Introduction to Mechanical Engineering

Manufacturing Technology

Introduction

What is manufacturing?

• Literal: Manufacture = Manus (hand) + Factus

(make) Made by hand

• Technological: Application of physical and chemical

processes to make parts or products,

including assembly of products.

• Economical: Transformation of materials into items

of greater value by means of proces-

sing and/or assembly operations.

• CIRP definition: Design + production + assembly

(CIRP = International Academy for Production Engineering=

Collège International pour la Recherche en Productique)

What is manufacturing?

Representation of ‘manufacturing’ in a technological way

What is manufacturing?

Representation of ‘manufacturing’ in a economical way

Importance of manufacturing

• Manufacturing is an important mean to create

material wealth!!!

• One job in a manufacturing plant generates about

four other jobs else!!! Question: How?

• Data from the USA:

- Manufacturing : ~ 20% of the GNP

- Agriculture, mining : < 5% of the GNP

- Construction, public utilities : ~ 5% of the GNP

- Service sector : ~ 70% of the GNP

(GNP = Gross National Product)

Question: What are the figures for Turkey?

Data from the Türkiye:

- Industry : ~ 12% of the GNP

- Agriculture : < 24% of the GNP

- Service : ~ 64% of the GNP

Historical perspective (1)

In broad outlines:

• Man’s discovery and invention of materials and

processes to make things, since 6000 years ago

• Principle of division of labour Adam Smith (~1750)

A.Smith'in Ulusların Zenginliği adlı kitabında en ünlü bölüm iş bölümüyle ilgili olan ilk bölümdür.18. yüzyılda yazılmış olmasına rağmen bugün için bile çok doğru gelmektedir. Smith bu bölümde iş bölümünün üretimi nasıl arttırdığını toplu iğne üretimiyle ilgili bir örnekle açıklar. Tek bir kişi, yapılması için on aşaması olan bir iğneden günde sadece on tane yapabilmektedir; fakat her aşamayı yalnızca bir kişi yapsa yani on kişi çalıştırsak bir günde üretilen iğne sayısı 4800'e çıkıyor; ama her biri her aşamayı yapsaydı sadece 100 iğne üretilecekti. Bu demek oluyor ki, iş bölümü iğne üretimini 48 kat arttırmış. Ayrıca işçinin belli bir aşamada uzmanlaşması o teknolojiyi kullanmanın yeni yolları bulunarak arttırılabilir, bu da daha hızlı üretime sebep olur.

• Industrial Revolution (1770 – 1850), steam engine,

machine tools, machinery for textile industry

Factory system, UK

• American system, interchangeable parts

Whitney (~1800), guns (muskets), USA

• Second Industrial revolution mass production,

scientific management, assembly lines, Ford

(~1915), cars, USA

Industries and products

Manufacturing industries

- Primary industries: natural resources as mining, fishing,

agriculture, petroleum

- Secondary industries: automotive, computers, electronics

- Tertiary industries (service): banking, tourism, education

Manufactured products

- Consumer goods: cars, TV’s, tires, tennis rackets

- Capital goods: aircraft, machine tools, machinery

- Discrete products: pumps, shavers, coffee makers

- Continuous produced products: sheet-metal coils

Manufacturing capability

• Technological Processing capability

- Available processes and machines

- Outsourcing of some operations (casting, heat

treatment, etc.)

• Physical product limitations

- Size, weight

- Machine dimensions, handling

• Production capacity (Plant capacity)

- Production quantity in a given time, output

Materials in Manufacturing

• Metals

- Ferrous: Steel (iron-carbon, 0,02% - 2,11% C)

Cast iron (iron + 2% - 4% C + silicon)

- Nonferrous: copper, aluminium, nickel, alloys

• Ceramics: clay, silica, carbides (Al, Si), nitrides (Ti)

• Polymers

- Thermoplastic polymers: PE, PP, PS, PVC

- Thermosetting polymers: phenolics, epoxies

- Elastomers: rubber, neoprene, silicone, PU

• Composites: more phases, particles/fibres + matrix

glass reinforced plastic, Kevlar, WC in cobalt

Materials in Manufacturing

Venn diagram

Historical perspective (2)

Manufacturing materials and processes:

• Neolithic period (~8000 - 3000 B.C.) in Mesopotamia

Mediterranean, Asia; hammering, gold

• Bronze age (3500 - 1500 B.C.), extracting copper

from ores, casting, hammering.

