posted May 03, 2003 03:34 PM               

Is there a typo in your post, do you have a "grooved" feed section on your barrel?

If so, grooved feed sections don't work well with regrind.

Ken's advice is absolutely correct, calculating output in Kgs per RPM will tell you what's happening with your extrusion parameters (particularly the feed section)
and averaging those figures over a month and keeping a month to month record, will tell you a lot about screw wear- without pulling the screw and measuring it.

If you want to maximize output, try varying the set temp in your feed zone in 5C steps, up and down over a range of 30C. At each step, determine what output you are getting with that setting. Once you have all the figures, plot them on a graph with output as the Y-axis and temp setting of feed zone as the X-axis. The resulting graph will be a humped shape, the most effective setting is some where around the top of the hump. You need to allow about 10 mins/per inch of diameter for every thing to reach equilibrium at the new setting

What's happening is that at the cooler settings, material is not sticking to the barrel and thus not being conveyed by the screw, go too far and the material is melting and not sticking to the barrel wall(with the same result)... get the feed zone temp on the money and you get maximum output. Even quite a small change can make quite a big difference. But you can only tell, if you have accurate figures to work from.