Thermoplastic Injection Molding
- Thread starter Flintlock
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Gigatron
Sr Member
While I don't have any contacts, injection molding is insurmountably expensive.
There's the R&D of the kit, then of the sprue design and layout. Then the machining costs of the injection molds. If this were a one-off type of thing, I doubt you'd find any company willing to even talk to you.
At best, if you think it would be a highly popular kit (i.e. several thousand unit production run), you might be able to start an online petition and then approach one of the manufacturers with those numbers. If they think there's profitablity there, they might consider it.
Good luck with whatever you're trying to get made.
-Fred
There's the R&D of the kit, then of the sprue design and layout. Then the machining costs of the injection molds. If this were a one-off type of thing, I doubt you'd find any company willing to even talk to you.
At best, if you think it would be a highly popular kit (i.e. several thousand unit production run), you might be able to start an online petition and then approach one of the manufacturers with those numbers. If they think there's profitablity there, they might consider it.
Good luck with whatever you're trying to get made.
-Fred
Gigatron has it spot on...Injection molds have to be out of either aluminum or steel, owing to the tremendous (1 ton and up) pressures exerted on them by the presses in order to force the molten plastic into all the cavities- where I work, we're getting an injection mold done of a buckle 3 in. by 2 in. by 3/16ths thick, and the mold is $9,500 for only a single cavity. That's why companies use rapid prototyping/silicone molds for the initial "looks like/feels like" prototypes, before having to commit that kind of money for a tool.
Flintlock
Sr Member
Thanks for the quick replies, fellas.
I already knew it was expensive - and of course this is not something I'd want to go alone.
"If there's a will, there's a way..."
Think of all the research that's already been done by this community. Do you think a company would go for near-exact injection-molded kits of, for starters:
-X Wing
-Y Wing
-TIE Fighter
-TIE Interceptor
, all studio scale?
Surely someone here knows something about sprue design, or knows someone who does...
And my vision includes going for a project like this as a community, not just me trying to get it made...
Or, if studio scale is too big, think about this - several model kit companies find it profitable to sell 1:48 airplane kits. I'd imagine 1:48 detail-for-detail Star Wars kits might have wider sales... but of course that's just a guess.
The model kits companies have provided to fans thus far have been much less than desirable. Perhaps they'd go for better kits, but do not have the resources. WE have a lot of resources they might not have.
I already knew it was expensive - and of course this is not something I'd want to go alone.
"If there's a will, there's a way..."
Think of all the research that's already been done by this community. Do you think a company would go for near-exact injection-molded kits of, for starters:
-X Wing
-Y Wing
-TIE Fighter
-TIE Interceptor
, all studio scale?
Surely someone here knows something about sprue design, or knows someone who does...
And my vision includes going for a project like this as a community, not just me trying to get it made...
Or, if studio scale is too big, think about this - several model kit companies find it profitable to sell 1:48 airplane kits. I'd imagine 1:48 detail-for-detail Star Wars kits might have wider sales... but of course that's just a guess.
The model kits companies have provided to fans thus far have been much less than desirable. Perhaps they'd go for better kits, but do not have the resources. WE have a lot of resources they might not have.
Flintlock
Sr Member
I'm already working on an X Wing fuselage using lens-corrected photos of Red 3. I also have 99% of the donor kit parts. And I am not the only one with access to this info... Designing the parts in 3D should not be difficult at all, I just know nothing about designing a sprue.
Or if it would come down to it... why not pool our resources and start our own darned injection molding company? License the rights and we're golden...
Yes I know it's ambitious, but I wanted to throw my thoughts out there.
Please, only provide comments that would be helpful or informative. Cautions, difficulties, etc are welcome, but please NO NAY-SAYING! I am not one for defeatist attitudes. Something like this would no doubt be difficult, but it's not impossible - obviously. I've already pointed out that people make extremely large styrene kits as it is. If that's not impossible, then neither is this.
Or if it would come down to it... why not pool our resources and start our own darned injection molding company? License the rights and we're golden...