• Iron age (since 1000 B.C.), heating, quenching

• Industrial Revolution (1770 - 1850), machining like

boring, turning, drilling, milling, shaping.

• Assembly methods (since ancient cultures), ships,

weapons, tools, farming equipment

• Fusion welding (around 1900)

• Rubber and polymer shaping, vulcanization (1939)

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Manufacturing processesClassification of

Manufacturing processes

Üretim sürecinin sonunda ortaya konan ürün; toplu

iğne de olabilir bir uzay aracı da.

Bir toplumun refahı için en başta gelen konu üretim

olup, bu durum, ekonomisi gelişmiş toplumlarda

açıkça görülmektedir. Üretim konusunda da en

büyük görev biz mühendislere düşmektedir.

The benefit of a product is profit when it is considered in terms of a

business, the benefit of a product is total added-value when it is considered

in terms of a society.

Ürünün faydası bir işletme açısından bakıldığında kâr, bir toplum açısından

bakıldığında da toplam katma-değer olarak değerlendirilir.

Productivity;

Benefit created by the product

Energy consumption for the manufacturing

The ratio of natural and financial

resources

Günümüzde rekabet koşulları, mümkün olduğunca

düşük fiyata ve istenilen zamanda ürünü pazara

sürme zorunluluğunu doğurmaktadır.

In summary: the expections from a recent

production

-High effciency,

-Quality production,

-Low total cost,

- Environmentally friendly production process

Processing operations

1) Shaping operations

- Solidification processes casting of metals,

moulding of plastics

- Particulate processing powder metallurgy

- Deformation processes forging, extrusion

- Material removal processes machining, non-

traditional, grinding

2) Property enhancing processes

- Heat treatments, sintering

3) Surface processing

- Cleaning, coating, deposition

CASTING

Casting - Process of Producing Metallic

Parts by Pouring Molten Metal in to a

Mould having a Cavity of the Part to be

Cast and then Allowing the Molten Metal

to Solidify.

Moulding – Process of Making a Mould

Using a Pattern.

Pattern – A Model or Replica of the Part

to be Cast.

CASTING

Sand Mould Casting – Molten Metal

is Poured in to the Cavity of the

Mould without Applying External

Pressure (Gravity Feed).

Permanent Mould Casting -

Gravity Die Casting

Die Casting – Molten Metal is

Forced under very high Pressure in

to the Die (Metallic Mould).

Hot Chamber Die Casting

Cold Chamber Die Casting

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Casting and moulding processes

Pouring of the

liquid or meltSolidification

Kum Kalıba Döküm

Kalıp boşluğu, bir model vasıtasıyla kumda

oluşturulur. Bu boşluk daha sonra erimiş metalle

doldurulur.

CASTING

CASTING

Advantages of casting

*Complex part geometries can be easily created.

*Both inside (hollow) and external shapes can be created.

*Final parts can be obtained by some casting processes.

*Very large and very small particles can be produced.

*Some casting methods are suitable for mass production.

*Casting is a commonly used method in the industryand generally cost effective.

Particulate processing

PowderSintering

Pressing

Powder metallurgy (PM)

Metal processing technology in which parts are produced

from metallic powders

In the usual PM production sequence, the powders are

compressed (pressed) into the desired shape and then

heated (sintered) to bond the particles into a hard, rigid

mass

Pressing is accomplished in a press-type machine using

punch-and-die tooling designed specifically for the part to be

manufactured.

