UHMW-PE stands for Ultra High Molecular Weight Polyethylene. It is the highest quality polyethylene (PE) available, engineered for tough jobs and a wide range of applications. It delivers savings in a number of difficult applications. Ultra High Molecular Weight is the secret of this polymer’s unique properties. Its high-density polyethylene resin has a molecular weight range of 3 to 6 million, compared to 300,000 to 500,000 for high molecular weight (HMW) resins. That difference is what ensures that this material is strong enough to withstand abrasion and impact better than lower level poly products. UHMW-PE’s high molecular weight means it will not melt or flow as a molten liquid. Processing methods are therefore derived from those of powder metal technology. UHMW-PE cannot be transformed and molded by conventional plastic processing techniques (injection molding, blow molding or thermoforming). Compression molding is the most common conversion process used with this resin because it produces a stronger, more consistent product.
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TIVAR® is the brand name (from Poly-Hi) for a special formulation of ultra high molecular weight polyethylene (UHMW-PE). UHMW-PE is a unique family of high-density polyethylene with a molecular weight 3 million or higher. UHMW-PE is a high performance polymer with a high melt viscosity that can be extruded, fabricated or compression molded.
TIVAR® is an acronym for Tough Inert Very Abrasion Resistant.
TIVAR® is known for its high abrasion resistance, natural lubrication, high impact strength, chemical-, corrosion-, and moisture-resistance and acoustic impedance.
Due to its abrasion-, corrosion-, chemical- and moisture-resistant properties, TIVAR® is commonly used in applications where conditions may be too harsh for other materials. It is a cost-effective high performance polymer used to produce low cost, high quality parts.
In most cases, TIVAR® will out-wear materials such as Nylon, Teflon® or Acetal. It can also outperform metals such as steel and aluminum when used in the proper applications. Material performance is of course dependent on the specific environmental conditions.
UHMW is a self-lubricating material which exhibits excellent wear and abrasion properties as well as adding extremely high impact strength. A few of the markets which would utilize these attributes would be snowboard bottoms, package handling, packaging, food processing and automotive.
The high molecular weight is what gives UHMW-PE a unique combination of high impact strength efficient of friction and abrasion resistance that outwears carbon steel 10 to 1 making it more suitable for applications where lower molecular weight grades fail.
Yes, UHMW-PE is both FDA and USDA approved for use in food processing and medical applications.
There are three tests you can perform:
UHMW-PE can operate continuously up to 180 degrees F and intermittently at 200 degrees F with custom blends available to enhance the temperature range up to 300 degrees F. UHMW-PE can perform without degradation at extremely low temperatures (-452 degrees F).
The sustained high temperature use is 180 degrees F and the intermittent use is 200 degrees F.
Not for short times but for longer times above 200 degrees F it loses mechanical properties, abrasion and impact.
Water solutions are generally safe except highly oxidizing chemicals such as bleach. Hydrocarbons such as gasoline, kerosene, oil and grease cause swelling. Chlorinated solvents cause swelling. Organic alcohols, ketones and acids have little effect.
UHMW has no UL recognition. It would be HB on UL-1 – that is slow burning (less than 3″ per minute).
It is hard to tell – maybe some black or other colored specks might be present. The only way to determine is by a sand slurry test. After that test, it would tend to feel stiffer or harder. There may be some increase in modules. If the resin has been reprocessed many times, abrasion and impact resistance can greatly affected.
Yes, UHMW does not absorb water and is chemically inert.
UHMW has the highest abrasion resistance of any thermoplastic polymer. When used as a wear liner, UHMW will not cake or stick to metal. It also offers excellent noise abatement in material handling applications.
No, UHMW is a self-lubricating polymer and requires no additional lubrication.
Hydrogen and nitrogen don't affect it, but oxygen could.
UHMW manufacturers have done extensive research on numerous additives that can enhance a property of UHMW-PE thereby providing customized products to meet customer requirements.
Yes
No, only pigmented white (the standard, stock color) and black FDA can be made. For black, minimum order amounts would apply. Other colors would bleed out at higher temperatures, and therefore something you would want to avoid.
While natural (milky white) and black are standard stock colors, UHMW-PE can be produced in a variety of Pantone colors.
Although TIVAR® never actually melts, it will begin to lose its excellent properties at a temperature of 180 degrees F (82 degrees C). TIVAR® will generally perform very well down to cryogenic temperatures, but like other plastics, it will expand and contract with variations in temperatures.
UHMW can be manufactured in conductive or anti-static forms making it ideal for use in electronics and semi conductor applications.
In its natural state, UHMW-PE is not UV stable, but formulations are available to provide UV stability in natural, black or any custom color.
No, you can’t coat UHMW on because of two reasons: It does not melt to form a continuous surface.; It requires pressure to weld all the unmelted particles at high temperatures.
Yes, wear tape is a thin film of UHMW with adhesive backing than can be bonded to the surface.
UHMW can be made in films .003″ through .125″ thick in continuous coil from ¼” up to 24″ wide and cut to length in pieces and in stamped parts.
Tolerance levels are dependent on the manufacturing method and part design. Contact us for specific technical data.
If you want to learn more, please visit our website HDPE Wear Strips Supplier.
Yes, again the process is much like regular HDPE. Thick sections of UHMW may be more difficult than HDPE because of lower modules. If the plastic is softer, like UHMW, more attenuation of the ultrasonic energy occurs.
Yes, it behaves much like regular HDPE. The minimum temperature is 400 degrees F and the minimum pressure of 300 psi is highly recommended.
0.8%.
Not for most applications. The reason is the large difference between the coefficient of thermal expansion of metal and UHMW puts high stresses on the bond if the bond encounters temperature extremes.
