Results 1 to 5 of 5

Thread: Mold Release Spray

  1. #1
    Join Date
    Sep 2012
    Lakewood, WI

    Mold Release Spray

    Not a big fan of it, but have a transfer tool an Aerospace part, so changes to part design or material composition would take an act of congress or worse. Have tried a few different mold steel treatments to no avail. There is allowance to use an external lubricant and I have some success with plain old Econo-mist but it does cause some visual defects (most notably splay) if applied to close to the gate.

    The part is directly gated into the top surface of this deep drawn 6" core of approx. 2" diameter. Core does not have proper cooling because the mold builder put 4 ejector pins up the center of the part. My limited experience with deep drawn cylindrical parts with little draft is that ejecting on that surface just doesn't work.

    We welded these ejector pins into the core to eliminate pin push on the top surface and added more pins to the flange/base area, but it sticks hard to the core unless some spray is used.

    Material: Ultem 1000

    This is a low EAU so I am looking for alternatives in external mold release sprays before looking at more mold modifications like adding air blow assist or poppet.

    Any one have some suggestions on a good release spray for molds running Ultem at 300F?

  2. #2

    Re: Mold Release Spray

    We use Dow Corning 360 Medical Fluid, 350 cst as mold release for class 2 and 3 medical device. It's more a liquid silicone than a spray but might be ideal to use as placement near the base with a Q-tip, and its cheap.

    Only would caution placing too much to where parts stick to the A side. Especially if you have little to no draft.

    Had some success with cylinder shaped parts..
    Mold temperature needed to be warm enough so the part wouldn't stick hard to the core, but cool enough to strengthen up the areas near the ejector pins to allow sufficient part ejection. Tricky balance between cooling time, mold temperature, and pack pressure.

    If you're ejecting near the gate at the coretip (as I understood it), ideally you want the base of the part to be Hot, and the core-tip to be Cold (where ejection is) as such a faster fill speed might benefit you because it'll allow less temperature-delta from core base to core tip.

    Also if you can permit the time, keep the mold open for a few seconds to cool the core before closing! It'll cool much faster in the atmosphere than having it closed in the mold with plastic on it.

    Hope some of that made sense.

    Good luck my friend

  3. #3

    Re: Mold Release Spray

    Might also be worth a try to use a ramped holding profile for this type of problem.
    Give it less pressure at switch-over, then slowly ramp to high pressure until you hit gate seal. The idea for this is you're giving less pressure influebce at the base of the part and effectively giving higher pressure near the gate for strength (where the ejector pins are) to allow part ejection. This has worked for me more than a couple times

  4. #4
    Join Date
    Aug 2014
    Saint Paul, MN

    Re: Mold Release Spray

    Keep in mind amorphous resins are susceptible to stress corrosion, so if you use mold release, watch out for crazing.
    Surface finish I’ve had most success with is nickel/Teflon (Poly-ond or similar) followed by a light draw-polish. Alternatively, shot-peening might help a bit.
    As far as cooling cores that are too narrow for water lines, I have had success with Noren (heat-transfer) pins.

    I can say that in a similar situation – a PC 6”x6”x8” “box” open on the B-side, sprue gated on the A side, mirror polish on the core – the only way we could get the part off the core was with a poppet/air blast. As I recall, we also used stripper bars on the base rather than ejector pins.

    Good luck!

  5. #5
    Join Date
    Aug 2011
    Upstate of South Carolina

    Re: Mold Release Spray

    Talk to Slide products or Stoner and tell them what you have and the issues. I’m sure either can help you. BTW PCS makes a nano mold release coating you can apply and strip/reapply in the tool room. It might help.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts