Follow these simple suggestions to help minimize the cost of your ceramic component.
DESIGNATE MODERATE “AS-FIRED” TOLERANCES ON PORTIONS OR FEATURES THAT ARE NOT CRITICAL.
I manufacture a variety of ceramic components that are used in a variety of applications and industries. Unique process technology is applied to manufacture these components in which green (unfired) bodies are formed from raw materials and are then machined, fired and then can be diamond ground and machined. Because the only material harder than ceramic is diamond, post sintering processing of ceramics can be relatively expensive because of the use of diamond grinding wheels and slurries, etc.
The most economical ceramic component you can design is one that uses “AS-FIRED” conditions and tolerances. You can minimize the cost of your ceramic component by allowing +/- 1% of a linear dimension as its tolerance (or +/- .005″ whichever is greater). If you can’t use +/- 1%, as a tolerance, review your design to see what you could use. In some cases, we can control our AS-FIRED tolerance to less than a half of one percent.
Allow for .010″ T.I.R. on parts that are “AS-FIRED”. On ground components, .005″ T.I.R. is the least expensive. On precision parts that have to be concentric, .001″ is the cheapest. Usually when we O.D. grind, we will be in the .0002″ / .0003″ ballpark. Concentricity of 1 tenth or 50 millionths require added cost and special operations.
FLATNESS OR CAMBER
Flatness (Camber) should be noted as .006″ of an inch…per inch.
The AS-FIRED surface should be specified to have a 63 microinch surface finish max. If you have a dimension that you have to have ground and polished, a 10 to 14 microinch surface finish is normal. A 2 to 4 microinch surface finish is the most expensive.
CAN YOU LEND US YOUR SAMPLE?
If you are considering changing an existing component to ceramic, we can make suggestions about tolerances, shapes, features, etc. if we can borrow a sample you have been working with so far.