Cheap ass fab for small run's of 1000+ plastic cap/plopps/knobs/hats/cogs etc? - Page 1
Forum section: electronics / projects

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 02:07:31 am
content: Is there any plastic injection molding service who does tiny runs like 500-1000+ units of tiny plastic switch/poti/diverse etc cap/plopps/knobs/hats/cogs etc and other small plastic components etc? Like the equivalent of a PCB manufacturer? Back in the day the master for injection mold and setup costs was a fortune. Some fab that you just send in your CAD drawing and back comes what you ordered?

author: james_s
author_rank: Super Contributor
timestamp: January 23, 2020, 03:02:26 am
content: That certainly would be nice, I'd love to have a bunch of gears made for Roomba brush decks but even a few years ago when I casually looked into it setup cost was huge.

author: wraper
author_rank: Unknown
timestamp: January 23, 2020, 03:08:02 am
content: Look for those which use aluminium injection molds for smaller runs.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 23, 2020, 04:33:57 am
content: That's the promise of 3D printing. If the part is small you can do many at a time.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 23, 2020, 06:09:54 am
content: I love 3D printing, but can imagine few parts that would be suitable for a run of 500. More suited to the dozen quantity range. Surface finish is also a challenge on 3D printed parts. Finally 3D is hard to integrate with molded in inserts, double shot molded labels and the like in a production setting. For hobby/restoration use epoxying in inserts is fine, but that labor would kill a manufacturing set up.

author: beanflying
author_rank: Super Contributor
timestamp: January 23, 2020, 07:24:19 am
content: One of the more affordable options for low volume parts is RIM Plasticshttps://en.wikipedia.org/wiki/Reaction_injection_moldingIt is a very large subject but one of the major benefits over conventional injection molding is the reduction in tooling costs. As the Temperatures are much lower it allows the use of Composite Tools instead of Metal.It was getting a lot of use in the Automotive industry (when we still had one) in particular for custom or special edition body molds and even full panels. It does scale down too but you would need to look more locally and better talk to a couple in that field.

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 03:05:46 pm
content: Quote from: wraper on January 23, 2020, 03:08:02 amIm aware of those as well, setup costs killed them too back in the day, wear is higher on alu then steel, but anyway should be able to do couple of thousands. I'm looking for all in one service fab.

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 03:19:03 pm
content: Quote from: beanflying on January 23, 2020, 07:24:19 amIt seams mostly focused on PU (foamy) materials although other polys is used to a degree but i suspect they are aswell only interested in big volumes as they use high pressure machinery in many cases, im not read up on RIM tech.

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 03:45:12 pm
content: Some Russian dude built his own mini kitchen table injection machine with automatic ejection , neat but no info about the precision. One could imagine some Chinese backyard manufacturer selling a machine kit at Bangood etc but nope!Everyone wants to buy the Russian dudes machine. Clearly a market for small desktop units.Close up on parts made.Here it makes much larger parts 2 at the time with longer cooling time.Here another one even smaller!

author: kosine
author_rank: Regular Contributor
timestamp: January 23, 2020, 04:07:21 pm
content: There's a company called Protomold who specialise in this area, but they're still not cheap:https://www.protomold.com/ProtoQuote.aspxOnly way to lower the costs is to make your own mould on a small CNC milling machine, then either find a friendly mould-shop that can run it on an existing mould base, or get a tabletop moulder yourself. (These machine are usable with a bit of practice, they go for a few hundred on eBay:http://www.travin.co.uk/)If you're looking at making more parts in the future, then you can often buy a secondhand CNC machine at auction for less than it would cost to get the mould tools made. But then you've got to do all the work yourself... If you want someone else to do it for you, then it's going to cost.There's a few homebrew injection moulding videos on YouTube using low cost & secondhand machines in a small workshop environment. So it can be done on the cheap:

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 04:19:56 pm
content: Quote from: kosine on January 23, 2020, 04:07:21 pmThanks but no thanks, Travin machines are way to expensive big and bulky and no auto ejector, secondhand industry ones is even worse , interest in worn out secondhand machines is low also not into making it to a business, just to make 1000 plopps of whatever. There is lot of "manual" injection machines for little money but thats not the issue.

author: beanflying
author_rank: Super Contributor
timestamp: January 23, 2020, 05:36:13 pm
content: Quote from: MT on January 23, 2020, 03:19:03 pmThat is ONE of the applications not THE application. Runs of a few Hundred were NORMAL as the process it relatively to slow for really high production runs. The lower cost tooling made it practical and cost effective and that is why you won't see short run injection molding which is high up front but rapid and low cost afterwards.The process if you bothered to do some reading rather than dismiss it is NOT Foam but FOAMED PU and runs densities to around 600kg/m^3 and down toward that of foam which is the nature of PU you can vary the density.Pick a supplier make a silicone mold and DIYhttp://polymech.com.au/moulding/buy-polyurethane-liquid-plasticUnless you can amortise the cost of the tooling or make your own Injection molding is the wrong process.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 23, 2020, 05:41:02 pm
content: There's also casting in silicone molds. If you had maybe 20 forms you could make a few molds and get into the hundreds or more. Lots of good resins available. I've made replacement gears that way with good precision and surface finish. Seehttps://www.smooth-on.com/

author: MT
author_rank: Super Contributor
timestamp: January 23, 2020, 06:09:53 pm
content: Quote from: beanflying on January 23, 2020, 05:36:13 pmI said: mostly focused on PU (foamy) materials although other polys is used. That suggest "applications".QuoteIm not dismissing anything and i told you im not read up on RIM tech to 100%. But what i have seen so far does not fit the bill and the thread subject is about avoiding exactly what you suggest chasing around for some local unobtainable shop and have to make all kinds of deals back and fort to get something done, cant you read?QuoteI allready know about siliconing and why the hell would i slab around with silicon molds who needs a master anyway and all this manual crap when this tread subject is about automating a process?!QuoteGeee man!If you bothered watch the Russian desktop machine videos instead of dismissing everything else thats not to your taste you clearly see its very feasible to do injection molding, even more so at home. Why do you even bother participate in this thread when not even reading thethread subject.You still havent learnt anything of the PCB manufacturing cost progress!

author: beanflying
author_rank: Super Contributor
timestamp: January 23, 2020, 06:22:56 pm
content: I give up then your arrogance clearly is better than my past experience where I have used poured PU for model parts and have a mate who is a Toolmaker with RIM customers SOME are/were Auto industry ones and plenty who are NOT.A custom run of 500-1000 the tooling cost is always going to be the bulk of the costing with plastics.