help with picking material for bumper application
help with picking material for bumper application
(OP)
Hi all,
Looking for some advise on picking a material for making some plastic bumper guard. These bumpers are long thin curved shaped. Since there are many different variation, I'm looking at injection molding the material, then machined to fit each application.
The materials that I'm thinking about are HDPE, ABS, Delrin, and Nylon. These bumpers are more for preventing scraping than hard hitting impact. The concern I have is the machinability and cost of each material. Also, I might be considering painting these bumpers (rather than molding a bunch of different color) and I don't know which one is possible for paint to stick to.
If someone can give me some pointer on any of these material or if there is another material that I should consider, I would really appreciate the help.
JC
Looking for some advise on picking a material for making some plastic bumper guard. These bumpers are long thin curved shaped. Since there are many different variation, I'm looking at injection molding the material, then machined to fit each application.
The materials that I'm thinking about are HDPE, ABS, Delrin, and Nylon. These bumpers are more for preventing scraping than hard hitting impact. The concern I have is the machinability and cost of each material. Also, I might be considering painting these bumpers (rather than molding a bunch of different color) and I don't know which one is possible for paint to stick to.
If someone can give me some pointer on any of these material or if there is another material that I should consider, I would really appreciate the help.
JC






RE: help with picking material for bumper application
What size are they? Do you mean by "bumper" what the US call a "fender"?
Rgds
Harry
www.tynevalleyplastics.co.uk
RE: help with picking material for bumper application
Dan - Owner

http://www.Hi-TecDesigns.com
RE: help with picking material for bumper application
RE: help with picking material for bumper application
For instance I believe Delrin is fairly pricey, not sure if you can vac form it either, though others here can say for sure.
I believe some car bumpers are made of ABS and they can be painted.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: help with picking material for bumper application
Dan - Owner

http://www.Hi-TecDesigns.com
RE: help with picking material for bumper application
Do you have any idea what an injection mould costs.
When you say 30" by 1" by 1" do you mean a hollow or open section like box or U section or do you men 1" wide and 1" thick.
Regards
Pat
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RE: help with picking material for bumper application
It's approx 1"x1" solid section. Length wise is about 20" long but curved. To cut it out of a 1" sheet would be wasting a lot of material. That's why I'm looking at injection molding. The quantity will be there to justify the cost of the mold. >4k pcs.
Looking at buying these material in sheet form, the cost difference seem to be (from high to low) Delrin>Nylon>ABS>HDPE
Would this cost difference hold true when injection molded?
So both nylon and abs can be painted?
JC
RE: help with picking material for bumper application
RE: help with picking material for bumper application
RE: help with picking material for bumper application
btrueblood: interesting suggestion. but i think curving it would add to the cost/pc. since the quantity will be enough to justify for the price of a mold made oversea.
RE: help with picking material for bumper application
1" section thickness involves cycle times running into quite a few minutes for thermoplastics.
If you must use thermoplastic, cycle time might impact on cost to a greater degree than material cost.
Nylon with a suitable foaming agent might be worth a look.
Regards
Pat
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RE: help with picking material for bumper application
I would guess cast nylon may be a possibility, although quantities have not been mentioned as this is also a slow process, but cheap tooling.
Yes, with Acetal and nylon close, with acetal almost impossible to paint. (Actually, it's easy to paint - the paint just won't stay on the stuff!)
Cheers
Harry
www.tynevalleyplastics.co.uk
RE: help with picking material for bumper application
That is why I suggested foam.
With a 1/2' by 1/2" gate he can pack out the voids and sinks but pack time and therefore cycle time will be quite a few minutes.
Bottom line, I agree it is impractical to injection mould and should be made from a thermoset, either by compression moulding or casting.
Regards
Pat
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RE: help with picking material for bumper application
What thermoset (machinable) would you suggest I look into?
I know very little about compression molding (so they put the plastic pellets into a mold, squeeze and heat, right?) How's the cycle time (cost) compare to injection molding?
Regards,
JC
RE: help with picking material for bumper application
I think glass fibre reinforced polyester will be the best. It can be supplied in several forms including bulk moulding compound which can be compression moulded. The glass will create a lot of wear on the cutters.
I think Harry has made the best recommendation of cast nylon which can be poured into a mould.
When casting or compression moulding you can economically add colour to the resin before moulding to give through colour.
Regards
Pat
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