Sintering is performed at a temperature below the melting

point of the metal

PM processes can avoid, or greatly reduce, the

need to use metal removal processes, thereby

drastically reducing yield losses in manufacture

and often resulting in lower costs

Powder

metallurgy

products:

gears

Toz metalurjisi küçük, karmaşık ve boyutsal

hassasiyeti yüksek parçaların seri imalatına son

derece uygundur. Malzeme kaybı çok azdır, belirli

derecede porozite ( gözenek ) ve geçirgenlik elde

edilir.

Dezavantajları:

- Kalıntı iç boşlukların çentik etkisi yaparak düşük

dayanıma sebep olabilmesi,

- Toz üretiminin ek bir maliyet gerektirmesidir.

Kullanım amaçları;

- Yüksek dayanım gerektiren parçaların imalinde,

- Talaşlı imalatı zor olan geometrideki parçaların

imalinde,

-Pahalı malzemelerde parça imalinde,

-Çok sert parçaların imalinde kullanılır

Permanent (plastic) deformation of a

material under tension, compression, pression,

shear or a combination of loads

Metal parçaların plastik deformasyona maruz

kalması ile şekillendirildiği yöntemler grubudur. Bu

şekillendirme yöntemi için metalin akma dayanımını

aşan gerilmeler uygulanır. İş parçası üzerinde

bunun sonucu olarak kalıcı şekil değiştirmeler

oluşur.

Deformation processes

Types of Deformation Processes:

-Bulk deformation: Forging, rolling, extrusion

drawing (wire, bar, tube),

-Sheet Metal work: Shearing, bending, deep

drawing and metal spinning.

FORGING

Hot Forging – Changing the Shape of

Metals, when it is in high temperature, by

Applying Compressive Force.

Cold Forging - Changing the Shape of

Metals, when it is at Room Temperature,

by Applying Large Compressive Force.

Hand Forging

Drop Forging (Closed Die Forging)

Press Forging (Open Die Forging)

Machine Forging

Forging

ROLLING

Forming Metals into Desired Shapes

by Passing the Metal in between a

Pair of Rolls.

Two High Mill

Three High Mill

Four High Mill

Cluster Mill

Rolling

Haddeleme işlemi prensibi

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Rolling products

Extrusion

A plastic deformation process in which metal is

forces under pressure to flow through a single, or

series of dies until the desired shape is produced.

Ekstrüzyon (Extrusion)

Bir metal bloğun bir kovan içinde büyük kuvvet uygulayan

pistonla sıkıştırılıp, belirli profil kesitini taşıyan matristen

püskürtülerek şekillendirilmesi işlemidir.

Pratikte daha çok sıcak uygulanır ancak yumuşak

malzemelere soğuk ekstrüzyon da yapılabilir.

*Billet is forced out of die into

desired shape

*Dies are machined to the

desired cross section

*Good process for long 2D

parts

*Controlling friction is the key

to the process

Sabit kompleks şekilli parçalar üretilebilir.

Ekstrüzyon ürünü daha sonra küçük

parçalara kesilebilir.

Ekstrüzyonla üretilmiş bir ısı gidericinin

kompleks kesiti (alüminyum)

Shaping (Machining) processes

*A material removal process in which a sharp cutting tool is used to mechanically cut away material so that the desired part geometry remains

*Most common application: to shape metal parts

*Machining is the most versatile and accurate of all manufacturing processes in its capability to produce a diversity of part geometries and geometric features

*Casting can also produce a variety of shapes, but it lacks the precision and accuracy of machining

Shaping (Machining)

processes

General aim: Minimize waste and scrap!!!

