What material should I use to make a mold for ABS injection molding?

I want to design a mold to be used for ABS injection, but I'm not sure which material would produce the best results.  I want to design it and upload it to a manufacturer like shapeways or i.materialise.  They have a few different materials to choose from here for shapeways, and here for i.materialise.  What do you suggest would be the best material for a mold used to create professional looking ABS parts?

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rickharris2 years ago

Injection moulding is a very specialised area. It takes a lot of pressure to accurately mould something - so aluminium, stainless steel etc are the materials to go with.

A manufacturer will give you guidance.

I don't think this is something your going to successfully do yourself.

Spaceman Spiff (author)  rickharris2 years ago

I was planning on having the mold made by a manufacturer, and building this to inject heated ABS into the mold. Honestly I don't have much experience in this area, but I'm considering this as a cheap option to make small plastic parts I need. The parts I need to make are about 1/2" x 1/4" and I will be making about 300 of these a year. I considered resin casting, but wasn't sure if this would be cheaper then injection moulding, and will need specific colors that I could pull off easier with ABS. Do you suggest an easier method?

A lot depends on exactly what you are making and how rigid it needs to be.

At school we demonstrated injection moulding with a glue gun.

2 rectangles of MDF are separated by a strip of aluminium which is bent to the shape you want your mounding to be - Note this is going to have 2 flat sides - We used to make a Christmas tree key ring fob at this time of year.

The plastic is injected through a small hole in the MDF and fills the cavity taking up the shape you require.

We also had a commercial version of the instructable you link to which used aluminium moulds machined in 3D using a CNC milling machine. - We have a golf tee and a chess man as moulds. The system was a bit hit and miss to be honest, took a long time to get to temp and often didn't smell very good.

NOTE: To get very sharp detailed objects you need a lot of pressure. so depending on what your trying to do or end up with you may be disappointed with a DIY system.


Good luck.

Spaceman Spiff (author)  rickharris2 years ago

Thanks for the info. I've looked into the machine you linked and it looks like the one from the instructable you can make yourself, just a little more professional. Do you think this one can provide the required pressure?

It's cheaper to have your molds CNC Milled from a block of aluminum or steel. Contact some Injection Molding places and see what they use and see how much it would cost you to get a set of good molds made. Asuming your wanting to do you own injection molding here.

Spaceman Spiff (author)  mpilchfamily2 years ago

I haven't considered this because the solid molds (pre milled) were so expensive, but I will look into this as an option.