On Tue, 3 Nov 2015 21:04:14 +0800, A2 wrote:

I'm working on a job where we are epoxy encapsulating some electronics.

My question - what to use for a pilot production mold?

Option 1.
---------
Aluminum
CNC cut pockets
Dowels adjacent recess to locate frame that aligns electronics to 0.5mm
Release coated mold - PTFE / Teflon?
Use release agent? Hope to avoid.


Option 2.
---------
Plastic mold
CNC cut pockets in a ~30mm thick slab
Dowels adjacent recess to locate frame that aligns the electronics.
Is there a plastic that epoxy won't stick to - no release agent needed?
Nylon? UHMWPE? Maybe $$ Teflon?
I imagine a silicone or urethane mold may not be rigid enough.

Any suggestions? Recommendations?
Thanks!



Background:
Prototypes have been cast in a mold made from epoxy and a aerosol mold
release used. It works ok, we ended up making the mold 2 parts as the
completed parts were a little hard to remove.


*The electronics is sat into a 130mm x 50mm x 20mm (5"x2"x3/4") mold
*Their is heaps of draft on the mold for easing release.
*Epoxy poured into the mold.
*After 24 hours they are de-molded.

*These will be made in batches of say 30 to 100 at a time.
*We are happy Doing say 6 at a time with a 24 hr turn around.
*Mold may be 6 units wide or 6 individual molds.

The machining marks (undercuts) will make the part want to stay in the
mold even if it doesn't stick. Polishing will be a lot of work. If the
mold material is rigid then be sure to have a healthy draft angle
(maybe 4 degrees or more).


--sp


--
Best regards,
Spehro Pefhany
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