Yes I know it's ambitious, but I wanted to throw my thoughts out there.
Please, only provide comments that would be helpful or informative. Cautions, difficulties, etc are welcome, but please NO NAY-SAYING! I am not one for defeatist attitudes. Something like this would no doubt be difficult, but it's not impossible - obviously. I've already pointed out that people make extremely large styrene kits as it is. If that's not impossible, then neither is this.
Sith_241
Well-Known Member
I can CNC molds, but i will charge you an arm and a leg as mentioned before.
I am a manufacturing engineer...i can do injection molding design from idea all the way to finished parts. Please let me know if you have questions.
Keep in mind: big kits with big parts are extremely tough to do well. The machines required typically use clamping forces of 50ton and up, so it is VERY expensive. A mold would be made of tool steel and cost 15K and up for that sort of thing.
EDIT: what do you want to know about sprues?
I am a manufacturing engineer...i can do injection molding design from idea all the way to finished parts. Please let me know if you have questions.
Keep in mind: big kits with big parts are extremely tough to do well. The machines required typically use clamping forces of 50ton and up, so it is VERY expensive. A mold would be made of tool steel and cost 15K and up for that sort of thing.
EDIT: what do you want to know about sprues?
Flintlock
Sr Member
I was just saying that I personally don't know how to design them.
This isn't an idea I had to go do on my own...
Have you considered rotocasting as an alternative?
Flintlock
Sr Member
No ... I am wondering about injection molding specifically. Can you rotocast plastic? How would the quality compare?
Sith_241
Well-Known Member
To answer all the questions:
besides the mold, the machine is required, plastic, maybe some release (not a big deal) and maybe some specialized ejector tooling for your part but not much else. However, the machines tend to be really big and expensive, but smaller ones do exist, they are just very limited in size parts they can do.
As for rotocasting plastic...yes you can do it. However, you are constrained to certain thermoplastics that flow well and melt at relatively low temperatures and you are highly limited in the shapes you can produce. The less detailed the better in most cases. However, you might be able to get away with small features by use of plugs and other such things, so i suppose it isnt impossible.
EDIT: Depends on the type of quality you are looking for between the 2 methods. If you mean small details, etc. then injection is much better.
besides the mold, the machine is required, plastic, maybe some release (not a big deal) and maybe some specialized ejector tooling for your part but not much else. However, the machines tend to be really big and expensive, but smaller ones do exist, they are just very limited in size parts they can do.
As for rotocasting plastic...yes you can do it. However, you are constrained to certain thermoplastics that flow well and melt at relatively low temperatures and you are highly limited in the shapes you can produce. The less detailed the better in most cases. However, you might be able to get away with small features by use of plugs and other such things, so i suppose it isnt impossible.
EDIT: Depends on the type of quality you are looking for between the 2 methods. If you mean small details, etc. then injection is much better.
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Flintlock
Sr Member
My purpose here is to discuss the plausibility of actually creating commercial kits for people. I look at the injection-molded Saturn V halves for the X Wing and say, "imagine four of those, exactly like they are (only modified in X Wing fashion), on a sprue of gray styrene." Imagine all the other parts exactly as they should be, on a large and inviting sprue. Imagine opening a box and seeing top and bottom hull halves - all just like any other off-the-shelf plastic kit, only it being a kit of one of these studio scale models.
I fully understand that it's extremely expensive - of course, only companies with sufficient resources can do it. But that's precisely what my vision is. As I said, it's not 'impossible,' though I understand it's very difficult.
I am not looking for any cheap alternatives so that I, myself, could make a kit... It doesn't matter to me if I am the one to do any of this. Mike S already makes an excellent X, and there are kits available for all the others... I wouldn't want to do what's already been done.
Opening a commercially packaged styrene kit of a 'studio scale' star wars model would be a really cool experience. I think I am not alone in thinking that... But I suppose it would be almost as cool if there were even commercial kits of these fighters in 1:48, provided the detail matched up perfectly to the off-the-shelf donor kits. Fine Molds kits are too small, and some of them have been disappointing to some...
