Abrasive Wheels Training Certificate Abrasive Wheel Types and Selection — Questions and Answers
Question 1: Which type of abrasive wheel is most commonly used for cutting ferrous metals such as mild steel?
- Silicon carbide wheel
- Aluminium oxide wheel (Correct answer)
- Diamond wheel
- CBN (Cubic Boron Nitride) wheel
Correct answer: Aluminium oxide wheel
Aluminium oxide wheels are the standard choice for grinding and cutting ferrous metals like mild steel, cast iron, and wrought iron. Silicon carbide is used for non-ferrous metals and stone.
Question 2: What does the letter 'A' represent in the standard abrasive wheel marking system (e.g., WA 60 K 5 V)?
- The bond type
- The abrasive grain type (Correct answer)
- The wheel grade (hardness)
- The structure number
Correct answer: The abrasive grain type
In the standard marking system, the first letter(s) indicate the abrasive type. 'A' stands for aluminium oxide and 'C' for silicon carbide. The sequence is: Abrasive type – Grain size – Grade – Structure – Bond type.
Question 3: Which abrasive wheel type would be most appropriate for cutting concrete and masonry?
- Aluminium oxide depressed centre wheel
- Silicon carbide flat cutting disc
- Diamond-impregnated cutting wheel (Correct answer)
- Wire-brushed flap disc
Correct answer: Diamond-impregnated cutting wheel
Diamond-impregnated cutting wheels are the preferred choice for cutting concrete, masonry, and stone. They provide superior performance and longevity compared to silicon carbide on these hard, non-metallic materials.
Question 4: A grinding wheel marked with a grain size of '60' would be classified as which type?
- Coarse
- Medium (Correct answer)
- Fine
- Very fine
Correct answer: Medium
Grain sizes are classified as: Coarse (8-24), Medium (30-60), Fine (70-180), and Very Fine (220-600). A grain size of 60 falls at the upper end of the medium range.
Question 5: What is the primary purpose of a flap disc when used on an angle grinder?
- Precision cutting of thin metal sheets
- Blending, finishing, and deburring metal surfaces (Correct answer)
- Drilling holes in masonry
- Polishing glass surfaces
Correct answer: Blending, finishing, and deburring metal surfaces
Flap discs consist of overlapping abrasive flaps bonded to a backing plate. They are designed for blending welds, finishing surfaces, and removing burrs. They provide a smoother finish than standard grinding discs.
Question 6: In the abrasive wheel marking 'WA 46 L 7 V', what does the letter 'V' indicate?
- The wheel's maximum operating speed
- The vitrified bond type (Correct answer)
- The vendor's quality rating
- The wheel's vibration class
Correct answer: The vitrified bond type
The last letter in the standard marking indicates the bond type. 'V' represents vitrified bond (ceramic), which is the most common bond type. Other codes include B (resinoid), R (rubber), and M (metal).
Abrasive Wheels Training Certificate Abrasive Wheel Types and Selection
Which type of abrasive wheel is most commonly used for cutting ferrous metals such as mild steel?