Plastic Injection Molding
 

I searched through here, but didn't find much on this particular tool.

I've been thinking of getting one of these (actually I'm trying to convince one of our engineers that we need one at work ;-)). It seems like a lot of manufacturing process' are being scaled down for home bench top work:

Easy Plastic Molding, Plastic Injection Molding, LNS Technologies Plastic Injection Molding Machines and Supplies

I have a Tormach 770 at home, and they also have an injection molding kit.

Does anyone have experience with Injection Molding at home? The only thing that bothers me with the one in the link is the shot size. I don't know what size parts you could make with it.

Re: Plastic Injection Molding
 

interesting little injection mold "thumbsup" ....I didn't know they made home sized injection machines, I used to work in a plastic injection place making all kinds of stuff electrical stuff....where those machines were the size of a suburban....the other half was doing metal injection that made electrical fittings like romex clamps for metal boxes and such....

Re: Plastic Injection Molding
 

I actually interviewed at a MIM facility a few years ago. They took me on the big tour...fascinating place.

I'm not looking to make a lot of parts. Just a few things here and there. What started this is my desire for larger helmets for some of the builds I'm working on. The HPI Apache drivers are great, but still a bit small for what I want.

Re: Plastic Injection Molding
 

That is a hand injection molding machine. I have that in my workshop sitting lonely. I used to design and build hand injection molds. The core and cavity are made of OHNS steel and rest is Mild steel. It takes considerable effort to fill a shot. Needs pre-heating of half an hour and the plastic granules too need preheating up to 60 degree Celsius.

Yes the part size is limited. The end result is calculated based on the largest cross sectional area of the molding and the weight of the end product with runner.

That machine could produce parts with a weight of 10 to 15 grams and less for nylon.

A 20 ton injection molding machine can produce a part with a weight of 40 to 50 grams max. Less for nylon.

Re: Plastic Injection Molding
 

Galomb Inc. has a very affordable benchtop unit. Benchtop Injection Molder - Home Page

I have used mine for a Miniature football company since 2008. Not a problem one. Its a great unit.

Re: Plastic Injection Molding
 

Since USA manufacturing has dried up you can buy a used industrial machine for pretty cheap.

Re: Plastic Injection Molding
 

Very interesting thread on scale4x4 about a guy who made these incredibly details CJ 7 bodies, who then went and built a home made injection machine to makes small parts like engine blocks and seats. Maybe that's more along the lines of what you're looking for?

Re: Plastic Injection Molding
 

Do you have a link? I haven't been on Scale 4X4 in years.

Re: Plastic Injection Molding
 

Check out these machines...

Morgan Industries • Plastic Injection Molding Machines for Small and Large Runs

More commercial than the hand operated machines.

Re: Plastic Injection Molding
 

I would think you might be able to make a version using 3D printer parts:
Heater core and thermistor (probably a couple of them; one for the mold to pre-heat it, one or more for the hold chamber...)
The plunger could be hand operated or stepper controlled.
Since you have access to CNC machines, all the rest of the pieces can be made from metal.
At this point, your shot size depends on the size reservoir you choose to make.
May take a little bit of design and engineering, but I'm sure you could get it done for (much) less than the one you linked in the OP...
Now you've got me thinking about making one myself... hmm...

Re: Plastic Injection Molding
 

Here you go. This guy is as creative as you are!

http://www.scale4x4rc.org/forums/sho...ection+molding

Re: Plastic Injection Molding
 

Exactly what I was thinking... recycling some 3D printed rejects would be a good way to use that material... Now I need to do this.

Re: Plastic Injection Molding
 

Well, now I have a pair of 12V 40W heaters and thermistors that I ordered by mistake (needed 24V heaters) that I can use for this very purpose...

Re: Plastic Injection Molding
 

Would a 3D printed mold hold up to temperatures needed to make abs parts? I know there have to be some high temp materials out there. If you could print a reasonable core and cavity, the whole process might be pretty easy.

Maybe something like Ultem backed with AL heat sinks?

Re: Plastic Injection Molding
 

Or high temp silicon with a plaster shell..?

Re: Plastic Injection Molding
 

Somewhat likely it will hold for the first 2 to 3 parts and more if there are no thin wall sections in the mold core.
Metal molds are continuously in a band of certain temperature and that helps the melted plastic to flow into the mold better. If a printed mold is used like you are saying, it will be cold and the mold itself will rob the injected plastic out of heat. If heat is removed from the fluid plastic when filling a mold, it won't travel to the intricate shapes of the mold and more likely give a half filled shot.

Another problem will be the inlet opening to the mold. In an hand injection molding machine, the hot injecting nozzle touches the top part of the mold and creates a seal with pressure. So we are seeing something quite hot which applies pressure on the mold. This is where your printed mold will fail instantly.

Re: Plastic Injection Molding
 

It would make more sense to make a mold from a 3D printed buck using silicone, plaster, or some other mold material.
I like the idea of preheating the mold with the heater so that when the plastic flows in, it's not instantly cooled. You can control the cool down phase with fans and reducing the mold temperature.

Re: Plastic Injection Molding
 

I don't think I would print a mold. My mill is capable of 3-axis machining, so I would machine mine out of aluminum. I wouldn't want to do high volume production runs, but I'd want the mold to last for more than a handful of shots.