Sep. 09, 2024
Aside from PTFE and PTFE blends, one of the most used seal materials at Eclipse is UHMW, or Ultra High Molecular Weight Polyethylene.
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Polyethylene is the most common and prolific plastic in the world today, utilized in everything from consumer-grade packaging to bags, bottles, and medical implants. It&#;s available in varying densities, such as Low Density (LDPE), High Density (HDPE), and the aforementioned UHMW.
The seal world focuses mainly on UHMW employing the favorable properties of the added density. Below we&#;ll discuss the benefits and advantages of using UHMW as a seal material, as well as some of the drawbacks.
UHMW has many desirable properties for a seal material. Probably its most notable attribute is its wear, abrasion, tear and cut resistance. If you have a thick, heavy plastic cutting board at home, it&#;s likely made out of UHMW.
So, you may have firsthand experience with UHMW&#;s toughness. Any material that you can cleave with a knife resulting in minimal damage will also serve well as a robust seal material.
Compared to even some heavily filled PTFE blends , UHMW&#;s wear resistance can be more than 10 times better. A seal working in abrasive media can greatly benefit from the properties of UHMW.
For example, Eclipse has had immense success employing UHMW spring energized seals in paint processing and dispensing equipment.
While paint might not be initially thought of as an abrasive media, it often contains very hard ceramic and metal oxide particles which can act like sandpaper against a seal. Eclipse&#;s EU038: Ceramic-filled UHMW is tailormade for such applications providing the maximum amount of wear life possible.
UHMW&#;s toughness also comes into play in heavy excluding and wiping applications. Media such as resins and epoxy require seals with a heavily point-loaded, leading-edge for scraping. Any wear or loss of this edge gives an opportunity for media to be forced under the sealing lip in a reciprocating application. UHMW&#;s durability helps maintain the sharp scraping edge for extended service intervals far better than any other seal material.
UHMW&#;s coefficient of friction is also quite low. While not better than PTFE&#;s famously low friction, it&#;s far better than any elastomer or urethane seal material and lower than most comparable plastics such as Nylon or Acetal. This is important when it&#;s used as a guide or wear ring or in a sealing application where the stick-slip nature of an elastomer is undesirable. In most cases, it can be used unlubricated.
Chemical compatibility or resistance to chemical attack is also an important attribute for a sealing material. While again, not being quite as resistant as PTFE, UHMW rates good or excellent with most media including many solvents and acids. It has low moisture absorption and typically outperforms PTFE in terms of leakage control in water sealing applications. Virgin UHMW also has the benefit of being FDA compliant.
Lastly, UHMW is relatively cheap and readily available. Especially in extruded rod form, UHWM can be less than 10 times the cost of PTFE. In high-volume applications where the raw material price is a significant portion of the final piece price, UHMW can be very economical.
We have a material that&#;s very tough and abrasion-resistant, low in friction, chemically compatible, and relatively inexpensive. So far there&#;s a lot to like about UHMW as a seal material.
Unfortunately, there&#;s one weakness that rules out UHMW for many applications in the seal world &#; its temperature range.
While UHMW&#;s lower temperature limit is quite good (it can be used in cryogenics) it&#;s the upper limit that often severely limits its potential. UHMW can start seeing reduced properties at 150°F [65°C] and has a continuous operating limit of 180°F [82°C].
While this means UHMW can&#;t be used in many applications that operate above this temperature, it also largely limits its use in rotary applications. With any amount of rotary surface speed, the interface temperature due to friction between the seal and the dynamic hardware surface can easily exceed the upper limit of UHMW.
This can even be the case if the ambient environment of the system is cool or at room temperature. Since a rotary seal is continuously operating on the same area of the hardware, there&#;s little opportunity for heat rejection.
Therefore, UHMW is infrequently used in rotary applications unless the motion is very, very slow. It&#;s typically best suited for reciprocating applications operating at nominal temperatures.
Along with this, UHMW has a relatively high coefficient of thermal expansion. This means it will dimensionally shrink or grow along with temperature changes. Because of this thermal instability, it might not be the best material for high-precision parts.
The thermal limitations can also make the machining of UHMW challenging. Due to localized heating while cutting, a part may dimensionally change drastically after it has stabilized to room temperature.
UHMW is also notorious for &#;chip wrap&#; while machining. This is because the chip, or material being cut away, stays in a long continuous strand rather than breaking off. (But, by all means, leave the machining to us!)
Have a reciprocating application sealing viscous or abrasive media, that&#;s operating at ambient temperatures? If you&#;re not already using a UHMW seal, there may be an opportunity for significant improvement in both wear life and sealing performance.
While not right for every application, UHMW can work wonders in certain situations.
Eclipse&#;s decades of experience in both the design and manufacturing of seals can ensure the best possible sealing solution is implemented. Whether it&#;s UHMW, PTFE, or something beyond, Eclipse has you covered.
