Lapping in Machines: What You Need to Know Now

If you want to produce a flat surface, read about lapping—a finishing operation. An abrasive slurry within a glycol solution is applied to a lapping machine’s cast-iron lap.

Likewise, a backing plate could do with a coated abrasive product. An abrasive’s fresh supply is ensured through a continuous feed system. The workpiece is rotated during the lapping process and is loaded to offer uniform pressure. This ensures uniform lapping.

While abrasives are typically brittle, hard materials, they can be softer than the work material. In this case, the finish generated or material removal involves chemo-mechanical or chemical action—not mechanical abrasive action.

How does it function?

Lapping machines comprises five components: machine, slurry, topweight, a variety of conditioning rings, the rotating table (also known as a lapping plate).

  1. Machine: It has the filter, engine, controls, along other subsidiary components to properly perform the mechanism operation.
  2. Slurry: It’s composed of a number of abrasive materials, for example, carbon/diamond, with a liquid base such as water/oil. It’s fed between the top and the lapping plate and is evenly distributed across the surface by the rotation of the plate. The small abrasives grind away at any micro irregularity in the surface of the part.
  3. Top plate: To ensure abrasion happens, it presses the pieces down. These can either be piston-like, mechanically operated covers or simple lids.
  4. Conditioning rings: It operates as the work holding device. These rings increase the life of the lapping plate by distributing the wear evenly across it. They also hold the workpiece together. For unusually long or cylindrical pieces, special rings can be fitted.
  5. Lapping plate: The motor only turns one thing, and that’s the lapping plate. As the plate turns, the conditioning rings automatically turn as well. Usually, the plate is composed of top-notch soft cast iron. However, soft metals like copper may also be used. The diameter of this plate can be 12-144 inches and may feature rings, cross-hatches, spirals, or other shapes.

What is the duration of a lapping-polishing cycle?

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A lapping cycle can be between 30 seconds to an hour. Typically, 3-15 minutes is the range for a lapping cycle. However, polishing cycles differ.

Usually, polishing cycles are up to 3 hours on the high end and 5 minutes on the low end. Typically, 10-30 minutes is the range for a polishing cycle.

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