Keep in mind, during the initial design stages, that alumina shrinks approximately 20% during firing. This means that the more complex the part design becomes the harder it is to hold tolerance stability.

The simpler designed parts can be produced more uniformly, i.e. green pressed density and sizes can be controlled. The more uniform the green density the tighter the tolerance can be held.

Tighter tolerances cost more during manufacturing, geometric tolerances look nice on the drawing, but if they are not necessary they will cost more during manufacturing and then cost you more during inspection. Even though it is easier to hold tighter tolerances on small parts, small I.D.s can cause excessive tool breakage. Wall thickness should be kept to approximately 10% of O.D. or a minimum of .020" when possible. This includes the distance between the holes as well as the distance from the I.D. to the O.D. Depth of blindholes should not be greater than 50% of overall length.

There should be as few steps or levels as possible in your new design. Multiple levels cause areas of compaction that may result in changes in green press density. These changes in density may cause the fired part to be porous and may also result in shrinkage differences causing the dimensional stability to be effected.