Lapping

Lapping
Lapping is the method of obtaining a fine finish. Lapping is basically an abrasive process in which loose abrasives function as cutting points finding momentary support from the laps. Following Figure represents the lapping process. Material removal in lapping usually ranges from .003 to .03 mm but many reach 0.08 to 0.1mm in certain cases.
Characteristics of lapping process:
 Use of loose abrasive between lap and the work piece.
 Usually lap and work piece are not positively driven but are guided in contact with each other.
 In order to avoid the repetitive path of the abrasive grains of the lap on the work piece, relative motion between the lap and the work should change continuously
Fig.10.Lapping process
Cast iron is the mostly used lap material. However, soft steel, copper, brass, hardwood as well as hardened steel and glass are also used.
Abrasives of lapping
LAP
Work Piece
Abrasive particle
Vehicle
 Al2O3 and SiC, grain size 5~100μm
 Cr2O3, grain size 1~2 μm
 B4C3, grain size 5-60 μm
 Diamond, grain size 0.5~5 V
Vehicle materials for lapping
 Machine oil
 Rape oil
 grease
Technical parameters affecting lapping processes
 unit pressure
 grain size of abrasive
 concentration of abrasive in the vehicle
 lapping speed