I need injection mold help...

[anchange]

Looking for some help with machining mold tooling for a simple injection mold. I know basic machining and CNC. I have access to a Tormach that I’d be using, but I don’t know much of anything about specifically machining molds for injection molding. Would really love some help. Would be willing to trade somehow. ANYTHING would be great local, remote, or over the internet. I’d be willing to even come to you even if it’s far. I’m in California near SF. Please reply or send me an email at – leong.brad.generic (at) gmail.com

THANK YOU!

Brad Leong

[mactec54]

I looked at your drawing how big is the part Outside Dimensions Height Wall thickness

[anchange]

The first piece I want to make is -
2.536"x2.236"x.754"
wall thickness of - .075"
STL here - http://dl.getdropbox.com/u/455762/rounded_underlip.STL

I'd really like to get some help in person if that's at all possible. Want to seriously learn how to make injection molds (and learn more CNC/machining in general) Like I said Id be willing to trade, not sure what I'd trade exactly but I do have time to spare right now.

Any advice you can give would be great.

[mactec54]

How many do you plan you want molded & what material for the part, that is a good part to start with, what cad do you have

[anchange]

I'm using solidworks to CAD with camworks to CAM outputting to a basic Tormach. As far as part quantity that's somewhat variable. We're developing a consumer product and trying to market it from scratch independently. So we'll only really need a few 100 pieces to start but I'd want the ability to ramp up easily without having to make new mold tooling etc.

As for material I'd like recommendations. There aren't any major stresses on the piece, it’s just a simple consumer production mostly for aesthetic value. Would want it to feel solid and have a very nice looking finish. Also bioplastic / starch plastic might be a good marketing point for us...

Let me know you're thoughts.Thanks for helping!!!

Brad Leong

[mactec54]

If you can have a radius on all of your corners inside & out it will make it a easyer mold to make for milling, & will have better flow for the material being injected,The core/inside is easy to have a sharp corner but the cavity would be hard to mill with square corner's, you would have to use a EDM, shaper, broach, or a wire EDM to clear the corners out in the cavity, Think how deep the cavity will be & how small the cutter you can get to do that depth,

The cavity you may get away with no taper on the walls but the core will have to have like .5deg taper as the part will shrink onto the core

[anchange]

mactec54, thanks for the help. I think I’m pretty good as far as designing the piece for molding. But I don’t know much as far as building the mold itself. I’ve been reading up though on sprues, runners, gates etc. and I think I have an handle on how to do all that for such a basic mold.
Some direct question if you’re willing –

How big of a block should I be working with to produce a fairly universal mold (leaning towards smaller runs / smaller machines)? Is there a specific size block or does it just need to be within a certain restraint?

How does the fixed side of the mold attach to the nozzle?

How do the blocks attach to the machine does this require any machining in the blocks?

Do I need to deal with ejection pins for a small run of an easy mold like this or not?

What should I tapper the sprue to?

I have a billion other questions but I don’t want to overwhelm. Please help with all/any of these, thanks!

Brad Leong

[mactec54]

Hi Brad


Your mold size will depend on the machine that it is going in, I will attach a photo of my machine it has a closed height of just under 10" so the mold can't be any less than the 10" closed unless you have a spacer /bolster plate for the machine, which I have a 2" thick bolster plate this then lets you use a 8" mold closed height one photo of the machine open you can see the mounting holes taped in the platens you will also see on the A side, there is a 4" round opening in the centre of the platen, this is were the A side of the mold is located, the mold will have a locating ring that will match the machine it is going in, the sprue bush goes in the centre of the A plate & the locating ring is outside of the sprue, most sprue bushings have a radius in the face that will match the injection nozzel

[mactec54]

Hi Brad

Ejector pin yes you will need them

The sprue bush it would be cheaper to buy one, as you would have to get a sprue reamer to make it, plus cut the correct radius in one end to suit the machine it is going in, the tapered bore is polished finish as well

You will also need to have water flowing around the core & cavity as well

[pmolds]

You can buy some ejector pin and sprue bush for the mold, actually, you can make the sprue by youself

[mactec54]

pmolds

You need to explain on how he can make his sprue bush

[gorton22]

You might want to ge a copy of Moldmaking and Die Cast Dies for Metalworking Trainees by John Kluz. Not sure if it is still avalible.