I tried Injection Molding using a 3D Printer!
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- čas přidán 27. 06. 2024
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I wanted to find out if I can use a 3D printer as an injection molding machine. I printed molds using resin and then injected the molten plastic using a hotend. But how well did it work, what are the limitations and what could this method be useful for? Let's find out more!
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Chapters
00:00 Introduction
01:11 Making a Mold
04:25 Sponsor
05:48 1st Attempt: PLA
07:31 High-Speed PLA
08:30 Why all of this?
09:42 Mold Pre-Heating
11:53 Switching Printers
15:25 Injection Molding with TPU
16:08 Building the Über-Extruder
17:39 Summary
#3Dprinting #DIY #injectionmolding
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QUESTION: Where could this method be useful?
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You need vent hole at the end of the mold 👎
why could you not set your mold on the printing bed? aligned at 0° on all axis will be a huge improvement from all your angled hand held molds.
You should press the mold against the heated bed with the nozzle, then you can create a bigger mold because you dont have to hold the mold by hand you dont have to wait the whole 4 min holding the mold by hand, pressing the mold against the bed will also help with heating the mold so the plastic won’t solidify fast
@@jowmind9277 it would help significantly more with the angle between mold and printhead, as that's always mis-aligned. there has to be a reason he chose not to print on the bed, but I cant think of why.
You need to preheat the mold in in injection molding, what your seeing is the plastic cooling quickly as soon as it touches a mold you are able to touch. Also I can't help thinking that at some point the air pressure building up could become a problem although it didn't look like you were there yet.
Hello from Montreal. So what I noticed is two things. 1- you need an air hole exit to allow the hot filament to make its way instead of possibly building pressure in the mold. 2- Why not lower the gantry to push down on the mold while sitting in the hot plate? Thanks for the video.
Glad you posted this, I was wondering the same two things!
I was wondering about those exact 2 things
You can make a flat slot for air exhaust, maybe one layer thick, and you probably won't even get any flashing since your pressure is so low.
I'm amazed Stefan didn't figure that out before he started!
Yeah, seeing that Stefan is a really really smart guy, I was surprised that he didn't at least try that out.
1. Air vent hole needed at the other side of hole for injection
2. You can inject plastic not at one end of detail, but at the middle - so plastic need just half path for fill all mold. Of couse you need air vent holes at the all end of detail.
And you could fill some molds first from one side and then from the other. It would have something like a layer line, but only one
Man, that was, what I wanted to write XD
I was also surprised not to see vent holes
Jesus, Stefan not knowing anything about mold design is kind've painful to watch! Air holes are a necessity. Start all over again from the basic 3D printer and it'd probably work with air holes!
@@dmatschekothat can cause really weak parts, more so than layer lines, due to the fact it would have completely cooled and only be warmed by the molten plastic and not the hot end aswell
I'm an injection molding designer. Here are some tips from my point of view:
1. The air vents like everyone said. But this may not be the only cause of failure.
Since you have a parting line all around the part. The air can escape through there.
2. The mold needs clamping force so it doesn't flash, BUT the injector machine (in this case the nozzle) MUST HAVE injection pressure, and it's not a small one. We are talking about more than 2 MPa.
This is because you need to inject quickly (around 1 to 3 seconds) and the solidifing plastic will give resistance to the filling.
3. In this case in particular, the mold should be heated around 80°C to 100°C temperature so the plastic stays liquid until it gets till the end.
If you need some help, please contact me.
I can't imagine you'd need that much pressure for these tiny mold volumes. There's gotta be a workaround
@@coledavidson5630 yes the workaround for low pressure is same as poured casting, a vent hole or more as required
@@coledavidson5630Actually, small parts do need a lot of pressure to get all the details filled in before it starts to solidify.
I am really curious to see if Stefan can do a revisit and incorporate all the tips he got from you all, I feel that he is close enough to success.
I had the same thought to heat the mold. Add water channels to run hot/warm water through. Or since they are little plastic molds, under a heat lamp before injecting the plastic.
i know nothing about this whole process, but why didn't he have the mold sitting on the bed, where it can stay warm and also perfectly flat? All of his injections have at least some gap because he's never holding it level
injection mold design engineer here.
-First, heating up the mold before injection is crucial, as you noticed yourself. It will delay solidification of the part.
-A vent at the end of the part might be a good idea, depends how tight your splitting surfaces are.
-You should feed the part into the thickest part, like head of the screw in your last try. You always want the melt to flow from thick to thin since it tends to solidify in the thin part first.
