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Plastic Injection Molding (2015) [video]
- rdiddly 8y agoThe visuals are good enough to watch this without sound... Always a high benchmark for visual aids.
- Judgmentality 8y agoThis is by far my favorite video of his: https://www.youtube.com/watch?v=hUhisi2FBuw https://www.youtube.com/watch?v=hUhisi2FBuw
- jstimpfle 8y agoAlso check out the "drinking bird".
- jcims 8y agoHere's the How It's Made version - https://www.youtube.com/watch?v=V7Y0zAzoggY https://www.youtube.com/watch?v=V7Y0zAzoggY Aluminum baseball bats have a similar manufacturing method - https://www.youtube.com/watch?v=didmRLz4vfU https://www.youtube.com/watch?v=didmRLz4vfU
- lopmotr 8y agoI once built a very simple one in my backyard using a shock absorber from a car as the barrel, which just worked like a syringe with no screw. It was driven by a threaded rod powered by an electric drill. The heater was a spiral stove element or a hot-air paint stripper or both - I forget which. The mold was a stack of aluminium plates that I'd cut with hand tools and bolted together. It was very fiddly to operate but worth the experience! Driving a car without shock absorbers is also a real experience! With alternating braking and accelerating, you can build up an oscillation that's big enough to bounce the wheels off the ground with almost no forward speed.
- giarc 8y agoThose are incredibly well done videos. Without realizing it, I just spent 30 minutes watching engineering videos. They are done in a way that anyone could understand.
- jcims 8y agoI wish he would Patreon up or something so this could be a full time job. He does an amazing job of making a variety of engineering disciplines accessible to the layman.
- Judgmentality 8y agoAdmittedly I don't know for sure, but I suspect he enjoys his profession as a university professor.
- Noumenon72 8y agoThey compare quite favorably to the Paulson training videos we watch in the actual industry, though those were more in depth, many hours longer, and came with interspersed quizzes that really helped my understanding. Both are infinitely superior to almost any classroom. Topics this video didn't cover include friction/slippage along the barrel wall, circulation in the melt between each screw flight, the thrust bearing at the back end of the screw that takes the load from pushing the plastic forward, two-stage screws that drop the pressure in the middle to let gases be removed from the melt, how the plastic cools differently at the edges and center if it is crystalline/amorphous, and more.
- Noumenon72 8y agoI operated a line like this for seven years before becoming a programmer, except that we extruded continuous paper-thin sheets of plastic for people to print signs on. That was a more skilled process, I guess; injection molders I talked to often had one person monitoring multiple machines. My plant was in Wisconsin but wasn't heated during the winter when the lines were running. Melting plastic takes so much heat that we were the main electricity consumer in my town. Because there isn't a check ring in place while the screw is turning, plastic is always trying to slip backwards over the flights of the screw. You have not just heater bands around the barrel, but also cooling water, which makes the plastic less melty so the flights can push it forward without slipping back. The more recycled material you use, generally the cooler you need the barrel because those little flakes melt faster and slip more than virgin pellets. The many challenges of fighting reality to get your plastic to come out correctly mixed and without bubbles build a lot more character than similar paying jobs like driving a forklift. Facing the same problems repeatedly helped me develop the quick-access note system I still use for debugging and syntax. I wouldn't be half the programmer I am without the life skills from manufacturing. The only problem with being a line operator was that most permanently solvable problems have been engineered out already, so being clever and organized about solving things didn't produce nearly as much value for the plastic factory as it does now that I'm a programmer.
- klausnrooster 8y agoI'd like to hear more about your quick-access note system.
- anitil 8y agoI'll second that!
- Noumenon72 8y agoJust posted. https://news.ycombinator.com/item?id=17389157 https://news.ycombinator.com/item?id=17389157 Glad at least two people will see it.
- gnicholas 8y agoPerfect for curious toddlers. My daughter is always asking to watch videos of how things are made, and this video has a great mix of very simple takeaways (chairs and legos are made out of plastic) and much more complicated concepts that she can be exposed to and grow to understand (the way screws work, how the runners attach). And now she can run around the house finding the ejector pin witness marks on everything.
- Exuma 8y agoLol, I guess I am a curious toddler then.
- trumped 8y agowatch How It's Made[1], this one is probably not my favorite: https://www.youtube.com/watch?v=2NzUm7UEEIY https://www.youtube.com/watch?v=2NzUm7UEEIY 1. https://www.youtube.com/channel/UCWBkudOTaVbvkCBc0pyZFMA https://www.youtube.com/channel/UCWBkudOTaVbvkCBc0pyZFMA
- viggity 8y agoI would have How It's Made on constantly in the background if I could stream more than the 3 most recent seasons on hulu. I love that show, but 3 seasons isn't near enough.
- sdrothrock 8y agoI'm not sure how difficult it would be to find them, but the old Reading Rainbow used to have a lot of visits of this kind, and so did Mr. Rogers' Neighborhood (though I watched less of that and can't remember how frequently it happened). If you can find them somewhere, hopefully she'd get a kick out of them. :)
- nojvek 8y agoMy dad took me to visit a Kenpoly plant in Nairobi. Had so much respect for machines. They were just ejecting ready made products from this little pellets. The worker let us cut one or two of those ejector thingis that are attached at the end. He even let us keep one, we called it “the cup with a tail”. Fun times, so easy to be amused as a kid!
- le-mark 8y agoI've had a project in mind for several years now that would be ideal for injection molding plastic parts, the only problem is a $10-20k in mold creation would take a long time to pay off and become profitable for a niche product (lego related for example). Does anyone have experience doing this?
