Has any one printed cavity and core blocks for plastic injection molding?

General Discussion
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Has any one used their printer to make tooling for injection molding parts? If so, what material did you use for the prints? It is my understanding that this can be done for sampling molded parts prior to building a steel mold so I’m curious if anyone has actually done it other than the videos from the printer manufacturers.

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I’m not sure any of the FL resins can take the temperatures of injected ABS. On my MakerBot, I print ABS at 230ºC and that’s still fairly “plastic” not “liquid”. The standard resins, and especially Tough, get soft well short of 200ºC.

But I’m not sure I see how a 3D printed mold helps you much before making a hard tool. The steel mold has to be cut by CNC, it’s a totally different fabrication process. Unless you’ve got some gross errors in the mold, success with a 3D printed version guarantees very little with respect to the steel version.

Now, you could maybe do a 3D printed part on your Form printer to check fit and finish, not actually inject anything, and then have Shapeways print the parts for you in steel which you could then use for production and you’d have a good idea of how good the steel version will be based on the plastic version.

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Check out our white paper about the Form 2 and injection molding here.

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While I understand the white paper concerning the Form2 and injection molding, that setup really is something of a modified arbor press. To me, that really is not injection molding; instead, it is squeezing a molten plastic into 3D printed cavity blocks that are toggle clamped together. I believe that the FormLabs resins have quite a bit of developmental work to be done before being able to claim that the material can be used for injection molding cavities. In a true injection molding machine, the machine platens apply tons of pressure onto the mold halves so that the mold halves do not get blown apart due to the tens of thousands of PSI of injection pressure. Different injection molding polymers have varying melt temperatures, as well as varying melt viscosities; so depending on the injection molding polymer, it may be more or less “friendly” to 3D printed mold cavities.

Stratasys is truly 3D printing injection mold cavities. Here is a link to what they are doing: http://www.stratasys.com/solutions/additive-manufacturing/injection-molding

In my professional estimation, FormLabs has a lot more work to do on their resins in order for them to be able to be used for real injection molding tool cavities. The FormLabs resins just are not robust enough yet.

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I think this misses the point. I’m ecstatic about the white paper. I have two desktop injection molders and it will help a ton. It sure beats epoxy molds, which is the one of the more common non-Cnc methods. You are right that this won’t work on a big IM machine. But if I had a 22+ ton IM machine I’d have some big CNC machines to cut the molds. I do cut my own molds. I can tell you printing one will save me 20+ hours per mold. I don’t need to run 10k parts, just 100.

I may not be the common use case, but I think this is an incredibly powerful option for those who do small mold short run parts. I appreciate FormLabs putting this together.

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We are an injection molding company and I see great potential for time saving if I can print the cavity and core blocks for prototype parts as opposed to cutting them in aluminum. Even if we had to print 2 or 3 sets of blocks and use the first set to dial in the process on the molding machine it would be worth it to have molded parts for testing instead of printed parts. We are new to 3D printing and our Form2 is on its way. Will keep the forum updated on how our trials go. I appreciate all the input so far.

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Do you, or anybody else have any updates for the process yet, temperatures, pressures, cure times on the printed molds, etc?

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I’d be very interested in this too. My company has this project on the back burner…never enough time in a small business. Although our smallest Injection Molding machine is a 300 ton behemoth…a far cry from a desktop machine. Knowing nothing about the process myself I’d be worried our machines would destroy a 3D printed mold.

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Yeah, our molder has large machines too, but we are hoping that this will work for short run small parts on the hand press (Medium Machinery) so we can avoid cutting metal, I’ll post what I learn and hope that others that are doing it will get in on this thread too.