When to Use Uhmwpe Plastics Plates?

12 May.,2025

 

Which UHMW Properties Are Best for You? - Slideways Inc.

UHMW (ultra high molecular weight polyethylene) plastic is the choice material for conveyors and packaging machinery. Its unique properties, ease of fabrication, and low-cost make it the optimal selection for this industry. Its ability to handle abrasion, impact, corrosive cleaning solutions, and wet environments enables UHMW to stand up to extensive wear and tear. Additionally, its dampening properties reduce conveyor noise and vibration. Made in large sheets for big or long parts, UHMW machines easily and can be extruded into complex profiles with thick or thin cross-sections. All these attributes make UHMW a great option for machine builders and maintenance personnel that are concerned with price, extending the life of initial installations, and repairs.

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Though it seems like the perfect material, applications can cross the performance limits of Natural UHMW. Conveyor speeds are faster than ever putting more heat and stress on wear strips.  Fortunately, UHMW is a great foundation to build upon. Additives can be blended with the UHMW resin that address heat, static, speed, load, and other operating conditions. Other specialized UHMW materials can be recognized by x-ray and metal detectors to protect food manufacturers from recalls. There is even UV-resistant UHMW for outdoor applications.

Here are the most common UHMW properties found in conveyors and packaging machinery:

1. Natural UHMW

  • The base material
  • Color: White   
  • FDA Compliant? Yes
Typical applications: Corner and Straight Tracks for flat top chain, chain guides, belt guides, pulleys, bearings, and custom machined components.

2. Repro (Reprocessed) UHMW

  • Contains 50% recycled UHMW
  • Color: Black or Green, may have multi-colored flecks  
  • FDA Compliant? No

Typical applications: Same as Natural UHMW, no additional attributes.

3. High-Temp UHMW (HT-UHMW)

  • Increases the maximum operating temperature from 180°F for Natural UHMW to 280°F
  • Color: White  
  • FDA Compliant? Yes

Typical applications: High-Temp UHMW is great for conveyor sections near ovens, steam tunnels, heat shrink tunnels, and anywhere heat will reduce the wear resistance of other plastics. HT-UHMW has been machined into components, chain guides, and SlideTrax plastic chain tracks for flat-top chain. Before High-Temp UHMW was available, Nylon could get you to a max operating temp of 220°F with Teflon being the next choice at 500°F. However, compared to UHMW, Teflon has a 10X price premium and not nearly the wear resistance or compressive strength of UHMW.

4. Oil-Filled UHMW

  • Reduces friction with fluid lubricant throughout the plastic 
  • Color: Gray   
  • FDA Compliant? Yes
Typical applications: Used in areas of conveyors that see higher speeds or additional pressure such as bearings and corner tracks since these sections can benefit from additional lubrication. Lubricant is homogeneously dispersed throughout the UHMW, so when parts are machined or become worn down, fresh lubrication is exposed at the surface.

5. Lub-X® C

  • Reduces friction with a dry lubricant dispersed throughout the plastic 
  • Color: Light Blue   
  • FDA Compliant? Yes
Typical Applications: We recommend this material for conveyors with multiple turns or tight radii and for areas of conveyors seeing higher speeds and loads. It has a very low coefficient of friction vs. acetal. This makes Lub-X® C an excellent choice for Slidetrax chain track curves where an acetal-based flat-top chain is being used. Since the lubricant is dry as opposed to wet, it will not attract dust making it suitable for areas where there is no washdown.

6. Glass-Bead Filled UHMW

  • Glass-beads increase the surface hardness of UHMW 
  • Color: Lime Green or Dark Blue   
  • FDA Compliant? No

Typical Applications: This material is most often used in facilities that bottle in glass and in abrasive applications like cement block plants. The increased surface hardness reduces the embedment of abrasive particles that could increase the wear rates of mating parts such as belts or chains. The glass content also increases the load capacity of the UHMW.

7. Electro-Static Dissipative (ESD UHMW)

  • Relieves conveyors of static charge 
  • Color: Black 
  • FDA Compliant? No

Typical Applications: ESD UHMW wear strips are a good way to relieve static charge from a conveyor system. This material has carbon throughout the material to move the charge to ground. V-belt and round belt guides are often made of this material.

8. Clean-Stat™ UHMW

  • This is an ESD UHMW that is food safe  
  • Color: White     
  • FDA Compliant? Yes
Typical Applications: Excellent for chutes where dry, dusty foods like breakfast cereals and grains need to be transported in bulk. Clean-Stat™ material will keep loads sliding smoothly with no static build-up.

