Grinding wheel glazing — when does it occur? Glazing is the condition where the wheel surface becomes shiny and stops cutting effectively. Under which conditions is glazing most likely to occur?

Introduction / Context:
Grinding relies on self-sharpening: dull grains should fracture or pull out to expose fresh cutting edges. When this does not happen, the surface “glazes,” reducing stock removal and increasing heat and burn risk.

Given Data / Assumptions:

• Abrasive type and grade influence grain retention.
• Peripheral speed affects force per grain and cutting temperature.
• Work material is steel for illustration.

Concept / Approach:
A hard-grade wheel holds grains too firmly; dull grains remain, rubbing instead of cutting. Excessive wheel speed raises rubbing action and temperature, further polishing the surface. Both conditions promote glazing. Conversely, a softer grade at appropriate speed allows dull grains to shed, maintaining a sharp wheel face.

Step-by-Step Solution:
Relate glazing to inadequate grain renewal.Identify causes: hard grade and/or excessively high surface speed.Choose the option that captures these causes.

Verification / Alternative check:
Dressing removes glazed layers; after dressing, the wheel cuts freely again, confirming that the previous surface was polished/dull rather than sharp.

Why Other Options Are Wrong:
Soft wheels or very low speeds tend to avoid glazing (but may cause other issues like wheel breakdown). “Hard + very low speed” reduces rubbing per grain; “soft + very high speed” more likely leads to breakdown, not glazing. Coolant flow alone does not cause glazing.

Common Pitfalls:
Confusing glazing with loading (chip packing). Loading is common on soft gummy materials like aluminum and appears as embedded swarf, not a polished surface.

Final Answer:
Wheel too hard or wheel speed very high