UHMW (Ultra High Molecular Weight Polyethylene) and PTFE Sheet(PolyTetraFlouroEthylene) are very similar materials, and yet very different at the same time. They both possess certain characteristics that make them similar to each other. For instance, they both have a very low co-efficient of friction, which means they are great for sliding applications and are easy to machine.
Both of these materials are very resistant to chemicals such as chlorine and some acids and have great wear resistance. They have low to no water absorption. They also are FDA approved for handling food. PTFE and UHMW Polyethylene are both nearly impossible to bond (without treatment) and are susceptible to sagging under tensile load which is called ‘creep’. These both have very low coefficient of friction and work well for wear strips, slide pads and truck liners to make it easy to empty. These two materials are different in many ways also, and choosing between the two materials for a specific job is critical.
Below are a few examples of how these two materials are different.
1. UHMW is a polyolefin and PTFE is a fluoropolymer. Polyolefins are double bonded carbon while Fluoropolymers are carbon and fluorine bonded. UHMW is a monomer which is consisted of one atom that will bond with another to form a polymer. PTFE is a polymer which is made up of a repeating chain of monomers.
2. PTFE has a higher temperature range than UHMW. The PTFE has a continuous use temperature of 500 degrees F. UHMW is much lower with a continuous use temperature of 200 degrees F and a melting point of 271 degrees F. The UHMW starts to become become soft at higher temperatures while the PTFE is much more resistant and with a melting point of 621 degrees F.
3. UHMW has higher abrasion resistance than PTFE. Both have great impact and wear resistance but because of UHMW having a molecular weight between 2-6 million making it the best wear resistance material in the plastic family, it makes it ideal to take wear and impact over a wider range and longer period of time without losing its properties.
4. UHMW has a much lower density than PTFE. This makes UHMW able to float in water while Fluoropolymers are significantly heavier (almost twice the density of UHMW) and would sink.
5. PTFE has excellent electrical and thermal properties. The virgin grade of PTFE is a better insulator and exhibits better electrical properties which can be used in radio frequencies, cables and circuit boards while UHMW cannot.
6. UHMW is much less expensive than the Fluoropolymers. Especially recently, PTFE has become harder to come by, and during the last 18 months there has been a global shortage of a key raw material called fluorspar that is used to make all Fluoropolymer materials. The ability to take lots of wear and tear and requiring low long term maintenance makes UHMW more cost effective.
7. The standard color of PTFE is Natural, which is a dense white. The UHMW comes in Natural (a deep milky white) or Black. The UHMW can be produced in many colors, and minimums are rather low. To obtain PTFE in colors is much more difficult, and would also have large minimum orders.
Click here for data sheet comparisons for each material…
Both the UHMW and the PTFE are available as sheet, sheets, sheeting, slab, bar, strip, panels, film, round rod, rods and block. Contact us for assistance with these or other shapes.
PTFE Sheeting Properties
Specific Gravity D792 2.14 – 2.24
Tensile Strength Yield D638 2,500 – 6,000
Tensile Modulus D638 80,000
Izod Impact – Notched D256 3.0
Hardness – Rockwell D785 D50 – D65
Deflection Temp @ 264psi D648 150
Deflection Temp @ 66 psi D648 250
Co. Thermal Expansion D696 5.5X10-5
UHMW Sheeting Properties
Specific Gravity D792 .93 – .94
Tensile Strength Yield D638 6,800
Coefficient of Friction – Static D1894 .25
Izod Impact – Notched D256 No Break
Hardness – Rockwell D785 R64
Vicat Softening Temp D1525 260
Deflection Temp @ 66 psi D648 174
Co. Thermal Expansion D696 11.0X10-5
These are just some examples of plastic materials being similar, and yet having very different properties. The PTFE Sheet and UHMW Sheet may appear very similar in color and can be used for some of the same applications, but when needed for a specific use or property needed, one might be dramatically better than the other. As the old saying goes, “You should never judge a book by its cover” and the same is true with plastic. Review the properties and test prior to choosing a final material for your application.
The Nylon® Family of plastics are all very tough, strong, machine well, and have excellent wear properties. Nylon is a very popular plastic material, and is found in numerous applications. One of the largest usages is the production of household carpeting because of the excellent wear resistance. Nylon frequently replaces materials such as UHMW, PET, Acetal Copolymer – Acetal Homopolymer, and ABS. It will outwear most plastics and is self lubricating.
The wide variety of types and colors is one of the largest in the plastic industry.
Nylon® Type 6/6 Rod, Sheet and Plate
The extruded Nylon 6/6 (Nylon Rod, Nylon Sheets and NylonTubes) material (aka: Polyhexamethylene Adiptimide) is available as Natural (tan – straw), Black, Glass filled (medium tan) and a molybdenum disulphide filled which is very dark gray. The most common size range for the extruded Nylon 6/6 is .125″ – 4.0″ diameter rod, and .125″ – 4.0″ thick sheet. The thicker materials should be cast due to cost and stress issues. For addition details on the Nylon Rod and Sheet 6/6 – see the data sheet.
Nylon Type 6 Cast Polycaprolactam
Cast Nylon Type 6 Rod – 26″ OD X 8.0″ Thick
The cast Nylon type 6 has almost limitless possibilities. Many colors are available in Cast Nylon, the natural color, black, blue, dark gray (normally molybdenum disulphide filled again), green and many more. Sometimes the color is determined by the additive (oil filled) or by industry. Because of its relative ease of manufacture, many companies prefer to get their Nylon in a special color to help ‘brand’ their parts.
