INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!

*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.

Jobs

Santoprene post mold shrinking

Santoprene post mold shrinking

(OP)
I have a part molded from Santoprene 101-64, after the parts are put into service and are exposed to heat (80 degree C) they shrink. I cannot find any data that says that this normal or how to design around this issue. Anyone else experience this?

RE: Santoprene post mold shrinking

Hi
mould shrinkage in TPE is quite common although at a much lower rate than thermosetting elastomers. how big the problem is depends on the tolerances you are working to shrinkage can occurr as a result of various strain relaxations.see below...

Shrinkage
Due to their anisotropic nature, GLS styrenic TPEs shrink more in the flow direction than in the cross-flow direction. Generally, SEBS TPEs have higher shrinkage and are more anisotropic than SBS TPEs.

Typical shrinkage values for SEBS-based TPEs are 1.3% - 2.5%, whereas those for SBS based TPEs are 0.3% - 0.5 %. Softer SEBS formulations (below 30 Shore A) will shrink more than harder materials. Some grades, such as Dynaflex G7700, G7800, and G7900 Series contain filler, which reduces their shrinkage.

The shrinkage values reported by GLS are determined using a 0.125" thick plaque. It should be noted that shrinkage is not an exact number, but a range value. This range can be affected by the part wall thickness, melt temperature, mold temperature, injection speed, hold/pack pressures and also the time between molding and measuring. As a result, prototyping is strongly recommended for parts with close tolerances to better quantify the realistic shrinkage of a specific grade of material in the application.

Johnnymat

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!


Resources


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