Machinable Ceramic Materials 3

[biomech21]

I am designing a heat staking fixture (inserts brass inserts into thermoplastic parts with the aid of heat) for the injection molding industry. The staking procedure requires temperatures of around 300 degrees F and the machine can handle a max of around 1000 degrees F as long as insulation is present between the heated probe tips and upper carriage. This insulation is generally 1" thick, but the identity of the material is kept proprietary by many manufacturers. The insulation must be MACHINABLE and able to withstand approx. 100psi. Does Macor sound like a probable alternative? Does anyone know of a cheap material that should be able to perform well in these conditions. I've attached a photo of a similar fixture for reference. The insulation is the layer sandwiched between the two aluminum plates.

 

[btrueblood]

Macor is nice stuff, but not that great of a thermal insulator (k = 1.4 W/m-K). Better than typical metals, but not as good as some other ceramic materials.

Foamed silica is about 10x better insulation, and is machineable if you are careful (.15 W/m-K):

http://www.foundryservice.com/Foam-50 Data Sheet.pdf

 

[btrueblood]

Sorry, forgot to add: Macor may well do ok for you, you'd have to do the thermal analysis and/or test it.

 

[ScottyUK]

If the thermal insulator block is permanently held in compression - as it appears to be - then would mica be an option?


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If we learn from our mistakes I'm getting a great education!

 

[desertfox]

Hi biomech21

Look at this material:-

http://www.cotronics.com/vo/cotr/pdf/914.pdf

More to choose from including MACOR on this page:-

http://www.cotronics.com/vo/cotr/cm_machinable.htm

desertfox

 

[unclesyd]

The OP was given similar information several days ago in his double post in the Ceramic Engineering Forum.

Here is the insulation, Super Firetemp, we use by the truck load for very similar applications. Super Firetemp is a good insulator and readily machinable.

http://www.monoco.com/Super_Firetemp.asp