Cast Type 6 Polyamide can be made in Nylon rod from about 1.25″ diameter to almost any size. Nylon sheet normally starts at about .75″ thickness, and once again, can be made to almost any thickness. In addition to standard rod and plate, other sizes and shapes can be cast from Nylon Type 6 – ie. discs, tubes, near net shapes, large profiles, etc. The only limitations are how much money you have, and the size of the truck to get it to you! We have had cast very large blocks (11″ X 11″ X 48″ solid), sheaves up to 66″ OD, large tubes 36″OD X 12″ ID X 14″ long, and many more massive Nylon Cast parts.
Nylon 6/12 -Low Moisture Absorption
The claim to fame for the Nylon Type 6/12 is the low moisture absorption of the material. This grade of Nylon Sheet and Nylon rod is more stable that the type 6 or 6/6, and with the lower water absorption, this resin can handle a wider range of environments. Our manufacturer partners can run this as an Extruded Nylon Rod or Nylon sheet item or as a Cast Nylon Rod item. This opens the door to a wide range of sizes and shapes. This material exhibits most of the same properties of the Nylon 6/6 and Cast Type 6, with some slight improvements in key properties.
Filled Grades of Nylon
Because of the processing of Cast Nylon, many additives can be mixed into the material. The most common are: glass filled, oil filled, Kevlar fiber filled (Hydlar Z) and the molybdenum disulphide (M0S2). In addition, other fills and colorants (pigments) can be added to assist in manufacture or processing.
Common specifications for Nylon are: L-P-410, ASTM D-4066,L-P-395C, Mil-M-20693B Comp A, Ty I, IA, II and III, Mil-M-20693B Comp B, Ty 4, Mil-P-17091B Type 1, and Mil-P-46060, PA0613, ASTM D-5989 S-PA0511, and more.
Before buying your next big chunk of Nylon, contact us for information on the benefits of a filled or near netshape Cast Nylon part.
Contact us with your specifications, we look forward to assisting you.
When we think of plastic, we think of plastic bags you get at the grocery store or maybe your child’s toy that’s made out of cheap throw away material. If you stop and think about it, plastic is everywhere and it’s uses are almost infinite. Take Acetal Copolymer, it is a plastic that replaces metal in numerous applications and is used to make gears, screws and other hard working parts. Consider PTFE for instance which is used to coat your frying pan to make it non-stick, make steam valves and fittings, and chemical resistant parts. Another material is Polycarbonate or Lexan® (a SABIC brand name -formerly G.E. Plastics) which is used to replace glass because it is shatter resistant and is also used for bullet resistant glazing and riot shields. Even the cup of coffee you grab for every morning is made of foamed Styrene – Styrofoam. But plastic has shaped our lives in countless ways, many of them you might not even think of or notice.
Plastics play a big part in the world of medicine. Some other advancements in the area of medicine include assisting people with debilitating injuries and serious afflictions, helping them feel more comfortable and move easier. Prosthetic limbs and joint replacements have come along way since the old days of metal and wood. Since the late 90’s UHMW or (Ultra High Molecular Weight Polyethylene) has become the standard in hip and joint replacements. With plastics like UHMW, which has great wear resistance, excellent strength and very low co-efficient of friction (very slippery), it has made people who need these surgeries have better mobility and better quality of life. These plastics also make prosthetic limbs lighter and stronger for athletes who wish to compete and lead near normal active lifestyles due to the use of plastic polymers (derived from the Greek meaning ‘many parts’) mimicking human flexibility. Prosthetic devices date all the way back to the ancient Egyptians where they used leather and wood for toe and foot replacements. But thanks to today’s technologies and advancements in as plastic, most amputees and athletes can regain their quality of life and enabling them to do what they love.
What has Medical Plastic Done For You Lately?
Another plastic material that has changed the medical field is PEEK (Polyetheretherketone). This material is a newer plastic which has high chemical resistance along with excellent high continuous temperature resistance of up to 480 degrees fahrenheit. PEEK has replaced many metal devices in the medical field, because PEEK is one of the only thermoplastics (plastic which can be bent or shaped) able to withstand high doses of radiation over an extended lifetime. In addition PEEK is used to help many people awaiting kidney transplants because it is used to make a critical component in dialysis machines. These machines need to clean the blood over a period of several hours and because of this, PEEK is the natural solution, as it can be steam cleaned time and time again with little effect on the material. Along with its great chemical, temperature, and fluid handling stability, PEEK is USP Class VI, making it ideal for these types of medical applications. The natural color of PEEK is a beige to tan and is available in sheet and rod. One of the largest manufacturers of PEEK resin is Victrex and their 450G resin.
Plastics In Medicine – Everyday
Plastic materials have become apart of our lives and has changed the way we take care of the sick and injured, how we protect our foods from germs, and prolong the storage of foods. Plastics protect medical instruments and insure they are sterile. It has made people’s lives better in both the short and long term. It has helped reduce pain, gain better movement and has given people their confidence back. The values of plastic can not be understated and in the future, hopefully plastics will save or prolong many more lives through advancements in technology and the limitless possibilities it presents.
For more information on these and other medical grade plastics like: Clear Nylon (look for blog post on this), Ultem, Polysulfone, Radel and more, contact us. E-mail us or call 866-832-9315