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There's misleading stuff on the internet about the options with injection moulding tools (terminology: the moulds are called tools) and this article doesn't he
by rkangel 3y ago
There's misleading stuff on the internet about the options with injection moulding tools (terminology: the moulds are called tools) and this article doesn't help clear that up much.
For a normal hard plastic like ABS, you basically have two options: a "soft" tool or a "hard" tool. These are both usually made of steel, even aluminium can be too soft at temperature and pressure for good parts.
The difference is that a soft tool is a fairly normal steel that can be milled on a standard 3D CNC machine. This makes it maybe $10k and a few weeks to make, given a suitable design. You can make probably 1000 parts with a tool like this (maybe more depending on the part and the tolerance needs).
A hard tool is made from a very hard "tool steel". There are some different alloys in use but there all extremely difficult to machine - the main method f is Electro-discharge machining. This is a rather involved process, usually involving milling heads that can then spark erode metal to he same shape (look up EDM if you haven't seen it, it's cool). This whole process is more like $300k and takes 3-6 months for a 1-2 action tool. It's likely to be the biggest capex line item for setting up mass manufacture.
For prototyping and low volume manufacture, I strongly recommend Model Solutions in South Korea (https://www.model-solution.com/en/m/main https://www.model-solution.com/en/m/main). For us they used to turn around injection moulded parts in quantities of 1k+ in 2 weeks (including postage), at very reasonable prices (used to because I haven't needed them for a couple of years).
- taneq 3y agoSurely that $10k figure for 'soft' tooling includes the iteration and engineering time required to get the mould right? I can't imagine that it'd cost $10k to produce another set of tooling if it can be done on a standard CNC machine once you have the CAD/CAM files created and tested.
- rkangel 3y agoThere's kind of two parts to the design: design a part that is suitable for injection moulding, and then designing the tool itself - where are the inlets, dividing points etc. If it's multi-action, how do the action mechanisms work. Similarly making the tool isn't just "CNC a block of metal and then you're done", you've got to make and assemble the mechanisms and there's things like acid washing the mould surface to control what the resulting plastic surface will look like. It adds up.
- taneq 3y agoThanks for the extra insight! Assuming a fairly simple part, surely most of the expense is still in the initial design and iteration, though? Even if there's more to it than re-running the CAM job, I'd imagine producing a second set of tooling would be much cheaper than the first? Alternately, would this be the point where you'd get the same tooling made up but this time in hardened steel? Or is it common to jump straight for the high-end tooling material?
- hef19898 3y agoThat depends or raw material costs, tool supplier availability and a ton of other factors. One of which is the initial tool design. Also, maybe a new tool design is needed. So, the answer is: it depends.
- iancmceachern 3y agoThe bulk of the cost is in labor, tooling, and material cost for the mold, not the NRE. Depending on the complexity of the part, you can easily spend that much in NRE labor just to design it
- Mistletoe 3y agoHow long can the hard tool last etc.?
- rkangel 3y agoHundreds of thousands of cycles usually. Bear in mind that your tool is probably multi-cavity, i.e. making multiple copies of your part in each cycle so you might get a up to few million from the tool.
- iancmceachern 3y agoDecades
- vasco 3y agoWould it be possible to design say 1000 of the soft tools and have the machines auto-replace the "tips", as if it were an ink cartridge that you replace but in an automated way, with an auto-feeding mechanism after their useful life?
- iancmceachern 3y agoNo, the tools are big chunks of metal that are carefully machined to very tight tolerances and polished or textured very carefully. You can use something called a MUD, which is basically a carrier block that you put inserts into which create the mold, this is what most of the quick turn shops do
- OJFord 3y agoI'm just an armchair YouTube-viewing machinist, but I'm pretty sure you don't need EDM for tool steel, carbide or a not less hard steel will do won't it? Or you could start with untreated steel of similar grade/purity/whatever and then harden it after machining?
- sschueller 3y agoOr use a water laser jet if you can just cut your tool in straight lines. [1] [1] https://youtu.be/Q_Kd_Y4BGs4 https://youtu.be/Q_Kd_Y4BGs4
- iancmceachern 3y agoTrue, but sometimes it's just easiest to edm it, depending on the geometry
- kweks 3y agoI'm curious about your pricing ranges - they seem to be vastly different to what I've experienced over the years (in both hard+soft molds for ABS injection). Our 2-piece "high-run" tool, built out of tool-steel cranked out its 1M iteration a few months ago before we retired it. The tool cost 6k USD to produce. Our 2-piece "low-run" tool, of a larger physical size cost ~10k USD to produce. ( For the curious - https://i.postimg.cc/MT8RT50P/tool.jpg https://i.postimg.cc/MT8RT50P/tool.jpg ) These prices also included the model prep (IE, taking an STP of the final product, inserting the ribs, internal structures, closures, etc required to make a real product) and tool design (Modeling the tool itself gates, etc etc). Perhaps it's the complexity involved, as injection-molding can scale from small parts to giant parts, but our pricing experience seems vastly different.
- rkangel 3y agoI've never encountered a high volume mould tool that was less than $50k. In addition to being two piece is it also a low complexity part, e.g. just a few straight faces with pretty lose tolerances? I'm still amazed you got it that cheaply - where did have it made? I should have stated above that I am neither an injection moulding expert, nor even a mechanical engineer. My experience is as tech lead for years of projects needing injection moulded parts, so I've worked through options with mechies, recommended things for purchase etc. Would be very to happy to learn of cheaper ways of getting stuff made!
- kweks 3y agoOur manufacturing (tool design, machining and production) is based in Guangdong, China. We have strong ties (15+ years working relationship) with the factory, which may have some pricing impact. The tolerances on the high-run part are non-critical (but still need to match the other part for a seamless ultrasonic weld). It's got curved surfaces, and the surface texture was EDM'd on. Likewise, not at all an expert - but have about 10 injection-moulded products under my belt; I just got back from China pricing out two new projects tooling projects. My email is in my profile if you ever want to reach out!
- deleted 3y ago[deleted]
- simonbarker87 3y agoYour maths is wildly off in my experience. We had 4 tools for custom parts making ABS plastic parts made in 2013. These were considered hard tools and produced over 100,000 parts each across 5 years and cost us £30k made in the UK in about 4 weeks after material was available. The parts were each around the size of an adult fist and the tools were multi impression. They weren’t large enough to have any hot runners (I think I’m remembering that term correctly) but they did have movers in them. If we had wanted to make the parts out of PVC we would have had to use stainless steels tools from memory and that would have been more expensive.