Plastic/polymer replacement for stainless steel

[Genesis7753]

Hello,
I am looking for a plastic to fit my engineering needs. Would like to replace a few hydro formed stainless steel parts with plastic to lower costs.

Criteria:
Must be a blow molded plastic part

Must meet food safe standards minimum, preferred would be food grade.

Accept pressures up to 100 psi... Will go through many on/off cycles on a daily basis.

Tapped and threaded preferred as I am not sure a blow mold will allow for inserts... Some guidance here would be appreciated as inserts would be the best way to achieve a long part lifespan. However, repeated unscrewing and screwing in would likely be low annually.

Minimal flexing/expansion during pressure application.

Keith

 

[btrueblood]

A photo, sketch, or even a brief description of the part would help. I have some polyethylene tubing that easily withstands 100 psi, because it is 1/4" on the outside diameter...but I wouldn't use that material for a frying pan, get the idea?

 

[cowski]

Must be a blow molded plastic part

Why?

 

[IRstuff]

Perhaps you should be looking at whether hydroforming is the least cost approach.

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[MikeHalloran]

I'm not aware of a way to attach an insert to a blow molded part.

It's possible to approximate the shape of a hydroformed stainless cup type part in thermoplastics or thermosets with injection molds or compression molds respectively. It's also possible to provide thickened rims, and bosses suitable for inserts.

The price of the molds will cause some sticker shock, as will the price of die steel blocks from which to make the molds if they are large.



Mike Halloran
Pembroke Pines, FL, USA

 

[Genesis7753]

Btrueblood...
This is a manifold for water distribution with an custom shape profile. sizes ranging from around 10 inches in diameter to 22 inches in diameter
This part would require 2 high flow threaded fitting ranging in sizes from 3/4" to 1.5" depending on the size and application
There would also be between 4 to 10 1/8" to 3/8" holes for threaded fittings depending on the size and application.

needs to be blow molded, possibly roto-molded though i dont believe the strength wil be there in a roto-molded part. It must be open to carry fluids and be pressure capable, unfortunately the shape will not allow for of the shelf tubing to form it.

Water temps on average of 70 degrees with slight acidity 6.4 PH or so.

 

[Genesis7753]

Cowski
Must be a blow molded part as it has to remain hollow to carry and distribute liquids. I have considered roto-molding but fear the pressure handling strength will be low.

 

[Genesis7753]

IRstuff
The current best process is hydro formed stainless steel. This is a very costly part to manufacture in stainless, though very nice, it doubles the cost at which I must sell it to pretty much price me out of the market. In stainless it requires the part be formed in separate halves, trimmed, fitted and welded together. Then all the fitting connections points to be drilled and bungs be welded in.
Plastic tooling will cost a bunch but part cost will be lower and faster to produce.

 

[Genesis7753]

Mike Halloran
I have little experience with plastic hydro forming, except for vacuum forming. I was hoping to find a blow moldable plastic or polymer capable of taking a thread strong enough to pressure without failing.

That being said I am interested in pursuing any means of doing this in plastic as I believe the part cost will be substantially lower, though tooling cost much higher.

In stainless it requires the part be formed in separate halves, trimmed, fitted and welded together. Then all the fitting connections points to be drilled and have bungs welded in.

Is this what you do for a living? do you have a place to recommend I start looking into this process if not?