This is the type of stuff that trips up many Kickstarter / crowd funded projects.<p>"I have a great idea, I'll just manufacture it in China and sell it as a product!"<p>This is a great overview of the process and complexity for *one part* of the manufacturing process for bringing a product to market and almost all of them are as complex (or more) and have pitfalls of their own. Add on wiring harness mfg, PCB/PCBA, machined parts, compliance testing, final assembly, QA testing, and revision management and then you're about halfway to running a successful product business.<p>From personal experience, the best advice in the article is to hire a domain expert when moving into a field you aren't intimately familiar with. Employing them for as little as a few months can help you avoid several years of very expensive lessons as you figure a new process out.
Keyboard.io's blog has in great detail, all the problems, wins with working with Chinese manufactuerers from wood workers, plastic injection, assembly, etc.<p>Highly recommend it because they give a lot of details and if you start from the beginning you can really see how they learned how difficult it was in going into the space. The multiple visits, quality control, the issues with who owns what, and where they lost money.<p><a href="https://shop.keyboard.io/blogs/news?page=19" rel="nofollow noreferrer">https://shop.keyboard.io/blogs/news?page=19</a>
My dad was (amongst many other things) a toolmaker who made plastic injection molds. These things can be hideously complicated, especially if the designer doesn't understand how it will actually be built, and as a result he once spent a year on one. In his days everything was manual, no CNC, no 3D models, no simulations, and probably no contact with the designer to make improvements.<p>He had to cut milling bits with custom profiles to cut custom tools such as a series of graphite and copper spark eroder forms to cut just some of the corners and shapes in the (paper) technical drawings, then repeat for the next ill-advised bevel or interior sharp angle or even lettering which is too close together to get a milling bit inbetween two letters. Figuring that out was his responsibility alone. Instead of computer control, he'd have to do something like first create a scale model of part of the tool out of a block of plastic, then use a pantograph (a mechanical linkage allowing you to trace a shape with a pen and have the movement magnified/minified) to copy the shapes on a milling machine -- even shapes that seem simple. And then maybe throw away (actually, take home as a souvenir) a month or two's work if you cut slightly too deep -- these were high precision parts. Not because the plastic had to be so precise, but because the completed dies are made out of many steel parts that have to fit tightly together and slide past each other, as you can see in the article.<p>Considering the ~two months quoted in the article for this mold, I'd think a lot of that complexity is still essential despite modern computerized machining. I'm sure a great deal of ingenuity and many steps are still needed.
One day I looked around at all the plastics in life - in particular looking at the plastic cases of vintage computers, and I realised that plastics is absolutely incredible. Often really beautiful when you think about it, incredibly precise, with beautiful lines and curves.<p>I've come to find plastics really quite interesting. It's kind of a magic material.<p>And at the same time it's a sort of like King Midas in which humanity gets this incredible material but now there's plastic everywhere polluting everything. Everything we touch is turning to plastic.
<i>You cannot have 90 degrees in your mold. For the mold to exit your plastic part, it needs to have a slight angle of a few degrees.</i><p>This is known as "draft":<p><a href="https://en.wikipedia.org/wiki/Draft_(engineering)" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Draft_(engineering)</a><p>I'm more familiar with metal casting, but plastic injection molding seems to have a lot of similarities, such as shrinkage and flow considerations.
Once you have molds, make sure you control them.<p>Here's a story [1] of a company that found that the Taiwanese plastic company that made its custom parts stopped responding after 15 years. They got another one of their Taiwanese suppliers to go to the plastic company to see what was going on--and found that the factory was now a hotel and the sales office was a now a strip mall.<p>[1] <a href="https://www.stlpr.org/arts/2013-07-24/on-chess-the-case-of-the-missing-molds" rel="nofollow noreferrer">https://www.stlpr.org/arts/2013-07-24/on-chess-the-case-of-t...</a>
Its a nice article regardless if you're going to manufacture in China or anywhere else, but a crucial bit of information for China manufacturing is missing. What about IP theft? Does keeping your mold make it more difficult for people wanting to make knockoffs of your parts? Does moving it to a different plastic injection part maker help? Is there anything you can do, or is it essentially something you account for when "manufacturing in China" and you send them components you don't really care that much about?
Bill Hammack, "The Engineer Guy" explains injection molding here:<p><a href="https://www.youtube.com/watch?v=RMjtmsr3CqA">https://www.youtube.com/watch?v=RMjtmsr3CqA</a><p>Interesting history of a process that's everywhere and invisible at the same time.
When I was a student I worked for a company who made injection moulded HDPE parts for fishing boat gear. After a few years on the market, the company noticed identical products coming out from China, the only difference being that the parts were far more brittle and broke easily (they still even had the company website printed into the plastic).
Out of curiosity, wouldn't it be easier/cheaper/faster to use some existing off-the-shelf design and drill/machine some holes if you need it slightly modified?<p>It seems everyone reinvents the plastic-rectangle-with-grooves. Is there some obvious reason for this?<p>And is there some canonical place you can get some proven high-quality boxes in bulk?<p>A friend and I made some sensor boards and used off the shelf waterproof enclosures - but I wonder if there is some go-to standard enclosures that people go for
Read the article and found myself nodding along. If you work with larger Contract Manufacturers, they often have design for manufacturing centers that will perform mold analysis and suggest modifications. They often have the advantage of having worked on lots of different designs.<p>And even further down the road: make sure to account downtime in your production schedule for mold maintenance.<p>I see others commenting on registration, certification and approval matters and I’ll only say: do not underestimate the time and cost of that for a global product. This landscape changes all of the time. One minute a country will accept evidence of an FCC filing; the next minute they require in country testing with a local authority.
