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    Default Plastic injection molding resources

    I would imagine there are some here with some overlap into plastic injection molding; Are there any communities like this one, but dedicated to plastic injection molding? I'm leaning toward buying a machine for producing some parts in house. I've calculated the general requirements for the machine I would need, but I have no idea what machines are solid and which to steer clear of, or what common problems to look out for when shopping around. Does anyone have any experience or resources to share?

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    No, unfortunately I've never found a molding forum that is worthwhile, not that I've looked in recent years. all that I found years ago were definitely hobby forums, with people discussing what size wood auger would work for a screw in their home built molding press. I think there are so few custom injection molding job shops left in this country that the remaining molders don't feel the need... whatever questions they had they figured out years ago.

    That being said, there are some folks here on this forum with knowledge of injection molding, either from the toolmaking end or running tryout presses to support a mold shop, so if you can formulate intelligent questions, just ask, you may get an answer. I don't really know If I can help with your press selection, as my newest press is now 25 years old, so I'm hardly up to date.

    I will, However, recommend a book; Injection Molds and Molding A Practical Guide, by Joseph B. Dym. Published in 1979, it's a bit dated, but the basics don't change. It will walk you through machine sizing, explain the basic concepts of mold design and setting up the molding cycle, and has useful tables of material properties. I haven't looked in my copy for years, in fact, I don't know where it is, but was a time I used it a lot.

    There also used to be a magazine (remember those?) Injection Molding Magazine, that had a lot of useful information, but I lost touch with it when they went to a digital format, and now I can't find the web site, but there must be others. The deal used to be subscriptions were free so long as you registered; those circulation numbers are what they'd base there advertising rates on. Now, in the digital age, I have no idea how it works, but there must be something similar.

    Dennis

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    Erie, pa and nearby Meadville, pa have many plastic mold shops.

    Penn State Behrend campus has a plastics research building & degree program.

    If you would indicate just where in O-HI-O you are located, I could suggest
    some local shops that might help you.

    Are you going to design & build the mold yourself ?

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    Quote Originally Posted by Modelman View Post
    No, unfortunately I've never found a molding forum that is worthwhile, not that I've looked in recent years. all that I found years ago were definitely hobby forums, with people discussing what size wood auger would work for a screw in their home built molding press. I think there are so few custom injection molding job shops left in this country that the remaining molders don't feel the need... whatever questions they had they figured out years ago.

    That being said, there are some folks here on this forum with knowledge of injection molding, either from the toolmaking end or running tryout presses to support a mold shop, so if you can formulate intelligent questions, just ask, you may get an answer. I don't really know If I can help with your press selection, as my newest press is now 25 years old, so I'm hardly up to date.

    I will, However, recommend a book; Injection Molds and Molding A Practical Guide, by Joseph B. Dym. Published in 1979, it's a bit dated, but the basics don't change. It will walk you through machine sizing, explain the basic concepts of mold design and setting up the molding cycle, and has useful tables of material properties. I haven't looked in my copy for years, in fact, I don't know where it is, but was a time I used it a lot.

    There also used to be a magazine (remember those?) Injection Molding Magazine, that had a lot of useful information, but I lost touch with it when they went to a digital format, and now I can't find the web site, but there must be others. The deal used to be subscriptions were free so long as you registered; those circulation numbers are what they'd base there advertising rates on. Now, in the digital age, I have no idea how it works, but there must be something similar.

    Dennis
    Thanks, I found the book used and ordered it. I still have a ton to learn. The machines I've been looking at are all ~20-25 years old; mostly mid to late 90's 40-85 ton, ~4-5oz shot Cincinnati Milacron's and Engel's that I find on ebay. Do you have any experience with either brand?


    Quote Originally Posted by digger doug View Post
    Erie, pa and nearby Meadville, pa have many plastic mold shops.

    Penn State Behrend campus has a plastics research building & degree program.

    If you would indicate just where in O-HI-O you are located, I could suggest
    some local shops that might help you.

    Are you going to design & build the mold yourself ?
    I'm located near Cincinnati and Dayton. I do hope to design and build the mold myself. Though I may start out with a prefab mold base to make things a bit easier.

