

• setting, where dowel is permanently determining the relative positions of parts of the

machine

• securing, where dowels protect machine elements from damage, because at the time of

overload the dowels are cut down

• motion dowel joints, where the dowel let to move connected objects, depends from the

type of the movement can be: sliding, tilting, rotating.

A keyway connection (keyed joint – fig. 34) is used to transfer torque from the shaft to

the mounted component for ex. gear, pulley, clutch disc (or vice versa). Keyed joints are

indirect connections in which the role of connector is done by the key which fits into a slot

(keyway) in the shaft or wheel or disc.

Fig. 34 The principles of keyed joint

Advantages of keyway connection are:

• simple design

• low cost of production

• easy assembly and disassembly

The main disadvantages of keyed joint:

• failure to establish a longitudinal wheel on shaft

• slot for the key weakens the shaft

• lack of good wheel alignment on the shaft

Splined connections are used, like keyed joints, for torque transmission and connecting shafts

with wheels and discs. We distinguish splined connections into:

• parallel (key with a rectangular outline) - fig. 35

• involutes (key with an involutes outline)

• serrations (key with a triangular outline)

Fig. 35 The principles of parallel splined connections

Fig. 36 The principles of involuted splined connections

Advantages of splined connections as compared to keyway connections:

• greater strength under loads that are variable and on impact

• more evenly distributed surface pressure on spline surface

• greater stiffness of the shaft

• easier installation and removal

• better alignment of the hub on the shaft

• better leading of the hub on the shaft in sliding connections

• smaller width of the hub

Clevis fasteners (fig. 37) are used in movement connections (swing or pivot), for ex. in

connecting the piston to the rod.

Fig. 37 The principles of clevis fastener

Fig. 38 Exact, simplified and symbolic threaded connection drawing,

An essential element of bolted joints is a connector, consisting of a nut and bolt. Twisting

together nuts and bolts creates a bolted joint. Bolted joints are divided into:

• indirect – machine parts are joined by a connector, the role of the nut can be fulfilled

by a threaded hole in one of the parts

• direct – the thread is made on the connected parts.

There are different types of cross-sectional shapes of thread discussed – known as thread

form:

• triangular (metric);

• symmetric trapezoidal;

• asymmetric trapezoidal;

• square;

• round


1. Ball screw threads

2. Spring connection

3. Standards in threads

Lecture no. 15 Basic mechanisms in engineering - Simple Machines Keywords:

1. Lever

2. Pulley

3. Inclined Plane

4. Screw

5. Transmissions

Basic definitions:

1. Mechanical advantage is the ratio of output force divided by input force. If the output

force is bigger than the input force, a machine has a mechanical advantage greater than

one.

2. Lever – is a rigid bar or plank that can rotate around a fixed point called a pivot, or

fulcrum.

3. Pulley is a wheel on an axle that is designed to support movement of a cable or belt

along its circumference. Pulleys are used in a variety of ways to lift loads, apply

forces, and to transmit power.

Description of contents: Lecture is related to the basic simple machines used in engineering. Simple machine is a

device that helps make work easier to perform by accomplishing one or more of the following

functions:

• transferring a force from one place to another,

• changing the direction of a force,

• increasing the magnitude of a force,

• increasing the distance or speed of a force.

Simple machine usually takes a small input force and increases the magnitude of the output

force, a mechanical advantage has been produced. A typical example of a simple machine is a

lever (fig. 39).

Fig. 39 Lever as a simple machine – main issues

The class of a lever (fig. 40) is determined by the location of the effort force and the load

relative to the fulcrum. Examples of classes of levers are

• 1st Class – Seesaw

• 2nd Class – Wheelbarrow

• 3rd Class – Rake

A first-class lever always changes the direction of force (i.e. a downward effort force on the

lever results in an upward movement of the resistance force). Second-class lever, the load is

located between the fulcrum and the effort force and it does not change the direction of force.

When the fulcrum is located closer to the load than to the effort force there is an increase in

force (mechanical advantage). With a third-class lever, the effort force is applied between the

fulcrum and the resistance force, that’s why it always produces a gain in speed and distance

and a decrease in force.

Fig. 40 Lever classes 1st, 2nd, 3rd Class

The next simple machine is wheel and axle, which consists of a large wheel rigidly

secured to a smaller wheel or shaft, called an axle.

