Mould polishing and texture advice

[r0bsk1]

Hi deisel, be careful creating a texture in a mould. It can cause the resin to lock in to the mould. On release you'd either leave bits of resin behind or possibly damage the mould.

I work with composites and a shiney mould is what you're looking to acheive for best release to maintain the mould lifetime. Refinishing the mould after a lock-in would of course make the mould slightly larger.

As for finishing the mould I use wet and dry paper through the grades to about 2000 grit. Then machine polish with mops for a mirror finish. You can then use a scotch pad to take away the shine from the moulded part. Depends on what kind of texture you're looking for i suppose.

[Jonathan]

I get the impression these are injection moulds for plastics, not resin. It's going to depend on the detail required for the parts in question - if its artistic parts that's quite different to general widgets with more flat surfaces than curved profiles.

[r0bsk1]

I get the impression these are injection moulds for plastics, not resin.

Plastic is a resin in its liquid state.

[Jonathan]

Plastic is a resin in its liquid state.

Actually it's the other way round - some resins are called plastics in their solid state. Plastics belong to the set of materials called resins, hence I specified plastics to narrow down the discussion since I suspect these moulds are for thermoplastics, so stating plastics is equally, if not more, accurate. The reason for this supposition is the user's previous posts regarding an injection moulding machine.

Anyway, what material are the moulds going to be made from? If aluminium then this article suggests they should be plated with nickel.

[r0bsk1]

Actually it's the other way round - some resins are called plastics in their solid state. Plastics belong to the set of materials called resins, hence I specified plastics to narrow down the discussion since I suspect these moulds are for thermoplastics, so stating plastics is equally, if not more, accurate. The reason for this supposition is the user's previous posts regarding an injection moulding machine.

Therefor they will be injecting plastic in the form of a resin.

[dazza]

Hi deisel, be careful creating a texture in a mould. It can cause the resin to lock in to the mould. On release you'd either leave bits of resin behind or possibly damage the mould.

Thanks for the info r0b,probably saved me a few quid right there!
The texture i was thinking of is the grippy eggshell like texture found on phones,remotes ect so nothing heavy , i will have to do a sacraficial mould maybe with the parts shrinkage when cooled i might get away with it.


Yes for injection molding jonathan,there sometimes referred to as resin pellets used,