Grinding of hard materials requires

Explanation:

Grain Size:

• The grain size of the abrasive particle is important in determining surface finish and material removal rate.
  • Small grit sizes produce better finishes, whereas larger grain sizes permit larger material removal rates.
  • Thus, a choice must be made between these two objectives when selecting abrasive grain size.
• The selection of grit size also depends to some extent on the hardness of the work material.
  • Harder work materials require smaller grain sizes to cut effectively, whereas softer materials require larger grit sizes.

Wheel Grade:

• Wheel grade indicates the grinding wheel's bond strength in retaining the abrasive grits during cutting. This is largely dependent on the amount of bonding material present in the wheel structure.
  • The grade is measured on a scale that ranges between soft and hard.
  • Soft wheels lose grains readily, whereas hard wheels retain their abrasive grains.
  • Soft wheels are generally used for applications requiring low material removal rates and grinding of hard work materials.
  • Hard wheels are typically used to achieve high stock removal rates and for grinding of relative soft work materials.