9. UV-Stabilized UHMW

  • Provides 3X longer life in direct sunlight as compared to Natural UHMW
  • Color: Black  
  • FDA Compliant? No

Typical Applications: For use on outdoor conveyor systems and agricultural applications. A recent application was a conveyor bringing inner-tubes to the top of a tall waterslide.

Detectable UHMWs

The next three detectable UHMW properties have become commonplace for food safety applications. Detectable materials are targeted towards applications that come into direct contact with food or food packaging. All three of these UHMW materials can reduce the risk of food contaminated with plastic particles being shipped to customers eliminating a recall before it happens.

10. Blue Virgin UHMW

  • For visual detection of plastic particles during food processing
  • Color: Blue   
  • FDA Compliant? Yes
Typical Applications: This material is used for return rollers, wear strips, belt supports, and belt guides. The blue color makes it visually detectable in food products.

11. Metal-Detectable UHMW

  • Metal content in this UHMW allows metal detectors to sense particles as small as 3mm cubes
  • Color: Dark Blue    
  • FDA Compliant? Yes

Typical Applications: Metal-Detectable UHMW is optimal for use around bulk and packaged food including conveyor components, wear strips, belt scrapers, or other parts that may break over time creating particles that can contaminate food. This material cannot be detected in metal packaging.

12. X-Ray Detectable UHMW

  • Contains x-ray detectable fillers that can be picked up by x-ray machines in particles as small as 3mm cubes
  • Color: Blue    
  • FDA Compliant? Yes


Typical Applications: This technology can be used to find plastic contamination even inside metal containers, so it is most often used for packaged foods. Applications for x-ray detectable UHMW include conveyor components, mixer paddles, wear strips, and belt scrapers or other parts that may break over time causing particles that can contaminate food.

UHMW properties are versatile and are well-suited for packaging machinery and conveyor applications. The next time you have a challenging application that is beyond the performance limits of Natural UHMW, consider one of the other formulations. The right choice of material will reduce friction and increase the usable life of your machinery.

Ultra-high-molecular-weight polyethylene - Wikipedia

Very long-chain polyethylene with high impact strength

Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass usually between 3.5 and 7.5 million amu.[1] The longer chain serves to transfer load more effectively to the polymer backbone by strengthening intermolecular interactions. This results in a very tough material, with the highest impact strength of any thermoplastic presently made.[2]

UHMWPE is odorless, tasteless, and nontoxic.[3] It embodies all the characteristics of high-density polyethylene (HDPE) with the added traits of being resistant to concentrated acids and alkalis, as well as numerous organic solvents.[4] It is highly resistant to corrosive chemicals except oxidizing acids; has extremely low moisture absorption and a very low coefficient of friction; is self-lubricating (see boundary lubrication); and is highly resistant to abrasion, in some forms being 15 times more resistant to abrasion than carbon steel. Its coefficient of friction is significantly lower than that of nylon and acetal and is comparable to that of polytetrafluoroethylene (PTFE, Teflon), but UHMWPE has better abrasion resistance than PTFE.[5][6]

Development

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Polymerization of UHMWPE was commercialized in the s by Ruhrchemie AG,[1][7] which has changed names over the years. Today UHMWPE powder materials, which may be directly molded into a product's final shape, are produced by Braskem, Teijin (Endumax), Celanese, and Mitsui. Processed UHMWPE is available commercially either as fibers or in consolidated form, such as sheets or rods. Because of its resistance to wear and impact, UHMWPE continues to find increasing industrial applications, including the automotive and bottling sectors. Since the s, UHMWPE has also been the material of choice for total joint arthroplasty in orthopedic and spine implants.[1]

UHMWPE fibers branded as Dyneema, commercialized in the late s by the Dutch chemical company DSM, and as Spectra, commercialized by Honeywell (then AlliedSignal), are widely used in ballistic protection, defense applications, and increasingly in medical devices, protective motorcycling gear, sailing, hiking equipment, climbing, and many other industries.

Structure and properties

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UHMWPE is a type of polyolefin. It is made up of extremely long chains of polyethylene, which all align in the same direction. It derives its strength largely from the length of each individual molecule (chain). Van der Waals forces between the molecules are relatively weak for each atom of overlap between the molecules, but because the molecules are very long, large overlaps can exist, adding up to the ability to carry larger shear forces from molecule to molecule. Each chain is attracted to the others with so many van der Waals forces that the whole of the inter-molecular strength is high. In this way, large tensile loads are not limited as much by the comparative weakness of each localized van der Waals force.

