Platen Design

[datbuko]

Hello everyone,
I am a recent graduate and working at my first job. As my project I am in charge of a platen structure design. As for how it is stacked up, from bottom up, it is a .5" steel contact plate, then a 2.5" al. heating plate, with cartridge heaters inserted through it, then finally the insulation/cover attached to a top frame. Right now, the current design has this all bolted down with 1/2" bolts. In my opinion, the heat is causing the contact plate to have local deformities due to the bolts not allowing for the platen to expand with increasing temperature (400+ deg F).
If I am correct, I was going to increase the size of the clearance holes and use PTFE washers to allow for the bolts to slide with the expanding plate. What do you guys think?

Thank you in advance for any help given.

David

 

[FredRosse]

Thermal expansion, and distortion due to constraining bolts is a common problem, and letting the plates slide on each other can reduce this problem. Judgement of this is difficult without details, is this platen 1 ft diameter or 20 ft diameter? You might also consider a thermal contact grease or other elastic material to reduce the thermal contact resistance, which can easily be the biggest thermal resistance in the system.

 

[datbuko]

Thank you FredRosse for your help. In regards to your question the platen is along the lines of 42x48". As for the elastic material, do you know of any with good thermal conductivity?