Injection PU foam on ABS molds

[bluecomp]

Hi guys, I need to produce a cheap mold to inject pu foam in order to obtain prototypes of foam to seat, anyone knows if the mold could be in ABS material.

Thanks,

 

[btrueblood]

Sure it could be.

1. If the ABS was thick enough (or backed by something thick enough) to take the pressure that the foam will generate, that pressure being dependent on how dense you want the foam to be. For reference, I've seen fractured aluminum molds 1/2" thick that were used to mold a small refrigerator insulation/wall.

2. If you use the right mold release. PU will want to stick to ABS, well, like glue.

 

[Demon3]

This will work for sure. How do I know that? Because that's exactly how domestic fridges and freezers are made.

You take a thermoformed sheet of HIPS or ABS then you place it in a metal box. At this stage the appliance has no rigidity. Then you inject a two part PU which foams, fills the cavity between the HIPS (or ABS) and the metal. It then hardens to create the insulation in your fridge. This is done on huge scale, I mean hundreds of thousands of units per year.

The PU does stick to HIPS or ABS to some extent. That could probably be prevented using some kind of mold release or coating on the plastic.

Chris DeArmitt PhD FRSC CChem

http://www.phantomplastics.com

Consultant to the plastics industry

 

[patprimmer]

If you use PE or PP sheet it will not stick.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[bluecomp]

Ok guys, thanks at all, after tests I will forward you the final results