There are two methods of adhering – the use of pressure sensitive systems (peel and stick) and allowing UHMW-PE to be bonded using epoxy systems or contact cements. A traditional metal mechanical fastening can also be used if preferred.
Bending or folding sheet can be done efficiently above the melt point at 300 degrees F. At that temperature, it shapes easily. However, it must be fastened in the bent or folded position until cooled.
The minimum UHMW thickness is usually 1/4″. The liner should be thicker in impact areas and thinner in slide areas. Important notes: UHMW cannot be firmly fastened to metals because of a large difference in thermal expansion. UHMW expands five times as fast as steel and three times as fast as aluminum and about the same as wood but slightly more than concrete.
Fasteners are the best way to secure UHMW to metal. The UHMW must be allowed to expand or float. Large flat head fasteners must be used. Fastener shaft holes in UHMW must be over-sized to allow for sheet expansion and contraction.
PE100 is the third generation of pipe grade PE.
It has an optimum balance of three key properties:
HDPE PE100 pipe is easy to install, light, flexible, corrosion-free and has a service life of up to 100 years. It can be jointed using butt fusion or electrofusion to create a leak-free pressure network for gas or water. For the trenchless applications butt fusion is most widely used because this results in a smooth exterior profile with no protrusions that might cause difficulties in pulling the pipe into the ground or host pipe.
Friction Co-efficients:
The properties ofHDPE PE100 pipe are determined at standard temperatures of 20°C or 23°C. These properties can be significantly affected by temperature, so at higher temperature the properties, including MRS, decrease. At higher temperatures it may be necessary to apply reduction factors to MRS, and consequently MOP. Some Codes and Standards define the reduction factors that must be applied; AWWA C901 and C906 for example. Otherwise there are standard reduction factors that can be applied in design. ISO: defines reduction factors to be applied to MOP at higher temperatures. These are shown below.
* ISO-1: Annex A states 0.62 for the reduction factor at 50°C
In the USA the Plastics Pipe Institute Handbook of Polyethylene Pipe Table A.2 includes the following reduction factors. The correlation with the ISO factors is clear. ISO: defines reduction factors to be applied to MOP at higher temperatures. These are shown below.
This is a consideration in wastewater rising/force mains in which there are solids transported with the water and pump operation sequences can result in solids rubbing along the pipe invert. PE100 & PE100-RC has the best abrasion resistance of the commonly used pressure pipe materials. This is illustrated in the Figure below.
The magnitude of wear depends on the angle of impingement and the type of material being eroded. At close to 90 degree impingement angles (impact abrasion), the erosive wear rate is highest in brittle materials and lowest in ductile materials. In ductile materials, the repeated impinging particles plastically deform the surface to generate wear debris. With brittle materials, the impingement causes particles of material to be fractured off as wear debris. Brittle materials are less wear resistant than ductile materials in an impact erosion condition. At low angles of impingement (abrasive erosion), the reverse is the case. Harder materials better resist the gouging or ploughing action of abrasive particle flow.
There is an approximate relationship between hardness and the ultimate strength of the material. The amount of abrasive wear decreases as the strength/hardness of the piping material increases. To resist abrasion, the piping system must be harder than the material being conveyed. The wear rates of various piping materials are often similar, so long as their hardness is greater than the slurry so selecting a pipe material considerably harder than the conveyed material offers no wear advantage and typically costs more. Conversely when the mineral is harder than the pipe, there is a very sudden and steep rise in the abrasive wear rate.
There are distinct types of wear experienced in a typical piping system. The straight sections most commonly experience abrasive erosion. Size transitions and directional changes experience both abrasive erosion and impact abrasion and should be designed with this in mind.
Design process for surge & fatigue loading ofHDPE PE100 pipe
In addition to conventionalHDPE PE100 pipe there are several variants that have been developed for specific applications.
RC indicates resistance to cracking. PE100-RC is a resin that has an increased stress crack resistance while maintaining the same MRS and rapid crack propagation resistance as conventional PE100. It is intended for use in more severe conditions and is especially suitable for trenchless methods. In Europe approximately 25% of PE100 usage in trenchless applications, both new installation and rehabilitation, is PE100-RC.
Certain gases and liquids can permeate through PE. Therefore whenHDPE PE100 pipe is laid in contaminated ground and the fluid in the pipe must be protected from contamination, for example when potable water is carried, then a barrier pipe is necessary. Barrier pipe is co-extruded with a barrier layer sandwiched between layers of PE100. The barrier layer is most commonly an aluminium foil but may also be a special polymer such as EVOH.
Image courtesy: GPS PE Pipe Systems
PE100 barrier pipes are made by several PE manufacturers. Examples are:
CoatedHDPE PE100 pipe has a co-extruded harder outer layer, usually of polypropylene, to protect the PE100 itself in installation conditions that are more severe. It is especially well suited to trenchless techniques such as directional drilling andpipe bursting where there may be a risk of damage to the pipe during installation. In certain coatedHDPE PE100 pipes, such as ProFuse, the outer layer is peelable to enable electrofusion couplings to be fused directly to the PE. This peelable layer has the additional benefit of keeping the PE surface clean for electrofusion.
Image courtesy: RADIUS SYSTEMS
Coated PE100 pipes are made by several manufacturers. Examples are:
Co-extrusion of PE100 enables several additional pipe variants to be manufactured, often with several layers each with a different function. These include internal coatings, internal and external coatings, and conducting layers or strips for leak monitoring or pipe detection. Pipes with detection layers or strips have some application in trenchless installation because methods such as directional drilling do not permit warning marker tapes to be buried above the pipe.
Several manufacturers have particular multi-layer HDPE PE100 pipes and can provide further information.
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