Fig. 41 Wheel and Axle as a simple machine – main issues

Next simple machine is a friction gear, which is a group of one or more gears where the

motion of the gear is created by the friction of two surfaces. The two surfaces travel in a

rolling motion against one another when they come into contact with each other. There are

distinguished: direct friction gear and indirect friction gear. Advantages of direct friction gear:

lack of additional elements, simple structure, overload resistance. Cons of direct friction gear:

large slip which means low efficiency and lack of synchronization connection. For indirect

friction gear (for example belt transmission – fig. 42), main advantages are: simple structure,

possible power transmission over long distances, little sensitivity to inaccuracies and dumping

vibrations.

Fig. 42 Belt transmissions

Next gear transmission is discussed (fig. 43 and 44). Advantages of gear over other

mechanical developments are:

• stability of transmission

• high efficiency (up to 99% for a single gear)

• compact design

• reduced pressure on shafts and bearings

• operational reliability

There are also disadvantages of gear transmission:

• the higher cost (due to the high accuracy version)

• smaller overload resistance

• noise emissions

• the need for very large spreads

Fig. 43 Gear transmissions

Fig. 44 Gear transmissions – main issues

A pulley is discussed, which is a machine that consists of a grooved wheel that turns

freely in a frame called a block. A pulley can be used to simply change the direction of a force

or to gain a mechanical advantage, depending on how the pulley is arranged. A moveable

pulley rises and falls with the load that is being moved. A single moveable pulley creates a

mechanical advantage; however. The mechanical advantage of a moveable pulley is equal to

the number of ropes that support the moveable pulley.

The mechanical advantage of an inclined plane is equal to the length of the slope

divided by the height of the inclined plane. While the inclined plane produces a mechanical

advantage, it does so by increasing the distance through which the force must move. The

screw is also a modified version of the inclined plane - the threads of the screw can be

considered as a type of circular ramp (or inclined plane).


1. Types of transmission

2. Planetary Gear

3. Differential

Exercises

Exercise no. 1 Basic units used in engineering

Theoretical basis of exercise

The International System of Units – base and derived units.

Quantity Units Symbol

Length meter m

Mass kilogram kg

Time second s

Electric current ampere A

Temperature,

thermodynamic kelvin K

Amount of matter mole mol

Angle radian rad

Solid angle steradian sr

Luminous intensity candela cd

Area square meter m2

Volume cubic meter m3

Frequency Hertz, cycles per second Hz

Density kilogram per cubic meter kg/m2

Velocity meter/sec m/s

Angular velocity radian/sec 1/s

Acceleration meter/second squared m/s2

Angular acceleration radians per second square 1/s2

Volumetric flow rate cubic meter per second m3/s

Mass flow rate kg per second kg/s

Force Newton N

Surface Tension Newton per meter N/m

Pressure, stress Pascal N/m2

Dynamic viscosity Newton-second per square meter N*s/m2

Quantity Units Symbol

Work, energy joule, newton-meter, watt-second J, N-m,

W-s J

Power watt, joule per second W, J/s

Specific heat, gas constant joule per kilogram degree J/kg*K

Enthalpy joule per kilogram J/kg

Entropy joule per kilogram degree J/kg*K

Thermal conductivity watt per meter degree W/m*K

Electrical charge coulomb C

Electromotive force volt V

Electric field strength volt per meter V/m

Electric resistance ohm ohm

Electric Conductivity amperes per volt meter A/V*m

Electric capacitance farad F

Magnetic flux Weber Wb

Inductance henry H

Magnetic flux density tesla T

Content exercises / tasks

1. Transform velocity from km/h into m/s

2. Transform rotational velocity into angular velocity

3. Calculate the gravitational force

4. Transform between volume units

5. Calculate volume knowing density and the mass

6. Calculate torque

7. Calculate amount of work,

8. Calculate the required power of a machine

9. Calculate the cost of 1 MJ obtained from electric energy

10. Calculate the cost of 1 MJ obtained from gasoline

11. Calculate the cost of 1 MJ obtained from foodstuffs

12. Transform power from HP into kW

Methodology / instructions solutions the tasks

Transform given by the teacher data into engineering units expressed in SI standard.

Solution sample task

Calculate the power required for an electric motor to pump 20 kg of water up to ground

level from a borehole of depth 10 m in half a minute.


1. The role of units in the shaping engineering structures

2. Pros and cons of the different standards of measurement

Exercise no. 2 Friction in engineering


Friction results from relative motion between objects. Frictional forces are forces that

resist or oppose motion.

T = µN (1)

T - Sliding friction force

µ - Coefficient of friction

N - Normal force (N=G=mg)

When the block will hold.

