Question

Which of the following statements is/are CORRECT in grinding wheel selection?
1. Soft grade for soft material
2. Hard grade for hard material
3. Hard grade for soft materials
4. All of the options

Answer 1

Correct Answer - Option 3 : Hard grade for soft materials

Concept:

• The degree of hardness possessed by the bond is called its grade. Grade also indicates the ability of the bond to hold the abrasive grains in place.
• A soft bond permits the grains to break away more readily than a hard one and should be used where the abrasive becomes rapidly dulled or blunt, i.e., when grinding hard materials.
• A hard bond retains the abrasive grains longer and should be used when grinding soft materials.
• A simple rule to follow is to use a hard wheel for soft materials and a soft wheel for hard materials.

Factors affecting the selection of grade:

• Hard materials - Soft wheel
• Soft materials - Hard wheel
• Great area of contact - Soft wheel
• Low wheel surface speed - Hard wheel