Precision Lapping: How Lapping Tool Material and Shape Affect Accuracy
In precision lapping, the lapping tool that carries the abrasive grains affects the geometric accuracy and surface condition of the workpiece. This article covers key points on lapping tool material hardness, manufacturing accuracy and structure, and explains the difference in function between lapping sleeves and lapping plates, to help readers understand the applicable boundaries of different lapping tools.
This article discusses the lapping tools used in precision lapping: the lapping tool carries the abrasive grains, which can become embedded in its surface layer. The lapping tool's material, geometric accuracy and surface condition jointly affect the machining result of the workpiece.
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Hardness and wear resistance of lapping tool materials
The source states that the lapping tool material should have a uniform structure, a hardness lower than that of the workpiece, and should combine elasticity, wear resistance and minimal deformation. Lower hardness helps the abrasive grains embed in the lapping tool; however, if the material is too soft, it is also prone to premature wear and deformation of the lapping tool.
The manufacturing accuracy of the lapping tool should be no lower than the requirements for the workpiece, and its surface roughness value should be no higher than that of the surface being lapped. Cracks, spots and casting defects are all surface issues that require attention.
Common materials each have their corresponding applications
The source lists several categories of lapping tool materials for precision lapping (Lapping): gray cast iron, ductile iron and high-phosphorus cast iron are commonly used for hardened steel parts; babbitt metal can be used for copper and other soft metals; mild steel can be used for complex profiles such as threads. When copper or aluminum is used for rough lapping with a larger stock allowance, the lapping tool itself also wears more; felt and leather are used for lapping or polishing soft metals.
Lapping tools of similar shape also differ in function
Flat precision lapping (Lapping) commonly uses lapping plates and lapping straightedges. The grooves on a plate serve to remove excess abrasive and improve contact uniformity; the source also notes that extremely fine lapping places different requirements on the plate structure. Lapping straightedges are mostly used for machine tool guideways.
For precision lapping (Lapping) of external cylindrical surfaces, a lapping sleeve can be used to improve cylindricity; a lapping plate mainly improves the straightness of the generatrix, and it cannot be inferred from this that cylindricity will also improve. For precision parts with irregular surface structures such as oil grooves and grooves, the source explicitly states that lapping plates should not be used. Conical lapping tools must match the shape of the workpiece and have an accurate geometric form.
Source and Compilation Notes
Source: VTOALL Machining Encyclopedia, original date: 2024-07-09. This article is a summary and compilation of technical information.