-Pressure is not the key actually, speed is more important since melt solidifies with time. Viscosity also tends to decrease with increased speed. Normal injection of a part takes max few seconds.
-350bar of pressure is not the lower end in industry. Most of the parts I made molds for were injected with lower pressures. Machines go up to 2000 bar but it's rarely necessary. If part needs that kind of pressures then it's (mostly, not always ;) ) a badly designed part.
Do you know why the printbed was not used to maintain a warm and *most* importantly a level surface for the mold and printhead mating?
Was all the tilting he did with the handheld mold to let air out? I would think a flat surface would be best, but there was never an attempted zero tolerance injection
Agree with venting. It is the only way to allow air to escape from those bends or turns in the mold. @10:38 -- add a vent to the "J" part of the hook that didn't fill, creating a vent pipe that will exit to the left side (where your left thumb is in the frame). Otherwise you will face air trapped by the rapidly cooling filament.
EDIT: Since you are using the PRUSA bedslinger, I would think you could make a jig that would "lock" the mold on the center of the bed using the two vertical extruded aluminum Z parts as braces. Once the mold is locked into place, You could lower the print head until it makes contact with the sprue. Keep the Z-axis locked into place and then start the extrusion. Having the bed turned on, in contact with the mold, may allow the filament to flow better at the bottom of the mold.
10:50 injection molding operator here. You may need to optimize the mold first, like the placement of the sprue. currently, you have it at the very top of the part meaning it is quickly cooling down causing undershoots. move it more or less in the middle of the parts volume and you will be fine. I'm gonna be doing my tests soon enough as well so I'm gonna check it
Yes I was thinking the same thing!
Letting the mold sit on the bed and heating it may also help to keep a nice flow temp?
I think also finding a way to get a good seal would help. Maybe the mold could have space to encapsulate the nozzle tip?
Leaving the mould on the bed and lowering the nozzle into the mould may help seal this better than trying to hold the mould to the nozzle at a random height. This will allow you to be less hands on also.
Good suggestion KleikPL. He also needs to vent his part.
I really hope you revisit this with an air escape hole, the hotend assembly down and pressing onto the mold sitting on the printer bed (potentially heating it) so you don't need to hold it and also a bigger mold. I wonder how far this technique could be pushed!
Yeah the holding it in place really took me aback when it's in the context of a machine that can press down an exact amount by itself
Keep in mind actual injection and ISBM machines charge the barrel before injection. That is to say, they melt enough plastic to fill the mold in advance, then inject it all at once.
I don't think that can be done with a 3D printer nozzle (still don't own one), but him using longer and longer nozzles feels like an attempt to approximate that behavior within the spec of 3D printers. It's definitely an important consideration though, and it's what makes me think that part of making this level of hobbyist injection molding accessible will involve people designing DIY/semi 3D printable injectors that let you preheat a load of the plastic and then shoot it in like a syringe.
The first application to this that immediately comes to my mind is reusing filament waste (failed prints, calibration prints, purge waste/ams poop, etc). Would love to see some experiments in how to melt and inject those into a mold, considering your past videos on reusing waste for filament extrusion
that would be probably the most sensible use of waste filament.
injection molding skips the step of forming it into a filament which must be done with tight tolerances as diameter variability messes up the prints.
You need a hole on the top on the mold to get trapped air out
And also lubricate the mold to avoid the plastic to stick too much
The two halves of the mold will have enough of a gap to where vents aren’t necessary unless he was machining them post printing.
@@user-it7kg3pm4q Nah they're squeezed together really hard and it's causing a LOT of back pressure to try to evacuate air through the microscopic gap. The precision fit is evidenced by the complete lack of flashing, so it's perfectly liquid-tight and probably very nearly air-tight. Considering he's fighting with insufficient pressure to fill the ends and corners, properly venting the mould can only be a good thing.
@@user-it7kg3pm4q I would assume that the slightly flexble resin-halfs, if get pressed together with enough force, seal up very tight.
On top of that, you can design the mold to fit around the head of the nozzle so that when clamping down it holds pressure in there, thus not allowing material out around it, and increasing pressure inside the mold.
Stefan, I believe you forgot a small vent hole towards the end of the mold (to let air escape) that and achieving higher temp in the mold
I feel a little bit relieved seeing someone so competent making multiple stupid mistakes... like I often do myself.
@arbitrary_username I like Stefans approach to things, even if he isn't an expert in an area, that doesn't mean he can't quickly come up to speed enough to get value.
