Material Selection for Rapid Prototype

[1Khaleel]

We are asked to produce six functional prototype units of a new product.
The material used must have:
- V0 flammability rating.
- HDT close to 200C.
- High dielectric and mechanical strength.
(equivalent properties of DAP or attached high temp Epoxy).

All rapid prototype suppliers that we contacted could not specify a material that meets these requirements and lends itself to Vacuum Casting, SLA or SLS.

Does anybody know of a material that lends itself to vacuum casting/SLA/SLS and meets the specs above?
Or alternatively, can you recommend any other process to produce these prototypes using DAP/Epoxy without having to go for a full molding tool?
Any thoughts?

Thank you,

 

[Pud]

A silicone based RIM casting can go up to 200ºC - the company we use (in the UK) are here. Even if you are from elsewhere (probably ), they might be worth call to find out what you need to ask your suppliers for.

Incidentally, specs. like "high dielectric" and "high strength" do not mean much...

H.

www.tynevalleyplastics.co.uk

It's ok to soar like an eagle, but weasels don't get sucked into jet engines.

 

[MikeHalloran]

Maybe you can CNC machine some Bakelite blocks into what you need.

RP does not produce parts that are completely equivalent to parts traditionally made by other means.
In particular,
- surface finish, especially in the Z direction, is awful, typically requiring filling and sanding to begin to look presentable.
- thermal properties will not be the same.
- material choices are limited to what will flow through the printhead or whatever.
- mechanical properties are generally terrible because of all the cold joints and porosity and such.

Recent hype in the popular press about printing plastic guns and such is vastly oversimplified and overstated. Yes, it's possible to print something that looks like a gun, and will accept a regular cartridge, and might fire the cartridge, or might blow up in your hand.

Reliable highly stressed RP parts, like gun parts, will come around some time after literate intelligent reporters have been replaced by dangerously ignorant naive and gullible robots.
... on second thought, the latter may have happened already.




Mike Halloran
Pembroke Pines, FL, USA

 

[1Khaleel]

Pud,
Our suppliers ruled out RIM as more suitable for large size parts. Ours are about 50 x 100 x 130mm each.
The "high dielectric" and "high strength" specs are supposed to be equivalent to those of DAP or the attached high temp Epoxy.

Mike,
You are 100% right about RP and the recent hype, and hence my post; trying to see how others went about solving such challenges.
We've tried to go down the machining option, but moulders refused to produce blocks/extrusions of these dimensions, as they believe the thermoset will not fully cure.

The search continues.

 

[MikeHalloran]

What I meant was to buy sheets or bars, of whatever bulk material you wish, sawcut it into blocks for CNC machining, and produce your parts subtractively, as before RP came along.

Using RP to make machining billets would be slow and expensive, and, well, odd.


Mike Halloran
Pembroke Pines, FL, USA

 

[1Khaleel]

Mike,

Using RP to make the billets, then machining them is indeed odd and a lot of hassle.
I'm referring to machining billets which are made from the actual thermoset material of the final parts.
You can get thermosets in sheet or thin plate form to machine a prototype, but you cannot get it in thick billets, because the billets don't cure fully.

Of course we can use other non-thermoset bulk, but they won't have the temperature or strength required.

 

[Demon3]

Stratasys have a machine called the Titan that can do high temperature polymers like Ultem. Check here. The spec sheet says the Tg is over 200C and it's V0 too.

http://www.stratasys.com/materials/fdm/ppsf-ppsu

Chris DeArmitt

Expert consulting & training

http://www.phantomplastics.com

 

[1Khaleel]

Thanks Demon3. I'll contact them.