- Net shape processes no subsequent machining

- Near net shape processes minimum machining

Turning Drilling Milling

Figure 22.5 - Turning operation

FacingTool is fed

radially inward

Bir torna üzerinde yapılabilecek çeşitli uygulamalar: (a) alın tornalama, (b) konik tornalama, (c) çevre çizgisel tornalama, (d) biçimleme tornalaması, (e) pah kırma, (f) kesme, (g) vida açma, (h) delik işleme, (i) delme ve (j) tırtıl çekme

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Drilling

Creates a round hole in a workpart

Contrasts with boring which can only enlarge an existing hole

Cutting tool called a drill or drill bit

Customarily performed on a drill press Figure 21.3 (b) drilling

Through Holes vs. Blind HolesThrough-holes - drill exits the opposite side of work

Blind-holes – drill does not exit work on opposite side

Figure 22.13 - Two hole types: (a) through-hole, and (b) blind hole

Milling

Machining operation in which work is fed past

a rotating tool with multiple cutting edges

Creates a planar surface; other geometries

possible either by cutter path or shape

Other factors and terms:Milling is an interrupted cutting operation

Cutting tool called a milling cutter, cutting edges called "teeth"

Machine tool called a milling machine

Figure 21.3 - Two forms of milling:

(a) peripheral milling, and (b) face milling

Peripheral Milling vs. Face

Milling

Peripheral millingCutter axis is parallel to surface being machined

Cutting edges on outside periphery of cutter

Face millingCutter axis is perpendicular to surface being milled

Cutting edges on both the end and outside periphery of the cutter

Profile Milling

Form of end

milling in which

the outside

periphery of a

flat part is cut

Figure 22.20 (d) profile milling

Pocket Milling

Another form of

end milling

used to mill

shallow pockets

into flat parts

Figure 22.20 (e) pocket milling

Figure 22.28 - Operation of a mill-turn center: (a) example part

with turned, milled, and drilled surfaces; and (b) sequence of

operations on a mill-turn center: (1) turn second diameter,

(2) mill flat with part in programmed angular position, (3) drill hole

with part in same programmed position, and (4) cutoff

BroachingMoves a multiple tooth cutting tool linearly relative to work in direction of tool axis

Figure 22.33 - The broaching operation

Broaching

Advantages:

Good surface finish

Close tolerances

Variety of work shapes possible

Cutting tool called a broach

Owing to complicated and often custom-shaped

geometry, tooling is expensive

Internal Broaching

Performed on internal surface of a hole

A starting hole must be present in the part to insert broach at beginning of stroke

Figure 22.34 - Work shapes that can be cut by internal broaching;

cross-hatching indicates the surfaces broached

Sawing

Cuts narrow slit in work by a tool consisting of a

series of narrowly spaced teeth

Tool called a saw blade

Typical functions:Separate a workpart into two pieces

Cut off unwanted portions of part

Figure 22.35 (a) power hacksaw –linear reciprocating motion

of hacksaw blade against work

Figure 22.35 (b) bandsaw

(vertical) – linear

continuous motion of

bandsaw blade, which is in

the form of an endless

flexible loop with teeth on

one edge

Figure 22.35 (c) circular saw – rotating saw blade provides

continuous motion of tool past workpart

Mutual relationships

Function

Shape

Process

Material

Product attributes

• Mechanical properties, e.g. tensile strength

• Physical properties, e.g. thermal expansion

• Dimensions, e.g. mm

• Tolerances: bilateral, unilateral tolerances

limit dimensions

• Geometric attributes: angularity, circularity,

concentricity, cylindricity, flatness, parallellism,

perpendicularity, roundness, squareness and

straightness (See table 5.1)

• Surface quality, e.g. roughness

Specification of tolerances

Bilateral tolerance

Unilateral tolerance

Limit dimensions

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Surfaces

• Importance of surface quality

- Aesthetic reasons

- Safety aspects

- Influence on friction and wear

- Influence on mechanical and physical properties

- Important for assembly

- Better electrical contact

• Surface technology is concerned with

- Surface texture

- Surface integrity

- Relationship with manufacturing processes

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Characteristics of surfaces

A microscopic view shows:

- Substrate bulk material

- Altered layer different structure

- Surface texture exterior part with roughness

- In addition: Mostly an oxide film

Surface roughness values

Table 5.5