Tag Archives: material selection

Typical Properties of Dupont Vespel® and UL Ratings for Plastics

vespelWhen customers ask us about DuPont™ Vespel® the most often asked question is about UL approvals. The properties of Vespel® are ideal for high heat applications. Does DuPont™ Vespel® meet UL ratings for plastics? If so, which DuPont™ Vespel® meets which UL approval?

DSC_1986_composite RodWhat Are the Different UL Approvals for Plastics and What do they Mean?

The UL 94 rating is specifically for plastics flammability. Underwriters Laboratories created this standard to give people a consistent standard to be able to communicate and compare different types of plastics and how they react to flame. The system goes from lowest being the least flame retardant, to the highest being the most flame retardant. The rating also gives information about the exact testing method used such as:

  • Was the material vertical or horizontal
  • How thick
  • Were colors added

All of these can vary how a material such as DuPont™ Vespel® will react when exposed to flame. In the selection of materials for high heat applications, electronics, or areas that have potential for fire, UL ratings and their purpose must be fully understood and considered carefully.

One possible example is the Boeing Dreamliner. Although it will likely take years to determine, the materials used in the Boeing 787 Dreamliner are being carefully looked at with an eye toward the UL ratings and whether or not selected materials were used appropriately with regard to their rating.

  • UL 94-5VA Surface Burn; Burning stops within 60 seconds, test specimens MAY NOT have a burn-through (no hole). This is the highest (most flame retardant) UL94 rating.
  • UL 94-5VB Surface Burn; Burning stop within 60 seconds, test specimens MAY HAVE a burn-through (A hole may be present)
  • UL 94 V-0 Vertical Burn; Burning stops within 10 seconds, NO flaming drips are allowed
  • UL 94 V-1 Vertical Burn; Burning stops within 60 seconds, NO flaming drips are allowed
  • UL 94 V-2 Vertical Burn; Burning stops within 60 seconds, Flaming drips ARE allowed.
  • UL 94 H-B Horizontal Burn; Slow horizontal burn test (H-B) are considered self-extinguishing”. This is the lowest (least flame retardant) UL94 rating.

UL Ratings and the Typical Properties of DuPont™ Vespel®

ASTM or UL test Property SP-1 SP-21 SP-22 SP-211 SP-3
Filler Material Unfilled 15% Graphite 40% Graphite 10% PTFE, 15% Graphite 15% Moly
UL94 Flammability Rating V-0 V-0 V-0 V-0 V-0
D792 Density (lb/in³) (g/cm³) 0.051 1.43 0.055 1.51 0.060 1.65 0.056 1.55 0.058 1.60
D570 Water Absorption, 24 hrs @ 73°F (%) 48 hrs @ 122°F (%) 0.24 0.72 0.19 0.57 0.14 0.42 0.21 0.49 0.23 0.65
D638 Tensile Strength, Ultimate @ 73°F (psi) @ 500°F (psi) 12,500 6,000 9,500 5,500 7,500 3,400 6,500 3,500 8,200 –
D638 Tensile Modulus (psi)
D638 Tensile Elongation, Ultimate @ 73°F (%) @ 500°F (%) 7.5 6.0 4.5 6.0 3.0 2.0 3.5 3.0 4.0 –
D790 Flexural Strength, Ultimate @ 73°F (psi) @ 500°F (psi) 16,000 9,000 16,000 9,000 13,000 6,500 10,000 5,000 11,000 5,500
D790 Flexural Modulus @ 73°F (psi) @ 500°F (psi) 450,000 250,000 550,000 370,000 700,000 400,000 450,000 200,000 475,000 270,000
D695 Compressive Strength, 10% strain @ 73°F (psi) 19,300 19,300 16,300 14,800 18,500
D695 Compressive Modulus (psi) 350,000 420,000 475,000 300,000 350,000
D785 Hardness, Rockwell E45-60 E25-45 E5-25 E1-20 E40-55
D256 IZOD Notched Impact (ft-lb/in) 0.8 0.8 0.4
Poisson’s Ratio 0.4 0.4
D696 Coefficient of Linear Thermal Expansion (x 10-5 in./in./°F) 3.0 2.7 2.1 3.0 2.9
D648 Heat Deflection Temp (°F / °C) at 264 psi 680 / 360 680 / 360
Max Continuous Operating Temp (°F / °C) 500 / 260 500 / 260 500 / 260 500 / 260 500 / 260
C177 Thermal Conductivity (BTU-in/ft²-hr-°F) (x 10-4 cal/cm-sec-°C) 2.0 6.9 6.0 20.7 12.0 41.3 5.3 18.3 3.2 11.0
UL94 Flammability Rating V-0 V-0 V-0 V-0 V-0
D149 Dielectric Strength (V/mil) short time, 1/8″ thick 560 250
D150 Dielectric Constant at 1 MHz 3.55 13.2
D150 Dissipation Factor at 1 MHz 0.0034 0.0106
D257 Volume Resistivity (ohm-cm)at 50% RH 1014 – 1015 1012 – 1013

How long before the material stops burning (It must stop within 10 seconds for approval) Remember that UL ratings do not tell you the operating temperature of a material. UL ratings only refer the the behavior of a material when it if exposed to a flame source. Material sample are held over an open flame from a Bunsen Burner. After being ignited and allowed to burn the material is removed and testers monitor:When considering use of DuPont™ Vespel® and it’s UL rating there are other important factors to consider:

  • If material continues to burn does it drip or run. If it does, the material cannot be UL approved

Learn more:

This article by Homi Ahmadi in Compliance Engineering’s online magazine gives a good description of UL approvals for the electronics industry.

