UNIT 1 CASTING PROCESS

Casting types, procedure to make sand mould, types of core making, moulding tools, machine moulding, special moulding processes – CO2 moulding; shell moulding, investment moulding, permanent mould casting, pressure die casting, centrifugal casting, continuous casting, casting defects.

Define Casting?

In this process the raw material is melted, heated to the desired temperature and poured into the mould cavity where it takes the desired shape. After the molten metal solidifies in the mould cavity the product is taken out to get the casting.

What is the sequence of operations required in sand casting process?

1. Pattern Making

2 Mould making

3 Core making

4 Melting of metal and pouring

5 Cooling and solidification

6 Cleaning of castings and inspection

Define Pattern?

A pattern is defined as a model of a casting, constructed in such a way that it can be used for forming an impression (mould) in damp sand.

What are the requirements of a good pattern?

Light in weight, Smooth and wear resistance surface, Secure the desired shape and size of the casting, Ability to withstand rough handling.

Types of Patterns:

Types of patterns depends on the following factors

1. The shape and size of casting.

2 Number of castings required.

3 Method of moulding employed.

4 Anticipated difficulty of the moulding operation.

The following types of patterns are commonly used:

1. Solid or single piece pattern 2. Split pattern

3 Loose piece pattern 4.Match plate patterns

5 Gated pattern 6 Skeleton pattern

7 Sweep pattern 8 Cope and drag pattern

9 Follow board pattern 10 Segmental pattern

11 Shell pattern 12 Lagged-up patterns

Pattern Allowances

Shrinkage Allowances

Shrinkage allowance is an allowance added to the pattern to compensate for the metal shrinkage that takes place while the metal solidifies.

Draft or taper allowance

It is the taper provided on vertical surfaces of a pattern to facilitate its removal from the mould without excessive rapping or breakage of cavity edges.

Machining allowance

Machining or finishing allowance is the extra material provided on certain details of a casting so that the casting may be machined to exact dimensions. It depends on the following factors

(i) Casting process

(ii) Size of the casting

(iii) Degree of finish

(iv) Machining method.

(v) Metallic alloy

Rapping or shaking allowance

This allowance is provided to compensate for enlargement of the mould cavity because of excessive rapping.

Distortion allowance

This allowance is provided on the pattern to compensate for possible distortion of the casting because of the unequal cooling rates of different sections of the casting and uneven internal stresses.

UNIT – 1 CASTING

PART B

1. With reference to metal casting, explain the following types of patterns with suitable sketches of examples:

(i) Solid pattern (ii) Spilt Pattern(iii) Loose piece pattern (iv) Sweep Pattern

2. What are pattern allowances? Explain briefly each.

3. Discuss the properties of mould sand?

4. What is core? Describe the different types of cores used.

5. Briefly explain the carbon dioxide moulding process and state two important merits and demerits?

6. Explain the following types of core making methods in detail.

Hot core box methodCold curing CO2 process

7. Explain the procedure of sand moulding process with a neat sketch.

SPECIAL CASTING PROCESS

1. Explain the sand moulding process with a neat sketch. List their merits, demerits & applications.

2. Describe the procedure of making castings by the investment casting process. State its advantages, disadvantages & applications

3. With a neat sketch, explain the continuous casting process in detail.

4 What do you meant by centrifugal casting ? Explain the following types with a neat sketch.

1. True centrifugal casting 2. Semi Centrifugal Casting

3. Centrifuge Casting

5. Explain the following process in detail

l. Hot Chamfer Die Casting 2. Cold Chamfer Die Casting 3. Gravity Die Casting

6. Describe the castings made by Permanent Mould Casting process

7. Explain any six casting defects in detail?

UNIT II WELDING

QUESTION BANK

TWO MARKS

1. Define welding process?

2. State the classification of welding process?

Note : Fusion Welding, Pressure Welding

Note : Autogeneous, Homogeneous, Heterogeneous

3. What are the different types of fusion welding?

4. What are the different types of pressure welding?

5. State the flame characterstics of gas welding process?

6. State the difference between TIG & MIG welding process?

7. What do you mean by Arc blow?

8. What is the principal of arc welding?

9. Difference between the A.C & D.C arc welding process?

10. List out the common types of electrodes?

11. What do you mean by distortion?

12. What are the influencing factors for the below welding process?

1. Resistance Arc Welding 2. Oxy-acetylene welding

3. A.C / D.C are welding 4. Tungsten inert gas welding

5. Metal inert gas welding 6. Submerged arc welding

7. Ultrasonic welding 8. Electron beam welding

9. Plasma arc welding 10. Laser beam welding

13. Define the term Brazing & Soldering?

14. What is the principle of the following welding process?

1. Resistance Arc Welding 2. Oxy-acetylene welding

3. A.C / D.C are welding 4. Tungsten inert gas welding

5. Metal inert gas welding 6. Submerged arc welding

7. Ultrasonic welding 8. Electron beam welding

9. Plasma arc welding 10. Laser beam welding

PART –B QUESTIONS

1. Explain the oxy-acetylene gas welding process with a neat sketch. State its advantages & Disadvantages?

2. Explain the flame characterstics of gas welding process?

NOTE : MENTION TEMPERATURE,COLOUR OF THE FLAME IN DRAWING

3. Discuss any four ways to control output of arc welding transformer?

4. With the help of suitable diagrams, explain the following types of welding: State its applications, advantages & disadvantages?