As I think about this, it's highly possible that the air was able to escape via other means like the somewhat poros polymer. I think.if the air was escaping out the cracks, we would have seen some fleshing. Plus he used a release in the mold, which likely would have sealed any porous issues with the resin.
To me, I think he was fighting against a building up of pressure. The more polymer that was forced into the mold the more a leading area of pressure was building and fighting his max 300bars.
With proper venting and heating those molds, I think for the size parts he was working on, it would have been perfect.
Question would be how much bigger could he go with this technique (and the mentioned enhancements) before the leading polymer cooled too much.
With real injection molding you have metal molds that are heated to 149*C-426*C and apply anywhere from 500-1500 bars of pressure (some even have air assist for ease of release).
Without more pressure, heated molds, and proper vents; his technique will be very limited (though I believe that was his goal any way).
I am one of those who builds injection molding tools and here the recesses on the side are sufficient, especially since the cavity of the finished part has no sharp edges and is not compressed by several tons, and air can also push these tons apart, creating degrees. If this tool were made of steel, I would place the vent closer to the cavity so that the vent has more space more quickly and no holes are created. With a hole at the top as a vent, you only create unnecessary work to remove it because you also have to remove the sprue
King the same thing
I hope you make a part 2. The comments are full of great wisdom and I can't wait to see how this develops
I used to teach injection moulding theory at university and we would print a few moulds and run them with a small injection moulder, like this, as a demonstration. As most people have noted, position of the gate and airs are key. The only thing I would add is that with an injection moulding tool, you actually leave a tiny margin where between the two halves of the mould so that air can escape but plastic cannot. That's why you almost always see a tiny bit of a step along the seam where flashing eventually occurs, if the pressure becomes too great or the mould deteriorates. Hope this helps.
Always gate into the thickest part of the geometry, especially when as pressure and flow limited as you are with your setup. The flow channel that develops inside the part will rapidly narrow as the material cools, so you’re fighting an uphill battle.
I thought this - the last mould for the screw should have been into the head, not the tip.
You should consider venting your mold so you aren't building up pressure by compressing air.
p.s. You don't need a draft for very short walls, as there is sufficient shrinkage to allow release.
A local company has done simular as you. They take all the waste plastic from milk jugs, packaging etc, and then injection mold it into 3d PRINTED(FDM) molds of combs, hair clips, cloths line clips, etc and sell them at local farmers markets. Its really cool
SUPER!! It honestly surprises me that no one has done a 3D Printer mod kit for something like this yet. It seems like one could rather easily develop fixturing and use bed heater to preheat molds and then custom g-code to move the nozzle to each sprue hole and start shooting molds. Just a matter of time I suppose before we see it.
Well done as always Stefan!
I feel like every expansive manufacturing techniques has started coming home, 4 axis CNC with the carvers, EDM with the power code and now injection molding
I wouldn't use a 3D printer for injection molding the specialized tools do a way better job for it. But there's DIY and home versions now so it is like you said way more accessible and less expensive.
I had this idea where you use few generic hotends and extruders to melt filament and inject it into larger heated cylinder, and when it's ready, a piston pushes the plastic to inject it.
Because even if you get hold of a hobby grade desktop moulder, you will struggle to buy the pellet material, and if you find it, it will probably be more expensive than filament or you will be required to buy entire euro palet at once.
Couple of ideas, which come from my experience working for a molding company:
Keep the mold hot at around 10 to 20 degrees (celsius) below the melting point of the material. This will give you plenty of time to inject.
Make tiny channels at the corners and dead ends of the form to let air escape. This will reduce the needed pressure and it can serve as
an indication when the material has filled the mold.
You can make the mold outline smaller, reducing the needed resin.
Inject from center outwards, not from one end. This will spread the material more uniformly. Best is to make the input port on the larger side of the mold - that way it will be as short and as close as possible, thus reducing the heat loss before filling the form.
We are using thin motor oil as releasing agent. Sometimes petroleum jelly. Depends. These are cheaper.
You can easily print shapes like that directly on the plate of the resin printer. No need for putting it at an angle with supports, it just slows the print down, uses more material, requires cleanup, etc. Even dimensional stability is better when printing functional parts directly on the plate, you just have to dial in the elephant foot compensation and properly set the exposure for the first couple of layers.... It was a revelation for me when I started doing it that way...
Okay so, from what I’m seeing in the comments, he MIGHT have forgotten a vent hole. However, only a few people have said it so I’m not sure…
Haha, yeah only a very small number of people have mentioned it.
Maybe we should also tell him?