θµθµθ

tan

cossin

<<

s

smgmg

N

T = fN/R (2)

T - Sliding friction force

f - Coefficient of friction

N - Normal force (N)

According to the law of conservation of energy, no energy is destroyed due to friction,

though it may be lost to the system of concern. Energy is transformed from other forms

into heat when an object is pushed along a surface, the energy converted to heat is given

by

E = µ ∫ RN . x dx (3)


1. Calculate the static frictional force of the block resting on a horizontal plane, knowing

the mass of the block and the coefficient of friction,

2. Calculate the power that the squeeze on both sides wooden block to prevent it from

slipping down, knowing its mass and the coefficient of friction between the walls and

the block

3. Calculate the minimum force, which must be applied to a block resting on an inclined

plane to move it up, when the mass of the block, angle of inclination and the

coefficient of friction is given

4. Calculate how many coils must be brought to the shaft to maximize the pitch and at

the same time that the thread is irreversible (self-locking), we know the length and

diameter of the shaft and the friction coefficient,

5. Calculate how much energy will be consumed by the work of friction in the bearings,

knowing the type of bearings, the friction coefficient, the diameter of the wheel axis

and the speed of the vehicle.

6. Calculate what force must act on the bullet to move it from its place when knowing

the mass and the coefficient of rolling friction

7. Calculate the force with which you need to act on the handles of a wheelbarrow to

move it out of place, the data is mass of the wheelbarrow and location of the center of

gravity of the wheelbarrow and coefficients of friction in the bearings and the wheel.

Methodology / instructions solutions for the tasks

Make calculations in order to obtain the value indicated by the teacher.


A 10 N force pushes down on a box that weighs 100 N. As the box is pushed

horizontally, the coefficient of sliding friction is 0.25. Determine the force of friction resisting

the motion. Also find F at the point of sliding?

Solution

T = µN = 0,25 x 110N = 27,5N


1. The role of friction in engineering

Exercise no. 3 Conservation of energy in engineering


The law of conservation of energy states that the total energy of an isolated system

cannot change—it is said to be conserved over time. Energy can be neither created nor

destroyed, but can change form.

Fig. 45 Conservation of energy practical example

Energy formulas:

Kinetic Energy KE = 1/2 m v2

Kinetic Energy KE = 1/2 I ω2

Potential Energy PE = mgh = Fwh


1. The potential energy of a 40-kg cannon ball is 14000 J. How high was the cannon ball

to have this much potential energy?

2. What percentage of energy is the work of friction consuming in the wheels of the

wagon if you know its mass, velocity, diameter of the wheel axles and the coefficient

of sliding friction in the wheel bearings. Friction between wheels and tracks and other

frictional resistance should be omitted.

3. How much it costs to heat 100 liters of water from 20 to 100 degrees Celsius, if we

know that the specific heat of water is 4.185 J / kg * dgC and kWh costs 50 cents.

4. How to design a safety brake for mechanical presses equipped with a flywheel, so that

it is able to stop the flywheel through one revolution. We know the density of the

metal from which the flywheel is made, its diameter, width, speed, friction coefficient

axis of the brake lining.




How to design a safety brake for a flywheel, so that it is able to stop the flywheel

through one whole turn. How high should be the force of the break?

Data:

ρ= 6800kg/m3 density of the material

Øs= 20cm diameter of axis

ØB= 120cm diameter of wheel

a= 20cm width of wheel

n= 30 turns/minute speed – which gives ω = 30*2Π/60s = 3,14s-1

µ=0,1 friction coefficient

radius way – turn which gives φ - 2Π

Solution.

Kinetic Energy of the flywheel

KE = 1/2 I ω2

The brake must produce friction, whose work consumes kinetic energy. So we need to put the

assumption that the work of friction is equal to the kinetic energy.

1/2 I ω2 = Mφ

M - friction torque is friction force times the arm – M=TØs/2

T – friction force - T = µN

I - moment of inertia for a roller rotating about its axis of symmetry I = mR2/2 = m (ØB/2)2/2

1/2 m (ØB/2)2/2 ω2 = µN φØs/2 /*2

mass of the disc must also be calculated m=V ρ

V ρ ØB2 ω2/8= µNØsφ

We are looking for the force N, knowing that volume is V= Π ØB2a

N= Π a ρ ØB4 ω2/(8µØsφ)

N= 3,14*0,2*6800*0,64*3,142/(8*0,1*0,1*2*3,14)= 108 613,3536 [N]


1. Where and how we can use the rule of conservation of energy

2. What other physical quantities are conserved

Exercise no. 4 Basic units used in engineering


An ideal machine would transfer all of the energy it receives to the load, but there is no

machine that works this efficiently. Some energy is always lost. Another way of saying this is

the amount of work put out by a machine is always less than the work put into a machine. No

lever or machine is perfect. The efficiency of a lever tells you how much of the energy you

gave to the machine was transferred to the load by the machine. Efficiency is a comparison of

the useful work provided by a machine or a system with the work supplied to the machine or

system. Efficiency is usually stated as a percentage.

