20 Ton press for injection molding machine

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    Default 20 Ton press for injection molding machine

    This area of the Zone looks a little less traveled.
    I have had a 20 Ton press for a long time. It doesn't do much. I already outfitted it with an air assist hydraulic jack. I have used it some, but really very little use. I doubt seriously that I will be using what I make here for production. Much more hobby type use.
    With the standard press as it comes from HF and a vise that I took off the mill because it was replaced with two double vises, I should have just about everything I need for this project.
    That is less the band heater and PID control. I have ordered the initial testing heater. I will likely need two of them. The one I bought is only an inch ID. I will be using some standard 3/4" stainless steel pipe to start with for the pot or chamber. It is just about an inch OD. .82" ID. It will have a standard SS cap on it which will become the nozzle. I will machine a steel press plate that will conform to that caps shape. That press plate will be used on all the molds I make. So far, I only have one planned. That means that each mold will be at least three pieces with the top plate. That may change, but that is the initial plan. The mold itself will be in the milling vise which will get mounted. The ram is .813" W1 Tool steel. It will have an attaching collar to affix it to the presses ram. It is 1.5" steel.

    I have researched this quite a bit over the years. Can't stomach paying for anything I have seen on the market so far. So, I will post more when I have more info. This will be a fairly slow hobby use only build.

    I intend to initially make my own knobs. I would love to have some in red. Those babies are either scarce or expensive. I order black ones at 1200 a time. Less than a buck each, but I have never been pleased with any of the ones I have bought in bulk. They work, but....
    I can get SS wing nuts already threaded for about 35 cents each low volume. I intend to overmold those into a red ergonomic knobs. Probably do 4 knobs per shot. Now what I would really like is some translucent red so you could see the wing nuts inside.

    I haven't researched low or hobby volume plastic pellets yet either. Not much that is.
    The knobs I have been using are polypropylene. That stuff is readily available, but not sure how to tint or color it. I have only seen white. Another option might be the ABS etc from my 3D printing days. It was fairly stout stuff even 3D printed.
    I have seen that in pellet form.
    Anyway, enough rambling for now.
    If anyone has any input or sources for raw materials, feel free to chime in.

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    Lee


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    Default Re: 20 Ton press for injection molding machine

    Posting to subscribe.

    You always have some interesting project going on it seems and this one is no different. Looking forward to what you come up with.



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    Default Re: 20 Ton press for injection molding machine

    Thanks, Ed.
    It has held my interest for awhile. My Son is hunting Buddies with a guy that owns an Injection Molding company right down the road. The biggest issue with any of that is the mold cost. He has a local company that machines all of his molds too. It can be incredibly expensive. Since I do not want to get into the knob supply business, my only option is low volume hobby stuff for knobs. I could not imagine the cost of a mold that would do 50 encapsulated knobs at once.
    He has a lot of different machines though. He may have lower volume machines too. I haven't talked to him or seen the inside of his shop. Might have to take the time to get an introduction.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Any of the typical supply places sell pellets at like 55 pounds for the smallest package. Hobby Lobby sells PP pellets that are mainly used as stuffer helper to add weight to dolls, bean bags fillers, etc. I have no clue how it would melt. We do have a local Hobby Lobby that is fairly new. I have been meaning to take a stroll through there anyway. I will probably pick up a package for testing.

    Plastic Pellets | Hobby Lobby | 213199

    I'll check out Ebay as well for some ABS pellets in red.
    Okay. Plenty of ABS pellets on Ebay.
    ABS Plastic Pellets 3D Printing Polylac PA 758 Transparent Red 10 lbs Free SHIP | eBay

    That is a good source and cost effective.


    Now the nicest knobs I have had are molded twice. First layer is polypropylene and the second is some type of rubber for a cushion grip. I can get these in low volume at just under $2 each. In fact, I like them so much, you will likely see them on my guards when my stock runs out.
    They, of course, are in black.