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    The machines I've been looking at are all ~20-25 years old; mostly mid to late 90's 40-85 ton, ~4-5oz shot Cincinnati Milacron's and Engel's that I find on ebay. Do you have any experience with either brand?
    I have a Cincinnati Milacron T-75 that is somewhat older and It's been a solid machine, but not trouble free These early Cincies with the PC3 control used a servo controlled flow control valve that is both expensive to replace, and expensive to repair. Aside from that, one disadvantage of a toggle press is a Bijure oiling system with about fifty, yes 50 lube points, and if one fails the bushing it serves will wear until it spins in the link and becomes an expensive repair. I have a friend that has a shop full of Van Dorns of about the same vintage and he is very happy with them; they seem to be a better machine all around.

    I don't know anything about Engle, other than I've never heard anything bad about them. I did buy a used BOY 15-s some years ago, and am very impressed with both the machine and their US office, very helpful. While my little BOY is only 15 ton, they make a full line up to 88 ton, I believe.

    I do hope to design and build the mold myself. Though I may start out with a prefab mold base to make things a bit easier.
    Unless you put no value on your time, you cannot build a mold base as cheaply as you can buy one. Standard in the industry is D-M-E:
    DME - Global Mold Based Supplier - Homepage

    I've found slightly better pricing and good quality from Superior Die Set:
    Die Set – Mold Bases – Components - Superior Die Set

    For side action components, take a look at Omni Mold:
    MOLDs by OMNI Mold Systems
    If nothing else, their detailed catalog drawings are a good source of design data.

    PCS Company also has some good stuff:
    PCS Company | Mold Components | Mold Bases | Molding Solutions

    Good luck,

    Dennis

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    Quote Originally Posted by jhov View Post
    Thanks, I found the book used and ordered it. I still have a ton to learn. The machines I've been looking at are all ~20-25 years old; mostly mid to late 90's 40-85 ton, ~4-5oz shot Cincinnati Milacron's and Engel's that I find on ebay. Do you have any experience with either brand?




    I'm located near Cincinnati and Dayton. I do hope to design and build the mold myself. Though I may start out with a prefab mold base to make things a bit easier.
    Might want to post some pix or screen shots of the intended part.

    The mold base is only one part of the problem.

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    Hi Dennis:
    I'm intrigued by your experience buying mold bases rather than building them.
    I've tried buying DME sets and Hasco sets and I've been disappointed with both.

    When I was trained as toolbreaker in the early 1970's we always built our own, and the claim was that if you took a blank mold base and hogged a big insert pocket out of it, the block would often move so much you couldn't put the set back together because the leader pins had canted when the set warped.
    So I was trained to rough the pin (or bushing) bores, rough the pockets and then finish grind the set.
    Then we'd go back in and finish the pockets and bores.

    I can't say I've had that particular problem with pre-built sets, but it always pissed me off that the pins were all over the place, the sprue bushing bore was all over the place, the return pins didn't run real nice, and the sets were always the wrong size for the job, so I had to buy bigger than I needed, and then had to hump around all that extra steel.

    So I've always built my own ... seems you have had a better experience with pre-built sets than I have.

    Cheers

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

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    Quote Originally Posted by implmex View Post
    When I was trained as toolbreaker in the early 1970's we always built our own, and the claim was that if you took a blank mold base and hogged a big insert pocket out of it, the block would often move so much you couldn't put the set back together because the leader pins had canted when the set warped.
    So I was trained to rough the pin (or bushing) bores, rough the pockets and then finish grind the set.
    Then we'd go back in and finish the pockets and bores.

    I can't say I've had that particular problem with pre-built sets, but it always pissed me off that the pins were all over the place, the sprue bushing bore was all over the place, the return pins didn't run real nice, and the sets were always the wrong size for the job, so I had to buy bigger than I needed,
    This has been my experience with off-the-shelf bases as well. I’m re-tooling the business to focus heavily on moulds, and purchased the suggested text yesterday.

    If it wasn’t for Sars-Cov2, we’d have little business in moulds right now. It would appear that businesses that were happy to spend less for more headaches from China are starting to appreciate the lag in shipping times.

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    I've really isolated bushings with deep insert and slide pockets in pre-built bases but once the mold was assembled the leader pins and bushings always aligned up pretty well. Still, I am a 100% make it from scratch type. I like the freedom of design and am also 100% in favor of using aluminum for everything. Aluminum molds just run so much faster, and our mold lifespans rarely exceeded 300,000 shots before the design would change anyway.