Efficiency = yInputGrossEnerg

utEnergyOutpusefulNet )(

Pinp

Pout=η

Some energy is always lost as friction. So a machine can be made more efficient by reducing

the amount of friction it produces, which can be done by adding a lubricant, such as oil or

grease (see lecture 3). The efficiency of the entire system is calculated by multiplying the

efficiency of its individual elements (series connection).


1. Calculate the output power of the machine when at the start 10kW power is provided,

and the efficiency of the gear connected in series is respectively, 0.96 and 0.92.

2. What is the approximate efficiency of a petrol driven internal combustion engine?

3. Explain why an engine with an output of 500 W and an input of 480 W would be

impossible.

4. Calculate the angular velocity, torque and power of the working unit with the given

parameters of gear.




Calculate the angular velocity, torque and power of the working unit with the given

parameters. To the engine power 10 kW is provided, a small pulley runs at 300 revolutions

per minute.

1 - SE electric motor

2 - belt transmission

3 - gear drive

i g = z1/z2 ratio of gear drive

i bt = d1/d2 ratio of belt transmission

d1 – 20 cm diameter of the small pulley

d2 – 80 cm diameter of the small pulley

z1 – 30 number of teeth in small gear

z1 – 90 number of teeth in big gear

η bt – 87%

η g – 96%

Pinp

Pout=η

Power of the working unit (CR) is:

P(CR) = Pη btη g

P(CR) = 10 kW* 0,87*0,96 = 8,352 kW

Velocity of the working unit (CR) is:

ω(CR) = ω * i bt* i g

ω(CR) = 300 *2Π/60s* 1/4* 1/3 = 2,61(6) s-1

Torque of the working unit (CR)

M(CR) = ωP

M(CR) = 1-s62,2

W8352

M(CR) = 3187,79 Nm


1. How to increase the efficiency of machines?

2. Where efficiency matters most?

Exercise no. 5 Accumulation of energy in engineering


The accumulated energy of a rotating flywheel is its kinetic energy

2

2ωIE =

Where the I is the moment of inertia of a uniform cylinder, for instance, is

2

2mRE =

where m is the mass and R is the radius.

The accumulated energy can be in the mass of water, and is dependent on the pressure and

volume.

E= pV or E = mgh

The accumulated energy can be in the elastic elements

2sF

E∆=

for springs where F=-kx, x is a distance and k coefficient

2

2kxE =

The accumulated energy can be in twisted shaft

2Mϕ=E

where M is a torque, and φ is a angular way


1. Calculate the energy stored in the flywheel

2. Calculate the energy stored in the spring

3. Calculate the energy stored in the oil accumulator

4. Calculate the energy stored in the gas tank

5. Calculate the energy stored in the twisted shaft

Methodology / instructions solutions the tasks



Calculate the energy stored in the twisted shaft by a 12o with a torque of 25 kNm

2Mϕ=E

radial way has to be transformed into φ angular way

φ = 12o/360o*2 Π

φ = 0,209(3)

so the energy stored in the twisted shaft

20,209(3)*000 25=E = 2616,(6)


1. Energy storage methods in engineering

2. Efficiency of methods storing the energy

Exercise no. 6 Use of liquids in engineering


Pascal’s Principle. The 1 pound load on the 1 square inch area causes an increase in

pressure on the fluid in the system. This pressure is distributed equally throughout and acts on

every square inch of the 10 square inch area of the large piston. As a result, the larger piston

lifts up a 10 pound weight. The larger the cross-section area of the second piston, the larger

the mechanical advantage, and the more weight it lifts.

The formulas that explain Pascal’s Principle

P1 = P2 (since the pressures are equal throughout).

Since pressure equals force per unit area, then it follows that

F1/A1 = F2/A2

Bernoulli's equation shows that the pressure, P, of a fluid of density p decreases as the

speed, u, increases or as the height, h, increases (u). It is usually described as applicable to

incompressible fluids.

21

2P u gh constρ ρ+ + =


1. A car has a weight of 2500 pounds and rests on four tires, each having a surface area

of contact with the ground of 120 square cm. What is the pressure the ground

experiences beneath the tires that is due to the car?

