Ask the experts! These processors and consultants have been there and done that. Post your enigma now!


UBBFriend: Email This Page to Someone!
   Plastic processing forums for extrusion information and advice and for other feed screw applications.
  Extrusion, Single Screw
  Melt Temperature

Post New Topic  Post A Reply
profile | register | preferences | faq | search

next newest topic | next oldest topic
Author Topic:   Melt Temperature
Robin
Member

Posts: 2
From:Nottingham, UK
Registered: Jul 2002

posted July 02, 2002 02:46 PM     Click Here to See the Profile for Robin   Click Here to Email Robin     Edit/Delete Message   Reply w/Quote
Hi... there.

I am having problem in determining the melt temperature from measurable barrel temperature and screw temperature. Could I get some suggestions?

Thank you

IP: Logged

Steve H
Moderator

Posts: 386
From:Christchurch,New Zealand
Registered: Jun 2001

posted July 02, 2002 03:20 PM     Click Here to See the Profile for Steve H   Click Here to Email Steve H     Edit/Delete Message   Reply w/Quote
G'day Robin

Measurement of the temperature of the melt is
normally achived with a thermocouple just beyond the tip of the screw. The tip of the TC protrudes into the melt stream. Dynisco used to make one that traversed the melt stream, but they no longer offer it.

You can get TC's that have an adjustable stem to achive the same result. Infrared systems can also be obtained.

Screw speed, screw design, and barrel settings influence melt temperature, but you
cannot say that because I have set the final barrel zone at 250C, the melt temp is 250C- it may be much higher, or lower.

Depending on what you are extruding, you could immerse a TC into the material to give
you an approximate idea of the melt temp you
are getting.

Steve H

IP: Logged

griffex
Senior Member

Posts: 38
From:bethesda MD USA
Registered: Sep 2001

posted July 07, 2002 09:57 PM     Click Here to See the Profile for griffex     Edit/Delete Message   Reply w/Quote
Further to Steve's reply, which I agree with, you can also get an infrared sensor and point it at the emerging extruded product, the closer the better. Raytek makes them, maybe others. It works better on flat products than round ones. For all products you can stick a needle pyrometer into the melt as it comes out, takes a little experience, biggest problem is that you mess up the product.
Whatever you do, don't give up, as a good reading of melt temperature is important.

IP: Logged

JeffdlS
Senior Member

Posts: 10
From:Grand Prairie, TX, USA
Registered: Jun 2001

posted August 05, 2002 04:05 PM     Click Here to See the Profile for JeffdlS     Edit/Delete Message   Reply w/Quote
Another type of melt thermocouple you might want to try is a fixed depth thermocouple. We are using some Graff fixed thermocouples for some of our extrusion lines. Their web address is http://www.graeff-messtechnik.de It might help to have some sort of translator since the sight is in German. But their product is one of the best. Hope that helps

IP: Logged

All times are ET (US)

next newest topic | next oldest topic

Administrative Options: Close Topic | Archive/Move | Delete Topic
Post New Topic  Post A Reply
Hop to:

Contact Us | Feed Screw Designs

Powered by Infopop www.infopop.com © 2000
Ultimate Bulletin Board 5.45a