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    Never had a problem with binding leader pins, standard leader pin / bushing clearance is .0015" after all, but in my work I typically don't need deep pockets. 1" is my usual max, any deeper and I add an extra plate with a through pocket. If I need better alignment, tapered locks are the order of the day. The thought occurs to me, however, that if the size of the pocket makes the plate move that much, the mold base is too small, and will squiggle around when locked up in the press.

    In addition, I'm a small one man shop that does in-house tooling for our own product line. I'm really only equipped to handle work the size of our inserts, building a 12x20 base from scratch is just too big for the equipment. I still contend, however, that the average shop can't build that base for the same $$$ that they will pay to buy it off the shelf.

    Dennis

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    Quote Originally Posted by Modelman View Post
    I have a Cincinnati Milacron T-75 that is somewhat older and It's been a solid machine, but not trouble free These early Cincies with the PC3 control used a servo controlled flow control valve that is both expensive to replace, and expensive to repair. Aside from that, one disadvantage of a toggle press is a Bijure oiling system with about fifty, yes 50 lube points, and if one fails the bushing it serves will wear until it spins in the link and becomes an expensive repair. I have a friend that has a shop full of Van Dorns of about the same vintage and he is very happy with them; they seem to be a better machine all around.

    I don't know anything about Engle, other than I've never heard anything bad about them. I did buy a used BOY 15-s some years ago, and am very impressed with both the machine and their US office, very helpful. While my little BOY is only 15 ton, they make a full line up to 88 ton, I believe.



    Unless you put no value on your time, you cannot build a mold base as cheaply as you can buy one. Standard in the industry is D-M-E:
    DME - Global Mold Based Supplier - Homepage

    I've found slightly better pricing and good quality from Superior Die Set:
    Die Set – Mold Bases – Components - Superior Die Set

    For side action components, take a look at Omni Mold:
    MOLDs by OMNI Mold Systems
    If nothing else, their detailed catalog drawings are a good source of design data.

    PCS Company also has some good stuff:
    PCS Company | Mold Components | Mold Bases | Molding Solutions

    Good luck,

    Dennis
    I'll add Van Dorn and Boy to my shopping list. One of my prototypes will certainly require a few side action components. I didn't know there were prefabs available for those parts, thanks for the links and info.

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    Quote Originally Posted by digger doug View Post
    Might want to post some pix or screen shots of the intended part.

    The mold base is only one part of the problem.
    One of the more complicated parts I want to make (as far as mold design at least) is an AR-15 grip. Similar to the picture below, but with some features to make it unique.



    The current part volume is ~3.6 cu.in. with a cross sectional area of 6.88 sq.in and a mass of 2.074 oz (PS). From what I could gather, injection pressures run around 24ksi for the machine size I'm considering and the resulting cavity pressures should be somewhere between 7-10ksi, requiring ~30 tons of clamping force. The material will be either PA6 based or PC (probably PA6 for good chemical resistance) requiring a screw L/D > 15 and a shot size of 2.074 oz / 0.6 ~ 3.5 oz.

    I'm having some trouble finding small machines with such a large shot size. Most 30-40 ton machines seem to be 2 oz or less (sometimes less than 1). Even some 75-90 ton machines have shot sizes under 3 oz. Did I run the numbers wrong?

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    You can never have too much clamp tonnage, considering you don't have to use it if you don't need it, but if you need it but don't have it, you're screwed. Nylons are notable for being easy to flash, so you may well end up needing more clamp tonnage than you think. 50 and 55 ton machines are common, go even larger if you need the shot capacity.

    Barrel sizing is normally on the large side for a given clamp tonnage, but a smaller barrel will allow higher injection pressure, because the hydraulic injection cylinder remains the same size. Bigger machines with small barrels were custom ordered because the intended work was known to have small details that would require the higher injection pressure. I run some acetal parts on a 66 ton, 2 oz. machine that would physically fit in the little 15 ton BOY, but it won't fill them.

    Dennis

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    Quote Originally Posted by Modelman View Post
    You can never have too much clamp tonnage, considering you don't have to use it if you don't need it, but if you need it but don't have it, you're screwed. Nylons are notable for being easy to flash, so you may well end up needing more clamp tonnage than you think. 50 and 55 ton machines are common, go even larger if you need the shot capacity.

