Monthly Archives: November 2012

How Tribology Led to the use of DuPont™ Vespel®

Tribology is based on the Greek word for “rubbing, grinding”, or “wearing away”. It’s study has lead to advances in material selection for high load applications such as bearings. Plastic materials such as DuPont™ Vespel® have been key in reducing friction and adding cost savings in the long run.

Tribology is a highly pervasive occurrence that can cause parts to have a much shorter life. So pervasive that it became a study all it’s own. In 1964, Peter Jost, a lubrication expert was inspired during a conference and out of this he began an entire discipline around tribology. You can learn more about Professor Jost in this interview Today we have many lubricants that range from the natural to the synthetic. They can all help to reduce friction. Thanks to the world of plastics we also have some materials like DuPont™ Vespel® that provide vast improvements beyond lubricants These new polyimide materials allow engineers to create parts and machinery they never thought possible and to greatly improve the efficiency and life of those parts.

We can thank the discipline of tribology for longer part life.

We can thank the discipline of tribology for longer part life.

Just think, if you had asked for a 10 year / 100,000 mile warranty 20 years ago the sales person would have laughed for a very good long time. Now, it’s the standard thanks in part to the discipline of tribology and new materials like Vespel. Due to their properties materials like DuPont™ Vespel® have found their way into commercial transportation industries, medical, food processing and manufacturing of all types. They simply have a unique combination of properties that makes them highly durable even under the harshest conditions.

Plastic materials are making a big difference in our ability to reduce friction and cost due to reduced wear and less need for lubrication and maintenance.

DuPont™ Vespel® has been a marvel of the plastics industry for decades. Now the SCP family of materials has been added to help with extended part life in sealing and bearing applications. It is most noted for it’s ability to be used in non-lubricated high-friction environments because of it’s exceptional heat and pressure resistance capabilities. The SCP 5009 material in particular performs well with or without lubrication under conditions that would cause severe wear or destruction of most other plastics. SCP 5009 is often used in bearing applications because it will reduce or eliminate problems with abrasion, corrosion, adhesion fatigue, and wear that plague conventional options such as metal bearings. Addition of a lubricant can improve performance even more!

Technical Properties of DuPont™ Vespel® SCP 5009


Technical Data for DuPont Vespel SCP 5009

Technical Data for DuPont Vespel SCP 5009

(Technical data provided by DuPont)

Using DuPont™ Vespel® SCP-5009 shapes for seals, valves, bearings, bushings, and other components can mean savings due to lower replacement rates which leads to reduced maintenance costs. It’s also easy to machine. Most Vespel can be machined on the same equipment used for metals like brass. (See our video on machining techniques) and that can mean fewer rejects, higher productivity and reliability.

Key industries that have studied tribology and found that DuPont™ Vespel® SCP-5009 shapes can offer substantial processing, performance and metals replacement advantages include analytical instrumentation, medical devices, aerospace and energy and material handling.

In a comparison to metal ball, needle and roller bearings, a part made from high temperature material like DuPont™ Vespel® SCP-5009 has advantages that include:

• No external lubrication
• The ability to hold up in temperature where lubricants fail
• Perform in dirty environments including dusty or where lint is present
• They typically weigh less and are quieter
• Compared to porous metals, bronze and brass the wear life may be much greater
• Vespel holds up to high pressure and high velocity
• Creep resistance

In addition, SCP 5009 can perform at temperatures and velocities beyond that of other plastic materials.

SCP 5009 is just one example but it’s one that shows how, thanks to the discipline of tribology, plastics are becoming more mainstream in manufacturing and it’s not due to a short term gain of cheaper material. Rather tribology has given us a longterm view of parts that looks at longer life, less maintenance and improved performance. Therein lies the true value and savings.

For more information on any of the information in this blog feel free to contact me.

Kendall Montague
Sales & Marketing Manager – DuPont™ Vespel®
ThyssenKrupp Materials NA
AIN Plastics Division

To ask me a question please comment on my post here or contact me directly:
Phone: (314) 502-0813


Read More:

The Patriotism of Plastics

In remembering Veterans Day this past week I thought it might be interesting to consider some of the various and unique ways that plastic materials have contributed to safety, security and defense.

