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

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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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.

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.

http://www.designnews.com/author.asp?doc_id=264158

Good luck.

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.

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