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People may not realise this but we have wonderful methods to quickly mass produce plastic parts. These pieces might take several hours to print which means one

• ggm 7y ago
  I am in a kickstarter for an injection moulded item (a photo scanning holder) which has run 18 months late because of massive systemic backlogged production issues with the injection moulds requiring repeated re-re-re-re-fabrication. its a kickstarter, and undercapitalized but please don't over-state the "ease" with which injection moulding can work. Its true but, it has a high capital burden up-front to "get it right" which clearly, this current medical emergency demands and we should expect. No, we can't just mint things with zero cost, injection moulding. It requires craftspeople to make the moulds.
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  • colechristensen 7y ago
    Is this uncommon? Did you design a difficult to manufacture part? Is your manufacturing team incompetent? Or are you just unlucky? (No offense meant but there has to be a reason, though I'm not familiar with the space)
  • nl 7y ago
    Injection moulding isn't hard but it's not uncommon for even experienced teams to take a couple of goes to get it right. "Re-re-re-re-fabrication" is excessive though and sounds like it was an inexperienced team. Source: worked at a place that made injection moulded hardware.
    • ggm 7y ago
      its somebody else's kickstarter, not mine. Its the PIXLater, a diffuser and three or four parts which need to all fit the same size hole, to provide the right 35/128/70mm shaped holes for negatives, to be backlit by the diffuser, and sit on a tablet. The problems relate to the repeated click-unclick of the parts, which require strong corners and chamfers to insert, and friction hold. Every single iteration of design required re-design of the injection moulding. I think had the design been well worked out in advance it would have only been 2-3 cycles, but since the design had to overcome mechanical rigidity, re-insertion, keystoning the parts, over-dimension outcomes, under-dimension outcomes, it was fraught. Its finally reached production. A large amount of the 1960s dislike of plastics vests in the super-bad job injection moulding of the time did, with both bad plastic stock, and badly made moulds. Now, we think its fantastic but we're standing on the shoulders of giants who made it work. Lego's fab is pretty awesome, to maintain dimensional fit for click-fit on millions of parts like that. The Mint, is not exactly injection moulding, but similar: they have to replace coin dies frighteningly often because they just wear out. The CSIRO did work with the Australian mint doing ion beam vapour deposition to create hardened surfaces to try and preserve the die lifetimes. Stamping out CDs speaks to how accurately we can do this now. (injection moulding CDs is not a thing)
      • Dylan16807 7y ago
        So when you talk about getting anywhere near lego you're talking about a type of problem that's in a completely different ballpark. 3D printing can't even hope to reach those tolerances. If they were making a part that could simply be 3D printed, the type of manufacturing relevant to the article, I'm pretty sure they wouldn't have had all those problems.
  • redis_mlc 7y ago
    If I was doing a kickstarter, I wouldn't go injection molding. You can have a service bureau use a $250,000 nylon 3D printer to get small to medium-sized runs for something more affordable than making a mold.
    • samatman 7y ago
      This somewhat defeats the purpose of a classic kickstarter, which is to 'kickstart' the commercial production of something. The platform is of course used for many different sorts of project.
  • ben_w 7y ago
    Naïve question: can you 3D print a useful injection mould? And assuming yes, is there enough capacity to print enough moulds?
    • shiftpgdn 7y ago
      Yes and yes, though there are lots of caveats as to material types used. Whitepaper from formlabs here: https://formlabs.com/blog/3d-printing-for-injection-molding/ https://formlabs.com/blog/3d-printing-for-injection-molding/
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• jfoutz 7y ago
  although I don't own this specific book, the gingery books I have are pretty great. https://gingerybookstore.com/InjectionMoldingMachine.html https://gingerybookstore.com/InjectionMoldingMachine.html if you've got time and space, you can do way cheaper than $10k. You need a drill press and a metal lathe. If you're feeling ambitious, there are other books that will show you how to build a drill press and metal lathe. Really depends on how committed you are to bootstrapping and saving nickels.
  • 6nf 7y ago
    Yes! I've seen several machines on Youtube that's either built from this book or pretty close to that design. You could definitely make a fully automated DIY machine at home for less than $3k no problem.
