posted January 16, 2005 02:27 PM               

I'm not sure if the gels are crosslinked or unmelted polymer. We have tested the polymer but haven't found anything special. I'm not sure though that we have the right expertise to analyze the polymer correctly. What puzzles me is that we haven't changed anything. Could it be the polymer itself, or something to do with the process? Of course it would seem logical to get crosslinked gels from stagnated polymer overheating while reheating the extruder. But, we have never had any problems before. Is there something the polymer supplier can hide from us? Perhaps to much reclaim in their polymer? How would it react in our extruder? If we analyze it, will it show gels or will we see it only in the extruder? How can we know that the polymer contains reclaim? Darker color?

Thank you

[This message has been edited by poly (edited January 16, 2005).]

[This message has been edited by poly (edited January 16, 2005).]

posted January 16, 2005 08:49 PM               

Two thoughts;

1) Examine the materials microscopically as raw material, extruded without screens, contaminates on the screen and product. This will tell you the source.

2) Sounds as if you might have wear in your extruder. This will allow a film of material to reside on the barrel and/or screws and nor purge out. This film can degrade during the startup and shutdown. I can help with wear measurement devices if you are interested.

Tom C
www.ExtrusionTechnicalServices.com

posted January 16, 2005 09:06 PM               

Anything you can provide will be of great help to me.

posted January 18, 2005 08:47 AM               

Are we having wear in the extruder? It's a possibility because one of our additives is very corrosive.

posted January 18, 2005 01:40 PM               

Tom Cunningham
www.ExtrusionTech.com

posted January 19, 2005 12:02 PM               

Unfortunately, I don't have the authority to hire you. I'm only an extrusion operator.

I'm living the eternel battle between operators and engineers. I work with young green engineers freshly out of school. They have a lot to prove...

I've been an operator for 20 years and I know how an extruder works. I have also dealth with gels before. This company is so narrow minded when it comes to listenning to other people's opinions.

I don't think I will be able to convince them to hire you or anybody else for that matter.

Yesterday, as usual, they decided to patch the problem instead of finding the cause. We purged the extruder at lower temperatures before shutdown (everybody already knows this procedure!). After 7 hours of shutdown, we restarted again and the flow seemed pretty clear. As I'm killing myself to make them understand, we'll never know the cause if we keep working like this. I reminded them many times that for the past 2 years we never had this problem. Why now?

I think next time I get another problem with the process, I will leave it to them and sit down comfortably in the cafeteria while they find the solution (even if I now for sure what is the solution)!

Thank you for your offer.

Best regards

[This message has been edited by poly (edited January 19, 2005).]

posted January 19, 2005 02:33 PM               

It would be nice if your organization appreciated your concern. I have worked at all levels within companies, and I know exactly what you are talking about. In fact the operators complain about the engineers, the engineers about the operators and the mechanics complain about everyone!

Fact is extruders are very hard to run, control, and diagnose when there are problems. It has taken me 20+ years to start to get a handle on things, and that is with the assistance of hundres of thousands of dollars worth of training and software.

There are plenty of problems and failures to go around if you spend enough time with extruders. Hats off to anyone who has the guts to stick it out.

I'm here to help if I can.