Abrasive Wheels Training Certificate Ring Test & Speed Ratings

Question 1

What is the purpose of the 'ring test' for abrasive wheels?

Accepted Answer

To detect cracks in the wheel by listening for a clear ringing sound when tapped — a dull or dead sound indicates a crack

Answer

To check whether the wheel is in balance on the spindle

Answer

To verify the wheel bore diameter is correct

Answer

To measure the wheel's RPM rating accuracy

Question 2

Which types of abrasive wheel can be reliably ring-tested?

Accepted Answer

Vitrified and silicate bonded wheels — resinoid, rubber, and shellac bonded wheels cannot be reliably ring-tested as they absorb sound

Answer

All abrasive wheels regardless of bond type

Answer

Only wheels above 200mm diameter

Answer

Only new wheels that have never been used

Question 3

How should a wheel be supported when performing the ring test?

Accepted Answer

Suspended on a finger through the bore or held vertically on a peg, so the wheel is free to vibrate naturally

Answer

Placed flat on a bench and tapped on the upper face

Answer

Clamped in a vice at the bore

Answer

Held firmly in both hands against the chest

Question 4

Where on the circumference of the wheel should the ring test be applied?

Accepted Answer

At four points approximately 45 degrees from the vertical (not at the top) to assess the full circumference of the wheel

Answer

Only at the top (12 o'clock position)

Answer

Only at the sides (3 and 9 o'clock positions)

Answer

At the bore only — the outer rim does not affect ring test accuracy

Question 5

What constitutes a failed ring test and what action must be taken?

Accepted Answer

Any dull, dead, or inconsistent sound instead of a clear ring — the wheel must be destroyed and disposed of; it must not be used or returned to stock

Answer

A slightly quieter ring is acceptable for wheels that have been stored for over a year

Answer

The wheel can be used at reduced speed if it produces a dull sound

Answer

A failed ring test can be confirmed by a second test; if the second test passes, the wheel is acceptable

Question 6

What additional check must be carried out for large vitrified wheels after mounting, beyond the ring test?

Accepted Answer

A static balance check to ensure the wheel runs without vibration, which can cause cracking and bearing wear

Answer

A dynamic balance check using specialist equipment for all wheels above 150mm

Answer

An ultrasonic scan to confirm no internal voids

Answer

A hardness test at four points around the circumference