81) The best position to hold the job in the vice when filing is
Related Cutting Tools MCQ - Machinist(Set-1) with Answers
The tap has coarse threads
The job will be out of round
If the job is loosely fitted between centres in cylindrical grinding the job will become out of round.
Grain size is too fine and Wheel is hard
When a surface of the wheel develops a smooth and shining appearance, it is said to be glazed. This indicates that the wheel is blunt, i.e. the abrasive grains are not sharp.
When such grinding wheels are used, there is a tendency to exert extra pressure in order to make the wheels cut.
Excessive pressure on the grinding wheel will lead to the fracture of the wheel, excessive heating of the wheel, weakening of bonding of the wheel and bursting of the wheel.
Vitrified Bond is the most widely used bond. It has high porosity and strength which makes this type of wheel suitable for high rate of stock removal. It is not adversely affected by water, acid, oils or ordinary temperature conditions.