Hoping AirGradient can become a serious competitor to the far too expensive PurpleAir<p>But they cannot compete with the purple network in the USA right now.<p>I've suggested this before but if they somehow partnered with WeatherSTEM that could change things in a hurry. Even if they had to provide discounted units. WeatherSTEM appeared to have their own open database so I think the costs of long-term data storage would be avoided once integrated.
Really interesting, thanks.<p>Can you provide ball-park costs - how much was your mold, and how much did you pay for 5,000 units to be made?<p>Even if just a rough estimate that would be really helpful, thanks.
Anyone know if AirGradient plays nicely with Home Assistant? i.e. running local without the cloud?<p>I've been in the market for a few more CO2/air quality monitors around the house, but I'm unhappy with the very proprietary nature of the uHoo and it's incredible expense.
It's interesting how for electronics projects, injection-molded enclosures can dominate non-R&D/salary costs unless scale is very large. Ie, the PCB, electronic components, SMT assembly are probably not that expensive, especially with some of the ops out of Shenzhen available. Shipping materials, shipping costs to you and the customer add cost. Unintentional radiator certification adds cost. Intentional radiator certification adds more. All these together might cost 10% of the injection mold.<p>One escape hatch is custom machined and printed ABS or metal enclosures, like from Polycase and Hammond. It is limiting and forces you to design around the enclosure, but is much cheaper for small/medium runs than injection molding. Ie a few hundred $USD upfront depending on turnaround time, enclosure size and material etc, then not much more than the plain enclosure per-unit.<p>If you are injection-molding, hopefully you can use a 3D printer to prototype, but you may still end up screwing up the first (or more) mold due to issues highlighted in this article.
There's a middle ground to creating a dedicated mold in MUD tooling[0]. Your mold is a set of inserts that go into a standardized base mold. You get less longevity out of a MUD mold, but it's typically much cheaper up front and you can reuse a substantial amount of the cavity and insert design when you go to a dedicated mold.<p>I did work for a US contract moldmaker. The amount of knowledge about the performance of thermoplastics and metals was really impressive. They used some interesting off-the-shelf software to do simulations of mold performance, too. It was a fun gig. I appreciated the tactile, tangible technology that went into their operation.<p>[0] <a href="https://www.dme.net/mud/" rel="nofollow noreferrer">https://www.dme.net/mud/</a>
Questions to the author whom I see is reading the comments:<p>- What is the plastic used for the part (ABS, PC)?
- What was the material for core/cavity (tool steel)?
- What was the lowest tolerance on the part?
- Were US/EU manufacturers considered at all?
I didn't see it mentioned, but depending on the type of volumes you're working with, you can opt for a more durable, expensive steel mold vs a cheaper aluminum mold. The molds wear out over time, steel will typically last longer.<p>For one of our products, we used an off the shelf plastic enclosure. Unfortunately, the process of getting our equipment certified with an off the shelf enclosure was much more difficult than expected. Finding an enclosure manufacturer who would support us through certification was challenging.. the sticking point was trying to get manufacturers to provide test samples of the gasket materials being used.
Thanks for sharing!<p>How did you find your mold maker and consultant?<p>> It is super important that you review in depth this mold 3D with your own expert as sometimes mold makers try to do shortcuts that save them money but could create problems later on.<p>Any examples?
They made a custom mold? At their volumes? Are they insane?<p>They could have powder 3D printed this stuff for a <i>very</i> long time given the NRE on that complex of a mold.<p>If they needed to control costs, they could have negotiated with a case supplier:
<a href="https://www.takachi-enclosure.com/" rel="nofollow noreferrer">https://www.takachi-enclosure.com/</a><p>Only <i>after</i> they were shipping enough product to make it worthwhile (100K+ units), should they even <i>think</i> about making a mold.
A lot of these challenges can be avoided by hiring an experienced mechanical engineer, product designer, etc.<p>Many of these things you would expect not to leave the initial design phase that way.
Is it really worth making a mould for making 500-1000 units?<p>At those kinds of quantities, I would just fire up the 3D printer, and leave it printing in the corner of the office for a few weeks (with an auto-ejector).<p>It would end up costing ~10 cents/part, assuming you already have a 3d printer for prototyping and already have someone who knows how to load a new reel of filament into it every morning and evening.<p>Thats hard to beat for anything under 10k units...
Somewhat surprising mold production would even be considered to be sent to China. Every place I've been either does their own on-site or has a local partner doing the machining. After all, these are not mass-produced parts, they're generally one-off with dimensions and fixtures designed to fit specific machines and materials.
I bought one of their kits, spent a decent amount assembling it, and then 5+ hours trying to diagnose it only connecting to their dashboard once every few hours, and sometimes not for days at at time. Even a replacement ESP didn't fix it. Disappointed that it's not really functional for my needs given the cost.
I appreciate the point about not being 90 degrees because I periodically need plastic bins for board game organization and the ideal shape is a perfect rectangle of an even fraction of both box inner dimensions. At least now I know why all the kits for this use laser-cut balsa wood or foamboard with home assembly….
That was an interesting read but sure would have been nice to have a cost breakdown, especially since the article made several references to cost tradeoffs. How can I understand the tradeoff of not hiring a consultant without having at least a ballpark idea of the costs involved?
Cool article, the piece that stuck out most to me is the "mold contract" bits about who owns the mold.<p>Makes me think about early production FRP sailboats and stories about Company B purchasing hull mold from Company A when they're starting out.
Excellent info! Thank you. Can I ask why it was not possible to find a USA mold maker? Even if you have to pay a little more surely it is better supporting jobs and prosperity at home? Thanks!