    Barrel sizing is normally on the large size for a given clamp tonnage, but a smaller barrel will allow higher injection pressure, because the hydraulic injection cylinder remains the same size. Bigger machines with small barrels were custom ordered because the intended work was known to have small details that would require the higher injection pressure. I run some acetal parts on a 66 ton, 2 oz. machine that would physically fit in the little 15 ton BOY, but it won't fill them.

    Dennis
    How small are small details to be concerned with? Would the grip texture pictured above be difficult to fill? I'm going to be limited to a somewhat smaller machine. My shop space for the machine is limited to about 14'W x 6'L x 8'H for the machine and I can currently only supply about ~55 amps @ 240v 3 phase. I'll probably have to buy a 460-480v rotary converter..

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    Hi jhov:
    Is this one part or two halves that are just photographed assembled together?
    If it's one part, this is not going to be straightforward to build a successful tool for.
    Even if it's two halves, there are still some design considerations that are not obvious to an inexperienced designer.
    But it WILL be a lot simpler as two halves even if they have to be ultrasonic welded together after molding.

    With respect to filling the smallest details, the attention to venting often is highly influential on whether you can fill the details or not.
    There are a few strategies that can be employed...vent pins can be incorporated into details if an effective place can be found for them, sometimes the whole cavity can be made from a porous mold steel (Porcerax is the brand I've used), or the mold cavity can be split into pieces to allow vent channels to be incorporated between them.

    Figuring this stuff out in a way that gives you confidence it will actually work is one of the arts of mold design.
    A useful tool to help is software that mimics how the mold will fill.
    The one I know is called "Moldflow", but there are others too.

    The other thing is design experience.
    There is no way around that reality; you have to spend the time in the trenches and do some failing to learn the ropes and get an intuitive sense about what you can and what you cannot get away with.
    I believe the lessons from failures are more instructive than the successes, because they define the limits better.

    So it's not just pushing the plastic real hard that fills the mold...yes, as modelman points out, you can do some things with that strategy and it is necessary to have enough grunt to fill the mold but it would be incorrect to believe you just need to push harder if your mold won't fill.

    I've been designing and building molds for 40 years.
    I don't see a slam dunk, totally straightforward, beginner design and build here.
    It's not rocket science, but I'd find myself a good contract mold designer to help you so you don't build an unworkable dog.

    Cheers

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

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    Quote Originally Posted by implmex View Post
    Hi jhov:
    Is this one part or two halves that are just photographed assembled together?
    If it's one part, this is not going to be straightforward to build a successful tool for.
    Even if it's two halves, there are still some design considerations that are not obvious to an inexperienced designer.
    But it WILL be a lot simpler as two halves even if they have to be ultrasonic welded together after molding.

    With respect to filling the smallest details, the attention to venting often is highly influential on whether you can fill the details or not.
    There are a few strategies that can be employed...vent pins can be incorporated into details if an effective place can be found for them, sometimes the whole cavity can be made from a porous mold steel (Porcerax is the brand I've used), or the mold cavity can be split into pieces to allow vent channels to be incorporated between them.

    Figuring this stuff out in a way that gives you confidence it will actually work is one of the arts of mold design.
    A useful tool to help is software that mimics how the mold will fill.
    The one I know is called "Moldflow", but there are others too.

    The other thing is design experience.
    There is no way around that reality; you have to spend the time in the trenches and do some failing to learn the ropes and get an intuitive sense about what you can and what you cannot get away with.
    I believe the lessons from failures are more instructive than the successes, because they define the limits better.

    So it's not just pushing the plastic real hard that fills the mold...yes, as modelman points out, you can do some things with that strategy and it is necessary to have enough grunt to fill the mold but it would be incorrect to believe you just need to push harder if your mold won't fill.

    I've been designing and building molds for 40 years.
    I don't see a slam dunk, totally straightforward, beginner design and build here.
    It's not rocket science, but I'd find myself a good contract mold designer to help you so you don't build an unworkable dog.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining
    I'd like to do it as one piece if possible. I'm starting from zero and I'd like to do this in house if possible and buy the equipment and develop the skills and processes to do so. But my budget is fairly limited, so if I can get by with less equipment and more time learning to do things smarter, that would be my preference. Looking at existing similar products on the market, they appear to be done in one piece with at least 2 sliding components to form the opposing cavities and the bolt hole through the grip. I doubt I'll be able to afford MoldFlow, but I'll look into it. Alternatively, I would assume such a problem could be solved to some degree of accuracy using OpenFOAM with the right set up.