Yeah I'm not sure, it's up in the air. Maybe another 30 comments would convince me
I think you might be into something
I wonder if a vent hole would have helped
I was exactly thinking about this then I saw your comment. He definitely needs a vent hole.
I've had this idea for so long I'm so glad somebody did it 1st so I can see how it works
What an awesome idea! I have a suggestion: Lay the mold on the print bed, and lower the extruder down to the hole, clamping down the two halves with the extruder. Then crank the heat up on the bed, and since it will be touching the bed throughout the entire injection, that will keep the mold hot, and will probably allow the plastic to flow more easily, and longer before the plastic inside cools. It might allow you to do it with less nozzle pressure too.
That might be a really good idea. It should helo solve all the problems that people are pointing out in a very simple way. 👏🏻👏🏻👏🏻
@@alvarolopez8514 I think the main issue others are pointing out is the lack of a vent hole, which is still necessary, but yeah I think with this and a vent hole, this could be incredibly viable.
there has to be a reason he didn't do this, it's way too obvious. he never addressed it, but keeping the mold flat and warm would've prevented many of his problems to begin with, since he talked a lot about those issues but kept using his mis-angled hand-held injections throughout the whole video. I'm truly baffled and was waiting the for him to inject on the bed, or at the *very* least tell us why he cant.
the fact that you can resin print a mold now is enough for me to get a small injection molding extruder tbh!
put the clamp ont he print bed, then lower the extruder into the mold and use the Z axis to hold it in place, and the nozzle and print bed can both pre-heat the mold from both sides :D
It's already been said but injection molds have micro air vents. It would allow the plastic to flow better
Wow! Your creative idea on 3D printer is amazing and endless. What a smart move to leave some room for everyone here giving their input and gain more engagement, which you tried not to put an air-release-hole to the mold as well as lower the print head to fix the mold in position with down pressure instead of hold by hands. 👍🏻
I'm being gaslit! I thought the topic of vents would eventually come up when it was the right time in the script, so I held back the urge to scream "VENTS!" at the screen for 18 minutes, but then the video just ended 😭
Lol the entire time, i was speeding that urge too! In fact, I'm still half through the video before checking the comments to see if anyone else pointed this out!
He's a smart guy, so i thought SURELY he'd come to the same solution!
@@Gendo3s2kI think he's a smart guy too, yet here he is trying to injection mold with a freaking 3D printer and printed mold. It's such a ridiculous waste of time. 🤦🏻♂️
@@Studio23Mediait is a step in brainstorming. It may be a waist of time, but may lead to other, better ideas
Look up the meaning of gaslighting
How about a nozzle that mechanically keys to the mould? And moulds that is designed to be clamped by screw hardware... That way you could put everything in a heated chamber and press until the hotend skips steps.
Really surprised as an engineer you didnt consider having a vent. Would thought that would be common sense. Without a vent you're just compressing the air inside.
Wow, what a ton of responses and suggestions; I believe everyone would appreciate a follow-up video on the same subject.
Thanks Stefan.
Tested this myself as well. SLA printed mold for a gear and that did work pretty well.
I had a hole for the air to get out (and when plastic came out of it I know the mold was full), was using some grease for easier release and I had the mold on the heat bed and I just used the Z-axis to lower nozzle tightly to the mold.
Ended up breaking the mold by moving the Z-axis the wrong way...
Good to hear!
Why no air escape channels? The trapped air pushes plastic out of the mold.
Two channels are needed at least, its simple logic and I dont know why Stefan didnt use this.
This was my first instinct as well
Well, I'd imagine that with the tolerance of a 3D printed mold air escapage would be fine.
@@captainironbat8193 Nah, that resin part was printed really freaking smooth and clamped down hard
I have had this idea before I’m actually excited to see your findings
Wohooo, nice idea. Classic CNC kitchen stuff. Loved it
Venting isn't required. You could add an extra chamber to be trimmed off later (often called a material saver, for some odd reason) that the gas could vent into. Remember, any gas inside the mold is being compressed. The seal between the halves will not be perfect enough to prevent gas escape at these low pressures. The suggestions to use the gantry to hold the hot end against the mold and to use the hot bed to maintain mold heat are very good ideas. Now I am wondering about standard 3DP resins......I don't think a glass filled 10k resin would be required for TPU.I've used resin printed molds for epoxy and composites, but hadn't really considered filling them with hot plastic without turning to specific tool resins. Good stuff!
yikes, this makes no sense, "Venting isn't required" but "You could add an extra chamber to be trimmed off later" so venting is required, this is just a worst solution that makes you waste more plastic + you have to refine it, and it's too generalistic aswell, maybe when casting resins you could be better served with an extra chamber due to the low viscosity of the resin, but that's it , in commmercial injection molding using plastic polymers air vents are what is needed, holding the gantry on to the hotbed is indeed a good suggestion tho
@@martimattia1997 Long-winded reply time. Plenty of "material savers" are used in commercial injection molding; that's where I've made my living for most of the past 30 years. Having dealt with injection molding machines varying between 33 and 4000-tons of clamping capacity from automotive to medical, I've been around a little.
