Grinding wheel structure selection An open-structure grinding wheel (more porosity, greater chip space) is recommended for which types of work materials?

Introduction / Context:
Grinding wheel structure refers to the spacing between abrasive grains. An open structure provides more voids to hold coolant and chips. Correct structure selection prevents wheel loading and improves thermal management and surface finish.

Given Data / Assumptions:

• Conventional abrasives (Al2O3 or SiC) and vitrified or resinoid bonds.
• Goal is to reduce loading and maintain cutting efficiency.
• Materials include soft, tough, or ductile alloys prone to smearing.

Concept / Approach:
Soft, ductile, or tough materials (e.g., aluminium, low-carbon steels, copper alloys) produce long, continuous chips that tend to clog the wheel. An open structure creates larger chip pockets and improves coolant access, reducing glazing and burn. Hence these materials benefit from open structure combined with a relatively soft grade and coarser grit.

Step-by-Step Solution:

Verification / Alternative check:
Handbooks recommend open-structure wheels for gummy or low-strength alloys; in contrast, hard-brittle materials often use denser structures and finer grits for surface integrity.

Why Other Options Are Wrong:
Limiting to only one category misses the broader application; all three categories can benefit.Only hardened tool steel: typically requires different grit/grade/structure and not necessarily very open structures.

Common Pitfalls:
Using dense, fine, hard wheels on soft metals causes glazing, heat, and poor finish. Balance wheel grade, structure, and coolant for best results.

Final Answer:

All of these