    I plan to fail as I experiment and I expect to blow a decent chunk of money making scrap molds. I have some simpler parts I plan to start with so hopefully I can keep it to a minimum. Speaking of costs of failure; professional molds are made of tool steel for obvious reasons; how viable are aluminum or mild steels for prototyping molds? If I were to develop a die in a cheaper material, can the design be transferred to a tool steel mold or do the materials react differently enough to require some changes?

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    You will get better heat transfer in an Al mould as the thermal conductivity is higher than steel. There is no reason you cannot build a mold from Al for prototyping. It won’t last as long in production as a dedicated steel mould but so long as you realize the durability limitations that’s a non-issue.

    Turbulence of the plastic melt abrades moulding surfaces- indeed the multi-cavity moulds we build for 100,000+ shots have BeCu core caps and fully hardened and polished surfaces. Those are hot-runners, totally different ballgame. For low quantities Al is an economical choice in labour and material terms. You won’t be building things like slides effectively out of Al, or even sprue bushings but I don’t really work with cold runners.

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    Couple of thoughts on the mold material. P20 is a decent material for short to medium runs. I am familiar with Porcerex. Used it to make disks with sharp details running PBT. Problem is the gases that vent through the material will plug up the pores. Hot acetone in a ultrasonic cleaner was the only way we found to clean the cavities.100_0282.jpg

    Tom

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    Hi again jhov:
    When I approach a project like this, the first thing I ask my customer is:
    How many parts do you want to make and how fast?
    The second thing I ask is : How long must the tool last between major rebuilds?

    These two simple questions define a great deal about the build and set the conditions for the next question which is: What's your budget?

    To help you with this here are a few rules of thumb I like to use to give me a reality check:

    1) A single cavity mold running on a 30 second cycle working three shifts can produce 60,000 parts per month.

    2) An aluminum tool runs a bit faster than a steel tool (better heat conduction) but is quite a bit more fragile and quite a bit less fixable.

    3) An aluminum tool is typically pretty much done with 60,000 shots but it can last as little as one shot if the molder fucks it up. By contrast a steel (prehard P-20) tool will often go 300,000 shots and still be usable.

    4) An aluminum tool is not really cheaper to build than a steel tool, unless a ton of material has to be milled to turn it from raw blocks into a finished mold.
    Aluminum is faster to machine, but a pain in the ass to surface grind (it's non magnetic); it costs more to buy; thermal expansion has to be considered and mitigated in a different way; it can't tolerate shallow draft shutoffs on features like parting surfaces and pass cores etc etc.

    5) Hot tip and hot runner molds are to be avoided unless you need them for something you can't get with a simple cold sprue especially for short run projects.

    6) A fully hardened mold for high volume production (Class 101) is going to cost around three times what the equivalent pre-hard steel or aluminum mold is going to cost.

    Moving on to your part specifically; without seeing a part design and without knowing all the details I see a mold consisting of two big slides with the part cavities cut so the part is molded standing up between the slides, upside down and stripped off the main core that come from the cold side with a floating stripper that carries the slides.
    There's about a gazillion reasons why this part orientation is attractive to me; not the least of which is that I can eject the part without having to accept ejector pin marks on it, and I can gate it on the bottom and achieve good plastic flow naturally out to the periphery.
    A mold like this would probably be about 10" x 16" x 10" tall, cost around thirty grand Canadian to build out of mold base alloy with nitrided P-20 slides, case hardened locks, a P-20 prehard core, a fully hard stripper insert and a simple DME cold sprue
    If you don't know what all of those terms mean, I recommend you look them up or ask here.

    I'm sure Dennis will have more to say about what he sees as the best way forward, and it may well differ from mine!
    Be aware if you mold these in one piece, the plastic will be awfully thick, which brings its own problems...if you do it in two halves you have more options to core it out and also a simpler mold to build with no slides and no stripper and a simple ejector plate and etc etc. (assuming there are no features I can't see in this one picture).

    Cheers

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

    Oh yeah, while I'm thinking of it...you wrote about scrapping unworkable molds...are you aware of just how much you would have to scrap if you inadvertently build a dog?
    The mold I sketched out above would be around 200 to 300 pounds and about 200 hours of work...that's a lot to do over if you didn't get it right the first time.