Adding a vent to atmosphere isn't always feasible, but a material saver can help with filling. Imagine if your problem area with gas-trapping ended up being inside another feature. Having an extra chamber to fill and have the material pass through can help with filling, even if the gas just gets compressed and doesn't vent to atmosphere. Vents go to the outer edge of the mold. That likely isn't required with c-clamp forces and the kinds of speeds and pressures involved here. Also, in commercial injection molding, temps are very high, so the viscosity can be surprisingly low, and there is a lot of speed and pressure moving the plastic.
When you get to a point where the surface area of the mold actally counteracts injection forces before the plastic "freezes off", gas pressures can stop flow or cause the clamp to open slightly (the handheld example), and a highly polished mating surface (not part molding surface) can actually be a bad thing. I don't think 3D printing is yet at that level of surface finish. If the mating surfaces of the mold are highly polished AND match perfectly enough, you will get gas trapping and the gases still generally find their way out - not always in the manner expected.
The larger issue for small scale molding is temperature control - keeping the mold hot and even cooling it in strategic places.
@@Tech-gu5ge maybe i didn't explain myself well, i'm not sayng that material savers are not useful in any way, i was just pointing out that in this case, was easy enough to vent out really easily and could be a more efficient solution, im not in the industry from that long, so i'm not debating about common molding pratices, you probably have seen way more than me, but from what i saw, airvents are really a common choice
@@Tech-gu5ge I suspect that your opinion is based on industrial molding techniques that operate at hundredfolds/thousandfolds higher pressures and velocities.
Despite the clamping force being so much smaller, and the surface finish being much rougher, the air will still create enough resistence while seeping out to slow down the flow significantly, even if it can eventually escape. It's not just a yes/no matter, whether air can escape, it's how much resistence it produces while doing so, and since here you're operating so near the limit, any extra slowing might be the straw that breaks the camels back. Since you are already operating at crawling speeds compared to industrial injection, and in a cold mold, any slower is easily enough to make the injection fail. An air vent instead will reduce the resistance significantly.
While your experience with real-world industrial molding is impressive, it may not be aplicable, or even lead to wrong assumptions in the present case. Plus, here it is even easier to have a vent than to have a material saver, so it is hard to justify logically.
In the end, the only way to see whether anyone here is right, is doing some experimentation. That is the only way of verifying the various assumptions that have been made for both arguments.
Most likely, anyhow, the biggest difference would indeed be mold heating.
@@professorfrog7181 I think heat is going to be the key, retaining heat in the mold and, if possible, adding thermal mass to the column of plastic going in. The addition of mold release to promote surface flow solved a larger issue than venting: it moved the material across the surface quicker, keeping it from freezing off. I think moving to a 3mm extruder would also help keep heat in the material (a molten column behind what was already injected), and likely improve things by moving the plastic faster, even with the same nozzle diameter (higher pressures due to increased piston area) but I would think a larger nozzle would be better by reducing pressure in the extruder and just pushing more plastic into the mold more quickly.
Even in industrial injection molding, we tended to do some questionable "experiments".....right down to "squish molding" in wooden molds where you would throw in a blob of molten plastic and squish the 2 halves of the mold together. Heat makes the most difference in material flow. Same with "hot glue molding", using a hot glue gun to try to fill s small mold. Being able to 3D print the molds is a major step forward over the way I did it, and allows for much more detailed molds. Spare time on your hands makes you want to test the "rules" with some hands-on time. I've moved on from injection molding to medical 3D printing; still doing questionable experiments to test the limits.
you could try heating the mold in a toaster oven and too 150C, you can also change the place where you fill it and widen the sprue to allow more flow. Lastly adding air vents will help prevent air getting trapped. oh and you could make bolt holes to clamp it down they will keep a constant pressure.
Suggestions: slather some two part silicone or 500C gasket sealant around the edge of the entrance hole to create a squishy seal around it. That should increase your pressure.
Additionally, the exit hole others have mentioned will help a lot.
And yeah, pushing the preheat to the limit will help. Home injection molding machines typically require that you bake the mold in the oven before injection to keep the plastic from cooling part way through.
