Anybody using plastics in complex geometry with internal passages?

[TZellers]

I am looking for individuals or companies that have used plastics in applications where internal passages are required and not produceable with standard injection molding tooling. Say, for instance, plastic casting and sand cores or similar.

Anybody?

 

[nbucska]

Do you need one or mass production?
Would stereolithography do it?


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[TZellers]

Sorry, mass production. I'm thinking it would have to be a process like resin transfer molding with urethanes, esters, etc.

 

[insideman]

Disposable cores have been used in injection molding. I don't recall a vendor's name....

 

[patprimmer]

Gas injection can also sometimes work, as can over moulding over a metal insert.

How do you know it is impossible to mould with a standard injection moulding tool.

Low melting point bismuth tin alloys can be used for lost core, even ice might be feasible in some circumstances.

Some automotive inlet manifolds are made by bismuth tin alloy, and some are made by welding components together.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[TZellers]

Thanks, points taken.

However, I have to understand the tin alloy example: melt temp and the thermoset used. It sounds interesting.

 

[CoryPad]

Take a look at this document:

http://www.basf.de/basf/html/e/produkte/kstoffe/

plastics/archiv/a1999-01/plastics1_1999_e.pdf

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CoryPad]

My link didn't work correctly - just cut and paste the URL into your browser.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[patprimmer]

The Bismuth tin alloy works with thermoplastics. Glass filled nylon in the case of inlet manifolds.

The metal melts at below the melting point of the nylon, but still has a high enough melting point to withstand the moulding process when it's conductivity, mass and specific heat are taken into account.

After moulding, it is placed in an oven for some time to melt out the metal.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.