×
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!
  • 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

Jobs

May resin puncture the bag during cure cicle?

May resin puncture the bag during cure cicle?

May resin puncture the bag during cure cicle?

(OP)
From time to time vacuum leak occure during autoclave cure cicle. Sometimes because bag bridging, or seal compound sliding or vacuum port bridging  the bag crash, and sometimes unknown reasons. When inexpilcable bag puncture arrive we chalk  it up against resin. I heard that during gelation stage resin may form chips which probably cut through the bag. It is possible that a gummy sticky viscous substance to penetrate a  laminated polymer foil plast material?

RE: May resin puncture the bag during cure cicle?

Viscous resin will not tear your bag but there are plenty of other causes, some of which you noted. Some resins, such as bismaleimide will chemically attack nylon film and degrade it but even that won't puncture the bag unless there is stress on the film. Ideally, you should never bag a part so that the film has to stretch when you pull vacuum. That is not always possible but stretched film is far more likely to tear duing cure than film that is properly pleated so it doesn't have to stretch. Stretched bagging film also applies forces to parts that will cause thinning or thickening of corners.
Probably, the main cause of blown bags is compaction of the part and breather materials during cure which requires the bag to move. If you don't anticipate this movement and place pleats where required to prevent the film from stretching then the film can tear. This is why experience is so valuble vacuum-bagging. Using high stretch film helps to make the process robust, but can also encourage poor bagging technique.

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