1.3 GRINDING WHEELS
• The wheels are typically made with a bonded abrasive.
• common abrasives used are,
Aluminum oxide
Silicon carbide
• Grain size is typically from 6 to 600.
• The bonding mechanisms used commonly are,
- vitrified
- resinoid
- rubber
- shellac
- silicate
• The Grade of the wheel is a measure of the ability to retain grit. If a wheel is Grade A it is soft, if it is Grade Z, it is very hard.
• The wheels are also given a structure number. 1 indicates a dense structure, whereas, 15 indicates an open structure.
• Loading of a wheel refers to the embedding of swarf in the voids.
• Glazing occurs when the grit has dulled, but is still bonded to the surface.
• Grinding wheels should undergo a dressing process.
• Many grinding wheels are shaped. This shaping is done while the wheel in the machine using diamond, or other hard shaping tools.
1.3.1 Operation Parameters
• The wheel can be made to act soft by increasing work speed, and decreasing wheel speed. The wheel can be made to act hard by reversing the parameters.
• Typical operation parameters are a depth per pass.
• The wheel normally turns to give a CS of 3500 to 6000 fpm and wheels range from diameters of a few inches to a few feet.
• The table feed is 80-350 fpm for finishing passes. Up to 1000 is reasonable.
• For surface grinding