2. Calculate the working parameters of the hydraulic press.

3. A hydraulic system is said to have a mechanical advantage of 40. Mechanical

advantage (MA) is FR (output) / FE (input). If the input piston, with a 12 inch radius,

has a force of 65 pounds pushing downward a distance of 20 inches, find a) the

volume of fluid that has been displaced, b) the upward force on the output piston, c)

the radius of the output piston.




Calculate force and distance on a big piston of hydraulic jack, knowing:

F1 = 100N

Øs= 2cm diameter small piston

Øb= 10cm diameter big piston

s1 = 4 cm distance on a small piston

2

2

1

1 FFAA

=

21

12

FA

AF =

∏∏= 2

22 5*1

100NF

NF 25002 =

To calculate distance on a big piston we will use the law of conservation of energy

W=F1s1=F2s2

s2=F1s1/ F1

s2 =100N*0,04m/2500N

s2 =0,0016m = 0,16cm


1. Selected hydrostatic issues

2. Selected hydrodynamic issues

Exercise no. 7&8 Simple machines designing and material features


Machines are devices that help us to do work easier. Some examples of early machines

are stones (used for tools), tree branches (pry up heavy objects), carts with wheels (carry

objects). Machines make work easier because they change the size or the direction of the

applied force. So, in other words, machines either lessen the amount of force you have to

fluid

apply and/or they change the direction and distance an object has to move. There are always

two forces involved when using machines to do work. Effort force (FE) and Resistance force

(FR). There are some features of simple machines:

• (FE) effort force is force that is applied to a machine.

• (FR) resistance force is force applied by a machine.

• (DE) effort distance is the distance through which a machine moves or distance

through which the effort force is applied to a machine.

• (DR) resistance distance is the distance through which the resistance force is applied

or the distance through which the object moves.

• (WI) work input is work done on a machine equal to the effort force times the distance

through which the force is applied.

• (WO) work output is work that is done by a machine equals resistance force times the

distance through which the force is applied.


1. What is the purpose of a machine?

2. Draw a diagram of a pulley system with a velocity ratio of 4.

3. A lever has a mechanical advantage of 5. What would be the mechanical advantage if

the load and effort were interchanged?

4. A pulley system has a velocity ratio of 3. It is used to lift a load of 1200 N. If an effort

of 450 N is needed and the system is frictionless find the mass of the moveable pulley

block.

5. A racing bicycle has wheels 68 cm in diameter. The pedal wheel has 50 teeth and the

rear sprocket 15 teeth. If the radius of the pedal crank is 17 cm find the velocity ratio

of the bicycle.

6. What would be a likely value for the mechanical advantage of a bicycle?

7. A screw jack has an arm 30 cm long and is used to raise a load of 800 N. If the effort

needed is 50 N and if the pitch of the screw is 4 mm find: a) the mechanical

advantage; b) the velocity ratio; c) the efficiency.

Question & Discussion

8. For castings, what materials are used?

9. Something that is sintered is?

10. Silumin is an alloy casting composed of?

11. Power transmission belt used in gears has a cross section that is?

12. Headstock, carriage and tailstock are components of?

13. Metalworking is changing the shape of the material?

14. The most accurate machining of cylindrical surfaces is provided by?

15. Grinding is a material removal process in which the cutting tool is the?

16. The standard point angle of drill bit used for drilling in steel is?

17. The main movement of the milling cutter is?

18. Which feature is the most important in the selection of the material for the soles of

shoes?

19. Which feature is the most important in the selection of materials used in the

manufacture of furniture?

20. Which feature is the most important for materials used on commercial aircraft?

21. What is the quenching of steel?

22. Which feature is the most important for materials used in lifeboats?

23. Up to what temperature can widely used thermoplastic materials operate (be under

load)?

24. Surface tension is a measure of what?

25. What is steel?

26. The coefficient of friction is a measure of what?

27. What changes are caused by the quenching of steel?

28. Up to which maximum temperature may wood operate (be under load) for a long

time?

29. Tensile strength is a measure of what?

30. Which feature is the most important in the selection of material for a sail boat?

31. Why do gold earrings shine?

32. Hardness is a measure of what?

33. Which feature is the most important in the selection of material for skis?

34. Which characteristics out of the following characterize ceramic materials?

35. Which feature is the most important in the selection of materials used in mines?

36. Up to what temperature can cast iron operate in the long run without deforming under

heavy load?


Discuss about the given by the teacher problems.


1. The role of machines in human life

2. Criteria for the selection of materials

3. Typification and standardization in engineering

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