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| Author | Topic: Barrel zones |
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dohastne Member Posts: 1 |
posted July 04, 2004 04:00 AM
   
I want to know whether each individual barrel zone serves to produce a specific effect or result on a plastic being run through it. I understand that in a foaming process the temperature of the barrel zones should be lower towards the end than at the feed so that the matrix does not foam inside the extruder. So, in other words, is the function of the barrel zones so specific that one would be able to say X barrel zone should typically be greater in temperature that Y barrel zone because it produces Z effect on the material (for any given recipe). IP: Logged |
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TomBlack Moderator Posts: 43 |
posted July 04, 2004 08:44 AM
Talk about Pandora's Box! I'm sure you'll get as many different answers as there are responders to this question. However, as a general statement it can be said that the early zones (zone 1 and sometimes zone 2) are set to affect solids conveying while the center zones (zone 2 and typically zone 3) are set to assist melting and reduce amp load. The following zones are typically set to affect melt temperature and either adding or removing heat for the desired effect. Clearly screw design has a major impact on zone settings with process conditions such as screw speed and discharge pressure coming in a close second. As a result, depending on the process conditions, material processed and desired results, you can make a case for just about any heat profile; flat, reverse, humped, camel back or other... I like to make a sketch of the screw profile and map over it the barrel zones so I know just what zone to manipulate to either increase feedrate, improve mixing, reduce melt temperature, etc... ------------------ www.ppsincorp.com IP: Logged |
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Steve H Moderator Posts: 306 |
posted July 04, 2004 04:01 PM
Welcome to the single screw forum, and what a great way to kick off posting here  I tend to agree with Tom's post, with perhaps the caveate that barrel profiles are material, process and machine specific. By this I mean, you can set up an extruder at any point above the melting point of any TP and "extrude" it, it may not come out in the quantity (Kgs/Hour) or the quality you want, but it will extude. Now if your extruder is capable of a maximum of 120Kg/hr and feeds a down stream process you need 110Kg/hr, you will want to optimise barrel settings to get the maximum output. Steve IP: Logged |
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