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    Hi again jhov:
    You can do this, but you have to allocate your resources to maximize your chances of success.
    There's a lot to know to design and build a successful mold and a lot more to know to successfully run a press.
    So I encourage you to do as I recommended earlier if you really want to make this happen.
    Find a contract mold designer and have them design the tool for you.

    Ditch the idea of buying your own press...there is so much more to a successful molding operation than just having a molding press.
    There are a gazillion molders out there who are infinitely better equipped to run your mold and the cost of the parts is trivial.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    I was not going to respond to this thread but I'll give you some much needed advice. I'm a 35 year mold maker in a top notch tool shop, and I will tell you it's a hell of a competitive business. Based on the questions you ask, I don't really think you thought out what your getting into. Marcus has the right advice for building this mold, but molding and selling 60k parts is a wet dream. Not when the aftermarket gun parts business is an already flooded market. And keep in mind your doing this during the Harris administration.

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    Our company ditched our last two hydraulic molders this year, both Cincinnati Milacrons. I don't recall their tonnage, but they were fairly large. We now have a small fleet of 7 Sumitomo Demag electric molders running full production. These are between 220 and 350 ton machines, so a bit larger than what you're looking at but they do make smaller machines in the same lineup. These electrics use toggle clamps for clamping the platens and the platens ride on linear bearings instead of bushings on the tie-rods. Both nice features for what we do. The biggest problem lately is chewing up ball screws on the ejector assembly but I attribute most of that to careless operators. As a one-man-band that shouldn't be an issue for you.

    Going from hydraulic to electric transformed our molding department. They are so much quieter, cleaner, and energy efficient. In fact, the energy savings were one of the big justifications for purchasing them. Now, by far the noisiest part of that department are the chillers for cooling the molds. No more hydraulic power units humming away.

    As mentioned before, the Cinci's were getting harder to fix and broke down frequently so it was time to part ways.

    I am by no means an expert, just sharing my observations.

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    Bulk molding compound may be an interesting route vs plastic injection molding if your quantities are lower. The physical properties are better, in most ways, and it is much cheaper to get into.

    A molder can fuck up your mold in a millisecond, it doesn't matter what the mold is made from. Aluminum molds run around 30-40% faster and are more thermally stable given the same cooling circuit. I used the same aluminum for shallow locks, shutoffs, and slides with the same clearance as I would with 4140 PH and never had a problem I wouldn't have had with steel. With a waxed wheel it grinds fine but I only milled so it was never an issue. When I needed to remove a few tenths during fitting I would just scrape it in. This is with QC-7 aluminum, very special stuff.

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    Have you even talked to the pros about this? Sent an RFQ to Protolabs? Injection Molding Service | Get an Online Injection Molding Quote

    Additive Manufacturing, LLC? Injection Molding / Compression Molding / Extrusion Molding : Additive Manufacturing

    Forecast3D: Injection Molding for Production | Plastic Injection Molding Services


    Not only do any of these people have decades of experience in designing mold tooling, they have all the tooling necessary to create your mold, and avoid the pitfalls you'll make in your first 5 iterations, ultimately saving you money, especially for prototyping.

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    TeachMePlease raises a great issue - do you want to be in the plastic injection molding business, the mold makeing business, or some particular parts business?

    Or do you just want to be in some strong stand-along business?

    Saying yes to any of those could be a good and sensible thing, but do sort out which .

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    **AND** - where would one read about the processes for "bulk molding compound" - these are different processes than injection molding right? Key textbooks, catalogs, vendors to go read about?

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    Quote Originally Posted by bryan_machine View Post
    **AND** - where would one read about the processes for "bulk molding compound" - these are different processes than injection molding right? Key textbooks, catalogs, vendors to go read about?
    I'm working on a series of compression molded parts presently, and my reference book is:
    Premix Molding by Rodger b. White

    I'm working with the molder on a daily basis, and have learned allot.

    The OP might have a chance, with hand slides, and a transfer operation.
    Simple press, with heaters underneath the die.

    One thing is for sure, compression molding with it's normal high fiber content, will make a very strong part.

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    Quote Originally Posted by TeachMePlease View Post
    Not only do any of these people have decades of experience in designing mold tooling, they have all the tooling necessary to create your mold, and avoid the pitfalls you'll make in your first 5 iterations, ultimately saving you money, especially for prototyping.
    I did not go into this discussion with the intention of raining on anybodies parade, but I have to say, I agree with everybody else; this part is much too difficult to learn to design, build, and run tools. I see about the same mold layout as Marcus, with the exception that if I was going to all that work, the mold would have a single drop hot tip, not only for the sake of cycle time, but to keep from having to regrind the massive sprues that will result from a conventional sprue bushing in a cavity that deep, and the attendant degrade of material properties as it gets recycled endlessly.

