B.E./B.TECH. degree examination, model question paper-3

B.E./B.TECH. DEGREE EXAMINATION, MODEL QUESTION PAPER - 3

ME 3493 - MANUFACTURING TECHNOLOGY (Regulation 2021)

Time: Three hours

Fourth Semester

Maximum: 100 marks

Mechanical Engineering

Answer ALL questions

Part A - (10x2 = 20 Marks)

1. Define Tool wear.

Tool wear is defined as the gradual failure of cutting tools due to regular operation. It is associated with tipped tools, tool bits or drill bits which are used with machine tools.

2. Deduce the factors that contribute to poor surface finish in cutting process.

(i) Low cutting speed

(ii) Coarse feed

(iii) Heavier depth of cut

(iv) Hardness of both workpiece and cutting tool.

3. What are the principle parts of lathe?

(i) Bed

(ii) Headstock

(iii) Tailstock

(iv) Carriage

(v) Feed mechanism.

4. List out the various types of lathe.

1. Speed Lathe

(a) Wood working lathe

(b) Metal spinning lathe

(c) Metal turning lathe

(d) Polishing lathe.

2. Engine lathe

(a) Step cone pulley drive lathe

(b) Geared lathe

(c) Variable speed lathe.

3. Bench lathes

4. Tool room lathe

5. Semiautomatic lathe

(a) Capstan lathe

(b) Turret lathe

6. Automatic lathe

7. Special purpose lathe

(a) Crankshaft lathe

(b) Wheel lathe

(c) Duplicating lathe

8. Copying lathe.

5. What are the different methods of indexing?

The common methods of indexing are given below.

1. Direct or rapid indexing 

2. Plain or simple indexing

3. Differential indexing

4. Compound indexing

5. Angular indexing.

6. Define grinding ratio.

Grinding ratio is the ratio of the volume of ground material removed from the workpiece to the volume removed from the grinding wheel.

G = Volume of material required / Volume of wheel wear

7. Compare NC with CNC in machining process.

8. State the limitations of CNC machine tools.

(i) CNC machines are more expensive than manually operated machines, although costs are slowly coming down.

(ii) A CNC machine operator only needs basic training and skills which are enough to supervise several machines. Engineers are needed years of training to operate centre lathes, milling machines and other manually operated machines. It means many of the old skills are been lost.

(iii) Less workers are required to operate CNC machines compared to manually operated machines. The investment for CNC machines can lead to unemployment.

9. State the functions of the following G and M codes: G00, G03, M06 & M03.

G00 means Point to point positioning

G03, means Circular interpolation, anticlockwise

M06 means Tool change

M03 means Spindle clockwise.

10. What is a Canned cycle?

A Canned cycle is a combination of machine moves that performs anyone particular machining function such as drilling, turning, milling, boring, tapping etc.

Part B - (5 x 13 = 65 Marks)

11. (a) (i) In orthogonal cutting operation, the tool has a rake angle 15o. The chip • thickness before the cut = 0.3 mm and the cut yields a deformed chip thickness 0.65 mm. Calculate the (1) shear plane angle and (2) shear strain for the operation. 

Same as AU Problem 1.3 on Page 1.54.

(ii) Turning tests have resulted in 1-minute tool life at a cutting speed of 4.0 m/s and a 20-minute tool life at a speed of 2.0 m/s. (1) Find the n and C values in the Taylors tool life equation. (2) Project how long the tool would last at a speed of 1.0 m/s.

Same as AU Problem 1.11 on Page 1.90.

Or

(b) (i) Identify the four forces that act upon the chip in the orthogonal metal cutting model and draw the merchant circle and identify these force. 

Refer chapters 1.14 & 1.15 on Pages 1.25 & 1.27 respectively.

(ii) Name the three models of tool failure in machining and identify the two principal locations on a cutting tool where tool wear occurs?

Refer chapter 1.29 on Page 1.66.

12. (a) (i) Detail the procedure for thread cutting operation.

(ii) How special attachments help in improving the procedure? 

Refer chapter 2.9.19 on Page 2.31.

Or

(b) Discuss about the construction and working principle of single spindle automatic screw type machine with illustrative sketch.

Refer chapter 2.22 on Page 2.104.

13. (a)Write short notes on gear shaping. List the advantages and disadvantages of gear shaping process.

Refer chapter 3.8.22.1 on Page 3.144.

Or

(b) (i) Discuss briefly the standard specification of grinding wheel. 

Refer chapter 3.9.12 on Page 3.194.

(ii) What are the factors to be considered during the selection of appropriate grinding wheel?

Refer chapter 3.1.15 on Page 3.38.

14. (a) (i) Explain the constructional and special features of CNC machine. 

Refer chapter 4.3.5 on Page 4.21.

(ii) Describe the advantages of CNC turning centres over conventional machines.

Refer chapter 4.15.3 on Page 4.78.

Or

(b) (i) With a neat sketch explain the recirculating ball screw used in CNC machine tools.

Refer chapter 4.16 on Page 4.79.

(ii) What are machining centres? Describe various features of machining centre.

Refer Page 4.27.

15. (a) With a suitable example, explain the part programming procedure. 

Refer chapter 5.9.1 on Page 5.20.

Or

(b) Explain the following terms with reference to CNC machines.

(1) Tool length compensation.

Refer chapter 5.9.6.2 on Page 5.27.

(2) Cutter radius compensation.

Refer chapter 5.9.6.3 on Page 5.28.

Part C - (1 × 15 = 15 Marks)

16. (a) (i) Explain the part program segment given below. Draw the trajectory of table motion that this program seeks to create.

N0010G90;

N0011G01X1Y2;

N0011G01X2Y2;

N0013G91;

N0014G01X1;

N0015G92X2 Y2;

N0016G01XIYI

Same as AU Problem 5.1 on Page 5.66.

(ii) Is there any connection between the choice of coordinate system and the position sensor used in the machine tool?

Refer Page 5.8.

(iii) What are the important steps to be followed while preparing part program?

Refer Q8 on Page 5.104.

Or

(b) Write a note on heat generation in metal cutting. What is the importance of analysing the thermal aspects of machining?

Refer chapter 1.27 on Page 1.63.