Abrasive Wheels Training Certificate Safe Mounting & Dressing Procedures

Question 1

Under PUWER 1998, who is authorised to mount abrasive wheels in the UK?

Accepted Answer

Only a person who has received adequate instruction and training — an 'appointed person' designated by the employer

Answer

PUWER 1998 requires that only persons who have received adequate instruction and training — typically designated as an 'appointed person' or 'competent person' for abrasive wheel mounting — may mount abrasive wheels. This applies to both angle grinders and bench grinders. Untrained mounting is a legal offence.

Question 2

What checks must be made before mounting an abrasive wheel?

Accepted Answer

Ring test, visual inspection for cracks/damage, check wheel specification matches machine speed rating, check bore size matches spindle

Answer

Before mounting: (1) perform the ring test; (2) visually inspect for cracks, chips, or damage; (3) confirm the wheel's maximum RPM rating exceeds the machine spindle speed; (4) verify the bore size matches the spindle; (5) check the wheel is the correct type and specification for the intended work. All checks must be completed.

Question 3

What is the purpose of blotting paper (compressible washers) between the wheel flanges and the abrasive wheel?

Accepted Answer

To distribute clamping pressure evenly across the wheel face, preventing stress concentration and cracking when flanges are tightened

Answer

Blotting paper (or paper, felt, or rubber) washers distribute the clamping load from the flanges uniformly across the wheel face, preventing point-loading stress concentrations that could crack the wheel when the flanges are tightened. They also provide slight damping and protect the wheel face from direct hard metal contact.

Question 4

How should the flanges (clamping plates) that retain an abrasive wheel be sized?

Accepted Answer

Each flange must be at least one-third of the wheel diameter and of equal size; the recessed face must bear on the wheel

Answer

Regulations and standards require that both flanges be at least one-third the wheel diameter and of equal diameter. Undersized flanges concentrate the clamping force near the bore, creating stress and leaving the outer portion of the wheel unsupported. Recessed flanges must have their flat face in contact with the wheel.

Question 5

In which direction should the flange nut be tightened on a right-hand grinding spindle?

Accepted Answer

Clockwise (right-hand thread) — the grinding reaction torque self-tightens a standard right-hand thread

Answer

On a standard right-hand (clockwise) rotating spindle, the thread is RIGHT-HAND so that the cutting reaction torque tends to self-tighten the nut. This prevents the nut loosening under load. However, angle grinders with left-hand spindle threads (to self-tighten with the rotation direction) use left-hand thread nuts — always check the machine manual.

Abrasive Wheels Practice Test

Abrasive Wheels Practice Test

Abrasive Wheels Training Certificate Safe Mounting & Dressing Procedures