Breviary Technical Ceramics


      From Powder to Part




4.2 Finishing

4.2.1 Hard machining

Final machining (hard machining)

is carried out on fully sintered items that have been brought as close as possible to the final dimensions through forming, or through green or white machining. The closest possible tolerances can be achieved through a final machining procedure involving material removal.
Tight requirements for dimensional precision and the wide variety of geometries and surface qualities require the use of modern machine tools for processing ceramic components. Due to the high hardness of ceramic materials, diamond tools (bonded or pastes) are used here almost exclusively.

Figures 65 and 66: Hard machining components: grinding and lapping

Table 7: Possible finishing processes.

Grinding is of central importance. A large number of factors affect the grinding process and the result of the grinding. For this reason, the appropriate grinding wheel for any particular workpiece is selected with great care for its grain type and size, the bonding, and the hardness of the wheel. Extremely flat surfaces such as for slip rings and sealing surfaces must be lapped and then polished after grinding.



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