Solved Anna University Question Papers (Reg 2017 / Dec 2019)

B.E./B.TECH. DEGREE EXAMINATION - NOVEMBER/DECEMBER 2019

Third Semester

Mechanical Engineering

ME 8351-MANUFACTURING TECHNOLOGY-I

(Common to Industrial Engineering and Industrial Engineering and Management) and Mechanical and Automation Engineering)

Time: Three hours      Maximum: 100 Marks

(Regulation 2017)

Answer ALL questions

Part A - (10 × 2 = 20 Marks)

1. Mention the different types of patterns.

The following types of patterns are normally used in foundry:

1. Solid or single piece pattern

2. Split pattern

3. Loose piece pattern

4. Match plåte pattern

5. Sweep pattern

6. Skeleton pattern.

7. Segmental pattern

8. Shall pattern.

2. What are the core prints? Explain.

A core print is the projection on a pattern. Core print forms a seat in the mould. The core is supported in the seat formed by the core print. Core prints are used to make holes in engine blocks, gears and pulleys.

3. How the C2H2 is preserved in the cylinders?

Acetylene (C2H2) gas is mixed in liquid acetone for safe storage and usage. Acetone in acetylene cylinders helps stabilize the gas making it non-reactive within the cylinder. In this process, acetylene is dissolved in liquid acetone under high pressure. The cylinder is then filled with porous material like firebrick.

4. What are the functions of flux in arc welding?

The stick electrode consists of core metal wire with an outer coating called flux. The which flux assists in creating and stabilizing the arc and it provides the shielding gas which prevents the reaction of the molten metal with atmospheric air. It also removes the impurities from the molten metal and it forms a slag. This slag gets deposited over the weld metal. This slag protects the weld seam from rapid cooling.

5. What is the difference between a bloom and a billet?

A bloom is an intermediate product, rectangular in shape with a cross sectional area typically larger than 230 cm2. It is a first breakdown product from ingots. A billet is rolled from a bloom and has a square or round cross section from 16 cm2 to 230 cm2.

6. What are the four major drawbacks of hot working?

1. Surface finish may be poor due to oxidation and scaling.

2. Close tolerances and automation cannot be achieved due to high working temperature.

3. Tooling and handling cost are high.

4. Sheets and wires cannot be produced.

5. On account of the loss of carbon from the surface of the steel workpiece, the surface layer loses its strength. It may give rise to a fatigue crack.

7. Differentiate between blanking and piercing.

The differences between blanking and piercing are as follows:

8. What is formability?

Formability is the ability of a given metal workpiece to undergo plastic deformation without being damaged.

9. What are the advantages and disadvantages of compression moulding?

Advantages:

1. Due to its simplicity, compression molding is very cost-effective when compared to other techniques.

2. Little material is lost during the molding process.

3. Compression molding is ideal for manufacturing large, fairly intricate parts.

Disadvantages:

1. Production rate is low.

2. It is limited largely to flat or moderately curved paths with no undercut.

3. Scraps cannot be reprocessed.

10. What are the different plastics used for blow moulding?

1. High Density Polyethylene (HDPE)

2. Low Density Polyethylene (LDPE)

3. Polypropylene

4. Polyvinyl Chloride (PVC)

5. Polyethylene Terephthalate (PET).

Part B - (5 × 13 = 65 Marks)

11. a) i) How the size of the silica sand is identified? Explain with suitable example.

Sand grains are of paramount importance in moulding sand because they impart refractoriness, chemical resistivity, and permeability to the sand. They are specified according to their average size and shape. The finer the grains, the more intimate will be the contact and lower the permeability. However, fine grains tend to fortify the mould and less than its tendency to get distorted.

The grain size of sand is expressed by a number called Grain Fineness Number (GFN). GNS is a system developed by American Foundry Society (AFS) for rapidly expressing the average grain size of a given sand. It approximates the number of meshes per inch of that sieve that would just pass the sample if its grains of uniform size. It is approximately proportional to the surface area per unit weight of sand, exclusive of clay.

To determine GFN for a given silica sand sample, it is customary to use a standard sieve set which contains several sieves one above the other, having a varying but known number of meshes. The coarsest sieve is placed at the top and finest at the bottom. After separating the clay and the moisture from the sand under test, the sample is placed in the top sieve and the whole set is shaken in a sieve shaking machine for a definite length of time. The amount of sand remaining in each sieve is then collected, weighed, and expressed as a percentage of the original sample weight.

The percentage collected in each sieve is multiplied by its own multiplying number a constant, one for each sieve and all the products are added to the arrive at the total product. Thus

Grain fineness number = Total product collected in each sieve / Total sum of percentages

Example:

ii) Explain the working of sand slinger machine.

Refer chapter 1.12.4 in Page 1.61.

(b) i) Explain the CO2 process for making of cores with a neat diagram.

Refer chapter 1.9.7 (4) in Page 1.48.

ii) What is the importance of allowance considered on pattern? Explain. 

Refer chapter 1.7 in Page 1.10.

12. a) i) What are the differences between friction welding and friction stir welding?

ii) Explain the working of gas tungsten arc welding with neat diagram.

Refer chapter 2.6 in Page 2.21.

Or

b) i) What are the different welding techniques used in gas welding process? Explain.

Refer chapter 2.4.6 in Page 2.11.

ii) Explain the working principle of spot welding with a neat diagram. 

Refer chapter 2.10.4 in Page 2.37.

13. a) i) How the tooth paste tubes are manufactured? Explain the process with neat diagrams.

Refer chapter 3.19.2 in Page 3.78.

ii) What is rolling? Explain the principle of rolling mills with neat diagrams. 

Refer chapter 3.10 in Page 3.39.

Or

b) i) How the metallic wires are made? Explain the process with neat diagram. 

Refer chapter 3.16.1 in Page 3.64.

ii) What are the different forging operations? Explain with neat diagrams. 

Refer chapter 3.6 in Page 3.28.

14. a) i) Explain the metal spinning process with a neat diagram.

Refer chapter 4.14.4 in Page 4.47.

ii) Describe the principle of stretch forming operation with neat diagrams. 

Refer chapter 4.11 in Page 4.33.

Or

b) i) Explain the magnetic pulse forming process with a neat diagram.

Refer chapter 4.14.6 in Page 4.52.

ii) Explain the bending operation with a neat diagram. Mention the applications. 

Refer chapter 4.7 in Page 4.22.

15. a) i) Explain the principle of operation of transfer moulding process with neat diagram.

Refer chapter 5.4.2 in Page 5.32.

ii) Explain the characteristics of plastics.

Refer chapter 5.1.4 in Page 5.4.

Or

b) i) Explain the principle of operation of blow moulding process with a neat diagram.

Refer chapter 5.3.2 in Page 5.18.

ii) Explain the principle of operation of injection moulding process with plunger and screw set up with a neat diagram.

Refer chapter 5.3.1.2 in Page 5.12.

Part C - (1 × 15 = 15 Marks)

16. a) What are the different types of welding defects? Explain the causes and remedies.

Refer chapter 2.21 in Page 2.80.

Or

b) Enumerate the step by step procedure involved in shell moulding process. State its advantages and disadvantages.

Refer chapter 1.14.1 in Page 1.73.