Direct Visual Observation
Color Change: A normal resin grinding wheel has a uniform color. After overheating, the surface will turn black, showing burnt yellow marks. Localized carbonized areas will become significantly darker, and the larger the carbonized area, the more severe the overheating.
Abnormal Surface Condition: After overheating, the resin softens, accelerating the shedding of abrasive grains. The grinding wheel surface will show uneven wear, with abrasive grains flakeing off in pieces. Some wheels may also show minor cracks or edge chipping.
Odor Judgment
After overheating, the resin will decompose, emitting a distinct burnt resin odor, clearly different from the metallic smell of normal grinding. The stronger the odor, the higher the degree of overheating and carbonization. If it is a rubber-bonded grinding wheel, prolonged overheating will produce a sour, aging rubber smell.
Vibration and Hand Feel Judgment: Overheating and carbonization disrupt the grinding wheel's balance, causing significantly increased vibration during idle running. A sudden increase in vibration during normal grinding likely indicates overheating and damage to the grinding wheel structure.
When using hand tools, significantly greater-than-normal handle vibration and abnormally hot workpiece temperatures also indicate excessive heat buildup on the grinding wheel.
Abnormal Machining Performance: Overheating can cause two extreme performance abnormalities in the grinding wheel:
Sudden Increase in Wear: Extensive abrasive shedding leads to a sudden drop in cutting/grinding efficiency; the grinding wheel wears much faster than normal for the same machining load.
Passivation and Chip Exhaustion: Softened resin clogs pores, resulting in a shiny, passivated surface that cannot grind the workpiece, with significantly increased feed resistance.
