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Opinions on a Morgan Injection Press please....

swarf_rat

Titanium
Joined
Feb 24, 2004
Location
Napa, CA
I know very little about injection molding, but these come up for sale every so often, don't take a lot of floor space, and seem like they would be a way to mold a few plastic parts when there is no other way to make them. Are they finicky to use and maintain? With time and care can you make just about any plastic part you want? What are the limitations and headaches?

Thanks for any response. I have done the search and read what was in the archives. Hoping for a little more color on the subject.
 
Swarf rat

I don't know if you are interested in building one but there is a GINGERY BOOK. I haven't seen the book but Model Engineering Workshop #92, Aug/Sept 03 ran an article on a guy's improved version of the Gingery machine. I made some sketches of a my version of it but it will have to wait.:oHe made some good looking knobs and model parts. Also someone on the HSM board built one maybe IOWOLF. You might search there.

I worked eight LONG years in a plastic factory(I enjoyed the tool room work but the company culture sucked). The basic concept of molding isn't hard. What gets hard is running good parts on a 10 second cycle 24/7. With a home brew machine you won't care if there is flash to trim or the part sticks in the cavity. Just be careful around molten plastic, I still have scars that stuff sticks and burns.

I can make copies of that article if you have any interest.

Jon
 
Jon,

Thanks, but I already have too many projects! Even a used commercially made press is going to be a project, if experience serves.

I know there are several on this board who have used the Morgan press, hoping to hear some first hand experience.
 
I've used one a fair bit - the R&D shop I used to work in had one, and I now teach a course that uses one for student labs. Probably the most important thing to mention is that it is not a screw-feed machine, just a pneumatic plunger. So you don't get real great mixing of your resin, and you can get burning or cold spots in your shot pretty easily until you get a few parts made and get into the right timing of heating and injecting.

Controls are simple - clamp pressure and plunger pressure adjustments, one or two temperature adjustments, and "clamp" and "inject' buttons. There are interlocks on the mold guard and the feed hopper guard which can be kind of finicky. Also, the clamp uses an over-center arm that has to be adjusted if you use molds of different heights.

We tend to stick with easy-to-mold resins like PE or PP. The R&D shop ran TPE and some other resins. Not sure how ABS, nylon, etc. would do. I learned the hard way that PVC emits hydrochloric acid gas when you leave it too long in the barrel . . .
 
CCC

Thanks for the info. If you want to injection mold a few parts, a few times a year, is this the right tool? Are there any alternatives? Are the drawbacks you mention (not a screw type injector) limiting the sort of part you can make, or just it more difficult?

I would like to inject glass filled nylon and ABS, don't know how much more difficult that makes the problem. I have read that all the vinyls are potentially caustic and smelly.
 
I think it's a great tool for molding a few parts every now and then. I think you just have be prepared for a bit of trial and error on your shots, and even then, quality is going to be somewhat less than a full production machine. It was acceptable for us for prototype parts, and we even used them for functional testing, so I'm not trying to be too critical.

I'd guess that you could get ABS to work. Not sure about the glass-filled nylon. If I get a chance today, I'll try to ask the guy here who really knows that machine.
 
Hey Swarf Rat,

you might consider this one too, if you're only doing small batches infrequently. It's definitely down on the hobby end of the scale, but might meet your needs. I believe the price is in the $1500 range (new)

http://www.injectionmolder.net/

I don't have any experience with injection molding machines however. I just thought this machine might be of interest... and maybe you want to get in an upper body workout too...
-- doesn't look too good for the resins you mention though...

ciao

lino
 
Without a screw, there may be cosmetic issues, ie different shades from the plastic not getting mixed as well. I would think there could also be problems with getting the mold "filled" if the shot isn't a uniform temperature. That's probably the trial and error CCC is refering too. The homebrew IM machines seem to do a good job so a professionally made one should do what you are looking for. If not, you can always sell it to me for dirt cheap.:D
 
I ended up buying the Morgan. It is old but looks functional. I got a good price, probably can't get hurt, even if it needs a bit of work. I don't mind fiddling around to get reasonable shots and wouldn't expect product type quality - just don't know how else you go about making some plastic parts.

I would like to hear about glass-filled nylon.

Also does anyone injection mold wax for investment casting in something like this? I have run into a situation where I wanted to have 10 pieces of SS cast, they ended up wax printing 10 forms which was time consuming and expensive. I probably could have milled 10 wax forms in less time (7 hours of printing time each), but if I wanted 20....

For my education, what is a screw injector? This one appears to have a very large air cylinder on top, connected to the smallish ram which injects the plastic. I could see how that wouldn't mix things up well, but if you are only using native colored plastic not a problem?
 
depending on what you are doing, you may want to look into rubber mold casting. Use a SLA as a pattern and cast in a variety of resins. Not cheap per part, but this thing won't be either unless you are making a fair number of parts.
 
I ended up buying the Morgan. It is old but looks functional. I got a good price, probably can't get hurt, even if it needs a bit of work. I don't mind fiddling around to get reasonable shots and wouldn't expect product type quality - just don't know how else you go about making some plastic parts.

[FONT=&quot]A friend had one of these in his shop some years ago, but since you just bought it, I won't bother to dwell on my opinion of them. Just let me say there are so many used ones for sale because there are so many disappointed owners. [/FONT]:bawling:

I would like to hear about glass-filled nylon.
I don't run any Nylon, but from what I know, you have several strikes against you:

1)Nylons require high molding temperatures, then become chemically unstable if held at processing temperature too long. The Morgan press is not particularly easy to make "air shots" with to purge material during cycle hold ups. :willy_nilly:

2)When at molding temperature, nylons run like water. I don't know if the plunger seal on a Morgan is sufficient to deal with this, but if material blows past, see item 1 above. :( The vertical design of the Morgan means the nozzle will drool. I believe that Morgan sold a shut-off nozzle to prevent this.

