Abrasive Wheels Training Certificate Mounting and Balancing 2

Question 1

What must be checked about the flanges before mounting an abrasive wheel?

Accepted Answer

That they are clean, flat, undamaged, and of equal diameter (at least one-third of wheel diameter)

Answer

Flanges must be clean, flat, undamaged, and of equal diameter. The flange diameter should be at least one-third of the wheel diameter. Damaged or unequal flanges create uneven pressure distribution, which can cause the wheel to crack during operation.

Question 2

Why should an abrasive wheel never be force-fitted onto a spindle?

Accepted Answer

Forcing can crack the wheel, leading to catastrophic failure at operating speed

Answer

Force-fitting an abrasive wheel can cause invisible internal cracks. When the wheel is spun at operating speed, centrifugal forces can cause these cracks to propagate rapidly, resulting in catastrophic wheel failure and potential serious injury or death.

Question 3

On a double-ended bench grinder, what is the purpose of the tongue guard (spark guard)?

Accepted Answer

To prevent sparks from reaching the operator and to limit the exposed portion of the wheel

Answer

The tongue guard (also called a spark guard or spark arrestor) serves to deflect sparks away from the operator and to limit the exposed portion of the wheel. It should be adjusted to within 6 mm of the wheel as the wheel wears down.

Question 4

What should be the maximum gap between the tongue guard and the abrasive wheel on a bench or pedestal grinder?

Accepted Answer

6 mm

Answer

The maximum gap between the tongue guard and the wheel should not exceed 6 mm. As the wheel wears and its diameter decreases, the tongue guard must be adjusted to maintain this clearance. This is separate from the 2 mm work rest gap requirement.

Question 5

What is the correct method for checking an abrasive wheel for cracks before mounting (the 'ring test')?

Accepted Answer

Suspend the wheel on a pin or finger through the bore and tap gently with a non-metallic implement, listening for a clear ring

Answer

The ring test involves suspending the wheel vertically on a pin or finger through the bore hole and tapping it gently with a non-metallic implement (such as a screwdriver handle). A sound, undamaged wheel produces a clear, metallic ring. A dull or dead sound indicates a crack.

Abrasive Wheels Practice Test

Abrasive Wheels Practice Test

Abrasive Wheels Training Certificate Mounting and Balancing 2