What is UHMW-PE (Ultra High Molecular Weight Polyethylene) and Why is Crown Plastics Unique?
First, UHMW Polymer is incredibly slick, it is used to reduce friction and wear on parts, as well as to eliminate operation noise and energy use in thousands of applications. It is a Linear Polyethylene with a molecular weight in the range of 3,000,000 to 6,000,000. This value represents the “average molecular weight”. Therefore, UHMW Polymers have a molecular weight average 10 times that of conventional high density polyethylene resins. The higher molecular weight is what gives UHMW Polymers a unique combination of characteristics making it more suitable for many applications where lower molecular weight grades fail.
Second, Why Crown? While UHMW-PE has great advantages, its biggest disadvantage is that it is very difficult to produce. It will not melt in a traditional sense, it must be sintered under great pressure and temperature requirements. Having no melt-flow point, Crown Plastics utilizes the world’s only true continuous compression molding process to heat, compress and cool the UHMW directly to thickness in a continuous flow. This allows for long continuous rolls with low stress and tight tolerance. Crown also mixes resin in many different ways to meet customer needs. Special mixes of colors, Silicone and many other combinations are made daily.
Peel and stick! After producing the UHMW-PE to specific requirements, Crown Plastics has also mastered the art of surface treatment of UHMW thereby transforming UHMW into a material or coating that is highly bondable. UHMW can be supplied from Crown Plastics with a pressure sensitive adhesive system (peel and stick) or one side abraded for use with contact cements or epoxies. These options eliminate the need for mechanical fastening and open up unlimited application opportunities for UHMW. UHMW (Ultra High Molecular Weight Polyethylene) coatings, sheet, tape, and wear strips
The incredible durability and versatility Crown’s manufacturing and use of UHMW-PE makes it a favorite among engineers and designers in nearly every industry worldwide. UHMW-PE’s long molecular chain gives it a host of exceptional attributes: high abrasion resistance, low coefficient of friction and unparalleled impact resistance, even in cryogenic environments.
UHMW-PE’s molecular weight ranges from a low of 3.1 million to as high as 10 million. While impact strength is maximized at 3.5 – 4 million, abrasion resistance continues to improve as the molecular weight increases.
UHMW-PE is the ideal solution for reducing wear and friction and enhancing efficiency and productivity in automotive and railroad applications, in agriculture, medical, printing and packaging applications, and in material handling and food processing.
UHMW-PE has no melt-flow point, so Crown Plastics utilizes the world’s only true continuous compression molding process to heat, compress and cool the UHMW directly to thickness in a continuous flow. This allows for long continuous rolls with low stress and tight tolerance.
Crown Plastics has also mastered the art of surface treatment of UHMW thereby transforming UHMW into a material or coating that is highly bondable. UHMW can be supplied from Crown Plastics with a pressure sensitive adhesive system (peel and stick) or one side abraded for use with contact cements or epoxies. These options eliminate the need for mechanical fastening and open up unlimited application opportunities for UHMW.
Just a few of the advantages of Crown Plastics Products:
- The highest abrasion resistance of any thermoplastic polymer
- Outstanding impact strength even at very low temperatures
- An excellent sliding material due to the low coefficient of friction
- Self-lubricating (non-caking and sticking)
- Sound dampening properties
- Good chemical and stress cracking resistance
- Easily machined
- Electrical insulating material (static reduced available)
- FDA and USDA approved
Crown stocks a wide variety of pressure sensitive adhesives to accommodate nearly every imaginable application.
Crown’s pressure sensitive adhesive systems include: rubber adhesives for UHMW, and acrylic adhesives for UHMW.
Rubber based pressure sensitive adhesive systems typically offer the highest adhesion and shear properties in comparison to acrylic or silicone, are best in indoor applications, and work with a wide variety of substrates and satisfy most adhesion requirements.
Acrylic based adhesive systems are more versatile than rubber based systems and offer UV stability, higher temperature performance and good to excellent chemical resistance. While rubber based adhesives have a higher initial bond, the acrylic pressure sensitive adhesives go through a 24 hour cure cycle or “wet-out” period where over time, the bond continues to improve. Acrylic adhesive systems are usually a little higher cost but offer longer life than rubber adhesives.
