Materials Science and Manufacturing Engineering Miscellaneous Easy Questions and Answers

Materials Science and Manufacturing Engineering Miscellaneous

A drilling machine has to be designed with 8 spindle speeds ranging approximately between 120 to 1200 rpm. The 5th spindle speed is

Assertion (A): Single start threads are used for fastening purposes.
Reason (R): Single start threads are easier to produce in a lathe.

1. Both A and R are true and R is the correct explanation of A
1. Both A and R are true but R is not a correct explanation of A
1. A is true but R is false
1. A is false but R is true

A through hole is drilled in an aluminium alloy plate of 15 mm thickness with a drill bit of diameter 10 mm, at a feed of 0.25 mm/rev and a spindle speed of 1200 rpm. If the specific energy required for cutting this material is 0.7 N-m/ mm³, the power required for drilling is ___ W (round off to two decimal places).

The length, width and thickness of a steel sample are 400 mm, 410 mm, 40 mm and 20 mm, respectively. I ts thickness needs to be uniformly reduced by 2 mm in a single pass by using horizontal slab miling. The miling cutter (diameter: 100 mm, width; 50 mm) has 20 teeth and rotates at 1200 rpm. The feed per tooth is 0.05 mm. The feed direction is along the length of the sample. If the over-travel distance is the same as the approach distance, the approach distance and time taken to complete t he required machining task are:

Q = MRR =	π D²	× f × N
	4

=	π × (10)²	× 0.25 ×	1200	= 125π mm³/sec
	4		60

Q = MRR =	π D²	× f × N
	4

=	π × (10)²	× 0.25 ×	1200	= 125π mm³/sec
	4		60