Stephen Malkin

This comprehensive, self-contained work brings to the reader what is known to date about grinding and how that knowledge can be translated into exceptional precision in part manufacturing. Structured to educate as well as serve as a shop-floor reference, the book bridges the gap between theory and application, presenting a critical and unified picture of the grinding process and how its use brings part quality in harmony with customer expectations.

An investigation is reported of the forces and energy in circular sawing and grinding of gray granite. Measurements were made of the forces and power over a wide range of sawing and grinding conditions. Calculated tangential force components were found to be much different than the measured horizontal force components for sawing, but the two forces were almost identical for grinding. The location of the resultant force was proportionally further away from the bottom of the cutting zone with longer contact lengths. For sawing, the normal force per grain was nearly proportional to the calculated undeformed chip thickness. The G-ratios at different sawing rates reached a maximum value at the same intermediate undeformed chip thickness, which was attributed to a transition in the diamond wear mechanism from attrition to fracture at a critical normal force per grain. SEM observations indicated material removal mainly by brittle fracture, with some evidence of ductile plowing especially for grinding and to a lesser extent for sawing. The corresponding fracture energy was estimated to constitute a negligible portion of the total energy expenditure. About 30 percent of the sawing energy might be due to the interaction of the swarf with the applied fluid and bond matrix. Most of the energy for sawing and grinding is attributed to ductile plowing. Analogous to recent studies on grinding of ceramics and glass, the power per unit width was found to increase linearly with the generation of plowed surface area per unit width.

Experimental measurements of grinding temperatures are used to estimate the energy partition to the workpiece. In the present investigation, three different temperature measuring techniques are compared for estimating the energy partition in grinding. Grinding temperatures were measured in the workpiece subsurface under identical surface grinding conditions using an embedded thermocouple and a two color infrared detector, and on the workpiece surface using a foil/workpiece thermocouple. All three methods gave comparable temperature responses which were consistent with analytical predictions for the same energy partition.

A new thermocouple fixation method for grinding temperature measurement is presented. Unlike the conventional method using a welded thermocouple, this new method uses epoxy for affixing the embedded thermocouple within a blind hole in the workpiece subsurface. During grinding, the thermocouple junction is exposed and bonded to provide direct contact with the ground surface by the smearing of the workpiece material. Experiments were conducted to evaluate this simplified thermocouple fixation method including the effect of thermocouple junction size. Heat transfer models were applied to calculate the energy partition for grinding under dry, wet, and minimum quantity lubrication (MQL) conditions. For shallow-cut grinding of cast iron using a vitreous bond aluminum oxide wheel, the energy partition using a small wheel depth of cut of 10 μm was estimated as 84% for dry grinding, 84% for MQL grinding, but only 24% for wet grinding. Such a small energy partition with wet grinding can be attributed to cooling by the fluid at the grinding zone. Increasing the wheel depth of cut to 25 μm for wet grinding resulted in a much bigger energy partition of 92%, which can be attributed to fluid film boiling and loss of cooling at the grinding zone.