• e12e 7y ago
  > 3d printing has an extremely small window where they are useful for bulk use parts like this. If you can have enough printing capacity on site (per hospital, per unit) to meet demand (keep you X number of ventilators running indefinitely) it might make sense. Still having 1000s of spares in a closet might be safer than relying on a 3d printer bein online some n percent of the time.
  • Damogran6 7y ago
    It's a corner case...albeit a corner case we're currently experiencing. There's a limited amount of space and logistics to have 1000s of spares of everything you might possibly need.
• archi42 7y ago
  Depends a lot on the part and on the printer. Did you see the update? Some company "massprinted" them using a powder based printer. From the image I'd say 40 or 50 pieces.
  • ncmncm 7y ago
    That was likely 40 from a single print run, probably under a half hour. They probably could print 200 on a single two-hour run, but were told the quicker turnaround was more valuable.
    • 6nf 7y ago
      Lol there's no 3d printer that will print those in one hour.
      • archi42 7y ago
        With FDM it's difficult to impossible, yes. Even with a really fast delta & klipper. With SLS this is however realistic. Maybe two hours for a batch.
        • 6nf 7y ago
          SLS is pretty slow, not sure which machine can actually print all those parts in an hour.
• kragen 7y ago
  I think the situation may be a little more complicated than that. For US$10k you can buy 28 brand-name Prusa Minis or 50 off-brand knockoffs on DealeXtreme. If a part takes three hours to print on one of these FDM printers, as you're suggesting, you could print 2500 of them in a week with your 50 off-brand knockoffs; if you can get the printing time down to an hour, 8400. And, unlike with an injection-molding machine, they come out of the machine sterile, and PLA is biocompatible and aquadegradable, implants having been one of its few significant uses prior to its uptake for FDM. Such FDM mass-production is in fact how Prusa produces a lot of the parts for its printers. Aside from sterility, it has some other significant advantages over injection molding: its dimensional tolerances, shitty though they are, remain stable over the entire print volume, so you can get a 200±0.1mm dimension on your part on a typical cheap FDM printer; and the parts you print are much ligher in weight, due to the standard honeycomb infill, and (though this is not relevant in the case of duplicating an injection-molded part) they have much more geometric flexibility than injection molding — they can include voids and enclosed spaces, and even preassembled mechanical assemblies. The article says that after the initial FDM parts, they switched over to SLS, which is a faster and more precise 3-D printing process which can also process metals, although in this case they were doing plastic SLS. SLA is another higher-speed, higher-precision 3-D printing process, and both SLA and SLS can produce several parts at once for a further gain in speed. On the other side, I hear it's common to have to go through three or four revs of injection-molding dies before you get to the rev that works properly, and it's common for that to take months. Maybe that's a problem that can be avoided by sacrificing something else, like cycle time or die durability; do you have experience in the area?
  • 6nf 7y ago
    I do have experience in this area and all I can say is look at the market - injection moulded parts are literally everywhere. How often do you see 3d printed parts in commercial products?
    • kragen 7y ago
      I see more blow-molded parts than injection-molded parts, but there sure are a lot of injection-molded parts. And the cup I'm drinking from is made by metal-spinning, filled with a drink poured out of a deep-drawn can with a stamped top. As for 3-D printed parts, I only see them occasionally in commercial products, but remember that low-cost 3-D printing is only about ten years old — a lot of product designs, and even more product designers, date from more than ten years ago. And even ten years ago 3-D printing prices were a lot higher than today, and there was no such thing as a US$1000 SLA machine, for example, or PETG filament, or PLA filled with wood or brass. So I think we're going to see a big move toward 3-D printed parts in the next decade or so as designers wake up to the new possibilities afforded by these processes. A few years ago the crossover where injection molding was cheaper might have been 100 parts, then 1000, and now it's 10000 — and that's when you can make the part at all by injection molding, with the extra weight, imprecision, and geometrical restrictions it adds. Maybe in another few years the crossover point will move to 100,000; but I fully expect to see designers trained in the 1980s and 1990s continuing to use injection molding even where 3-D printing would be a lot cheaper. What do you think about the questions I asked, about why some injection dies take multiple back-and-forth cycles over several months to get to the production rev instead of the one week you cited, and how that can be avoided?