Grinding wheel grade selection The grade (hardness) of a grinding wheel should be chosen considering which of the following factors?
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AHardness of the material being ground
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BSpeed of the wheel and the work
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CCondition and rigidity of the grinding machine
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DAll of these
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ENone of these
Answer
Correct Answer: All of these
Explanation
Introduction / Context:Wheel grade indicates how strongly the bond holds abrasive grains. Selecting the correct grade controls self-sharpening behavior, heat generation, and surface quality. An inappropriate grade leads to glazing, burn, or rapid wheel wear.
Given Data / Assumptions:
- Conventional surface/cylindrical grinding with Al2O3 or SiC wheels.
- Work materials vary from soft to hard, ductile to brittle.
- Machine stiffness and speed conditions differ.
Concept / Approach:Hard work materials usually call for a softer wheel grade to expose fresh sharp grains. Higher speeds or light cuts often pair with softer grades to avoid glazing. On flexible machines, a softer grade helps prevent chatter by limiting rubbing and heat buildup. Thus, multiple factors must be weighed together.
Step-by-Step Solution:
Relate work hardness → choose softer grade for harder work to promote self-sharpening.Relate speed/load → higher speed and lighter DOC benefit from slightly softer grades.Relate machine condition → poor rigidity favors softer wheels to reduce forces.Verification / Alternative check:Manufacturer selection charts correlate grade with work hardness, speed, feed, and machine power/rigidity.
Why Other Options Are Wrong:Focusing on only one parameter ignores interactions; tool–work dynamics are multivariate.
Common Pitfalls:Selecting a hard grade for hard steels causes glazing and burn; selecting too soft a grade for robust setups leads to rapid wear and loss of form.
Final Answer:
All of these