    A lot of my customers are older retired guys. I am sure that Arthritis bugs some of them and have been told so. For those customers alone, a better solution is in order.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    For the heat chamber, I am using 3/4" stainless steel nipple 5" long and threaded both ends.
    I chose this because it is readily available. Trying to make basically an off the shelf solution first to keep things simple. Stainless steel should heat quickly and evenly and retain heat for some time.
    Now my plunger fits the pipe very well, but the threaded ends are narrower than the rest of the pipe. So not really optimal. I will likely see some blowby on the ram. That is not ideal. I think most plastics does have some lubricating qualities when heated, so may not become an issue.
    I do have a plan in place to bore out the pipe nipple on the Tormach lathe to a consistent ID. Then get a ram that fits closer. In fact, I will most likely do that anyway, but I want to see how it works without a machined fit.
    I also chose the threaded pipe to use a cap on one end for the nozzle. This makes disassembly a breeze if it needs cleaning or replacing the nozzle. The other end is getting a flange. This will make mounting the heat chamber pretty easy. The cheapest 3/4" pipe flange at Mcmaster was aluminum. I can make a threaded funnel for it too to make charging pretty clean.
    As far as home made injection presses go, this one will be a rather large capacity.

    Here is the heater and controls that I ordered for it.
    110V 300W 25mm x 30mm Metal Screw Fixing Flexible Mica Band Heater - - Amazon.com

    Inkbird Dual Digital PID Temperature Controller 2 Omron Relay Thermostat 110-240V ITC-100VH + 40A SSR + K Sensor - Hvac Controls - Amazon.com

    I also ordered a heat sink for the relay.

    This is very similar controls to what I used for my heat bed on my 3D printer, so pretty simple.
    I know I will probably need a second band heater, but wanted to make sure it will do what I need first. With two band heaters, I would machine a collar for the heat chamber and thread a hole for the thermocoupler. That collar would be between the two heaters.

    This one is Celsius only, but that is really all that is needed.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    This is a great site for anyone wanting to do a bit of bench molding or have something done in the thousands or millions even. Lots of good stuff there.
    https://www.protolabs.com/injection-molding/

    I have had a few samples from them. They offer those from time to time. They usually include lots of little molded in features to show what is possible.

    I have also changed my mind about wanting a wing nut style knob. I received some nice samples that are three lobe knobs. These allow a much better grip in a very small knob. I think I will shift the focus of a mold design to that type knob. I can fall back to the two arm knob anytime.
    I will be designing it in Fusion 360. I haven't done a lot with it, so this will give me some needed exercise with it.


    I know how to use ABS. I will use it first I think. I am trying to find some bright red pellets and not having much luck. I can get the filament all day long fairly cheap in the exact color I want. I am not interested in coloring my own. With such a small heat chamber, a few more or a few less color pellets would probably make a big difference.
    I am also interested in using TPE. Ebay is a good source for that in black. I think this is the stuff that the soft touch knobs use as an over mold. Feels kinda rubbery. I am still researching that though. I may be wrong about it. Exact formulas and sources must be a semi-trade secret for some of this stuff. I don't know if my Son's buddy will shed some light on it or not, but worth a try. Stay tuned.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Okay. I hooked up the electronics and heater. Man, that heats up fast. Before I could get the controller set correctly, the heater blew out. I knew I should have disconnected it first.
    I considered the heater part to be consumable anyway. I have a few more on the way, but USA made ones too. A couple Chinese and a couple USA made should keep me going. I don't think the heater should have burned out, so it probably had a factory issue anyway. It was only up around 300 C, which is hotter than I will typically be using, but within operating range on the heater.

    The controller works great though. I was thinking that I might need two heat bands on this? No way. Now my pipe is 5" long. I have ordered a 3.5" instead. I think that will be a more suitable length.
    I also ordered the next size up for the ram. I will go ahead and bore out the new SS pipe nipple anyway. I am sure that will help eliminate some messy situations I could have had with standard pipe nipples.
    Since I already had the press, this is turning out to me one of the simpler things that I have made or tried to make. I still have a couple more projects that are in limbo for one reason or another, but still on the to do list.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Here is an excellent video with other great videos at the end.
    Well worth watching.



    Lee


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    Default Re: 20 Ton press for injection molding machine

    And another video that starts my mind wandering. Very useful for installing led inline and using a clear rubber or silicone type over molding to see when power is being applied to a cable.



    Lee


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    Default Re: 20 Ton press for injection molding machine

    Now I am considering whether I should install a plasticizer in the barrel. It seems that the plastic can be different temps inside the barrel when not using a screw. A plasticizer would spread the melted plastic around the outside of the barrel keeping all of it basically the same temperature, and therefore flow rate. It make sense to me. Inside the nozzle on this, which is a threaded pipe cap, there are threads and a space between the bottom of the cap and the pipe. That would be a perfect spot to fill with a plasticizer. Simply a piece of steel or SS that will allow the plastic to flow round it to the orifice. Threads and ports on the bottom end and a bullet or dome shaped top should work pretty well. This would lessen the size of the shot, but would probably make it a much more consistent shot.