How Are Plastic, War And Women’s Stockings Related?

In the late 1800’s Cellulose based products began showing up in the marketplace. This was followed in the 1900’s with materials like PVC’s (PolyVinylidene Chloride) and Phenolic materials (formerly known commonly as Bakelite).  However the big turning point needed to launch plastics into the mainstream industrial world would be that of necessity.  World War II required rationing of many raw resources such as costly silk from Asia which was used in parachutes, cords and cabling, as well as stockings.  DuPont introduced Ladies’ Nylon stockings right from their Wilmington Delaware headquarters and they sold out of the new hosiery within a few hours!  No longer did women have to struggle to afford costly silk stockings (if they could be found) or paint their nylons on. The new stockings looked great, fit well, and outlasted traditional silk or leg painting.
Nylon went on to become one of the most common polymers used in industrial applications, prized for its toughness and excellent wear properties, not mention it’s ability to be quite stylish and fashionable!

Posted by:

Lin Poulin
Telemarketing Manager
ThyssenKrupp Materials NA
AIN Plastics Division

Better Insulator Materials Take the Heat

When selecting an Engineering Plastic for insulator use the term “dielectric strength” is often of great consideration. But be aware, the term “dielectric strength” has multiple meanings.

In physics, the term “dielectric strength” has three meanings:
1) In an insulating material it is the maximum electric field strength that the insulating material can withstand without breaking down or failing and losing it’s insulating properties.

It can also mean…
2) For a given configuration of dielectric material and electrodes, dielectric strength is the minimum electric field that causes a breakdown of the properties.
3) The maximum electric stress the dielectric material can withstand without breakdown

Overall, dielectric strength is considered to be a natural property of a given material. It’s just a part of what it is. When a material’s dielectric strength is pushed past it’s limit the electric field of the material frees bound electrons. If the applied electric field is sufficiently high an event called an avalanche breakdown occurs. This happens very, very fast (within nanoseconds) and basically it causes the material to severely degrade or even completely destroy it’s insulating properties.


Example of a Typical Dielectric Strength Test

What to look for in an Insulator Material
When looking at Engineering plastics there are several things that will affect the material’s dielectric strength. When an insulator is subjected to increasingly high voltages, it eventually breaks down and allows a current to pass. The voltage reached before break down divided by the sample thickness is the dielectric strength of the material, measured in volts/mil. It is generally measured by putting electrodes on either side of a test specimen and increasing the voltage at a controlled rate. Factors that affect dielectric strength in applications include: temperature, sample thickness, conditioning of the sample, rate of increase in voltage, and duration of test. Contamination or internal voids in the sample can also have an affect on the outcome of testing.

Another way to Look at Dielectric Strength…It is…
directly proportional to the thickness of the material
inversely proportional so it decreases as operating temperature increases
inversely proportional to an increase in frequency
inversely proportional to an increase in humidity

To see how dielectric strength compares let’s take a look at some common insulator materials:
(All Dielectric Strengths are given in MV/m)

DuPont™ Vespel® – 700
Ultem PEI – 830
PEEK – 480
Cast Nylon – 500

The Ultimate Insulator Material
When looking at materials that provide a high dielectric strength many engineers look to DuPont™ Vespel® This line of materials has been designed into many Electronics applications as an Insulator material due to their high dielectric strength combined with other properties.

Scientific Instrumentation, Semiconductor Manufacturing, Analytical Equipment, Ultrasonics, Communications, and Avionics are just a few of the places where you will find Vespel.  Recently DuPont extended their Vespel® line to include SCP-5000, with even higher dielectric strength than standard SP-1.

Do you have more questions about choosing the right Engineering Plastic based on electrical properties, feel free to call me directly. I’d be happy to assist.

Paul Hanson

Sales and Marketing Manager, DuPont™ Vespel®
ThyssenKrupp Materials NA
AIN Plastics Division

Phone: 770.362.9712