When formed into fibers, the polymer chains can attain a parallel orientation greater than 95% and a level of crystallinity from 39% to 75%. In contrast, Kevlar derives its strength from strong bonding between relatively short molecules.

The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers. Its melting point is around 130 to 136 °C (266 to 277 °F),[8] and, according to DSM, it is not advisable to use UHMWPE fibres at temperatures exceeding 80 to 100 °C (176 to 212 °F) for long periods of time. It becomes brittle at temperatures below −150 °C (−240 °F).[9]

The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, nor wet easily, which makes bonding it to other polymers difficult. For the same reasons, skin does not interact with it strongly, making the UHMWPE fiber surface feel slippery. In a similar manner, aromatic polymers are often susceptible to aromatic solvents due to aromatic stacking interactions, an effect aliphatic polymers like UHMWPE are immune to. Since UHMWPE does not contain chemical groups (such as esters, amides, or hydroxylic groups) that are susceptible to attack from aggressive agents, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms.

Under tensile load, UHMWPE will deform continually as long as the stress is present—an effect called creep.

When UHMWPE is annealed, the material is heated to between 135 and 138 °C (275 and 280 °F) in an oven or a liquid bath of silicone oil or glycerine. The material is then cooled down to 65 °C (149 °F) at a rate of 5 °C/h (9 °F/h) or less. Finally, the material is wrapped in an insulating blanket for 24 hours to bring to room temperature.[10]

Production

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Ultra-high-molecular-weight polyethylene (UHMWPE) is synthesized from its monomer ethylene, which is bonded together to form the base polyethylene product. These molecules are several orders of magnitude longer than those of familiar high-density polyethylene (HDPE) due to a synthesis process based on metallocene catalysts, resulting in UHMWPE molecules typically having 100,000 to 250,000 monomer units per molecule each compared to HDPE's 700 to 1,800 monomers.

UHMWPE is processed variously by compression moulding, ram extrusion, gel spinning, and sintering. Several European companies began compression molding UHMWPE in the early s. Gel-spinning arrived much later and was intended for different applications.

In gel spinning a precisely heated gel (of a low concentration of UHMWPE in an oil) is extruded through a spinneret. The extrudate is drawn through the air, the oil extracted with a solvent which does not affect the UHMWPE, and then dried removing the solvent. The end-result is a fiber with a high degree of molecular orientation, and therefore exceptional tensile strength. Gel spinning depends on isolating individual chain molecules in the solvent so that intermolecular entanglements are minimal. Entanglements make chain orientation more difficult, and lower the strength of the final product.[11]

Applications

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Fiber

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Dyneema and Spectra are brands of lightweight high-strength oriented-strand gels spun through a spinneret. They have yield strengths as high as 2.4 GPa (350,000 psi) and density as low as 0.97 g/mL (0.035 lb/cu in) (for Dyneema SK75).[12] High-strength steels have comparable yield strengths, and low-carbon steels have yield strengths much lower (around 0.5 GPa (73,000 psi)). Since steel has a specific gravity of roughly 7.8, these materials have a strength-to-weight ratios eight times that of high-strength steels. Strength-to-weight ratios for UHMWPE are about 40% higher than for aramid. The high qualities of UHMWPE filament were discovered by Albert Pennings in , but commercially viable products were made available by DSM in and Southern Ropes soon after.[13]

Derivatives of UHMWPE yarn are used in composite plates in armor, in particular, personal armor and on occasion as vehicle armor. Civil applications containing UHMWPE fibers are cut-resistant gloves, tear-resistant hosiery, bow strings, climbing equipment, automotive winching, fishing line, spear lines for spearguns, high-performance sails, suspension lines on sport parachutes and paragliders, rigging in yachting, kites, and kite lines for kites sports.

For personal armor, the fibers are, in general, aligned and bonded into sheets, which are then layered at various angles to give the resulting composite material strength in all directions.[14][15] Recently developed additions to the US Military's Interceptor body armor, designed to offer arm and leg protection, are said to utilize a form of UHMWPE fabric.[16] A multitude of UHMWPE woven fabrics are available in the market and are used as shoe liners, pantyhose,[17] fencing clothing, stab-resistant vests, and composite liners for vehicles.[18]

The use of UHMWPE rope for automotive winching offers several advantages over the more common steel wire rope. The key reason for changing to UHMWPE rope is improved safety. The lower mass of UHMWPE rope, coupled with significantly lower elongation at breaking, carries far less energy than steel or nylon, which leads to almost no snap-back. UHMWPE rope does not develop kinks that can cause weak spots, and any frayed areas that may develop along the surface of the rope cannot pierce the skin like broken steel wire strands can. UHMWPE rope is less dense than water, making water recoveries easier as the recovery cable is easier to locate than wire rope. The bright colours available also aid with visibility should the rope become submerged or dirty. Another advantage in automotive applications is the reduced weight of UHMWPE rope over steel cables. A typical 11 mm (0.43 in) UHMWPE rope of 30 m (98 ft) can weigh around 2 kg (4.4 lb), the equivalent steel wire rope would weigh around 13 kg (29 lb). One notable drawback of UHMWPE rope is its susceptibility to UV damage, so many users will fit winch covers in order to protect the cable when not in use. It is also vulnerable to heat damage from contact with hot components.