- sporkologist 8y agoMake sure you take care of patent issues first—if you're making something that someone else has patented, they can make you stop producing them and/or sue for legal fees. Consult with a patent atty. first if you haven't done so yet. Having said that, epoxy tooling is another lower-cost option besides aluminum.
- Gibbon1 8y agoYou can I think get simple short run molds made for under $5k. Molds made out of CNC milled aluminum instead of hard steel.
- countzeroasl 8y agoPossible, depending on how simple the molds are. Typically, this is easier if you have a MUD unit (Master Unit Die) where you can just mill inserts, rather than the whole injection mold (ejection, injection, clamp plates, etc...)
- wtracy 8y agoYou might want to test the market first with 3d printed parts. There's a little cottage industry making 3d printed accessories for Lego.
- starky 8y agoHow complicated/large is the part? $10-$20k is a pretty expensive mold these days even for production tools (from China). If you only need 2000 or so for a simple part to start, and are willing to pay 2-3X the part price, Protolabs is a good option. Another low tooling cost, low volume option that might be worth looking into is cast urethane.
- beautifulfreak 8y agoThe book, Serendipity: Accidental Discoveries in Science, claims that some early plastic billiard balls were made of nitrocellulose and sometimes exploded. I suppose Hyatt's celluloid billiard balls were the nonexplosive kind. https://www.amazon.com/Serendipity-Accidental-Discoveries-Royston-Roberts/dp/0471602035 https://www.amazon.com/Serendipity-Accidental-Discoveries-Ro...
- evgen 8y agoFun history there and if you ever get a chance to watch it, there is a nice episode of Connections ('Countdown', https://archive.org/details/james-burke-connections_s01e09 https://archive.org/details/james-burke-connections_s01e09) that uses this as a key point for one of Burke's nice random walks through the history of technology. Nitrocellulose was initially a failure as an explosive, but when mixed with a few other things it was used to replace the ivory in billiard balls as hunters were decimating the elephant populations. Nitrocellulose ended up being the base for smokeless gunpowder that had a huge impact on guns and cannon later in history, but the other big thing it was used for was early film stock. One source of so many fires in theaters (and film storage vaults at studios) in the early 20th century was due to this particular type of film stock.
- Animats 8y agoThat's a great talk and animation. Amusingly, the cheap plastic resin chair shown prominently in the video probably isn't injection-molded. Those are usually formed from a flat sheet.
- deleted 8y ago[deleted]
- saagarjha 8y ago> Likely the device you're watching this on has injection molded parts; you should be able to find ejector pin witness marks and parting lines. I'm not seeing these on my MacBook. Is that because the parts are not injection molded, or is it because these features have been sanded off or done in a clever way so that it's not easily visible?
- NickNameNick 8y agoThe body of your MacBook is cnc machined, and bead-blast finished. There may be some markings from the original casting, but they'll be on the inside. All the ejector pin marks on the keyboard keys should be on the inside.
- xyzzy_plugh 8y agoOn top of that, Apple has some of _the_ most advanced manufacturing technology on the planet. They're continuously a couple years ahead of everyone else for anything similar to their product line, especially around molding processes. If a new, better process hits the market, Apple often snaps them up. The original unibody aluminum Apple TV remote is a masterpiece. A lifetime ago, we were working with Foxconn and a colleague managed to sneak onto an Apple floor and take a look at some of their tools -- he was gobsmacked at what they were capable of. The stuff of industrial design engineers' dreams.
- kennywinker 8y agoIt’s 2018 - ceeating a product from new plastic is probably morally indefensible. This guy has open source plans for garage-scale plastic recycling machines. If you’re interested in alternatives to new plastic from china https://preciousplastic.com https://preciousplastic.com
- trumped 8y agodidnt injection molding startup the industrial revolution?
- deleted 8y ago[deleted]
- onesun 8y agoNo, the steam engine started the industrial revolution.
- KamiCrit 8y agoI still can't believe some tool & die maker machined a die large enough to house an entire plastic lawn chair.
- Noumenon72 8y agoAt my job, we extruded plastic sheets, so we had dies which were 84 inches wide with an opening of 0.020 inches. It's quite a challenge to get the plastic to spread evenly from the barrel opening all across that width like a river delta. There are two flexible lips inside, you can supply more heat to individual die zones to make it meltier, and at the very edges you stretch the plastic out a little so that several inches of the die end up contributing to one inch of the finished sheet.
- countzeroasl 8y agoThe other option that is commonly used is using a mold with an internal manifold to heat the plastic, which is injected through heated tips or pneumatic/hydraulic valve gates. This shortens the space on the part such that the flow length of the plastic will be sufficient to fill the part, where with a single gate, it may not due to the part thickness and thermodynamic freeze.
- ggambetta 8y agoThis looks super fun! What's the viability of doing this at an artisanal scale in the kitchen? E.g carving a mold out of something, melting plastic in the hob, and pouring it into the mold? I remember as a kid my dad once got some sort of plastic that you made by mixing two liquids (they were very liquid, so not epoxy), and I made molds of things out of putty (or clay?) and then "copied" them with the plastic. Any idea of what this room-temperature binary-plastic could be?
- countzeroasl 8y agoI am an engineering manager for a plant that does contract manufacturing and specializes in injection molding. I'm happy to answer any questions someone might have about this process, plants that utilize it, or design/manufacturing limitations of it.