    I will get a little more progress done on this later this week in the evenings and will post some pictures as well.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Cleaning out and purging different color and types of plastics did not appeal to me from the start. It looked like it could be a real chore. Especially since I would like to get to a point where I would do two colors and types.
    Red and black.
    Then it hit me that if I design this correctly, I can make the barrels hot swappable. So to speak.It will only be the pipe, cap and plasticizer inside the barrel.
    Now the thermocouple will screw into a threaded hole in the cap. (nozzle) unscrew it. Then unscrew the barrel from the mounting flange and install the next one. The heater band does not have to be very tight on the barrel. Just a slip fit will work fine.
    That should solve that extra work and wasted material.

    I plan on having a thin stainless guard made out of preforated sheet. I will have to figure out how to make that easily removable as well.


    Now on designing the plasticizer. The cap is 3/4" pipe thread inside, but it doesn't thread all the way to the bottom. I want to design the insert (plasticizer) so that it seats in the bottom of the nozzle. It will also be threaded into the cap and take up all the space between the end of the pipe nipple to the bottom of the cap.
    A little trial and error will get me there I think.

    My first test nozzle will use an 1/8" hole for the orifice.
    The insert needs to move the material from the outside close to the barrel to the inside at the nozzle. Holes drilled at an angle around the insert is the only way I know of to accomplish that in such a short part. Now, how do I drill accurate angled holes? I would need a consistent way to do it.
    The rest of it can be turned on the Tormach lathe. I do have a manual Ridgid pipe threader and will probably use it for the threading. It does a good job. Then again I want to do some threading on the Tormach too, so now is my chance to see how well it works.

    The heater band that did come in is the wrong size. I'll have to return it, but I have a few more coming.
    Thats about all the update for now.
    I have started modeling the first knob mold in Fusion 360.
    I'll show something when I have it.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Well guys, I gotta say that designing a mold in Fusion 360 or any CAD really is not such an arbitrary thing. I did manage to design some knobs that I think will work okay for the first trial runs. Just making this mold out of 6061 2" x 1" flat bar.

    I will post some images later when I get the first sprue and runners figured out.
    The future ones should be a little easier. The knobs I designed have embossed letters, so that was a little challenging, but I think it will work. I still do not like how F360 handles Fonts, but I guess I will get over it.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Quote Originally Posted by LeeWay View Post
    Okay. I hooked up the electronics and heater. Man, that heats up fast. Before I could get the controller set correctly, the heater blew out. I knew I should have disconnected it first.
    I considered the heater part to be consumable anyway. I have a few more on the way, but USA made ones too. A couple Chinese and a couple USA made should keep me going. I don't think the heater should have burned out, so it probably had a factory issue anyway. It was only up around 300 C, which is hotter than I will typically be using, but within operating range on the heater.

    The controller works great though. I was thinking that I might need two heat bands on this? No way. Now my pipe is 5" long. I have ordered a 3.5" instead. I think that will be a more suitable length.
    I also ordered the next size up for the ram. I will go ahead and bore out the new SS pipe nipple anyway. I am sure that will help eliminate some messy situations I could have had with standard pipe nipples.
    Since I already had the press, this is turning out to me one of the simpler things that I have made or tried to make. I still have a couple more projects that are in limbo for one reason or another, but still on the to do list.
    Hey Lee thats pretty neat what your doing. 20 Ton press for injection molding machine. I may eventually try some molding also. Oh and btw I have mfg electric heaters for a living last 24 years and yes here in the USA baby20 Ton press for injection molding machine20 Ton press for injection molding machine. You ever in need of a heater, T/C or controller just PM me and I can set you up.
    If you want really HOT I'd use a mineral insulated type nozzle band heater. The mica bands are good for barrels in larger diameters but the watt density is low like 30-40
    MI's can go to 150 watts/sq-in
    And ya hooking a heater up across the line and letting it rip will end badly20 Ton press for injection molding machine.



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    Default Re: 20 Ton press for injection molding machine

    Thanks, Paul.
    I think I am covered on heaters for the moment, but I am interested in what you make.
    I will shoot you a PM and give you my email.