3)Glass filled materials are exceedingly abrasive. Soft temporary tooling won't last long at all.[FONT=&quot] :angry:[/FONT]


Also does anyone injection mold wax for investment casting in something like this? I have run into a situation where I wanted to have 10 pieces of SS cast, they ended up wax printing 10 forms which was time consuming and expensive. I probably could have milled 10 wax forms in less time (7 hours of printing time each), but if I wanted 20....
[FONT=&quot]

While wax can be injected, it is common practice to use unfilled HIPS (High Impact Poly Styrene) for investment masters. The parts are more robust, and as long as there is no color pigment to form ash, it burns out as clean as wax. I would suppose some grades of polyethylene would work as well, since PE is basically polymerized paraffin.

[/FONT]
For my education, what is a screw injector? This one appears to have a very large air cylinder on top, connected to the smallish ram which injects the plastic. I could see how that wouldn't mix things up well, but if you are only using native colored plastic not a problem?
Practically ALL injection molding machines (except the Morgan) built since the fifties have been "reciprocating screw" machines. During the plasticizing stage of the injection cycle (which occurs concurrent with the cooling of the previous shot in the mold) the extruder screw turns, forcing the plastic feedstock (normally pellets) forward, while displacing itself back. The plastic is heated not only by heater bands around the barrel, but also by shear imparted by the screw. As you can see this provides a very efficient mixing action. When the shot is to be injected, the screw stops, and is driven straight forward like a piston, a movable check ring at the tip of the screw preventing any backflow. It is such an efficient system that it totally replaced plunger presses in one generation of equipment. The only remaining plunger presses are toys, educational models, and the Morgan. :(

Dennis
 
Injection molding screws are like augers with a decreasing pitch. So as it turns it mixes and compresses the resin which helps to melt it(the barrel also has lots of band heaters). For the actual injection, either the screw is used as a plunger or it feeds the plastic into another injection chamber. With natural colors, it would probably be okay but you could still get lines from uneven melting. Remember I'm coming from a background where anything slightly wrong had me dragging my box to the production floor so I look at would couold go wrong. I'm not trying to be Debbie Downer.

I've seen set-ups to inject plastic molds with wax to get a sample to measure without running it through a press. I don't see why you couldn't do the same thing with your Morgan to make patterns.

The only thing I know about glass-filled nylon is that it is abrasive and hard on molds. Again probably not a concern for your situation. When I get home IA'll look up a link for a reference guide for injection molding which is real handy.
 
… One additional thought. One of the best entry level references for injection molding I've found (and I'm basically self taught) is Injection Molds and Molding by J.B. Dym. It goes through the basics of the machine, the mold, and material properties in a way that is understandable to the beginner, but still useful as a reference later on; I still used my copy to look up the basic properties of unfamiliar materials, size gates, and whatnot, until I lent my copy to some p...k who didn't return it. :angry:


A $200 book, I just bought a replacement copy on Amazon.com for $9.77 plus shipping, ( thanks for making me think to look
:) ) and there is another copy of the same book up for the same price right now.

Dennis
 
We have had a Morgan press for over 20 years. It has served us well, but does have limitations. It's shot size is limited. It's a good press for prototyping or short production runs. We use it for runs up to 150 parts or so.
 
Morgan Presses are OK !!!

Back thirty years ago, when I worked for Uncle Sam at the NARF in Norfolk Va. We had a morgan press. I made probably 50 or more molds for and they were used for glass filled parts, The molds were made from 6061-T6 Aluminum with a 3.5 to 7 degree draft on the part depending on the depth of the part in the mold. The molds were run constantly of several years at a time. The biggest hazard was keeping the operator from using a large hammer on them to get them apart. Usually a pair of large screw drivers were all that was needed just cut slots in both sides to gain an even separation. The aluminum held up very well as long as you preheated the mold prior to use. Also be sure to vent the molds with a .25 by .010 slot to insure a good fill. Follow Morgans recommendations for mold setup and sprue size. Yes they have a very good web site with a lot of info.

Scott
 
HERE is the booklet I referenced earlier. Lots of good info: vent depths & melting temperatures of different resins and is worth the money just for the chart that gives the mV that a thermocouple should read at a certain temperature.

I just found the MORGAN website. They look to be a couple steps above the lever-operated machines.
 
[FONT=&quot]A friend had one of these in his shop some years ago, but since you just bought it, I won't bother to dwell on my opinion of them. Just let me say there are so many used ones for sale because there are so many disappointed owners. [/FONT]:bawling:

Too late now! But again for my education, what is the alternative to the Morgan? By that I mean something that is simple, takes very little floor space, doesn't require much maintenance, and is capable of the 4 oz or so shot? I didn't research this extensively, but the offerings certainly seem limited (to the Morgan, primarily). I know on ebay you can get larger machines pretty cheap, I suspect there are plenty on the East Coast to be had for the price of hauling, but those don't meet the criteria listed as nearly as I can guess.

I tried to get that $10 book but someone beat me to it: now $185!
 
I think the Morgan fills a useful niche. I've used everything from a hobby lever press to a 30-ton production machine. (And that's small for some of you, I know.) The Morgan isn't either of those.

Compared to the hobby machines, it has much better temperature and pressure control and larger shot size. The pneumatics really help when you have several dozen parts to run. Compared to a screwfeed machine, it's a lot less complicated, so less setup and/or repair, plus the molds are much simpler.

I don't love it, but I don't hate it.

BTW, our expert here says ABS should be no problem, but he wouldn't recommend nylon. Modelman seemed to have the best reasons for why.
 








 
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