Anyone have experience with bench top injection molding machines

SBAER · Apr 24, 2017

As a prototyping shop making electric motors we often require small plastic parts that made from resins that are not 3D printable, resins with glass reinforcement, high temperature stuff. I machine parts when I can but geometry is often a limitation. I am interested in the idea of making very simple molds in-house and making parts (quantity 50-500) using a simple bench top injection molding machine

Something like this

Manual Benchtop Injection Molding Machine MIM-2,a standard mold&Free Shipping | eBay

Or this

Alibaba Manufacturer Directory - Suppliers, Manufacturers, Exporters & Importers

Long cycle time is not a problem, I just want to shorten the time between design and part in hand as well as cut the cost.

I have no experience with plastic injection molding so I don't know how hard it is to get the process to work.

Anybody done this?

scadvice · Apr 24, 2017

I just ran across this as I also was looking to mold some parts this looks like it would handle what your wanting to do.

Model 15A
| LNS Technologies

They are showing demo’s using Polypropylene which has an operating temp of up to 130C. The vise setup is a little funky I’d most likely do a little rebuild on it. And make my molds a lot different.

It’s kind of a hobby toy but may work. I’m still looking to see what is out there though…

If I can find the parts I may build my own.

j lewis · Apr 24, 2017

we used something called a 'huff n puff' benchtop injection machine. Having a mold background, they had me make the tools and run it when we needed some parts made. It worked just fine. There was a hopper and heating element up top, some sort of pressure device to push the plastic out a nozzle down into the 'sprue'. The mold was held in a vise. Very primitive but it worked!
As an alternative, could you find a prototype molder to run your mold? I've done that too.
JinNJ

goldenfab · Apr 24, 2017

I have never had or used one but a guy I know has one very similar to the one you shared. I think his was made by Emco. He showed me several parts he made with it and they looked good. He made it sound like it was easy to make parts with. Might check this out too Small Manual Benchtop Plastic Injection Molding Machine

John Welden · Apr 24, 2017

SBAER said:
As a prototyping shop making electric motors we often require small plastic parts that made from resins that are not 3D printable, resins with glass reinforcement, high temperature stuff. I machine parts when I can but geometry is often a limitation. I am interested in the idea of making very simple molds in-house and making parts (quantity 50-500) using a simple bench top injection molding machine

Something like this

Manual Benchtop Injection Molding Machine MIM-2,a standard mold&Free Shipping | eBay

Or this

Alibaba Manufacturer Directory - Suppliers, Manufacturers, Exporters & Importers

Long cycle time is not a problem, I just want to shorten the time between design and part in hand as well as cut the cost.

I have no experience with plastic injection molding so I don't know how hard it is to get the process to work.

Anybody done this?

We had one of these Morgan Industries • Plastic Injection Molding Machines for Small and Large Runs

I think it was about 10 grand.

I can't imagine using the hobby ass shit you linked to. At least the Morgan is kind of a real machine.

John Welden · Apr 24, 2017

car2 said:
John, so how well/easily did yours work? What sort of tools were you using, size of part, etc. I've seen some of the parts made with thermoset resin rapid-prototype tools which looked pretty good. I know the difficulty increases with higher temp and filled plastics. Thanks for any firsthand info. Cheers Charles

I just wrote out a bunch and erased it. I don't think my experience with the machine will be good advice for you. I'd call morgan and see what they have to say about your parts and materials. I'd be very skeptical if they act like everything is a slam dunk. (not saying they will)

There are quite a few molding experts on this forum. Hopefully they'll chime in and help you out. Molding high temp materials and filled materials is a whole world that I don't have much experience with. It can be very tricky.

Good luck.

snowman · Apr 24, 2017

Are there liquid rubber castable resins that will work? Smooth on has a pretty big line, and there are a lot of other companies like them.

SBAER · Apr 24, 2017

John Welden said:
We had one of these Morgan Industries • Plastic Injection Molding Machines for Small and Large Runs

I think it was about 10 grand.

I can't imagine using the hobby ass shit you linked to. At least the Morgan is kind of a real machine.

I like this machine, I have filled in their "Contact us" form for more info. I am trying to get around the $5000 for a simple mold problem that we currently have. At the moment we are better off paying the Chinese to make a full blown tool than to get it prototyped locally. It is both faster and cheaper to get it done in China.

Modelman · Apr 24, 2017

snowman said:
Are there liquid rubber castable resins that will work? Smooth on has a pretty big line, and there are a lot of other companies like them.

I think the original post said he needs to mold the prototypes in the specified material, or he'd just have them 3-D printed.

