Page 163 - Module DMV20173

ANSWERS

EXERCISE 2.1

A 200-mm-long, 20-mm-diameter 304 cast irons rod is being reduced in diameter to
15.00 mm by turning on a lathe. The spindle rotates at N = 500 rpm, and the tool is
traveling at an axial speed of 100 mm/min. Calculate the cutting speed, material-
removal rate, cutting time, power dissipated, and cutting force.

Cutting speed:
V= πDN = π (20/1000)(500) = 31.42 m/min
Material Removal Rate:
d = (20-15)/2 = 2.5 mm

f = 100/500 = 0.2 mm/rev
3
MRR = π (17.5)(2.5)(0.2)(500) = 13744.47 m /min
Cutting Time:
t = 200/[(0.2)(500)] = 2 s
Power dissipated:

p = (5.4)(1924)/60 = 173W [Table 2.1, cast iron 5.4 Ws/mm ]
3
Cutting Force:
Torque, T = 173 x 60/[(500)(2)( π)] = 3.3 Nm
Force, F = 3.3 (1000)/(17.5/2) = 377 N

EXERCISE 2.2

Name two basic categories of cutting tools in machining.
Give two examples of machining operations that use each of the tooling types.

Answer: The two categories are:
(1) single-point tools, used in operations such as turning and boring;

(2) multiple-edge cutting tools, used in operations such as milling and drilling.