    MC

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    Quote Originally Posted by implmex View Post
    Hi again jhov:
    When I approach a project like this, the first thing I ask my customer is:
    How many parts do you want to make and how fast?
    The second thing I ask is : How long must the tool last between major rebuilds?

    These two simple questions define a great deal about the build and set the conditions for the next question which is: What's your budget?

    To help you with this here are a few rules of thumb I like to use to give me a reality check:

    1) A single cavity mold running on a 30 second cycle working three shifts can produce 60,000 parts per month.

    2) An aluminum tool runs a bit faster than a steel tool (better heat conduction) but is quite a bit more fragile and quite a bit less fixable.

    3) An aluminum tool is typically pretty much done with 60,000 shots but it can last as little as one shot if the molder fucks it up. By contrast a steel (prehard P-20) tool will often go 300,000 shots and still be usable.

    4) An aluminum tool is not really cheaper to build than a steel tool, unless a ton of material has to be milled to turn it from raw blocks into a finished mold.
    Aluminum is faster to machine, but a pain in the ass to surface grind (it's non magnetic); it costs more to buy; thermal expansion has to be considered and mitigated in a different way; it can't tolerate shallow draft shutoffs on features like parting surfaces and pass cores etc etc.

    5) Hot tip and hot runner molds are to be avoided unless you need them for something you can't get with a simple cold sprue especially for short run projects.

    6) A fully hardened mold for high volume production (Class 101) is going to cost around three times what the equivalent pre-hard steel or aluminum mold is going to cost.

    Moving on to your part specifically; without seeing a part design and without knowing all the details I see a mold consisting of two big slides with the part cavities cut so the part is molded standing up between the slides, upside down and stripped off the main core that come from the cold side with a floating stripper that carries the slides.
    There's about a gazillion reasons why this part orientation is attractive to me; not the least of which is that I can eject the part without having to accept ejector pin marks on it, and I can gate it on the bottom and achieve good plastic flow naturally out to the periphery.
    A mold like this would probably be about 10" x 16" x 10" tall, cost around thirty grand Canadian to build out of mold base alloy with nitrided P-20 slides, case hardened locks, a P-20 prehard core, a fully hard stripper insert and a simple DME cold sprue
    If you don't know what all of those terms mean, I recommend you look them up or ask here.

    I'm sure Dennis will have more to say about what he sees as the best way forward, and it may well differ from mine!
    Be aware if you mold these in one piece, the plastic will be awfully thick, which brings its own problems...if you do it in two halves you have more options to core it out and also a simpler mold to build with no slides and no stripper and a simple ejector plate and etc etc. (assuming there are no features I can't see in this one picture).

    Cheers

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

    Oh yeah, while I'm thinking of it...you wrote about scrapping unworkable molds...are you aware of just how much you would have to scrap if you inadvertently build a dog?
    The mold I sketched out above would be around 200 to 300 pounds and about 200 hours of work...that's a lot to do over if you didn't get it right the first time.

    MC
    Maybe I'm overly ambitious to even attempt this, as I said, I'm starting from zero. I have some product designs I think could be successful and I've invested in the tools and developed the skills to prototype them, and now I'm looking to expand to producing them. I would probably be better off contracting with professionals to have this done, but I have a personal interest in learning to do it all myself; it's just something I've always wanted to do and I have a day job that pays better than I could make starting from over again in the trade, so I'm just going it alone.

    So with that.. I have no idea how many I will need or how quickly. The AR accessories market can be feast or famine, so I could struggle to sell 60,000 units over 10 years or I could need 60,000 per month for a short duration. I'd like to position myself to be capable of meeting a high demand if required to capitalize on what would probably be a short window of opportunity. And if not required, I'll do a limited run of that part and switch to another design for another industry. If I could sell 60,000 units in total over several years, I'd call that a success. At this point, if I can break even with what I've spent for all my equipment, I'd be happy. I was 3/4 of my way through an engineering degree until the college decided to change the curriculum on me, adding extra class requirements and removing previous exemptions to extort more money out of me. I told them to pound sand and decided to spend the rest of my college funds on machine tools and CAD/CAM software. So the prospect of having to redo 200 hours of work is nothing compared to the time I wasted in college and in the end I get to learn something useful and keep a shop full of machine tools. The 200-300 lbs of scrap steel is the bigger issue, as my funds are not unlimited.


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