Machining instruction for 902 machinable ceramics

A. First the customer should:

- Machine parts to allow for expansion during firing. A machined dimension of 0.980" will be 1.000" after firing.               
- The diameter of a drilled hole will get larger during firing.
- The cross sectional thickness of the ceramic should be kept below ½ " to revent cracking during firing.
- Use a smooth, gentle transition from thick to thin sections and if necessary drill holes to keep the cross sectional   thickness below ½".
- Place the machined 902 ceramic part into a cold, air atmosphere furnace.

B. Heat treatment 1  - For parts with 1/4” or 1/2”thickness

 Protect from any direct flame impingement or direct contact with heating elements.Heat at 200ºF (90ºC) per hour (maximum) until a temp. of 1900ºF - 2000ºF (1035ºC - 1093ºC)is reached.

 IF part is 1/4” in thickness then hold at   1900ºF - 2000ºF (1035ºC - 1093ºC) for 1/2 hourIf parts are 1/2” in thickness then hold at this temperature for 1 hour.

 Furnace must be cooled to below 200ºF (90ºC) prior to removing the parts.for parts 1/2" in thickness (this is very important)

C.  Heat treatment 2 - Thick parts  

Protect from any direct flame impingement or direct contact with heating elements.Heat at 200ºF (90ºC) per hour until the furnace is at the temperature listed below               

Heat up to                                     
925ºF .............................................. hold for 4Hours, then heat to the next temp listed
1050ºF ............................................ hold for 4Hours, then heat to the next temp listed
1550ºF............................................. hold for 4Hours, then heat to the next temp listed
1700ºF ............................................ hold for 4Hours, then heat to the next temp listed
1950ºF ...........................................  hold for 4Hours, then Lower temperature at 200ºF/hour.                 
Cool parts for a minimum of 4 Hours, in the closed furnace
Note : Fired 902 Ceramic can be ground wet with Silicon carbide wheels.                 

D. Heat treatment 3 Should be used for difficult parts (can also be used for any part )

Protect from any direct flame impingement or direct contact with heating elements.
Heat furnace  at  a rate of 50ºF per hour until    600ºF
Then continue heating at 35ºF per hour between from 600ºF  to 1200ºF
Then heat at a rate of 15ºF per hour until you reach  1950ºF
Cool parts at a maximum rate of 200ºF per hour.                                
Furnace must be cooled to below 200ºF (90ºC) prior to removing the parts.