The guy who will shill for anyone for a dollar has an opinion.
Your silicone sock and this episode are most outstanding!!! You did and share a lot of great experimentations! Vielen Dank!
7:25 where is a channel to relase the air?
i think the pressure is not the problem - your problem is speed and coolingrate in the mold.
you have to melt all the needed volume and then shoot it in.
a slow printer extruder might be ok for very small parts.
maybe some air vents would help to reduce the airpressure in the mold, the plastic has to "fight" against. some small 0,5mm holes might help a lot.
Worked a lot better than i expected, this gives hope that for smaller parts a much smaller and cheaper machine than the huge usual DIY ones could work
I love this idea!!! Please do more!!!
I love this proof of concept; great work. I do think that the best part is the use of a resin printer to make molds. I don't know if you are aware but long before 3d printers were being made by hobbyists, some were making tabletop injection molding machines. Check out the Gingery book on the topic, its a much easier build than a 3D printer in every way except making the molds. So using a 3d printer to make the molds is the real game changer here.
My brother in christ you need a hole for the air to exit the mold LMAO
cnckitchen is all about half cooking ideas
You guys keep parroting each other. No hole is needed, tiny part and it’s not airtight 🤦♂️ you’re 12
“My brother in Christ” you pre-teens will say anything to sound edgy and dramatic 😂
@@_..-.._..-.._ The point of a mold is to press the two pieces tightly together so the plastic only fills the mold but doesn't escape through the gap. The reason it required so much pressure to fill the mold is because the air was trapped inside, come on that's common sense. Stop trying to be a contrarian.
A always great Stephan! Thank you for sharing your experiments. You've got very nice tips from the comments, I hope seeing more work about this subject, it's very interesting.
I love this. Thanks for trying this out
Maybe change the inlet position so plastic doesn't have to travel too far? For example try printing the hook from the middle? Also adding a very small channel to release air pressure could help. This could be interesting although it also can release the pressure too well which may result in under-fills. I'm amazed how well this worked.
In industrial molding pressure is everything.
If the mold temp is below optimum and/or the material is not up to the desired temp for optimal flow rates, putting 75 to 100 tons of pressure behind the plastic WILL get the job done.
Of course there is no way an extruder hot end can produce anywhere near that sort of pressure...
BUT if you can get temperatures of the melt and the mold right it should work for small parts.
Industrial machines have a screw that is moved back while the melt chamber/reservoir is filling and then gets forced forward quickly when injecting so maybe one of the hot ends that use raw/regrind material could be modified to work in a similar way.
But I really like the idea of 3D printed molds - if only you (or maybe someone else) could perfect the process it would be a massive leap forward for makers.
injection mold designer here - there's not a thing like "tons" of pressure.
@@fashionskillerserious question.
If something pressurized to 2000 psi, isn't that a literal ton of pressure?
@@DH-xw6jp pressure means force exerted on a certain area. 2000psi means 2000 pounds per square INCH, so a ton per inch roughly. But it depends on the surface area of the "something" that you mentioned. Such pressure exerted on 1 square millimeter will equal to around 1kg. 1psi on on a football field will be many many tons.
@@fashionskiller okay, so you can have literal (as opposed to figurative) "tons of pressure" on something.
But that "ton" would be a different amount depending on how big the part is... I can see why it isn't a good metric.
Thanks for the inspiration Camel!
Wow, I'm looing for a home injection molding solution and this idea is blow my mind
You should have homed the printer then use the clamping force between the nozzle and the bed to get a better seal on the nozzle.
Hi Stefan, es ist super wichtig das die Luft aus der Mold entweichen kann, oder du eine kleine Kammer einbaust wo das Material überlaufen kann. Ich habe viele solcher Molds im 3D Druck für meine Arbeit gebaut. Falls du interresse hast können wir uns hier gerne austauchen.
Excited to see a part 2 with all the suggestions from the comments but it seems like a great start!
I love how at the very end you get actual nice models injected
Very interesting concept, did you try putting the fill hole on the long side so the filament has less distance to travel? It would also allow active heating on the build plate
Wow, I found this on my recommended 8 seconds after it was posted.
4 mins here, must be a supercomsumer 😂
Same
15 mins for me, but I'd been out for a cigarette for 20 🤣
Really love these videos, high quality shots, good testing, with theory behind it and not overly serious. Keep it up man!
heck yeah man, always pushing the limits, love it.
Can you add a port at the other end of the part to let the melted filament all the way through then finish with a cut in post like casting?
