The Technique of Lapping
The Lapping Oil
The fluid used in the lapping medium must be chosen carefully. If the fluid (e.g. oil) is too viscous, the film formed is very thick, and if the particles are too small, their tips protrude insufficiently from the film. If the film is too thin, it may rupture and allow metal-to-metal contact between the working plate and the workpiece. An excessively greasy medium is inefficient. Abraded material therefore must be removed from the lapping area immediately. (This is comparable to the flow of swarf during machining.)
Large lapping grains – thick medium film
Small lapping grains – thin medium film
Wrong or untested fluids can lead to great time and quality losses. Inadequate or irregular rotation of the conditioning rings due to incorrect lapping agents has serious consequences for the correction effect on the working plate (also see Page 8-15).