Kathmandu University

Mechanical Engineering Department

Manufacturing Process III (MP III)

Year : IV  Sem : I   Faculty: R.C. Poudel

Tutorial Assignment

Modern Methods of Machining 

1.     In Ultrasonic Machining Process 100 micro-gram of abrasive particles make impact on work piece surface at a time. Each particle has a diameter of about 0.02mm and average density of the abrasive is 20gm/cm³. It can be assumed that each particle dislodges about 2.0 x 10 ^{– 9} mm³ of material from work in each impact. The tool oscillates at 10KHz. Calculate the material removal rate in mm³/min.  

2.     What are the advantages of non-conventional machining processes over the conventional ones? 

3.     Find out approximate value of time required to machine a cylindrical hole of diameter 6mm and depth 5mm in a Tungsten Carbide work piece. The abrasive grains are of 0.01mm diameter and the indentation caused by each particle on the surface of work is about 0.0006mm. About 1500 particles make impact at a time and frequency of tool oscillation is about 15Khz. 

4.     Discuss the mode of material removal in Abrasive Jet Machining. 

5.     Explain in brief Laser Beam Machining 

6.     In an ECM process, a pure copper block is being machined. If a current of 5000amp is used, determine the volume rate of material removal from the copper block. 

7.     Derive the expression for material removal rate in EDM with a Resistance-Capacitance relaxation circuit. 

8.     The composition of a Nimonic alloy turbine blade is 18% Cobalt, 62% Ni and 20% Chromium. It is being machined electrochemically with a current of 1500 amp. Find out the volume removal rate. The dissolution valency of chromium is 6, whereas that for both Nickel and Cobalt is 2. 

9.     Discuss various parameters affecting surface finish in ECM. 

10. Draw following characteristic curves for Ultrasonic Machining Process: 

i)  Material Removal Rate Vs Feed rate for various amplitudes.

ii)  Material Removal Rate Vs Mean Grain Diameter

iii) Material Removal Rate Vs Frequency

11.For spark machining of a 5mm x 5mm square through hole in a solid low carbon steel plate of 5mm thickness, a brass tool is used with kerosene as the dielectric. The resistance and capacitance in the relaxation circuit of the spark generator are 100 W and 15 mF, respectively. The supply dc voltage is 220V and the gap is maintained at such a value that the discharge takes place at 120V. Estimate the time required to complete the job. 

     12. List out at least seven practical applications of Water Jet Machining. 

     13.Describe the mechanism of material removal in EDM. 

     14. Write short notes on :

                i) Thread Rolling     ii) Explosive Forming