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Heat resistant plastic part

Heat resistant plastic part

Heat resistant plastic part

(OP)
Problem:
So I recently purchased an FDM 2000 3D printer.  It was very neat when it was working.  I had to reload the material and noticed the head was leaking (from previous owner) creating a huge ball of plastic.  I knew the problem would only get worse so I disassembled it.

The picture shows the cold side of the heat chamber where the solid material is fed in. The plastic fitting on the end of the aluminum tube (heating chamber) had a broken boss which caused the material to leak between the fitting and tube as seen in the picture.  You can also see the heating element dangerously close. The tube was wrapped in fiberglass tape and foil tape to keep the heat in.

The maximum recommended temperature to set the nozzle to is 290degC (There is a thermocouple at the other end (nozzle end) where the material comes out).  Clearly this plastic part is made from a high temperature plastic (no clue which one).  If it helps, this thing was designed in the early to mid 90's.  I looked at Ultem and PEEK neither of which are rated to 290degC operating temperatures.  I could assume that the part will shed heat fast enough to keep it below the tip temperature setting but I want a foolproof plan so I don't have to revisit the problem.



Solution:
So I need to replace this.  Put in a call with Stratasys to find out a new head assembly is $4k.  Yeah. Ouch.  They don't sell individual parts.  Awesome after sale service huh?

I plan to have a local shop I work with machine a bunch of these for me.  Why does it need to be made from plastic?  Was this just a cost savings measure to allow the part to be molded/sintered?  The only thing I can guess is it was a combination of cost and thermal conductivity.

My guess is that because the material offers a very low thermal conductivity to become an insulator keeping its surface at below melting temperature of the FDM material (so it doesn't melt before it enters the chamber).  However, if it doesn't conduct heat well, then what keeps this plastic part from (eventually) reaching the same temperature as the rest of the assembly?  Wouldn't it need to be sandwiched between a heat sink and the heat chamber?

Any suggestions?

How about suggestions on material and sources?  Am I stuck paying $100+ for a one inch long 1" diameter bar of high-temp plastic?

Engineering Incredible Solutions
www.incredilution.com
 

RE: Heat resistant plastic part

Could it be ceramic?  There are machinable ceramics available (McMaster Carr for one).

RE: Heat resistant plastic part

(OP)
You're right, that looks very similar and would definitely work.

Mcmaster says its over $70/inch ... wow.  Guess this project isn't going to be cheap.

Engineering Incredible Solutions
www.incredilution.com
 

RE: Heat resistant plastic part

Agreed, this definitely looks like Vespel.

RE: Heat resistant plastic part

(OP)
Thanks all.

I've got some Vespel on order.  I'm hoping that it will be a seamless replacement and we'll be back up and running.

Engineering Incredible Solutions
www.incredilution.com
 

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