PDA

View Full Version : Need advice on injection material



originator
06-17-2009, 08:46 PM
I had a mold made, the guy made the mold with carbon and it looks precisely like I wanted the part to look, including the finish. I got the test parts back today (injected nylon) and they look really bad. I need a cosmetically nice looking part as it is included in a high end touch panel and very visible. He is trying abs tomorrow on a test, but the other samples of another product in abs did not impress me like the carbon original positive. BTW the way the mold was created with EDM, so it has the textured look.

I really need some advice on other methods to mold the parts to get an expensive, solid look. It can't look like a part made as cheaply as possible. Unfortunately, the sensor that mounts in the part cannot be metalized or conductive, else I would use powder coated aluminum.

Any suggestions?

dansutula
06-17-2009, 10:47 PM
Dear Originator,
There may be many plastics that would meet your requirements. But in terms of highest structural and aesthetic performance, Solvay's Primospire is in my opinion, at this point in time - the ultimate commercially available plastic.
It is however fairly expensive.

http://www.solvayadvancedpolymers.com/products/bybrand/parmax/0,,38808-2-0,00.htm

This material was originally introduced by Mississippi Polymer Technologies as Paramax, and was renamed Primospire after Solvay liked the product so much, they purchased MPT.

Primospire is also available in "stock shapes" from Bodeker Plastics under their tradename Tecamax.

http://www.boedeker.com/tecamax_p.htm

I can personally attest to the fact that it is amazingly machinable! The black Primospire can also be polished to a glass-like finish.

And for the record, other than being a satisfied customer, I have no affiliation with Solvay, MPT, or Bodeker.

Do you have a photo of the parts/resins you have molded thus far?

If you would like more info/input feel free to PM me. I have extensive experience designing plastic parts for both molding and cnc machining.
Good Luck!
Dan

Michael.lee
06-18-2009, 12:12 AM
1. I am from China, as a manager of moldmaking company ;

2. For the material selection, you need select the material prior to the project approach, as per the product style, its working condition, its function, its requirments...

3. The appearance of the product, texture. polish or secone treament like painting, silk-print... should also be consindered prior to the project approach.

4. If you have a strict size request, ABS test is completely invalid way as ABS have smaller shrinkage 0.5% than Nylon 1.5% ;

5. My suggestion: You need also make clear your product, where and how it will be used, then select the proper material. and make clear your product design makes great, otherwise you should get sink mark, flow mark ...

6. I think your mold made with carbon should only be a prototype model.

originator
06-18-2009, 01:42 AM
Hello and thanks for that info!

Here are the parts in nylon. We should have some tests in ABS tomorrow but I don't expect a big difference in look. It looks like basic cheap EDM process, which is fine if your application allows that.

I will check out the links tomorrow.

The part is for a fingerprint sensor module which sits on top of a glass touch panel for an entry system. The glass panel is screened from the read in a base color of black, and has a rich high gloss deep look that must be complimented by the fingerprint shroud.

Currently the part shown is a one piece mold, however I am not against a two part design. It has 4 mount holes on the bottom not shown.

Thanks again guys.

Michael.lee
06-18-2009, 02:25 AM
Can you send pictures to show the bottom side of your part ?

If you test with ABS tomorrow, please pay attention the size, it might have slight difference, even if your part is so small that the slight difference will not have bad influence on the assembly. Nylon has the big shrinkage 1.5%, but ABS with 0.5%.

If you want the part to keep high gloss look as glass panel, you can ask the mold maker to high polish the steel, thus you can feel better.

hope this helps.

mactec54
06-18-2009, 08:12 AM
Hi originator

As Michacl.lee has said you will have to have the mold polished to get the finish you want your mold guy should have told you this another material won't change the finish to much

originator
06-19-2009, 02:11 PM
Just an FYI, these products are no longer available. They have been 'pulled from the market'

Thanks for the links though.



Dear Originator,
There may be many plastics that would meet your requirements. But in terms of highest structural and aesthetic performance, Solvay's Primospire is in my opinion, at this point in time - the ultimate commercially available plastic.
It is however fairly expensive.

http://www.solvayadvancedpolymers.com/products/bybrand/parmax/0,,38808-2-0,00.htm

This material was originally introduced by Mississippi Polymer Technologies as Paramax, and was renamed Primospire after Solvay liked the product so much, they purchased MPT.

Primospire is also available in "stock shapes" from Bodeker Plastics under their tradename Tecamax.

http://www.boedeker.com/tecamax_p.htm

I can personally attest to the fact that it is amazingly machinable! The black Primospire can also be polished to a glass-like finish.

And for the record, other than being a satisfied customer, I have no affiliation with Solvay, MPT, or Bodeker.

Do you have a photo of the parts/resins you have molded thus far?

If you would like more info/input feel free to PM me. I have extensive experience designing plastic parts for both molding and cnc machining.
Good Luck!
Dan

MrMold
06-23-2009, 10:07 PM
Polishing the mold is the best solution. There are other things that you can take into consideration also. Lighter color- White parts hide surface impurfections best, black is the hardest. Clear parts- no short cuts here, only the best finish will work. Most materials also come in a variety of gloss, i.e, low gloss, med gloss, high gloss. Using a lower gloss material will hide bad surfaces easier than high gloss. No matter how good the surface finish of the mold, if you material is not dried properly, the resulting splay makes parts look bad. Also any material that has fillers( glass, talc, blowing agent) will look dull. Some times it's just a matter of tricking your eyes, even with a good finish, if your polish marks are not in all the same direction the reflecting light makes them look bad. Sometime a light sand blast will do the trick.

MrMold
06-23-2009, 10:20 PM
One other thing I should mention, if you want a really highend look. Look into hydrographics, it's a decal like process. You see it on all the high end cars. You can make it look like wood, snakeskin, carbon fiber, whatever. I know of a company in Detroit that does some outstanding looking stuff with dash panels for boats, custom cars and the likes.

jetski
06-29-2009, 09:03 AM
If this is an out door application ABS is a good pick. We mold a lot of ABS. Also PVC would work well, PVC needs to run in a stainless tool due to the acidity of the material. If the part looks bad maybe the material was not dry or the barrel was not purged clean. I do not know the molder or the experience level of the one you used. Maybe the problem is thick wall causing the part to sink. This could be helped by a filled material or foam. Both will have a different look. Since the tool was built for nylon its shrink is up there may be as much as .018 per inch. ABS will be less than .008 or .006 per inch. So expect some of your fits to change as you search for material. If we can be of any help please call and we would be happy to help..even if we do not get the job. Progressive Plastics 2200 South J Street Elwood, IN. 46036 go to our web site Progressive-plastics.net or call us at 765-552-2004 fax 765-552-7773