All the cost, difficulty, time and money in injection molding is in the molds. They are expensive.
When done well they can make 1000's of parts if not more.
It's a great project, an amazing POC. There is the potential for small scale (garage sized) manufacturing to exist, the equipment is the cost of a (nice) car...
$1000-1500 USD to build out a buster beagle with COTS components $700 for an anycubic photon plus a an anycubic treatment chamber $300 for all the ancillary materials like resin (Siraya tech is a great option), mold spray, pellets (purchased off eBay), $30 toaster oven from Walmart to keep the molds warm, etc etc
Design your molds in fusion 360 and print them on the Anycubic
So if you are patient and have more time than money it is theoretically possible to have a full fledged injection molding machine with up to 3 cubic inches (50 mL) in your garage for under $2000 USD
It takes a lot of time and research to do this properly however. Designing the mold has lots of caveats and is very custom work. This process is not at all as simple as operating an FDM printer, there are a ton more variables and failure modes that go into injection molding so you have to be able to create an environment where you control all of them.
One thing that could probably save a lot of time and heartache for people on this journey is finding someone on fiverr to design the mold for you for a few hundred bucks rather than trying to teach yourself some hardcore industrial engineering concepts. But it’s doable, I read an injection molding book and was able to produce something that worked after leveling up my Fusion 360 skills.
I do want to underscore that yeah, as your comment implies, even though recently the money component has significantly improved with innovative designs like these that use COTS components the time and difficulty part is still there. Injection molding is not for the faint of heart, it’s definitely one of the more hardcore industrial processes out there. I have seen the endgame of this journey so I am happy to answer any other questions if people have them
Not sure if you are talking about the PTFE molding process or not but this is just straight single shot injection molding, though it is possible to design multi shot processes with this setup. It’s just more complicated.
I used polypropylene which imo everyone should start with first because it’s by far the easiest to work with and pretty easily sourced off of eBay. It’s suitable for a wide variety of components for indoor use. For outdoor use you would want something like polycarbonate. I think working with polycarbonate would not be as lucrative in a home machine and here’s why: temp and pressures for polycarbonate are often a bit harder to achieve and the temps you need for molding polycarbonate are often at the upper limits of what these resins used to make the resin molds will tolerate. I think it’s possible though, but requires careful selection of a particular polycarbonate with the correct thermoplastic properties (such as lower melt temp) to operate within the acceptable ranges of your setup.
Were you using a PTFE release agent? Like this: https://www.antiseize.com/PTFE-SPRAY-HEAVY-COAT-Anti-Seize-L...
Polypropylene... Did this have (fiber)glass added?
The polypropylene I’ve used does not have fiberglass added. Though there are a LOT of options for thermoplastics, both ready made and custom mixed/compounded. You really learn to just go straight to the data sheet when thermoplastic shopping because that has all the relevant info you need
For example, a mould which is made of plaster/concrete with an inner layer of silicone?
That would be pretty easy/cheap to manufacture. You'd use a 3d plastic printer ($150), dip the print in casting silicone, then float the result in concrete, with the concrete surface being the parting line.
Then use a scalpel to cut the silicone along the parting line and add more concrete to make the other half of your mould.
A desktop CNC at that scale to make simple stuff like casing boxes is probably going to be more affordable and less hassle/mess than your suggested setup pretty quick though.
Desktop is definitely not going to be good enough to make aluminum molds themselves though. I think you need a 5 axis CNC for that. Surprisingly my makerspace actually has one of those and I considered learning how to use it but decided against it.
In practice however on these molding setups I’ve found you are already kind of constrained on your mold sizes a lot simply by virtue of your machine’s volume capacity. The one I have goes up to 3 cubic inches, but in practice you can’t use all of that capacity and you get weird/bad results for too small of capacity too so the actual ranges of shot volume I can produce in a mold are actually constrained to something like 1-2.5 cubic inches
If they can make their own molds at a machine shop, this could hit the sweet spot for a product that’s too high volume for 3d printing but not enough to justify a professional mold. Set it up and run it once a week to make a few hundred parts, that type of schedule. Just practical enough for a hacker-run lifestyle business.
You can 3D print high-temp resin, place it in an aluminum carrier and shoot roughly 20-50 parts.
This kind of machine is a really good match for that.