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Spun UHMWPE fibers excel as fishing line, as they have less stretch, are more abrasion-resistant, and are thinner than the equivalent monofilament line.

In climbing, cord and webbing made of combinations of UHMWPE and nylon yarn have gained popularity for their low weight and bulk. They exhibit very low elasticity compared to their nylon counterparts, which translates to low toughness. The fiber's very high lubricity causes poor knot-holding ability, and it is mostly used in pre-sewn 'slings' (loops of webbing)—relying on knots to join sections of UHMWPE is generally not recommended, and if necessary it is recommended to use the triple fisherman's knot rather than the traditional double fisherman's knot.[19][20]

Ships' hawsers and cables made from the fiber (0.97 specific gravity) float on sea water. "Spectra wires" as they are called in the towing boat community are commonly used for face wires [21] as a lighter alternative to steel wires.

It is used in skis and snowboards, often in combination with carbon fiber, reinforcing the fiberglass composite material, adding stiffness and improving its flex characteristics.[clarification needed] The UHMWPE is often used as the base layer, which contacts the snow, and includes abrasives to absorb and retain wax.[clarification needed]

It is also used in lifting applications, for manufacturing low weight, and heavy duty lifting slings. Due to its extreme abrasion resistance it is also used as an excellent corner protection for synthetic lifting slings.

High-performance lines (such as backstays) for sailing and parasailing are made of UHMWPE, due to their low stretch, high strength, and low weight.[22] Similarly, UHMWPE is often used for winch-launching gliders from the ground, as, in comparison with steel cable, its superior abrasion resistance results in less wear when running along the ground and into the winch, increasing the time between failures. The lower weight on the mile-long cables used also results in higher winch launches.

UHMWPE was used for the 30 km (19 mi) long, 0.6 mm (0.024 in) thick space tether in the ESA/Russian Young Engineers' Satellite 2 of September, .[23]

Dyneema composite fabric (DCF) is a laminated material consisting of a grid of Dyneema threads sandwiched between two thin transparent polyester membranes. This material is very strong for its weight, and was originally developed for use in racing yacht sails under the name 'Cuben Fiber'. More recently it has found new applications, most notably in the manufacture of lightweight and ultralight camping and backpacking equipment such as tents, backpacks, and bear-proof food bags.

In archery, UHMWPE is widely used as a material for bowstrings because of its low creep and stretch compared to, for example, Dacron (PET).[citation needed] Besides pure UHMWPE fibers, most manufacturers use blends to further reduce the creep and stretch of the material. In these blends, the UHMWPE fibers are blended with, for example, Vectran.

In skydiving, UHMWPE is one of the most common materials used for suspension lines, largely supplanting the earlier-used Dacron, being lighter and less bulky.[citation needed] UHMWPE has excellent strength and wear-resistance, but is not dimensionally stable (i.e. shrinks) when exposed to heat, which leads to gradual and uneven shrinkage of different lines as they are subject to differing amounts of friction during canopy deployment, necessitating periodic line replacement. It is also almost completely inelastic, which can exacerbate the opening shock. For that reason, Dacron lines continue to be used in student and some tandem systems, where the added bulk is less of a concern than the potential for an injurious opening. In turn, in high-performance parachutes used for swooping, UHMWPE is replaced with Vectran and HMA (high-modulus aramid), which are even thinner and dimensionally stable, but exhibit greater wear and require much more frequent maintenance to prevent catastrophic failure. UHMWPE are also used for reserve parachute closing loops when used with automatic activation devices, where their extremely low coefficient of friction is critical for proper operation in the event of cutter activation.

