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  1. #1
    Morning

    I figure theres a few on here that make ali and steel moulds for injection purposes im looking for tips advice do's and dont's on polishing the cavity materials/tools used.
    And also adding a visable texture to the mould sand blasting or acid?

  2. #2
    Hi Diesel, I don't do metal moulds (yet)
    but i do do Resin and Silicone.
    I'll wager that its a piece of string question, and dependant on a lot of factors. I.E. what size mould cavity etc.
    I'll put money on using toothpaste,auto sol. or other metal buffing compound with a cloth or polishing mop. rather than an acid though.
    I'd be tempted with a "dremel" type tool (without going into the bearing debate lol.)

  3. #3
    hello martin
    were talking small stuff here a couple of inches square tops but as there mechanical parts to be made ,need retain size or as close as possible.
    while searching i keep coming across ceramic fibre sticks in sets of various grades that can be shaped to suit,seem bloody expensive for what they are but may be just what i should be looking at,

    regarding texturing i cant find much info on it other than the usual sales patter,id like to do it myself, it seems ideal for hiding machining marks and looks great.
    theres sandblasting which ive never done,but will shell out for if need be,but id like to try out filling the mold with an acid and leaving it for the required time.ta

  4. #4
    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.

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  6. #5
    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.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

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  8. #6
    Quote Originally Posted by Jonathan View Post
    I get the impression these are injection moulds for plastics, not resin.
    Plastic is a resin in its liquid state.

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  10. #7
    Quote Originally Posted by r0bsk1 View Post
    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.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  11. #8
    Quote Originally Posted by Jonathan View Post
    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.

  12. #9
    oscar's Avatar
    Lives in Oxford, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 5-6 years. Has a total post count of 57. Received thanks 2 times, giving thanks to others 1 times.
    We use an ultra sonic polisher and then mops in a dremel type tool for very fine and mirror finishes. Anything that needs a textured surface is done on the spark eroder.

  13. #10
    Quote Originally Posted by r0bsk1 View Post
    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,

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