    Here is the first iteration of the mold for these knobs.
    I did a draft analysis in Fusion 360 and I did get a little orange on the part. Just a little red around the letters, but it is so shallow that it should not be an issue.
    I only drafted the sides of the knobs 1 degree. Where I did get some red was in the runner, but that should not be a problem. This is for a single color knob that gets no overmolding. It does get a stainless flange nut inserted into the part. It will thread onto a screw through the bottom holes and the screw will protrude into the molded knob about 1/2" depth. I include slots to help with the initial opening of the mold. Then unscrew the two screws a bit and tap them and the knob should pop loose.
    To reset, just spin another nut onto the screw. The two pins inside each knob just act to displace the plastic. I think I will add a third one right in front of the gate. I didn't want to disrupt the flow and not having any experience with it, I left it out. If it impedes the flow too much, I can just plug the dowel holes there.
    Anyway, there is quite a bit that goes into these molds, but F360 is certainly up to the task.

    20 Ton press for injection molding machine-open-mold1-jpg

    Lee


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    Default Re: 20 Ton press for injection molding machine

    A little more about my thoughts on this mold.
    It will have some vent channels. Very shallow vent grooves running to the outside at the extents of the part. I will mold those in and they will be on the top half of the mold.

    I can use the bottom half of this mold with several different top halves if I want to do other knobs. As long as they are three lobe knobs. I was thinking about a red under molded knob as shown with raised letter. Then overmold that with black rubber or TPE. You would basically have to use two top halves for such a mold. The knobs would easily realign in the bottom mold. The base and letters would be visible and red and the rest would be rubberized plastic with grips molded in. I have no idea how much a bunch of knobs like that would cost in the grown up World, but I think it would be both fun and challenging from a hobby standpoint.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    I have accumulated most of the stuff I need for this project.
    A few things still outstanding, but on the way. Switches and 1/16" end mills. I had a few, but all were too short.
    I will get to make some progress on it soon hopefully.
    I plan on machining the mold next week in the evenings.
    Stay tuned.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    Well, my Son took his vacation this week and went hunting. That leaves only two of us here for production, so did not make any progress on this project. I will get the mold machined out this weekend. I want to turn a few items on the lathe too. Assuming everything is cool with Fusion 360, there should be a showing soon. Still looking for a good source for bright red ABS pellets. I have a good source for black TPE already.
    I found some nice red polyethelene. Too expensive. Polypropylene would probably be okay. I am tempted to chop up some 3D printer filament.
    That stuff is everywhere.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    I'm actually selling a molder similar to what you are looking into building:

    http://www.cnczone.com/forums/tormac...8-tormach.html
    For Sale For Sale: Injection Molder | Panjo

    I hope you have a lot of patience. Injection molding is harder than it appears at first sight, especially with a hobby type machine. Your biggest issue will be that the injection speed is too slow and you will have to heat up the mold to a very high temperature just to be able to fill it (unless you are only doing tiny parts). Also, keeping the mold clamped shut might be a problem, the forces can be ridiculously huge. "Real" molders have huge amounts of clamping force (my new one has 50 tonnes). I would suggest to start with a mold with just one nest and a direct gate, less stuff that can go wrong



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    Default Re: 20 Ton press for injection molding machine

    Thanks for the info and suggestions. I have no doubt that I will run into some issues with this. I think i will take your suggestion about using a single cavity mold to start with. Then I will know more about designing a two cavity mold with runners.
    I will be using a 4" machining vise initially on this. I don't know what tonnage it can clamp to, but I think it should do.
    You mentioned on thing about the speed of injection and that has concerned me as well.
    This is the jack that I have on this press right now.


    I have the older orange version, but basically the same thing. It is no speed demon, but I can shorten the throw to only what is needed for the ram and that would be a couple inches. It can cover that distance pretty quickly. I still have the original manual jack as well if I need to redign to be more like the Medium Machinery design and get 20 tons of clamping pressure on the mold.
    I think that would be way overkill though.

    I would eventually like to design a small horizontal machine that would use a hydraulic pump and rams with an actual screw. That would be miles down the road though.
    Anyway, my current ambitions are only hobby grade at this point and this hot press should be enough to play with a few design elements.

    I would like to see your current machine though. Sounds like a nice one.

    Lee


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    Default Re: 20 Ton press for injection molding machine

    You can find a couple videos of my molder here: https://www.instagram.com/cordvision/ It's the yellow machine with Boy 50T written on it. I bought it used.

    About the speed: It really depends on the part. If it is thin walled, you need quite a bit of speed. Yours looks like it is solid all the way through, which will help but will take a very long time to cool off and you might have problems with sink marks. On a side note, make sure to have plenty of draft, especially if you have a big core, else it will be very difficult to remove the part from the mold.

    Those jacks move fairly quick when there is no load on them, but they slow down a lot with a load put on them.



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