×
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

Polycarb and hydrolisis

Polycarb and hydrolisis

Polycarb and hydrolisis

(OP)
What happens to polycarb when left in a injection molder barrel? What recomended minium temps for weekend shutdowns?

RE: Polycarb and hydrolisis

When left in the barrel at operating temp, the resin will begin to break down and leave carbon deposits on the screw and barrel. These will then come out as black specks in the material. This can also happen if plastic is left in the barrel with the heats off. As the plastic is heated back up to operating temperature, the resin can break down, again causing black specks. You can check with the supplier for a hold temperature, but all that I have seen recommend leaving the temp's at 300 to 350 degrees F when press is not running.

RE: Polycarb and hydrolisis

Is purging out with another resin recommended for downtime of several hours?  If so, what type of resin?  Thanks

RE: Polycarb and hydrolisis

(OP)
We use clear or natural polypro for long term shutdowns and also for screw removal. One must starve feed the polypro into screw throat to avoid bridging or creating a slug from the higher temperatures of polycarb.

RE: Polycarb and hydrolisis

You will be better of leaving the polycarb in the barrel and the temp set at 350 degrees F. I have used it in numerous medical jobs, and we would leave it for up to a week at a time. If the job you are using it for is highly visual, either clear or white, you can get black spec's. Purging will get rid of most of the polycarb, but you will always leave trace amounts behind. If you want to remove as much as possible, purging compounds such as Asaclean do a pretty good job, but are rather expensive. A cheaper option is to purge with cast acrylic. This is made from crushed acrylic sheets. This works well, but make sure you feed it slowly or it will bridge up in the feed throat worse than any other material I have ever seen.

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! Already a Member? Login


Resources

White Paper - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each person’s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. Download Now

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