The biggest problem with the manually operated machines is lack of injection pressure. Calculate the leverage on the diameter of the ram, and if you don't get up around 15,000 or 20,000 PSI, you'll be pissing in the wind unless the parts are dead simple, with no small sections or fine detail.

The manual machines work well for making rubber worms, and simple parts from polypropylene or polystyrene. If you need to prototype polycarbonate, acrylic, or anything glass filled, I don't think you will have sufficient injection pressure.

A friend had a Morgan Press when first starting out. What a joke. If you can find one used for a grand or so, maybe worthwhile, but at $10,000 they are waaaay overpriced for what they can do.

The other problem I see with the manual machines and the air operated Morgan is they are plunger presses rather than reciprocating screw. Some of the more exotic "engineering resins" behave badly if held at heat too long, and plunger presses are hard to purge quickly.

Maybe better to find a small used press... look for BOY (German make) either 15, 22, or even 50 ton clamp aren't too big. These are simple machines, rugged, and I think BOY still supports everything they ever made. I have an older 15S I bought used, and I'm constantly amazed when the molding guys find a cycle that will run a tool that was really intended to run in our 60 ton Battenfeld.

Dennis

SBAER · Apr 24, 2017

Maybe what I have to do is learn how to make simple molds that fit into a real machine owned by a small local company. The problem is that i can't imagine anyone wanting to deal with the pain in the ass of having to educate me to the point of being able to make acceptable parts.

scadvice · Apr 24, 2017

Dennis is this the one your talking about in a 22?

BOY 22S INJECTION MOLD MACHINE 18677 PLASTIC MOLDER INDUSTRIAL LABORATORY | eBay

TDegenhart · Apr 24, 2017

I vote with the "do it properly" crowd. The reason the OP came here is that he wants to work with glass filled material. I have spent a few hours around molding presses and designed a few molded parts. If you don't have a machine that can be set up with the correct time, temperature and pressures, you are kidding your self. Beside that, those simple two plate molds with the injection directly into cavity won't work except for very simple parts. Any detail or non-uniform sections with glass may not fill correctly or at all.

If you want to play with molding toys fine. If you want to base a design on the performance of a part from one of these machines, no.

Tom

edit:- I agree with the suggestion of the Boy or an Arburg. The next question is, who is going to design the mold? Mold design is just as important and more so than just the machine.

Farm it out to a qualified short run house. You will be money ahead.

Tom:-

John Welden · Apr 24, 2017

Modelman said:
A friend had a Morgan Press when first starting out. What a joke. If you can find one used for a grand or so, maybe worthwhile, but at $10,000 they are waaaay overpriced for what they can do.

Dennis

I may be way off on the price. I didn't buy the machine.

I disagree with them being a joke. It's like a bridgeport compared to CNC mill. Can you make parts on the bridgeport, yeah.

I've made a ton of good parts on our shitty little morgan. I've made simple molds and shot good parts in less than an hour. For quick and dirty, simple little parts, they are okay machines. I've made tiny little molds out of aluminum that were like 4x4x2". You can do shit like that with a Morgan.

To any professional mold person, they're pretty much a joke of a machine.

Modelman · Apr 24, 2017

scadvice said:
Dennis is this the one your talking about in a 22?

BOY 22S INJECTION MOLD MACHINE 18677 PLASTIC MOLDER INDUSTRIAL LABORATORY | eBay

Yes. The BOY machines 15 through 50 ton basically look the same, except for size. That one is missing its feed hopper. There is/was a welded bracket that allowed the injection unit to be mounted vertical, for parting line injection.

I have no experience with Arburg... I do recall a couple things from when I was actively looking for used machines twenty or so years ago: Arburg had a good reputation, and for a small machine their AllRounder was the cat's meow. It could be set up as a conventional horizontal with through the fixed platen injection, or the injection unit swung up for parting line injection, or the clamp swung down to make a vertical insert molder with through the platen injection, or the injection unit swung back down to make an insert molder with P/L injection. A really versital machine. One thing wierd with Arburg, however, is their platens and tiebar spacing were really small for their rated clamp tonnage compared to everybody else.

And, I was told that they would not support a second hand machine unless THEY did safety upgrades to current standards, and that wasn't cheap.

Davis In SC · Apr 24, 2017

Modelman said:
Yes. The BOY machines 15 through 50 ton basically look the same, except for size. That one is missing its feed hopper. There is/was a welded bracket that allowed the injection unit to be mounted vertical, for parting line injection.