I have a question, why not shape the hole after the nozzle and use the z-screw to hold it in place?
Really cool. Two things of note.
(1) You need a second hole to allow air/pressure to escape from. When doing stuff like metal casting using a mold without that second hole you get only partially filled molds. All the 1 hole system is doing is causing air pressure to build up toward the bottom of the mold and that prevents it from filling. Without the hole all their air either gets trapped and won't allow the plastic to fully fill it or it tries to escape, either through the top hole where the plastic enters or by forcing the mold apart.
(2) You need to find some way to continuously apply heat to the mold. No matter how hot you have the plastic it means nothing if the mold rapidly cools it and blocks the passage.
I think you need a clamp with heating elements inside to keep the mold warm. That, and you really need airducts. It will flow way better that way.
Love the concept, i appreciate you for shearing your ideas in a way that others can understand and improve on!! Even when you don’t have it perfect your self it still helps the community!
Yes keep pursuing this-this is something I would love to do at home
looking forward to the next stage
I wrote prusa about this exactly about six months ago. Never heard back. Glad to see you tried it out!
This is creative engineering spirit is exactly why I love the 3d printing community, I love this! Please keep sharing these awesome projects with us :)
Suggestion:
Why not use a threaded, hollow bolt as your nozzle and then design complementary threads into one side of your mold. Screw one side of the screw-like nozzle into your hotend and screw the other end into the threads on your mold. This should create a tight seal between the hotend and the mold, preventing leakage. Then clamp your mold together and proceed.
In addition to preventing leakage, by using a hollow, threaded bolt, you will also have more diameter to allow for maximum flow into the mol.
I was thinking to it yesterday!!!! thanks Stefan!
Molds usually have breather holes to let the air escape. Also, you should inject from the middle, so the plastic doesn't have to travel as far to reach all the corners
Agreed, I work with molds at my job and all of them need venting some times in multiple places inorder for the mold to fill completely.
Great Video. Even in a professional injection molding shop if your machine is on the edge of filling a part, what we did is to place air vents in the areas filled last. Add a sacrificial hole on the end of the hook and you will be amazed how easily you will fill the part
Interesting. Hope to see more on this subject
this idea is so cool
Good to see you have a Q1. I hope a review will come.
I’ve been thinking about this for over a year after a horrible failed print where plastic was injected everywhere. I think I suggested this to you a while back
Love how much feedback this is getting, if this improves so much in a short time the possibilities are endless
This is one of the coolest things you've done.
I love this. We need to continue the desktop injection mold technology. Stephon is doing it 💪🏾💪🏾💪🏾
Once upon a time before 3D printing machines were cheap I tried injection molding with hot glue and I actually got it to work after a fashion using milled aluminum molds. The thing that really helped was preheating the aluminum mold. In the end I got a small Creality machine when they became available and now I make all my parts that way.
Wow! Creativity never ends, i interesting on test all filaments in molding version it realy shows some interesting results
I'm glad other people are mentioning air. I was sitting through every failure thinking about where the air was suppose to go.
I have watched a LOT of DIY molding videos with metal and they always have Vent holes to let the air escape so it can fill easier and faster before the plastic hardens
For solutions to your issue: I believe you were on the right track by heating the mold prior to injection. As for why there are voids in the cavity leading to incomplete parts, I think what is happening is you are compressing the air left in the mold while simultaneously heating the air causing greater pressure than the rapidly cooling plastic can push.
The reason why I think this comes from making soft plastic fishing lures. The molds used in the injection method as well as the open pour method have small grooves cut from the end of thin fine detail parts to the mold edge. These fine grooves allow the air out so the plastic can flow into the finer points of the mold. There are plenty CZcams videos on home made soft plastics to reference. Some lead sinker molds also have thin grooves. I dare to make the comparison as soft plastic lures when at liquid temperature have a similar viscosity to maple syrup. I believe you could easily score your test hook mold with a dremmel cutting wheel from the up turned part to the edge. Less than a mm deep should be good. When or if a hair of the injection plastic comes out of the vent then you know the cavity has been full to the bottom.
As for the sucking in of the top after cooling that is from the shrinking of the cooling plastic. It happens in soft plastic injection molding as well. Often a bait maker will top off the sprew so there will be less chance of cavities in the top.
As for making molds, I have personally made a 5 cavity minnow open pour mold from elegoo water washable resin to see if it would take the heat of soft plastic and lead. The mold has been used several times for plastic and once for lead so far. It has held up well to the temperature I had plans to make a 2 piece mold like yours this past winter but found myself without the time or energy to 3d model the mold after a long days work. Hopefully I will get the chance later this summer.
