Abrasive Wheels Training Certificate Mounting and Balancing

Question 1

What is the primary purpose of blotters (compressible washers) when mounting an abrasive wheel?

Accepted Answer

To distribute clamping pressure evenly and prevent stress concentration

Answer

Blotters (compressible washers made of paper or card) are placed between the flanges and the wheel to distribute clamping pressure evenly across the wheel surface. This prevents localised stress points that could cause the wheel to crack.

Question 2

When tightening the spindle nut on an abrasive wheel, how tight should it be?

Accepted Answer

Hand tight, then one quarter turn with a spanner

Answer

The spindle nut should be hand tight plus approximately one quarter turn with a suitable spanner. Over-tightening can cause excessive stress on the wheel, potentially leading to cracking and catastrophic failure during use.

Question 3

What is the recommended standing position when first starting an abrasive wheel after mounting?

Accepted Answer

To one side of the wheel, out of the plane of rotation

Answer

After mounting a new wheel, the operator should stand to one side, out of the plane of rotation, when first starting the machine. If the wheel has an undetected defect, fragments will fly outward in the plane of rotation. HSE guidance specifically recommends this precaution.

Question 4

What minimum period should a newly mounted vitrified abrasive wheel be allowed to run at full operating speed before use?

Accepted Answer

1 minute

Answer

HSE guidance recommends that a newly mounted vitrified wheel should be run at full operating speed for at least 1 minute before applying any work. For resinoid-bonded wheels, the recommended time is 30 seconds. This allows any defective wheel to fail before the operator approaches.

Question 5

What is the maximum permissible gap between the wheel and the work rest (toolrest) on a bench grinder?

Accepted Answer

2 mm

Answer

According to HSE guidelines, the gap between the abrasive wheel and the work rest should not exceed 2 mm. A larger gap increases the risk of the workpiece being drawn into the gap and jamming, which could cause the wheel to shatter.

Abrasive Wheels Practice Test

Abrasive Wheels Practice Test

Abrasive Wheels Training Certificate Mounting and Balancing