Lapping is a surface finishing process that uses loose abrasive powders at low speeds to achieve very tight tolerances of flatness, parallelism, thickness, or finish. It involves mixing abrasive particles with a liquid to form a slurry, placing the slurry on a rotating lap plate, and placing the workpiece against the slurry-coated plate so the abrasive grains can modify the workpiece surface through rolling/sliding contact. A lapped surface exhibits a dull, non-reflective appearance with multi-directional texture, especially for hard materials with surface roughness under 5 micro-inches.

1. Lapping Process
By
Er. Rampal Singh Ojha

5. Lapping Process
• The term "lapping" is used to describe a number of various surface
finishing operations where loose abrasive powders are used as the
grinding agent at normally low speeds. It is a process reserved for
products that demand very tight tolerances of flatness, parallelism,
thickness or finish

6. Lapping Process
• Loose Abrasive Process-(LAP)
• Lapping Involves the Use of Abrasive Particles to Modify the Work-Pieces
• The Abrasive Particles are Mixed with a Water-Base or Oil Base Liquid. The
Combined Abrasive and Liquid are Called a “Slurry”, this is a Liquid Cutting
Tool
• The Slurry is Placed on a Rotating Motorized Platform Called a “Lap Plate”
• The Work-Piece is then Placed Against the Slurry on the Rotating Lap Plate
and the Surface of the Work-Piece is Modified
• Rolling/Sliding Action of Abrasive Grains Between Plate and Work piece

7. Lapping Process
• A surface that has been lapped exhibits a dull, non-reflective and
multi-directional appearance
• This is especially true if the material is relatively hard and the surface
roughness measurement is perhaps 5 (.127 micron) micro-inch and
below.