How do I make an injection mold?
How do I make an injection mold?
(OP)
I have a small 8" x 8" x 3" fiberglass/wood/bondo piece that I want to turn into plastic. It has to be done with an injection mold due to the various angles involved, and it's mostly hollow. Walk me through what I would need to go from prototype to product...
-I have a proto I can take measurements from.
-I assume I need some 3d modeling software.
-I have a proto I can take measurements from.
-I assume I need some 3d modeling software.






RE: How do I make an injection mold?
Failing that...
- That's not a small injection molded part; you will need a lot of money, for the mold, and for machine time.
- Injection molding gets really expensive for hollow parts.
- For some kinds of plastic, and some shapes, hollow parts are more easily made, in cheaper molds, by rotational molding or blow molding.
- You haven't given us a clue about the application environment the part will see, e.g. service temperature, electrical stress, required tolerances on geometry, anticipated loads, etc., so we can't make a recommendation or a guess about which 'plastic' you need.
There are basically half an infinity of 'plastics', and picking one, or one family, needs to be your first step, after the wallet biopsy.
Mike Halloran
Pembroke Pines, FL, USA
RE: How do I make an injection mold?
It is an automotive spoiler stantion. I already figured ABS would be good for it, for mechanical and temperurature requirements, and good paint adhesion.
I don't mind spending my time learning what I need to do, vs spending money. CNC machine time is cheap compared to people time.
RE: How do I make an injection mold?
You will probably abandon the project at that stage.
If you are still conscious and enthusiastic come back here with some real information and we will give you real advice.
There is an old story about this guy that had a secret product. He sought advice on what material to best make it from, but could not disclose it's design nor use. He also did not know the market size, but claimed he would need many millions of them.
The recommendation was to use this secret material. We cannot disclose it's properties nor price, but it will cost a truckload.
The quality of an answer can at best only reflect the quality of the question.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How do I make an injection mold?
I have access to CAD/CAM software at school. What software would be necessary to create a model that a toolmaker can use to create the mold? In other words, what is universally accepted, and what should I focus my time on learning?
RE: How do I make an injection mold?
Why not ask him what file types he can work with.
He should be able to plot one half to create a model, then flop it over to make the other half symmetrical. If he can't do that, he should know someone who can. Plotting a digital image from a model is very cheap these days, with the equipment being a built in option on machine centres.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How do I make an injection mold?
ABS gives you the option of molding it in two halves and solvent bonding them together. That mold will have a much shallower cavity, which is cheaper to sink and to polish, and will require a smaller block of die steel.
Mike Halloran
Pembroke Pines, FL, USA
RE: How do I make an injection mold?
If you just need 5-10 parts then you could probably get away with using aluminum, with out any complicated ejection mechanisams.
-Software can differ from company to company...I suggest you find out if the software at your school can export files as "iges" or "step" file format. Those formats are standard and can be imported into almost any CAD software out there, so you can use the software you know best
-If you are doing the cad model your self, one of the things to keep in mind is draft. You can't really have any vertical walls, 1 deg draft can be good enough....
-next thing you need is to develop a parting line (along with the designs) I suggest you leave this for the mold shop. But if you insist on doing it your self, I'll help you out...i like a chalange.
RE: How do I make an injection mold?
I'd rather not have any ejection system, and pay the penalty in increased production time per unit.
I guess the software at school is Solidworks, which I have used before, albeit briefly.
Good info on the draft angle, I likely would have forgot to include that.
RE: How do I make an injection mold?
-thick wall parts cool slower and shrink more then thiner parts...keep the material thickness nice and even.
-if you have any ribs, they should be no more then 70% of the part thicness (including the rad on top of the rib) otherwise you will get sink marks on the opposite side...
RE: How do I make an injection mold?
Bright
Sr.Project Manager&GM
HT-MOLDS
www.ht-molds.com
RE: How do I make an injection mold?