More about Ceramic Machining

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Ceramics are defined as non-metallic, heat-formed materials. They include non-crystalline varieties, or glasses, as well as traditional clays. Some recognizable ceramics are bricks of a brick building, dishes, and coffee mugs. Today, however, ceramics have found use in far more advanced applications. Examples include space shuttle engine components, tank armor, superconductors, and piezoelectric devices. Because of their brittle nature, and because of the many specific, advanced forms in which they are now used, there a variety of machining operations that are performed in order to properly create durable, finished ceramic parts.

Ceramic machining processes involve forming, firing and finishing. Here, forming is only meant to represent the various operations used to shape a ceramic piece. Such operations include dry axial pressing and isostatic processing, which are both used to form dry powder; slip casting, which begins instead with a powder/liquid mix, or slurry; and injection molding, achieved only with a ceramic-plastic blend. These processes are only used to set the ceramic piece in the desired shape, not to make it strong and stable. Typically, a usable component requires a subsequent firing, or sintering, process. This process fuses the ceramic’s particles together, yielding a more durable piece. In some cases, a cementation process is used instead of firing. Cementation involves coating the ceramic with a liquid binder material, which eventually reacts to form the desired bonds.

Finishing processes can be performed before or after the firing process. Each method has its uses. Pre-firing machining is typically a less precise process, since a ceramic component will normally shrink after firing, and because pre-firing ceramics are more fragile during this stage. It is performed mainly to simplify post-firing finishing. Post-firing machining operations concern processes we might typically associate with machining. These include grinding, lapping, laser cutting, cutting and chemical etching. Many modern ceramics are designed to endure the strain and force of these heavy machining operations. Other processes used on ceramics are diamond saw-cutting and drilling, as well as electron beam machining. Due to the advances in ceramic engineering, these operations can achieve far more precision than was previously possible.