Hello

We are looking for a screw to be used with EPDM/NBR. The extruder is 4.5" L/D 25:1. We don´t know what screw design would be appropriate and what compression ration is recommended for these type of materials

Thanks

Hello Bighead,

You asked this question before (July 11, 2006) and answers although not specific, were posted. I suspect serdar1970 was referring to a standard rubber screw. Please see this thread:

www.wirenet.org/forum/viewmessages.cfm?Forum=8&Topic=304

Talk with your material suppliers, with the extruder manufacturers and get their recommendations. Then, after second discussions with your material suppliers to resolve recommendation conflicts, if any, make your decision and purchase what you consider the best screw design. Finally, if able, please post what you have learned so that all can benefit from your investigation.

Sincerely,

Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Thank you

We have been quoting different extrusion equipment and/or screws but we have noticed that the suppliers vary the criteria specially for L/D ratios, compression ratios and screw designs for EPDM and NBR.
That is the reason why I am looking for help before taking any decision.

I have always said - give 100 screw designers, specifications for a particular process and you will end up with 100 different screws.

Machinery companies have the disadvantage of not actually doing the actual processing and most (aside from the biggest) use outside sources for their screws and designs. Material suppliers over the years have become less and less open with their opinions of design due to liability concerns.

I recommend that you talk to the people at Xaloy - world headquarters in New Castle, PA, USA tel # is 1-724-656-5600 or look at www.xaloy.com. They can point you to proper people to talk to in your specific location.


Erik Macs
VP North American Machinery Sales
Fine International Corporation
148 Oak Street
Natick, MA 01760 USA
508-315-8200 fax: 508-315-3621
This email address is being protected from spambots. You need JavaScript enabled to view it.

Thanks for the information

I will contact the company you suggested.

Bye