Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Plastic Mold Release for Thermoforming

Plastic Mold Release for Thermoforming

Plastic Mold Release for Thermoforming

Can anyone help me understand which plastics do well with Zinc Stearate or Calcium Stearte as mold release agents? Should these release agents be applied in a powder form or disolved in some sort of liquid? What plastics do well with Silicone or lecithin?


RE: Plastic Mold Release for Thermoforming

Most if not all plastics work with stearates, but it does not take much. Many already have them or something similar added at the compounding stage by the raw materials manufacturer and more can do harm.

To much reduces mechanical properties, gives splay marks or silver streaks and builds up on the mould surface as a mould deposit and even blocks air vents.

See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
for site rules

RE: Plastic Mold Release for Thermoforming

It is always best to avoid anything that can contaminate the material. Operators add it in varying amounts creating bad knit lines, etc.

The best way to fix the problem is to fix what is wrong with part or mold design so that the parts don't stick. Sticking is usually a correctable condition between mold and part design changes.

Adding air vents that can be pressurized as the mold opens can sometimes work to keep the parts from sticking on the Hot Half of the mold, plus there are a number of other options.

If time and money doesn't allow for changes, speak to your material supplier and see if they have a lubricated grade of your resin available. This makes for more consistent parts and higher quality parts.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close