    There is the option to design the part, then have someone who specializes in mold design design the tool, then build the tool in-house. We don't know how well your shop is equipped, but I see the need for a CNC machining center, and sinker EDM. I suppose the cavities could be entirely cut with the CNC, but the surface grip detail would be much easier / better if done with EDM.

    Then there is the matter of running the tool. It is much easier to learn toolmaking if you have your own press for tryouts, at least much cheaper, but you can't learn molding with a tool that you don't know will run, because you'll never know if the problem is in the tool, or your set-up. Experienced molders have a whole array of tricks they can try depending if the part won't fill, won't pack out the sinks, or won't come out of the cavity, and the SAME mold can exhibit all of these behaviors depending on the molding parameters. The average mold shop also typically has more press options if the set-up man decides what is really needed is, more tonnage, bigger shot size, or higher injection pressure.

    By the way, because someone asked, my idea of a "small, hard to fill detail" is a curved spring .011 x .020 x .300 long in acetal co-polymer.

    Dennis

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    Hi Dennis:
    I was gonna gate between the slides on the center of the bottom of the part. like gating on the center of a hat.
    (same way you'd position a hot tip)
    I was thinking of delaying the slides so I could just mill a cavity in each slide to act as a sprue puller.
    Were you thinking I wanted to drop the sprue all the way down the height of the slides and gate on the rim?

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    Marcus,
    I'm unclear if the part is open at both ends. In the photo, the bottom of the part (which I'd put nearest the machine nozzle, looks solid, or may be a snap in closure, I donno. Either way, I like hot tips

    Dennis

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    I really appreciate all the feedback. To clarify, I'm not just interested in just making the part and/or selling them. I want to learn how to design and make the mold, run the machine and make the parts. I plan to acquire whatever machines / tools I need along the way and learn those too. I might consider hiring a professional to hold my hand at times if needed, but I want to learn how it's done. Selling the part in the end is just a means of paying for the education and tools, and if I can make a living at it, that'd be fine.

    I'll have another look at compression molding. I don't know much about it, but I thought it was primarily used for relatively flat parts, like enclosures and such. And thanks for the book reference, I ordered it as well.

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    Hi Dennis:
    I also presumed the part was closed at that end.
    Who knows??

    In any event, I have had trouble with local molders not being able to run hot tip molds without a lot of tears and hand wringing.
    We've still got a few dirt floor operators around here, with presses from the 1960's and 1970's, and the short run, prototype, and inventor guys tend to gravitate to them because they're cheap.

    A hot tip is like a Martian to some of them... they are not happy to see one, even if they do save material and make better parts, and eliminate the need for a grinder.

    Ah well, thankfully we can happily offer our two cents' worth here but don't have to get too mixed up in or take responsibility for this project.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    Quote Originally Posted by jhov View Post
    I really appreciate all the feedback. To clarify, I'm not just interested in just making the part and/or selling them. I want to learn how to design and make the mold, run the machine and make the parts. I plan to acquire whatever machines / tools I need along the way and learn those too. I might consider hiring a professional to hold my hand at times if needed, but I want to learn how it's done. Selling the part in the end is just a means of paying for the education and tools, and if I can make a living at it, that'd be fine.

    I'll have another look at compression molding. I don't know much about it, but I thought it was primarily used for relatively flat parts, like enclosures and such. And thanks for the book reference, I ordered it as well.
    If you really want to learn this stuff, I would really suggest getting a job. Molded part design, mold design, mold construction, and mold operation are really four (really more that) distinct jobs that many people make entire careers of with minimal overlap. Trying do all of them without direct hands on advice available constantly is VERY challenging. You could easily spend months to become proficient at polishing/finishing a mold. That’s not even to get good, just enough to not screw things up.

    The molding industry is full of specialist for a reason. There are rare instances of one man shops that can do a whole bunch of the steps, but I’ve never met someone who does them all. There are rare people that could do it all themselves, but they are usually smart enough to know what makes sense for them to do.

    Molding is tricky. Complicated looking parts are often easy to mold. They look complicated because the designer employed a bunch tricks to make them easy. Easy looking parts of often really hard or impossible.

    As an example, a mold for a clear plastic Dixie cup, given the cosmetic requirements and volumes, is really a feat of engineering.

    The part you show is certainly not for beginners.