Sith, perhaps you can tell me something I've not really been able to figure out... exactly how would the manufacturing process for something like this go?
Say, for example, a company wanted to start off from nothing and make a full-size (studio scale) injection molded X Wing. The parts would need to be researched and designed in CAD, and they would need to be designed into a sprue. Each sprue would then have to be machined into a (probably steel) tool. I got that much...
What then do you do with the tools? Can any large injection machine handle any tool, so long as the tools are designed to fit? Is this machine responsible for the clamping? Couldn't you throw in the tools for one kit, do some runs, and then switch out the tools?
I fully understand that it's extremely expensive - of course, only companies with sufficient resources can do it. But that's precisely what my vision is. As I said, it's not 'impossible,' though I understand it's very difficult.
I am not looking for any cheap alternatives so that I, myself, could make a kit... It doesn't matter to me if I am the one to do any of this. Mike S already makes an excellent X, and there are kits available for all the others... I wouldn't want to do what's already been done.
Opening a commercially packaged styrene kit of a 'studio scale' star wars model would be a really cool experience. I think I am not alone in thinking that... But I suppose it would be almost as cool if there were even commercial kits of these fighters in 1:48, provided the detail matched up perfectly to the off-the-shelf donor kits. Fine Molds kits are too small, and some of them have been disappointing to some...
Sith, perhaps you can tell me something I've not really been able to figure out... exactly how would the manufacturing process for something like this go?
Say, for example, a company wanted to start off from nothing and make a full-size (studio scale) injection molded X Wing. The parts would need to be researched and designed in CAD, and they would need to be designed into a sprue. Each sprue would then have to be machined into a (probably steel) tool. I got that much...
What then do you do with the tools? Can any large injection machine handle any tool, so long as the tools are designed to fit? Is this machine responsible for the clamping? Couldn't you throw in the tools for one kit, do some runs, and then switch out the tools?
Beechy McFly
Sr Member
He must be busy as I would suggest talking to Mike aka Thermal Plastics, as he uses thermal plastics all the time and may have some details for you..
Sith_241
Well-Known Member
The basic process is like this:
Design the part you want. This is generally done in CAD these days. For an injection molded assembly such as this, the next step is to decide what pieces you want to break the model up into. This requires a fair amount of forethought and planning. Once that is done, all attachment points are put into the model etc.
Now to making a mold. In CAD/CAM(computer aided machining) what you do is basically build a mold around each piece or series of pieces you want to produce in a given shot. In this step you must account for shrinkage and and other warping effects that will occur. you also need to figure out the clamping pressure and shot pressure, as well as plastic temp you will need to do it.
Once this is decided, you add in the sprue design to move sufficient quantities of plastic to different area of the mold at specific times. Doing this right prevents bubbles, un-filled areas and other problems.
Now what?
You have your design and your mold design, now you have to make the thing. You have 2 options normally...machine a mold, or EDM (electo discharge machine) a mold. EDM is basically using an electrode in the positive shape of your mold interior to burn out the shape you want. Depending on the size and complexity of your mold this choice will probably be made for you. Deep molds wih sharp corners will most often be made using EDM. It is also easier to EDM tool steel than it is to machine it, but you loose some fine control in the process. This process is not generally condusive to small deatails, so in your case it would be machining.
Program the machine, load up your material block (aluminum or tool steel usually) and fire away with the CNC machine. THis process will usually take anywhere from a couple hours to several days to complete, depending on the complexity of the mold and the tolerance/ finish requirements. ( i have seen injection molds on a machine for 10 days non stop before).
Now you have your mold. Different size injection molding machines generally accept different sized molds. mold sizes use range from 6x6 in blocks to 4ftx 8 ft blocks used for huge stuff. Basically you want the outside of your mold (which will look like a big metal block in 2 pieces) to fit the machine you have planned for. Some molds break apart in 2 pieces, while others puzzle piece together. Some even have moving internal parts or plugs to make internal holes in parts.
