Injection molding dies

Hi, perhaps someone can shed a bit more light on the making of injection molding dies. Most are done with steel or aluminum that has been milled to shape. Are they created any other ways? FDM or SLS


Apparently you can make some simple - low run tools with FDM

Most tool steel is cut using an EDM (Electric Discharge Machining) process where an electrode chemically wears away the tool. CNC machining is typically done on prototype tools where the material is softer.

FDM and SLS are rapid prototyping processes for plastic parts - so that article is more of a science project than common practice.

You can also use urethane molds for low-volume casting.

ahh yes EDM was the other one I was thinking, Thanks! So EDM would be used for detailed part high run PP?

Thanks so much !!!

Just to mention as a curiosity, composite tooling was promoted years ago. Resins filled with various metal powders and cooling to dissipate heat. Seemed to require as much difficulty to make as metal tooling with more limitations. I have not heard it mentioned in a decade. Still used for manufacturing composites.

Naah, Iwouldn’t call it a science project. We did that on a project where we needed hundreds of parts to test them in correct material to evaluate spring functions, exhaustion, and assembly. We couldn’t be 100% sure of those things with urethane molds and some PU-mix. The firm that did it for us apparently does it quite a lot for all sorts of companies, it’s just another way of minimizing risk before cutting steel.

But yeah, it is still in the area of prototyping, not mass manufacturing. Parts could be evaluated by engineers, but not good enough for selling to consumers.

If I may, what does that cost? I currently can get a simple steel mud tool, I think 9x12, for about $12K locally. Good for 200K parts. The aluminum isn’t much cheaper and I have never had much luck swapping out inserts in aluminum tools. Don’t know why, but there always seems to be a delay. And swapping an insert in the steel tool is typically $1500-$2000.

It was about $3000 for everything. Let me explain what “everything” means, and I’ll let you break it down yourself what it might be worth.
There were 6 different parts, so 6 different HD-SLS toolings 1 cavity (material may have been PA+GF).
The parts - think of piece of flat plastic about 40x10mmx2mm, then bend it to the height of 30mm, so that the bounding box becomes something like 30x10x10mm. We injected those with POM.
Apparently there was a very high failure rate, but we collected 15-20 pieces from each (I think they injected something like 100 from each).
Actually, I spoke too soon because the engineers here who worked on this did considered it a science project and aren’t sure if it was worth the effort, but the firm does offer the service. We did that about 2 years ago.

You could probably 3D print a stainless steel part as a prototool, but given the cost of CNCing vs 3D printing metal I think the CNC would probably still be cheaper. That may change in the future though as costs come down.

3D printing binder onto sand for sandcast metal tooling.

I saw an interesting white paper about doing DMLS molds for the ability to have cooling channels that wouldn’t be millable here. The tool would probably need to be finished using a more traditional process to polish out the build lines though.