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    If your dead set on it then doing it all will be one hell of an education. I did art to part and it took me about 2 years to make plastic parts, another 2 and I was starting to get the hang of it, and a couple years later I learned of reducing the viscosity of the plastic through shear vs higher barrel temps with proper gate design. When I learned how to really design gates and how to take advantage of them by modifying how the molding machine injected the plastic into the mold is when I finally got good at it. I am in the camp that if you can't do it all you will be very limited. What you learn by using your own molds will totally change the way you build molds. Doing your own test shots will inform you far more about your mold than watching someone do it, let alone have the tech tell you how it went after the fact because you were not there.

    On the molding machine side you will need the molding machine, a way to heat and cool your molds, which can be real cheap, and a good dryer with good desiccant beds. The beds only last about a year so having to change them out is no big deal. An engine hoist to load your molds into the machine and a very accurate scale, a triple beam would work, and that's it, you don't need anything else.

    If your doing your own parts a good cnc mill, an engine lathe, and a way to cut your ejector pins to .001" are probably all you will need.

    Having someone to help guide you will be very helpful but learning by trial and error isn't impossible. There are a lot of details to deal with but if you keep your first parts and molds simple you should be able to make working examples on your first try. Insert your cavities, or at least leave room for it, and if you do mess up just make new cavity inserts. I think the hardest part to learn without help would be getting the molding machine running a mold for the first time. It's kind of like flying, you have to go at a set speed. Slow down too much and all hell will break loose. You really need to know what your doing, or someone does, to get it going from cold.

    Anyway, back to work.

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    Quote Originally Posted by jhov View Post
    I really appreciate all the feedback. To clarify, I'm not just interested in just making the part and/or selling them. I want to learn how to design and make the mold, run the machine and make the parts. I plan to acquire whatever machines / tools I need along the way and learn those too. I might consider hiring a professional to hold my hand at times if needed, but I want to learn how it's done. Selling the part in the end is just a means of paying for the education and tools, and if I can make a living at it, that'd be fine.

    I'll have another look at compression molding. I don't know much about it, but I thought it was primarily used for relatively flat parts, like enclosures and such. And thanks for the book reference, I ordered it as well.
    SO, let me get this straight, you want to be a designer, a toolmaker, a molder, a cnc operator, a programmer, an edm operator, a jig grinder, a wire edm guru, AND you want to purchase all the equipment along the way to learn on? Then you hope to mold and sell a quality part in a completely saturated market, in hopes to pay for your education? OK, keep us all posted on how well this works out for you.

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    Quote Originally Posted by 5 axis Fidia guy View Post
    SO, let me get this straight, you want to be a designer, a toolmaker, a molder, a cnc operator, a programmer, an edm operator, a jig grinder, a wire edm guru, AND you want to purchase all the equipment along the way to learn on? Then you hope to mold and sell a quality part in a completely saturated market, in hopes to pay for your education? OK, keep us all posted on how well this works out for you.
    For the most part, yeah. It will take years and I don't expect to be as competent in any single field as you all are in yours, but there's no reason why I can't learn enough to produce my parts. Reading this thread, it sounds like some here have already done just that. Learning it all is fun to me and in the end, whether I sell a single part or not, I'll spend about the same money to have a shop full of machines instead of just a bunch of parts.

    I think I'll return to working on my machined designs as I'm already equipped to produce those, and take some time to read the referenced books in this thread. Information on injection molding doesn't appear to have made the same jump to the internet that CNC machining has.

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    Hi again jhov:
    How much time and money could you part with and still see the experience as a positive one?
    Have you ever gamed out just what the cash out-of-pocket would be?

    Let's do a very quick provisional budget assuming you will pay yourself zero dollars and get excellent deals on everything you need to buy:

    So here we go:
    1) To design the part and design the mold:
    a) A computer with enough horsepower to run the software you'll need plus CAD software and CAM software...$10,000.00
    b) Molding/mold design textbook, hiring a designer for advice etc etc...let's say $500.00
    c) A gun to take apart and measure, tools to measure it with, digitizing if you need it...let's say another $1000.00
    d) Lots and lots of your time...free!

    2) To build the mold:
    a) A prebuilt mold set...$4000.00
    b) Mold steels, hardening mold components etc etc...$3000.00
    c) Machine tools, a Bridgeport, a grinder, a lathe, a sinker EDM...let's say you get super deals and can tool up a capable enough shop without any CNC capability and buy old machines but get lucky with every single one and they all come beautifully tooled...let's be optimistic and say $10,000.00 for the works (everyone will be super jealous of the deals you scored!)
    d) custom made graphite electrodes for your sinker (so you don't have to make them yourself)...let's say another $7000.00
    e) Lot's and lots of time ...Free!