I have no experience with Arburg... I do recall a couple things from when I was actively looking for used machines twenty or so years ago: Arburg had a good reputation, and for a small machine their AllRounder was the cat's meow. It could be set up as a conventional horizontal with through the fixed platen injection, or the injection unit swung up for parting line injection, or the clamp swung down to make a vertical insert molder with through the platen injection, or the injection unit swung back down to make an insert molder with P/L injection. A really versital machine. One thing wierd with Arburg, however, is their platens and tiebar spacing were really small for their rated clamp tonnage compared to everybody else.

And, I was told that they would not support a second hand machine unless THEY did safety upgrades to current standards, and that wasn't cheap.

Some of the old Arburgs, as well as others, are downright safety hazards...I have seen many with most of the safeties bypassed. The older Arburg tech I knew had a finger missing, lost it to an old C4B air operated machine.
As far a trying to build molds/run parts, etc... I think the OP would be better off to find a small mom/pop outfit to do the protypes.. Sounds like they are not terribly complicated molds/parts.

snowman · Apr 24, 2017

I have two bench top machines, but I think they are more for resin testing than anything. I used to have a machine that was clamped with a hydraulic jack, then driven with another hydraulic jack. It was used to test custom chemistry resins, created in small quantity. So the mold was simply a dog bone shape, but it did well.

An full on hydraulic injection molding machine is like a forklift...it's not a question of if it's going to leak hydraulic oil, it's a question of when. Having surfaces that are not brought to full polish will also increase your tonnage requirement considerably. But, you can knock out simple prototypes pretty quickly.

With that said, short term, it's always better to farm out new technology. Long term, it depends on your direction. If you are heading in a direction where you want to be able to make working prototypes in short order, it may pay off to bring it in house...if anything, my experience is that it will always pay off in delivery time, but cost may still be equal.

However, with that said, I would still look at pourable plastics if specific resins aren't required, just specific properties. You can do a lot with them.

boslab · Apr 24, 2017

From my expiriences with Austin Allen small moulders, if a run exceeding a few thousand is needed then they are worthwhile, however getting a new die to work is a time consuming excercise, gas venting, short mouldings, etc etc, I've unhappily spent days getting a die to even fill properly, sometime exasperated and taken a file to add venting and ruining the die, once their running their brilliant, getting them to do that is the problem.
Diemaking itself is a venture, we had a good mill, EDM etc in a well equipped shop and several diemakers, even then you understand why a new tool costs thousands, if money isn't a consideration (a rare condition) I'd think small cnc VMC would be better myself, just my opinion.
Mark

Davis In SC · Apr 24, 2017

boslab said:
From my expiriences with Austin Allen small moulders, if a run exceeding a few thousand is needed then they are worthwhile, however getting a new die to work is a time consuming excercise, gas venting, short mouldings, etc etc, I've unhappily spent days getting a die to even fill properly, sometime exasperated and taken a file to add venting and ruining the die, once their running their brilliant, getting them to do that is the problem.
Diemaking itself is a venture, we had a good mill, EDM etc in a well equipped shop and several diemakers, even then you understand why a new tool costs thousands, if money isn't a consideration (a rare condition) I'd think small cnc VMC would be better myself, just my opinion.
Mark

One thing people forget is auxillary equipment needed for any size molding machine.. Mold heat controller, AKA Thermolator.. and most importantly, drying equipment. Most of the higher end engineering resins are VERY sensitive to moisture. There is a fine line between drying the material and thermally damaging it..

John Allan · Apr 24, 2017

Quite a few years ago we were doing thermoset motor components using transfer molding, not injection. Molds were much simpler, the cycle time was longer, and our scrap rate approached zero. If you need the high heat properties of thermoset, that is a whole different ball game than thermoplastic.
John

adamm · Apr 25, 2017

SBAER said:
Something like this

Manual Benchtop Injection Molding Machine MIM-2,a standard mold&Free Shipping | eBay

Back in highschool machine shop we had a press like this. Now it was highschool and all, but it would only do parts that were fairly crude. It didn't seem to have injection pressure enough to hold fine details. We were molding gears, and they all had 1/8" tip diameters, and even at that, it was common to not fill the mold. Could have been a resin/operator problem though.

As for running in bigger presses, this isn't likely the proper terminology, but it is common to run aluminum inserts in master mold bodies. The main body is pretty much a steel die that has all the required heaters, coolers, etc, and there are square-ish cavities to put aluminum mold cavities in. I'm not sure if they still do it, but Samsonite (yes the luggage people) in Stratford spun off their injection molding business, and about 10 years ago I was working for a place that was prototyping load bearing parts with them. The molding company would then get the production contracts for those parts, so I don't know if they would just run prototypes, or if they are even still there. The parts were for structural applications and were made of glass-filled materials (I think they were mostly nylon).

Anyone have experience with bench top injection molding machines

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