I'm an injection moulding machine operator and for a while now have been trying to emulate the quality of injection with 3d printing, but I remember seeing this topic before and have often thought about it. It's easier to take an injection moulding machine and turn it into a 3d printer than to make a 3d printer perform injection moulding. I do have some suggestions, however. You may want to design your mould with small vents for the compressed air to escape, also preheating the mould is key - you're on the right track there. Allowing the molecules time to relax will help reduce internal stress and warping (i.e. slow, adequate cooling time). I think that mould release helps. However, I think your main bottleneck is injection time. Normal injection moulding occurs in a fraction of a second (i.e. 0.10 sec on the faster end of the spectrum), filling the mould in 5 to 10 seconds allows the plastic to cool and freeze before it has time to completely fill the mould. The leading edge of the injected plastic freezes first. Keep in mind that temperature increases with flow rate and pressure. Maybe add a gate to maintain a high flow rate.
I hope some of this insight helps, I would love to start injection molding with my FDM printers. 😄
i have a background in injection molding some tips i have found in industril cases
1 you need a holle for air excape this allows for better filling
2 the problem you have for the undershot is from the masive gate this like the support on resin is easier to remove the sprew
3 a mounting plate on the back side of the hex for the hot end will allow for heating the mold and betting injecor presures
4 when injecting you want the material almost to the point for burning this allows for faster injection and better fill
was waiting for this for a while :) great video
I always print (and design) my resin printed injection moulds flat on the buildplate or standing on their sides, to not get the stair stepping where the mould halves meet. I also just print in simple and cheap Siraya Tech Fast instead of all the hi temp stuff and it works just fine. Tiny air vents might help with filling the mould more easily. I'm no engineer or technical guy at all, just played a lot with resin printed injection moulds and found out some stuff. I still haven't made a longer video about my whole process and I am currently playing with concrete instead of plastics, but there are a few videos and shorts from the beginning of my tests from a while back, if you're interested. Curious to see more!
🤔 screwing/clamping the mould onto the nozzle/hotend?
I did this months ago, but I used an aluminum mold and secondary heater blocks to maintain temperature to keep plastic molten. It worked okay, but ultimately the limitation was maintaining heat. It's just a continuation of the hot-end, but without the high powered heaters and pressure used in injection molding, you're limited on part size.
I feel like the hook could still be successful With some modifications to the mold design. you could try adding sprues and events to the mold like what’s used with hobby aluminum casting. It would add additional post processing, but it could drastically increase consistency.
Amazing video! As always! :)
To achieve the necessary pressure, you could shorten an overly long nozzle, create a thin section immediately after the hotend, and then screw on the mold. Incorporating air holes and other suggestions from the comments, this approach could work very very well.
I love this idea! Very fun project and experiment. :)
I'd be interested to see more!
For the M4 screw mold where the head never completely fills, try a couple of well-placed weep holes through which air can escape as the head portion gets filled. The weep holes should be tight, perhaps 1/3 mm, because you want the air to escape the head allowing the head to fill with plastic, and you do not want a lot of plastic escaping through the weep holes. The goal is to fill the head portion and quickly plug the weep holes so that you can build pressure as quickly as possible. You may even experiment with weep holes that don't fully reach the edge and allow air to escape. Maybe the weep holes should have just enough empty volume to contain the air that isn't escaping your current M4 screw mold.
This is an amazing way to use a 3D printer. I would love to try this, if I had the correct setup. My 3D printer is way too old. I can't wait for what you and the community come up with to advance this.
This was amazing!
I'd love to see a strength test between a printed version and a home injection moulded version of the mini hook!
Keep up the good work!
Very cool idea. I to was 3D printing but wanted a way to make parts faster and stronger which was why I started developing DIY injection molding machines. I think one of issues that you will run into with using a 3D printer is how fast the plastic can be injected before cooling as you have seen. The other issue is that even if you are able to fully fill the part you would want to keep pressure on the part so the plastic has less shrinking and pitting as it cools. That also might be harder to do with an extruder over a plunger or screw type injection molding machine. Preheating the mold is important even on a regular injection molding machine but typically the heat from multiple injections is enough to keep it hot. I also can't remember if I saw vent holes for the air to escape but that is also very important. Last thing you could possible try is to switch the location of where the sprue is injecting the plastic in to the mold. If you did it from a more central location the plastic would have less distance to travel and thus potentially give you better results. Still super cool and can't wait to see what you are able to come up with!
Always interesting ideas here.