    3) The molding operation:
    a) An 80 to 100 ton press used but in good shape...$15,000.00
    b) A dryer...$2000.00
    c) A grinder (to re-grind your sprues and short shots and defective parts)...$3000.00
    d) A forklift to put the mold in the machine...$2000.00
    e) Plastic to squirt into your mold...$100.00. (bought from your friendly local molder because you'll never get Sabic to sell it to you in those quantities)
    f) Hand tools small power tools etc etc to keep the press running...$1000.00
    g) A place to house it all...say 1200 square feet...$2000.00 per month.
    h) Power to run it all and to heat the place in the winter...$500.00 per month
    i) Insurance so you are even allowed to rent a place...$500.00 per month
    j) All your other fixed costs...anyone's guess depending on how comprehensively you plan...let's say another $1000.00 per month.

    Anything I've overlooked...yeah plenty, like sales and marketing and distribution, but I'm just trying to make a point here.

    If you add up all the numbers do you still value the education enough to lay out the coin?
    If you do then go for it...you will have a bloody nose at the end of the fight, but you'll know a lot more than you do now.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

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    I think the naysayers are going to win this one. And rightly so, that AR grip is a complicated part for a saturated market.

    But I was/am in the same boat of wanting to learn a bit about injection molding. We had been machining a dozen or so different plastic parts in regular but small numbers, so I bought a used Morgan benchtop molder to move the parts over. A mold can be made for it in a matter of hours from $10 worth of aluminum, and you just set it on the platen. For prototypes up to a couple hundred parts it's not bad. Granted we already have everything machine tool wise except an EDM, and I'm not tackling anything like that grip, it's all very straightforward stuff.

    Speaking of the difficulty of being a one-man-band doing it all, check out Dragonfly Engineering on YouTube. I can not see how he stays profitable to pay for all that equipment.

    Edit to add: I'm not at all trying to contradict Marcus or Dennis or the other experienced guys, IM is a huge subject and I'm reading this thread to learn from their knowledge. This is just an alternate route to learn AND make money using a "hobby" grade machine. YMMV.

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    Quote Originally Posted by implmex View Post
    Hi again jhov:
    How much time and money could you part with and still see the experience as a positive one?
    Have you ever gamed out just what the cash out-of-pocket would be?

    Let's do a very quick provisional budget assuming you will pay yourself zero dollars and get excellent deals on everything you need to buy:

    So here we go:
    1) To design the part and design the mold:
    a) A computer with enough horsepower to run the software you'll need plus CAD software and CAM software...$10,000.00
    b) Molding/mold design textbook, hiring a designer for advice etc etc...let's say $500.00
    c) A gun to take apart and measure, tools to measure it with, digitizing if you need it...let's say another $1000.00
    d) Lots and lots of your time...free!

    2) To build the mold:
    a) A prebuilt mold set...$4000.00
    b) Mold steels, hardening mold components etc etc...$3000.00
    c) Machine tools, a Bridgeport, a grinder, a lathe, a sinker EDM...let's say you get super deals and can tool up a capable enough shop without any CNC capability and buy old machines but get lucky with every single one and they all come beautifully tooled...let's be optimistic and say $10,000.00 for the works (everyone will be super jealous of the deals you scored!)
    d) custom made graphite electrodes for your sinker (so you don't have to make them yourself)...let's say another $7000.00
    e) Lot's and lots of time ...Free!

    3) The molding operation:
    a) An 80 to 100 ton press used but in good shape...$15,000.00
    b) A dryer...$2000.00
    c) A grinder (to re-grind your sprues and short shots and defective parts)...$3000.00
    d) A forklift to put the mold in the machine...$2000.00
    e) Plastic to squirt into your mold...$100.00. (bought from your friendly local molder because you'll never get Sabic to sell it to you in those quantities)
    f) Hand tools small power tools etc etc to keep the press running...$1000.00
    g) A place to house it all...say 1200 square feet...$2000.00 per month.
    h) Power to run it all and to heat the place in the winter...$500.00 per month
    i) Insurance so you are even allowed to rent a place...$500.00 per month
    j) All your other fixed costs...anyone's guess depending on how comprehensively you plan...let's say another $1000.00 per month.

    Anything I've overlooked...yeah plenty, like sales and marketing and distribution, but I'm just trying to make a point here.

    If you add up all the numbers do you still value the education enough to lay out the coin?
    If you do then go for it...you will have a bloody nose at the end of the fight, but you'll know a lot more than you do now.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining
    Yes, I have run the numbers. It will cost about the same as a 4 year college education and take at least as long, but in the end I'll learn more (probably 1000x more) and acquire a shop full of useful tools and machines.


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