2.2.1 Uncut Chip Thickness or Grain Penetration Depth
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The starting point for any discussion on grinding parameters is “uncut chip thickness,” hcu, as this provides the basis for predictions of roughness, power, and wear [Shaw 1996]. Uncut chip calculations are typically based on representations of the material removed in the grind process as a long, slender, triangular shape with a mean thickness, hcu. However, a more practical way of looking at this parameter is to think of hcu as representing the depth of abrasive grit penetration into the work material. In fact, this parameter is often termed the grain penetration depth. The magnitude of hcu may be calculated from the various standard parameters for grinding and the surface morphology of the wheel.
where vs = wheel speed, vw = work speed, ae = depth of cut, de = equivalent wheel diameter, C = active grit density, and r = grit cutting point shape factor.
Other useful measures of grain penetration include equivalent chip thickness h = a. v Iv.
or і r eq e w s
However, equivalent chip thickness takes no account of the spacing of the grains in the wheel surface.
2.2.2 Wheel Speed
Wheel speed, vs, is given in either meterslsecond (mls) or surface feet per minute (sfpm). To convert the former to the latter, use a rule of thumb multiplication factor of approximately 200 (or 196.85 to be precise).
2.2.3 Work Speed
Work speed, vw, is a term most typically applied to cylindrical grinding; equivalent terms for surface grinding are either traverse speed or table speed.
2.2.4 Depth of Cut
Depth of cut, ae, is the depth of work material removed per revolution or table pass.