Medical

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UHMWPE has a clinical history as a biomaterial for use in hip, knee, and (since the s), for spine implants.[1] An online repository of information and review articles related to medical grade UHMWPE, known as the UHMWPE Lexicon, was started online in .[24]

Joint replacement components have historically been made from "GUR" resins. These powder materials are produced by Ticona, typically converted into semi-forms by companies such as Quadrant and Orthoplastics,[1] and then machined into implant components and sterilized by device manufacturers.[25]

UHMWPE was first used clinically in by Sir John Charnley and emerged as the dominant bearing material for total hip and knee replacements in the s.[24] Throughout its history, there were unsuccessful attempts to modify UHMWPE to improve its clinical performance until the development of highly cross-linked UHMWPE in the late s.[1]

One unsuccessful attempt to modify UHMWPE was by blending the powder with carbon fibers. This reinforced UHMWPE was released clinically as "Poly Two" by Zimmer in the s.[1] The carbon fibers had poor compatibility with the UHMWPE matrix and its clinical performance was inferior to virgin UHMWPE.[1]

A second attempt to modify UHMWPE was by high-pressure recrystallization. This recrystallized UHMWPE was released clinically as "Hylamer" by DePuy in the late s.[1] When gamma irradiated in air, this material exhibited susceptibility to oxidation, resulting in inferior clinical performance relative to virgin UHMWPE. Today, the poor clinical history of Hylamer is largely attributed to its sterilization method, and there has been a resurgence of interest in studying this material (at least among certain research circles).[24] Hylamer fell out of favor in the United States in the late s with the development of highly cross-linked UHMWPE materials, however negative clinical reports from Europe about Hylamer continue to surface in the literature.

Highly cross-linked UHMWPE materials were clinically introduced in and have rapidly become the standard of care for total hip replacements, at least in the United States.[1] These new materials are cross-linked with gamma or electron beam radiation (50–105 kGy) and then thermally processed to improve their oxidation resistance.[1] Five-year clinical data, from several centers, are now available demonstrating their superiority relative to conventional UHMWPE for total hip replacement (see arthroplasty).[24] Clinical studies are still underway to investigate the performance of highly cross-linked UHMWPE for knee replacement.[24]

In , manufacturers started incorporating anti-oxidants into UHMWPE for hip and knee arthroplasty bearing surfaces.[1] Vitamin E (a-tocopherol) is the most common anti-oxidant used in radiation-cross-linked UHMWPE for medical applications. The anti-oxidant helps quench free radicals that are introduced during the irradiation process, imparting improved oxidation resistance to the UHMWPE without the need for thermal treatment.[26] Several companies have been selling antioxidant-stabilized joint replacement technologies since , using both synthetic vitamin E as well as hindered phenol-based antioxidants.[27]

Another important medical advancement for UHMWPE in the past decade has been the increase in use of fibers for sutures. Medical-grade fibers for surgical applications are produced by DSM under the "Dyneema Purity" trade name.[28]

Manufacturing

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UHMWPE is used in the manufacture of PVC (vinyl) windows and doors, as it can endure the heat required to soften the PVC-based materials and is used as a form/chamber filler for the various PVC shape profiles in order for those materials to be 'bent' or shaped around a template.

UHMWPE is also used in the manufacture of hydraulic seals and bearings. It is best suited for medium mechanical duties in water, oil hydraulics, pneumatics, and unlubricated applications. It has a good abrasion resistance but is better suited to soft mating surfaces.

Wire and cable

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Fluoropolymer / HMWPE insulation cathodic protection cable is typically made with dual insulation. It features a primary layer of a fluoropolymer such as ethylene-chlorotrifluoroethylene (ECTFE) which is chemically resistant to chlorine, sulfuric acid, and hydrochloric acid. Following the primary layer is an HMWPE insulation layer, which provides pliable strength and allows considerable abuse during installation. The HMWPE jacketing provides mechanical protection as well.[29]

Marine infrastructure

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UHMWPE is used in marine structures for the mooring of ships and floating structures in general. The UHMWPE forms the contact surface between the floating structure and the fixed one. Timber was and is used for this application also. UHMWPE is chosen as facing of fender systems for berthing structures because of the following characteristics:[30]

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  • Wear resistance: best among plastics, better than steel
  • Impact resistance: best among plastics, similar to steel
  • Low friction (wet and dry conditions): self-lubricating material

See also

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  • Low-density polyethylene (LDPE)
  • Medium-density polyethylene (MDPE)
  • Twaron
  • IPX Ultra-high-molecular-weight polyethylene

References

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Further reading

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  • Southern et al., The Properties of Polyethylene Crystallized Under the Orientation and Pressure Effects of a Pressure Capillary Viscometer, Journal of Applied Polymer Science vol. 14, pp. – ().
  • Kanamoto, On Ultra-High Tensile by Drawing Single Crystal Mats of High Molecular Weight Polyethylene, Polymer Journal vol. 15, No. 4, pp. 327–329 ().