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Plastic Enclosure Help

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brentonw2004

New Member
Hello everyone. Recently I have been working on a product that I am wanting to eventually start selling. I have already breadboarded it, and I have designed most of the circuit board for it. I should have the circuit part completely finished within the next week. My main problem is getting a plastic enclosure and the plastic buttons. The design for the plastic isn't really complex, but it is a little more complex than a project box from RadioShack. Does anyone have any advice or links about how to make your own plastic molds, the different tyes of plastics, or just were to buy the supplies from. What type of plastic is most of the project boxes made out of? How complex is the process? What tools would I need? I am willing to buy the materials and tools needed to make future molds. I want to make a few custom pieces for my car also, so the plastic molding materials would be handy. Any help would be appreciated.
Thanks!
Brent
 

panic mode

Well-Known Member
plastics, superglue and dremel work for me
 

stevez

Active Member
Where I used to work they used a vacuum forming process and infrared lights to make prototypes. The molds were fairly easy to make and vacuum pumps are easy to come by - don't need super high vacuum.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
brentonw2004 said:
I am interested in making the molds and molding the plastic myself. Where can I find information on this?
Thanks!

It's commonly done in schools, as part of "Design and Technology", but it's only very thin plastic. If you have a secondary school near by it might be worth asking.
 

brentonw2004

New Member
Does anyone else have any more advice? I have tried searching the internet for hours and I haven't had much luck at finding something informative instead of just wanting you to buy something. Any advice would be appreciated.
 

brentonw2004

New Member
Thank you very much for the link. It looks like something that could actually work for me. Could you please tell me a few details about the difficulty of working with it, what exacty you used, and the quality of your finished product? Thanks!
 

pike

Member
Hi Brenton,

I normally use an aluminium frame riveted together with poly-carbonate panels to cover the sides. I built my amp's into this and it looks damn sexy!!

But, if it's a small project then that would seem impractical.
 

dingo

New Member
I think you are looking at this the wrong way around.

You need to determine the plastic you are going to use then you will know what sort of process that type of plastic will require. Does the plastic produce heat when it cures? Does it shrink? Do you need to heat it? Will it react to materials (for example fibreglass epoxy will eat most plastic moulds). I would go look at manufacturing wholesalers of plastics in your area and ask them to quote on your product, this will at least give you some information on the plastic and processes they use, it’s a starting point anyhow.
 

brentonw2004

New Member
One of my main problems with this is simply my location where I live. I live in West Virginia, and there is really no plastic wholesalers even remotely close to me, and I don't even know who to ask. I don't need anything really fancy, or extremely heat resistant. I am basically looking to make some plastic that is similar to a project box from Radio Shack, or a similar plastic. What type of plastic is this? I need a plastic that I can make without anything really special or extremely expensive. I have looked at some places on the internet that talk about injection molding that needs around 20,000psi and an extreme amount of heat. Are there any plastics that will form around room temperature and I don't have to have a cast iron mold to work with? Also what is vacuum forming? Thanks for everyone's help so far, but I am still very puzzled.
Thanks!
Brent
 

Phasor

Member
I am basically looking to make some plastic that is similar to a project box from Radio Shack, or a similar plastic. What type of plastic is this?

Project boxes are often made of ABS (Acrylonitrile-butadiene-styrene). Which is, strangely enough, also used in car tyres...

Alternatively, they could also be polypropylene or UHDPE (ultra-high-density polyethylene)
 

thup

New Member
Hi Brent
Could you sketch the box including the buttons? I guess that you don't want to use Radio Shack box b/c the size. If you need 1 or 2 I suggest buy them and use hack saw to cut and use Weld-on # 2354 (for ABS material, I just bought 1 qtr today) to glue them back together if you want this box look nicer you can sand & paint with the color you like. After do all these works if you want to produce 20 or 30 more you can use the sample box to make the silicon mold then use this mold to pot the new boxes. The quality of the parts come out this silicon mold depend on your skill it can be 95% I think this way is the cheapest way to make custom molded parts orther wise you have to spend 3-4k to make the steel mold but that is the way to make high volume parts. To make the silicon mold go to this web site
https://www-2.cs.cmu.edu/~rapidproto/manufacturing/molds/silicone.html
Good luck
Thup
 

KOEZE

New Member
@Phasor,

I think you got the ABS brake system confused with the ABS plastic. As far as I know a car tire consists of synthetic rubber, wires (reinforcing) and sooth (to counter wear).

EJK
 

TallPaul

New Member
It depends how big you want to make this box, and how complex the structure will be. How many holes and cut-outs you will need in it.

From preious experience, the cheapest and easiest way to produce custom boxes is to make them out of fiberglass. this will give you all the strength you will need and will be reasonably easy to modify if the design isn't perfect.

It does depend on how many you want to make though. making 50 of these can be quite tiresome!

If the function of the box is simply to hold the components, why not find a larger box? Or maybe a pre-designed box and slightly modify it. If you are planning on making alot of these, consider trying to find an "off the shelf" box. It will be cheaper in the short term.

Have fun, and let us know how you get on.

Paul
 

brentonw2004

New Member
I think I am going to go ahead and make my first box out of a project box from radio shack and try to modify it. This may work for my first, but I still need to get a way of mass producing professional looking enclosures, because I intend to try to patent and market my design eventually. The page that someone posted about the silicon molds looked like something that could be done fairly easy. What type of results would you get with this type of molding and what type of plastic would it produce? My design for the enclosure is not very complicated. I will have 4 cutouts for buttons, 1 cutout for a potentiometer, 1 13mmx65mm cutout for an LCD(unless someone can find a reseller of an Optrex C-51505NFQJ-LW-AD), 1 cutout for a wiring harness on the back. The overall size of the box needs to be roughly 40mmx130mmx15mm. I really appreciate all of your advise so far. Thanks guys!
Brent
 

stevez

Active Member
Vacuum forming - a sheet of plastic is laid over a mold or pattern, heated then pulled into place with a vacuum. The mold or pattern has to be made first.

I am not sure what you mean by "mass producing" but the must be a million ways to make plastic enclosures. Mass production means 10 or 20 to some people and 10,000 to someone else.

A rough rule of thumb is that materials/methods that require little up front investment will be labor intensive and have higher materials costs - especially if appearance is important. In order to bring the labor and material costs down some investment is required in fixtures, equipment, etc.
 
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