For more in-depth information and the UL-94 ratings and how it relates to plastics beyond DuPont™ Vespel® check out the UL website. http://www.ul.com/global/eng/pages/offerings/industries/chemicals/plastics/testing/flame/

For more information on the DuPont™ Vespel® materials Download  our guides or view a brief video on how to machine DuPont™ Vespel®

DuPont Vespel® SCP Parts

DuPont Vespel® SCP Parts

DuPont Vespel® Motion Solutions

DuPont Vespel® Motion Solutions

Insulator Solutions

DuPont Vespel® Insulator Solutions

DuPont Vespel® Sealing Solutions

DuPont Vespel® Sealing Solutions












Paul Hanson

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

Phone: 770.362.9712



Do I Need to use DuPont™ Vespel®?

It seems like nearly everyday we hear about a new breakthrough advancement in plastics materials. From biodegradable to new engineering plastics and more. Why I just recently posted one on our Facebook about a new invention that is being called OLED (https://www.facebook.com/AINPlastics). These new products and materials have features we couldn’t even imagine 10 years ago. So how do you know when you need to use certain products and when could you maybe use something a little less costly?

In this blog post, I wanted to take a look at one product in particular that we’ve talked about before; DuPont™ Vespel®. There has been a lot written and said about DuPont™ Vespel® and it’s with good reason. It’s been around for a long time (Since the early 1960’s) and the DuPont™ Vespel® product line offers some pretty unique features. But it’s also not the most inexpensive to purchase so we’ve created an easy top 10 list of things to consider when making product selection and considering whether or not Vespel® is right for your application…

The Top 10 Things to Consider when Thinking About Whether or not DuPont™ Vespel® Is the Right Material for Your Application:

1. When you have a critical application such as aerospace or military where DuPont™ Vespel® may be the ASTM specified product. (See our post “When Saving a Little can Cost you a Lot”). If it is specified you can stop reading here. You’ll want to be sure you follow the standard.

2. When you want a plastic material that will hold up in a high temperature environment and not lose it’s properties. DuPont™ Vespel® SP-1 and SCP-5000 can operate in temperatures up to 550° F with excursions up to 900° F! In fact, SP-1doesn’t even have a melting point. Gheesh, I’m melting in our Michigan weather this summer, but as hot as it is here, we aren’t even close to those temps!

3. When you have a high load application such as a bearing.

4. When you are looking for weight savings DuPont™ Vespel® can be an excellent alternative to metals such as aluminum or metallic alloys, or ceramics. It’s properties may even exceed that of metal and ceramic.

5. When you are working in a critical testing environment and need a low outgassing product.

6. When you need a long-lasting material. Low friction and high stability along with heat and wear resistance mean your parts last longer and require less maintenance.

7. Variety. In the “S” product line alone DuPont™ has over 10 products to choose from. This can help to save money as you don’t always have to get all the bells and whistles, but instead get a product that fits your specific application needs.

8. An easy to machine alternative to ceramic. VDuPont™ Vespel® has electrical insulative properties like ceramic, but the ease of machining using standard machining techniques means it can cost less to fabricate Vespel than it does ceramic. This is especially true for design that include details like under cuts, holes, or threads. Vespel is also tougher than ceramic and it can take high impact.

9. When lubrication may not be viable or when you need a low wearing material that can withstand poor tolerances or when you need low friction to improve efficiency. DuPont™ Vespel® Bearing Grade SC and SCP possess some of the highest unlubricated pressure-velocity limits among engineering plastics.

10. When you need a plastic with high chemical resistance, or that will work well under hard vacuum, radiation, oxygen compatibility, cryogenic conditions, and exposure to flame.

Common Uses for DuPont™ Vespel®
Now that we have 10 considerations did you want to know what DuPont™ Vespel® is being used in? OK, we pretty much mentioned aerospace and military. But beyond that you can find Vespel in snowmobiles, ATV’s, farm equipment, and semiconductors. Since 1964 Vespel has been used in transmissions, small motors, brake pad assemblies, seal rings, valve seats, bushings, washers, thrust plugs, anti-lock break systems, fuel systems, turbo chargers, vacuum pumps, door hinge bushings, belt tensioners, gear stick rollers, rubbing blocks,wheel disc nuts, steering and air conditioning systems, suspension systems, intake and exhaust systems, piston rings. Handling of hot glass in manufacturing of bottles and hot runner systems in plastic packaging manufacturing are two more! In other words it’s pretty tried and true in a lot of applications. It may not be right for yours, but to find out see how many of your needs are in the top 10. After that if you need more detail on specific DuPont™ Vespel® products, take a look at the following links. They will take you to product technical data for each DuPont™ Vespel® material. If you don’t have the time to do all that comparing, give us a call and ask one of our people. We can help you determine if Vespel is right for you, and if so, which one fits your application best.

New Video Coming Soon!
Just a heads up…we’ve got a new video coming soon. Above we mentioned Vespel machines easily and in our video we will show just how easily DuPont™ Vespel® machines and we will offer some tips and tricks we’ve learned over the years that can help you get the best out of these materials.

Until Next Time!

Lisa Anderson

Marketing Manager

ThyssenKrupp Materials NA

AIN Plastics Division