Grinding wheel selection for soft materials To grind comparatively soft materials efficiently without wheel loading, which grain size should be chosen?

Introduction / Context:
Grinding wheel selection balances grain size, grade (hardness), structure, and bond. For soft materials, chip size and wheel self-sharpening behavior determine performance and risk of loading (clogging).

Given Data / Assumptions:

• Material characterized as soft and gummy relative to wheel abrasives.
• Conventional abrasives (Al2O3, SiC) and standard bonds.

Concept / Approach:
Coarser grains provide larger chip pockets and stronger cutting points, promoting chip clearance and reducing wheel loading. Softer wheel grade is also typical so dull grains can release and expose new sharp edges.

Step-by-Step Solution:

Verification / Alternative check:
Grinding handbooks recommend coarse grit and open structure for soft, ductile metals to maintain cutting efficiency and surface finish.

Why Other Options Are Wrong:
Fine or ultra-fine grits have small chip spaces and quickly load up on soft materials; medium grit may still load. CBN selection depends on material (best for hardened steels), not merely softness.

Common Pitfalls:
Choosing a hard-grade, fine-grit wheel for soft metals results in glazing, burning, and rapid wheel wear.

Final Answer:

Coarse grained wheel