Mailbag.

Dear editor:

Not having been on the circulation list for Rubber World, I hadn't known until late October, 2001 that my letter to you was printed in the June 2001 issue. I thank you for that.

I also read Mr. Taylor's letter in the same issue. Yes, Mr. Taylor phoned me in the summer of 2000 stating that he had authored an article and used some of the material from my 1968 publication. He did not request my permission prior to his publication, and as you know, he used no footnotes or references.

Mr. Taylor did not contribute to my article. I was hired by GE Silicones because of my wire and cable background. My 1968 article was a result of that background. If the knowledge were common, why was I chosen by GE to give lectures throughout Europe and Japan during the 1970s to new silicone wire and cable customers?

Taylor didn't "dust it off and bring it into the nineties," he used it in kind. He made the title sound like a general extrusion article which it isn't. It was designed for cable extrusion. To make it a general extrusion reference, other specific information needs to be added.

I intend to author a new publication of a general nature pertaining to the attributes of silicone rubber and how they contributed to problem solutions for industry.

Walter H. Filbert,
Clifton Park, NY

Dear editor:

My compliments to you and your recent fine editorial regarding the Ford/B-F situation (November, 2001). Basically you have come forth and published the thoughts of a great number of rubber industry people, myself included.

I agree that it is very difficult to accept the automaker recommending tire inflation pressures that are different than those recommended by the tire manufacturer. Normally, when one operates outside the guidelines recommended by a product manufacturer, then that person or company assumes the responsibility for any problem and/or liability.

Richard J. Hupp,
South Bend, IN

(The following were sent to the Tech Forum section of our website, www.rubberworld.com. If you can offer assistance, you can answer through the website or contact our office.)

Dear editor:

Is it possible to manufacture natural and/or nitrile rubber impregnated with fine metal to enable worn or broken bits of the rubber to be detected using sensitive metal detectors during food manufacturing?

Eddie Perigo,
Industrial Rubber Parts
Whangarei, New Zealand

Dear editor:

I am working at a German institute in the field of research and development of microfluidic components and systems. At the moment, I am occupied with the design and manufacture of a miniaturized lubricant dosing system.

In this system, we use two o-rings made of Perbunan durometer 70 (NBR) with the dimensions of 1,0*0,6 mm. Those o-rings are used as a seal between a moving piston and a fixed cylinder wall. The movement is in an axial direction of the piston. The o-ring sealing is fixed in a nut in the piston and therefore moves relative to the cylinder wall. I have the following questions:

1. Is there an analytical method to calculate the friction forces for such a situation in dependence on the pressing of the o-ring?

2. Are there other geometries for such a sealing to reduce friction forces?

3. Which parameters influence the friction in such a system?

4. Are there models to solve such problems by FEM, which material laws are applicable?

I am interested in any information on this topic

Joerg Kohnle
Baden-Wuerttemberg, Germany

Dear editor:

We are a babycare products manufacturer. We use liquid silicone rubber for baby nipples and pacifiers. We want to sell our waste silicone materials which are unfilled. This waste silicone rubber is in the form of flashes and incomplete articles and cuttings. Currently we have about one metric ton in hand. Kindly tell us where we can find an appropriate buyer.

Kushif Mujeeb,
Karachi, Pakistan

Dear editor:

I need a good extrusion test. I need to discriminate among several extrusion resistant materials used in o-ring type seals in high pressure applications without a back-up ring. I want to prevent material from extruding into a gap.

David DeGrote,
Mossville, IL

Dear editor:

Is there any published quantitative analysis of the interaction between typical natural and synthetic rubbers and varying ppm levels of organic liquids, including a wide range from benzene and phenol to long carbon chain alkanes?

Matthew D. Viergutz,
Chesterfield, MO

Dear editor:

What is the damping effect of 0.050 inch of rubber on a 0.080 inch thick flat composite structure that is about l sq. foot? Assume the composite is graphite and the rubber is latex.

Fred Verd,
Santee, CA