The cast iron lapping plates are used for accurate hand-lapping of workpieces to obtain high accuracy of flatness and roughness. These cast iron lapping plates are extensively used in manufacturing or repairing the measurement tools, lapping parts, manufacturing high-precision mechanical parts and processing the optical instruments, etc. These lapping plates are coated with abrasive sand and can be used with a grinding tool to lap the parts to achieve a surface roughness less than Ra0.08mm.
These cast iron lapping plates are made of high-strength and close-grained gray cast iron available at Grade of GG-20, GG-25 or GG-30 on request. Also it can be made of cast steel. The lapping plate hardness is in the range of HB170-240. Cored and ribbed construction, twice annealing heat treaments at a temperature in the range of 600-700° C (the 1st annealing is done right after casting, the 2nd annealing is done right after the rough machining on the plate) and the following aging treatment are adopted on the plate to relieve the stress, ensure high stability and maintain its long-time accuracy free from distortion. These plates are necessary tooling base plates widely used in workshops.
The surface can be plain flush surface for lapping, marking and layout operations. Also top surfaces of these cast iron plates can be designed with T-slots, threaded holes for purpose of clamping workpieces.
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