Size and shape of abrasive grains can affect lapping action.
Water-based vehicles are most commonly used for lapping ceramic, although oil vehicles can work in some cases.
Depending on the equipment, the vehicle also may have to carry away heat developed by lapping.
Flat lapping and polishing achieve the highest parallelism and uniformity of size when set up to perform abrasive machining on both sides of workpieces simultaneously in batchmode processing.
Typically, double-side lapping in batch modes uses rotating workholders that guide workpieces uniformly between the rotating lapping wheels (Figures 7).
To lap or polish away taper, bow, and size variation, it's necessary to control lapping pressure accurately.
Today's double-side lapping machines achieve consistent results by providing programmed soft-touch approach and pressure application.
A continuous flow of abrasive slurry evenly applied to the top and bottom lap surfaces and uniformly distributed over the complete lapping area results in accuracy in size, flatness, surface finish, and uniform production.
Machines for cylindrical lapping employ two annular laps, each mounted on a vertical spindle (Figure 9).
Controlled lapping occurs as the parts slip and slide during rolling, caused by the nonradial direction of the workholder slots (Figure 8).
The starting lapping pressure is applied to the larger parts until all parts are of equal size and straightness.