Punching and press forming plastic sheet

Looking for some ideas on a little hypothetical issue.........
If I wanted to make a few hundred plastic parts per year like those at
the following links:
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I'm pretty sure the plastic is UPVC. Its around 1.2mm thick.
I'm thinking:
1) Turn up some quick dies from some mild steel scrap.
2) Use a porta-power or 2 ton arbor press to punch out the sheets as
circles and then re-punch as an annulus.
3) Machine up some dies in steel or aluminum.
4) Press form them to shape.
I'm not too fussed about the 3 small bosses - I can just drill those
holes later on.
Am I dreaming to think I might be able to get a nice clean edge and get
them to form nicely when pressed? I can buy them at $6 per unit but if I
could make them for $2 I might be able to earn a few dollars.
Thoughts?
Reply to
Stoob
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You're not likely to get the neat conical-to-flat transition by pressing cold. PVC forms easily when heated, and a two-part forming punch and die would get you the basic shape.
Commercial vacuum-forming setups for PVC use simple electric heaters and, often, plaster male dies, with no punch, and produce quite complex shapes.
It is possible to do this at home, but making the heater, rigging the vaccum pump, etc., would eat up a lot of your profits for just a few hundred parts.
Reply to
Ed Huntress
Larry Jaques fired this volley in news: snipped-for-privacy@4ax.com:
So... you only read the first line with the grin after it? What about the plastics comments, Larry?
Lloyd
Reply to
Lloyd E. Sponenburgh
Sarcasm is just another fine service I offer.
I don't know a thing about extruding or pressing hot plastic, so I abstained from the conversation on that level.
Reply to
Larry Jaques
Vacuum forming is something I hadn't thought of - that's another option.
I'm not too fussed about having a sharp transition from the angle to the flat. I just want them uniform and tidy looking.
Reply to
Stoob
================= While the size is at the upper limit for large hobby machines, it might be worthwhile to evaluate 3D printing to produce to need. Looks like a fairly simple design. This would set you up for many other similar projects/prototypes and would allow easy customization.
one possible machine
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machine in action
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download free control software for evaluation at
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Reply to
F. George McDuffee
Yeah the thought of that crossed my mind, I thought they make take waaaaay to long to be made. It's 5" diameter x 1" tall.
Reply to
Stoob
If this runs unattended, and you only need a few or one at a time this would not seem to be a problem, even if takes an hour or more per part.
While the actual generation of the part may take some time, there is little to no set-up, other than loading the program and possibly switching filiment. With vacuum or hot forming, the set-up/prep (heating the sheet) will be much longer and tooling (which you will have to make) in addition to being expensive and dedicated, will be occupy a lot of space even when it is not being used.
Also any changes will require reworking the tooling, for example, when the customer asks you "please make the OD 2.5 mm bigger, and while your at it, could you add some ribs for additional support, and add our logo, and we need three tomorrow."
Reply to
F. George McDuffee
All good points.
I was at an electronics shop a few weeks back. They had a range of thing made by a 3d printer that they sell. I was impressed by the strength but the finish was still a bit poor - clearly layered etc. I'm not sure how the plastic would cope with full time sun and weather exposure either.
Reply to
Stoob
Vacuum forming or pressing with heat would be fine but for the lugs, which would come out sloppy and weak. Also, with VF the parts would have to be trimmed. Could the lugs be a separate part?
Reply to
robobass
Yep, I can use separate spacers for the bosses.
Reply to
Stoob
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Reply to
hamza20461

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