Silicone based adhesive systems are primarily used for applications requiring very high temperature resistance or for applications where the adhesive will be bonding to a silicone filled material. These pressure sensitive adhesive systems typically do not possess high adhesion and would only be recommended for thin films where thermal expansion or shear will not be an issue. Silicone adhesives are also high priced which may exclude them from competitive situations.
Crown works with Avery Dennison as a primary supplier of pressure sensitive adhesives but also works with additional adhesive suppliers to handle custom applications or to be able to satisfy a requirement in which a specific adhesive is called out. For information on adhesives or to find out which adhesive will work best for your application, you can talk with one of Crown Plastics’ customer service representatives.
DuraSurf™ UHMW pressure sensitive tapes and materials are supplied with a variety of backside surface treatments to meet application needs. All polyethylenes are low surface energy materials that do not promote adhesion. Oxidation increases surface energy and transforms UHMW into a bondable material.
Plain, Untreated Surface
In addition to offering the DuraSurf family of products with a plain, untreated backside for applications where bondability is not an issue, Crown Plastics can offer a variety of surface treatments for bondability options.
Treated for Bonding
For applications where an external adhesive will be applied at installation, Crown Plastics offers DuraSurf with a mechanically abraded or a flame etched surface for adherence of epoxies and other liquid adhesives. For thinner films, a corona treatment is offered to change the surface energy to enhance adhesion.
Pressure sensitive tapes and materials can be applied in areas where mechanical fastening is undesirable due to cost or application demands. We process and treat the UHMW so it can be bonded to a pressure sensitive, adhesive backing, which eliminates the need for mechanical fastening and reduces waste. We utilize aggressive adhesives with a high initial tack for ease of application and excellent peel for long service life.
Crown Plastics employs an exclusive continuous compression process to manufacture UHMW (Ultra High Molecular Weight) film ranging in thickness from .003″-.250.” The continuous compression process has the capability of compression molding UHMW in a continuous form without skiving. This process is faster and far less labor intensive and produces a smoother, more consistent UHMW material for wear resistant coatings. This enables Crown Plastics to offer a high quality UHMW product at a lower cost in standard lengths regardless of thickness. Continuous processing also allows for special lengths with no scrap or waste for larger custom orders.
Ultra-High Molecular Weight Polyethylene (UHMW-PE) Continuous Wear Strip: Wear Resistant Coatings
Employing our exclusive continuous compression process process, Crown Plastics manufactures UHMW (Ultra High Molecular Weight) film ranging in thickness from .020″-.250″ in continuous wear strip or sheet rather than the conventional molding and skiving processes used for .003″-.020″ film. The continuous compression process process is faster and far less labor intensive and produces a smoother, more consistent UHMW material for wear resistant coatings. This enables Crown Plastics to offer a high quality UHMW product at a lower cost to our distributors in standard lengths regardless of thickness. Continuous processing also allows for special lengths with no scrap or waste for larger custom orders.
With the ever-increasing popularity of sheet, rod, tube and profiles, UHMW has rapidly become the staple product in the plastics industry. Although tape and film applications have also risen sharply, a surprising number of people are still unaware of the existing benefits of DuraSurf™ wear resistant coatings and materials. Countless washers and gaskets can be produced from UHMW and Crown Plastics roll capabilities allow for faster, cheaper stamping. Wear strip, mechanically fastened or adhered, eliminate numerous areas of friction and wear in material handling applications. Processing and treating the UHMW so it can be bonded to a pressure sensitive, adhesive backing also eliminates the need to mechanically fasten and reduces waste. Bushings, bearings, doctor blades, guides, rails, shims, wear plates, liners, and wipers are just a few of the many uses for DuraSurf™ wear resistant coatings and continuous wear strip.
As the only exclusive manufacturer of thin gauge UHMW, Crown Plastics has dedicated itself to servicing the needs of it’s customers with high quality, competitively priced products produced and shipped quickly and conveniently. Crown Plastics currently stocks DuraSurf™ in 16 thicknesses ranging from .003″-.250″ in widths from 1/4″ – 24″ (in skived thicknesses). Every effort is made to meet next day and second day air requirements when possible, with normal lead times quoted in days instead of weeks. The combination of large inventory and short lead time allows for lower stocking requirements on the part of the distributor, which combined with our direct shipment capabilities adds up to lower costs to the customer.