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Comparing Apples and Oranges: Injection Molding vs 3D Printing


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Is there any way that our 3D printer can be used to make short run molds?
Walt
#1 Walter Clark (Homepage) on 2013-02-21 21:38 (Reply)
Hey Walter,

We have heard of examples of people making 3D printed molds to then take to injection molding small runs. Depending on the material you may need to treat the surface to ensure smoothness/mold release and to seal any porosity.

Good luck
#2 Duann on 2013-02-21 21:44 (Reply)
There's also an issue in that ProtoMold's tooling is aluminium and works within very specific (albeit ever growing) constraints, so what you have here is a comparison between 3D printing and non-traditional-shorter-run-moulding-processes, not your toolsteel-run-a-billion-parts-off-tooling. In the 1,000 part range, that's not going to make much difference, I know.

The comment about "upfront investment required" doesn't really scan out either because Protolabs/Protomold store your tool, and you order more parts as and when you need them. They load it up in the moulder, shoot some more plastic and ship you the parts. There's no massive warehousing involved or investment in the tool. It's paid for with that first order and spread out "per part".

On a personal note, the whole "for simplicity, we just assume the cheapest material from each" worries the hell out of me. If you're not using the same material, then you've got two entirely different parts, made in entirely different ways, with entirely different performance characteristics.

They just happen to be the same shape. Which is about as useless for a comparison as a chocolate Thermos flask.

Al
#3 Al Dean (Homepage) on 2013-02-22 14:25 (Reply)
There is a problem with Shapeways in that the only business models that work are very small parts or extreme specialty parts. It would be great if Shapeways partnered with a firm that would offer injection molding based on the print models people upload to Shapeways. That would offer a production pathway to people looking to create a general purpose product like a toy. Currently scaling up requires starting all over again with a new manufacturer that does molding.
#4 Eric on 2013-02-22 16:53 (Reply)
It's not Shapeways, but with 3D printing in general, that the business models that work generally use small parts and/or specialty parts, particularly ones that are not suited to molding.
#5 Aaron on 2013-02-26 00:32 (Reply)
IMHO the problem is that you have to design for moulding or design for 3D printing. Given completely clean CAD for a 3d printable part is only the first step to get a set of CAD for the plastic moulding. (Having gone the other way moving low volume life expired plastic tooling to 3D print the same btw is true that way around and in some cases cannot be done due to wall thicknesses and accuracy requirements).

3D printing masters for lost wax casting and for white metal or pewter casting works for a lot of shapes but again some care is needed so it will come out of the mould. Resin is somewhat easier than plastics as beyond the obvious "can you get it out of the mould" concerns the wall thicknesses and the like are not disssimilar.

I'm finding 3D print is actually cheaper than going to white metal/pewters for small parts, but metal has advantages. If the FUD part itself is very delicate you can make a lost wax brass master and cast that in pewter or when you need weight low down then metal castings give you weight, which is one reason I'm still using metal for battery boxes on some of our model railway kits.

Interesting numbers. Ones that need ramming down the throat of all the "3D print piracy panic" press people and lobbyists.

Alan
#6 Alan (Homepage) on 2013-02-27 10:51 (Reply)

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