Once you load this into the machine (which looks like a long, horizontal press) it will clamp the mold closed, inject the molten plastic under pressure and hold until sufficiently cool. THen it will open and either automatically eject the part, or an operator will pull it out. Repeat this many times. As far as changing out a mold, it varies by machine and mold. Say between an hour to up to a day to switch molds depending on the situation. This makes small batches easy to do (provided you have a mold)
Hope this huge wall of text helps
Design the part you want. This is generally done in CAD these days. For an injection molded assembly such as this, the next step is to decide what pieces you want to break the model up into. This requires a fair amount of forethought and planning. Once that is done, all attachment points are put into the model etc.
Now to making a mold. In CAD/CAM(computer aided machining) what you do is basically build a mold around each piece or series of pieces you want to produce in a given shot. In this step you must account for shrinkage and and other warping effects that will occur. you also need to figure out the clamping pressure and shot pressure, as well as plastic temp you will need to do it.
Once this is decided, you add in the sprue design to move sufficient quantities of plastic to different area of the mold at specific times. Doing this right prevents bubbles, un-filled areas and other problems.
Now what?
You have your design and your mold design, now you have to make the thing. You have 2 options normally...machine a mold, or EDM (electo discharge machine) a mold. EDM is basically using an electrode in the positive shape of your mold interior to burn out the shape you want. Depending on the size and complexity of your mold this choice will probably be made for you. Deep molds wih sharp corners will most often be made using EDM. It is also easier to EDM tool steel than it is to machine it, but you loose some fine control in the process. This process is not generally condusive to small deatails, so in your case it would be machining.
Program the machine, load up your material block (aluminum or tool steel usually) and fire away with the CNC machine. THis process will usually take anywhere from a couple hours to several days to complete, depending on the complexity of the mold and the tolerance/ finish requirements. ( i have seen injection molds on a machine for 10 days non stop before).
Now you have your mold. Different size injection molding machines generally accept different sized molds. mold sizes use range from 6x6 in blocks to 4ftx 8 ft blocks used for huge stuff. Basically you want the outside of your mold (which will look like a big metal block in 2 pieces) to fit the machine you have planned for. Some molds break apart in 2 pieces, while others puzzle piece together. Some even have moving internal parts or plugs to make internal holes in parts.
Once you load this into the machine (which looks like a long, horizontal press) it will clamp the mold closed, inject the molten plastic under pressure and hold until sufficiently cool. THen it will open and either automatically eject the part, or an operator will pull it out. Repeat this many times. As far as changing out a mold, it varies by machine and mold. Say between an hour to up to a day to switch molds depending on the situation. This makes small batches easy to do (provided you have a mold)
Hope this huge wall of text helps
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Flintlock
Sr Member
Yes, it does. Thanks!
Expense is obviously always a concern, but when it comes to research into designing the parts ... that's already pretty much covered. I can design parts in CAD (Alibre Design - I love this program) based on the reference I have - donor kit parts, photos resolved in 3D space, etc... I am sure there are others who could do the same.
Designing the sprue, however, is not something I could be of much help in... unless I learned.
I guess what I am trying to say is that doing everything that would need to be done is probably something that members here, in this community, could do. Coming up with the funds for such a project would be difficult, to say the least... But if the prospect for profit is high enough, maybe some existing model kit company would be willing to take up some of the work - who knows?
If I had any experience in the field, I would consider pitching the idea to a few of them... I also lack the networking - I don't 'know people...'
What about the cost of the LFL license to produce the kits ?
Flintlock
Sr Member
Yes, that too... Unless a company that already had a proper license could be swayed...
Is that just for one sprue, or all? Look at this picture:
That's a very similar size, and a pretty comparable number of parts to the X (minus the wings and guns maybe). Again, I'm just using the X as an example. Would something like this run around 10k? What about half the scale?