1. Resistance Arc Welding 2. Oxy-acetylene welding

3. A.C / D.C are welding 4. Tungsten inert gas welding

5. Metal inert gas welding 6. Submerged arc welding

7. Ultrasonic welding 8. Electron beam welding

9. Plasma arc welding 10. Laser beam welding

For the above questions, explain any two/four process as stated in the question paper. Each process may carry 8 or 16 marks.

5. Distinguish between soldering and brazing?

6. Sketch the different types of weld defects and mention how they occur?

7. Explain different types of soldering methods?

8. Explain different types of brazing methods?

UNIT 3 MACHINING

General principles (with schematic diagrams only) of working and commonly performed in the following machines: Lathe, Shaper, Planer, Horizontal milling machine, Universal drilling machine, Cylindrical grinding machine, Capstan and Turret lathe, Basics of CNC machines.

General principles and applications of the following process: abrasive jet machining, Ultrasonic jet machining, Electric discharge machining, Electro chemical machining, plasma arc machining, Electron beam machining and laser beam machining

PART A QUESTIONS

MACHINING

1. What is swing diameter?

2. Write the Specifications of a typical lathe?

3. What is the difference between a ram-type turret lathe and saddle type turret lathe?

4. What is the purpose of a mandrel? How many types of mandrels is there in common use?

5. Write down any four operations performed by a shaper?

6. Under what conditions planning operation would be preferred over other machining process such as milling, broaching, shaping, etc?

7 Mention the operations performed by a planer

8. Write down any four operations that can be performed in a drilling machine?

9. What is point - to- point system?

10. What is the role of computer for NC machine tool?

11.Name various elements of CNC machines?

12. Classify CNC machines?

NON CONVENTIONAL MACHINING PROCESS

1. State the working principle of the following process?

(i) Electrical Discharge Machining

This process involves controlled erosion of electrically conducting materials by the initiation of rapid and repetitive electrical discharge between the tool (cathode) and workpiece (anode) separated by a dielectric fluid medium. A suitable gap between the tool and workpiece is maintained to cause the spark discharge.

(ii) Abrasive Jet Machining

This process consists of directing a stream of fine abrasive grains, (Al2 O3, SiC, Sodium bicarbonate, dolomite), mixed with compressed air (CO2 OR N2) or some other gas at high pressure through a nozzle on to the surface of the workpiece to be machined.

(iii) Plasma Arc Machining

Plasma is a high temperature ionized gas. The plasma arc machining is done with a high speed jet of high temperature plasma.

(iv) Electron Beam Machining

EBM is a process of machining materials with the use of a high velocity beam of electrons. In this process the material is removed with the help of high velocity focused stream of electrons which are focused magnetically upon a very small area. These electrons heat and raise the temperature locally above the boiling point and thus melt and vaporize the work material at the point of collision.

(v) Laser Beam Machining

The light energy of a particular frequency is utilized to stimulate the electrons in an atom to emit additional light with exactly the same characterstics of the original light source.

(vi) Electro-Chemical Machining

An electrolyte (usually a neutral salt solution such as sodium chloride, sodium nitrate, sodium chlorate ) is passed through a very little gap (0.05 to 0.03 mm) created between the workpiece and the tool whereas a direct current flow is made between them. When sufficient electrical energy is available, a metallic ions present in the electrolytic solution forming metallic hydroxides and other compounds. Hence the metal anodic ally dissolved with the formation of sledges and precipitates

PART – B QUESTIONS

FIRST PORTION

1. Explain the construction and working principle of a lathe with sketch?

2. Explain taper turning operation in a lathe by a taper turning attachment. Discuss its advantages?

3. Write down any four differences between shaper and planer?

4. With a neat sketch, explain the principal parts and angles of a plain milling cutter, Explain them.

5. How do you classify cylindrical grinders? What is the difference between “Plain and Universal” cylindrical grinder?

6. Write down the differences between a capstan and a turret lathe.

7. Define CNC and DNC. With a help of a diagram explain the working of NC machine tool.

SECOND PORTION

1. With a neat sketch explain the following process. List its applications, advantages and limitations.

1. Electrical Discharge Machining (16 or 8 MARK)

2. Electro Chemical Machining (16 or 8 MARK)

3. Ultrasonic Machining (16 or 8 MARK)

4. Electron Beam Machining (16 or 8 MARK)

5. Plasma Arc Machining (16 or 8 MARK)

6. Laser Beam Machining (16 or 8 MARK)

7. Abrasive Jet Machining (16 or 8 MARK)

UNIT 5 METAL FORMING AND POWDER METALLURGY

PART – A

1. What are the advantages of metal forming process?

2. What do you mean by recrysatallization temperature?

3. Classify Metal Forming process?

4. What do you mean by hot working and cold working of metals?

5. Draw a load deformation curve & mark hot & cold working?

6. State the advantages & disadvantages of hot working & cold working process?

7. State the factors influencing the semi hot/warm working process?

8.

PART –B

1. Discuss in detail about the hot & cold working of metals?

2. Difference between hot and cold working process?

ROLLING

1. Discuss in detail about mechanism of rolling?

2. Classification of different types of rollers with a neat sketch?

Two high rolling mill, Three high rolling mill, Four high rolling mill, Multiple-roll mills.

3. Explain in detail about the Rolling Defects

4. Explain the following shape rolling process with a neat sketch

Ring Rolling, Thread Rolling

FORGING

1. Comparision between press forging and drop forging?

2. Write the difference between open die and closed die forging process?

3. Explain the different types of hammer used in forging process?

4. With a neat sketch explain the process of upset (machine) forging?

5. Discuss in detail about the roll forging?

6. Explain the various kind of defects in forgings?

DRAWING

1. Explain the following process with a neat sketch?

Tube Extrusion and Tube Piercing

2.