Ultra-high molecular weight polyethylene (UHMW-PE) is a type of plastic classified as an engineering plastic.
Due to its excellent durability and lowest friction, it is used as a material for machine parts such as gears and guide rails, as well as hoppers, etc. We manufacture ultra-high molecular weight polyethylene adhesive tape.
In this article, we will explain the characteristics and uses of ultra-high molecular weight polyethylene, as well as how it differs from fluoroplastic.
Ultra High Molecular Weight Polyethylene refers to polyethylene whose &#; &#; molecular &#; &#; weight has been increased from the usual 20,000 to 300,000 to 1 to 7 million .
It is also sometimes called "UHMW-PE," "UHMW," "U-PE," or "UPE," which are the initials of its official name.
Ultra-high molecular weight polyethylene is a synthetic resin classified as a thermoplastic resin, and is one of the engineering plastics.
Because it has excellent abrasion resistance and lowest friction second only to fluoroplastic, it is used as a material for machine parts such as gears and guide rails, as well as hoppers.
Ultra-high molecular weight polyethylene has the following characteristics:
Contact us to discuss your requirements of UHMWPE Fiber. Our experienced sales team can help you identify the options that best suit your needs.
Its main features are its excellent lowest friction and abrasion resistance. It can be used for a long time in sliding applications because there is little risk of it being scratched or scraped.
It has extremely high impact resistance, exceeding that of polycarbonate (PC).
Its stable molecular structure also provides excellent chemical resistance, allowing it to be used in environments where liquids or chemicals are used.
Its water absorption rate is low at less than 0.01 %, making it an ideal material for areas where water is used.
The maximum operating temperature for ultra-high molecular weight polyethylene is generally 80°C, making it unsuitable for use in high temperature environments.
However, it can be used in low temperature environments down to -100°C.
Ultra-high molecular weight polyethylene has a large linear expansion coefficient, so it is not suitable for places where sudden temperature changes occur.
Because of its high self-lubrication, it is difficult to bond with dissimilar materials, so be careful when combining it with other parts or materials, as you will need to carefully consider the design beforehand.
Taking advantage of its excellent properties, ultra-high molecular weight polyethylene is used for a wide range of applications.
It is mainly used in applications where it has high wear resistance and self-lubrication.
&#; Gears
&#; Guide rail
&#; Roller
&#; Liner
&#;Food machinery
&#; Hopper
&#; Marine rope
Ultra-high molecular weight polyethylene is used for a variety of purposes, and in addition to being used as molded products such as machine parts, it is often processed into films and adhesive tapes.
When used as an adhesive tape, it can be partially imparted with the properties of ultra-high molecular weight polyethylene, making it easy to use in food factories and transportation processes.
We manufacture adhesive tapes made from ultra-high molecular weight polyethylene.
Please consider this product if you are looking to partially add the properties of ultra-high molecular weight polyethylene!
&#; AUE-112B
This adhesive tape has an ultra-high molecular weight polyethylene (UHMW-PE) film base and an acrylic adhesive applied to one side, providing lowest friction resistance.
&#; AUB-112B *Anti-static type
This adhesive tape uses a conductive carbon-containing ultra-high molecular weight polyethylene (UHMW-PE) film as a base material, with an acrylic adhesive applied to one side.
These products can be used for the following purposes:
By attaching it to the guide of roller conveyors used in food and beverage factories and logistics plants, it prevents products from getting stuck and ensures smooth product transport. It also prevents damage to the products and the guide.
Additionally, in hoppers used in food factories, etc., attaching it to the slope of the material inlet area allows the material to flow smoothly and reduces residue inside the hopper.
It is also used in automobile parts due to its excellent abrasion resistance and impact resistance. In automobile applications, it is used in places where it is subject to impact and where lowest friction is required.
It is also used on skis and snowboards where lowest friction is required, and in the sliding parts of office equipment.
The differences between ultra-high molecular weight polyethylene and fluoroplastic are summarized in the table below.
If you are using it in an environment with temperatures between 100&#; and 200&#;, you may want to consider fluoroplastic (PTFE).
When selecting a material, we recommend that you decide in advance which characteristics are important and then compare them.
*The displayed data is a representative value and is not a quality assurance value.
More information about fluoroplastic can be found here .
If you are considering a fluororesin adhesive tape instead of ultra-high molecular weight fluoroplastic adhesive tape, we recommend the product below.
&#; ASF-110FR
This adhesive tape has fluoroplastic (PTFE) film base and a silicone adhesive applied to one side. It has excellent heat resistance, lowest friction, and chemical resistance.
&#; PTFE Cutting Products
For those considering molded products other than ultra-high molecular weight polyethylene, we can also propose PTFE machined products, which are processed by cutting PTFE processing materials into various shapes according to the customer's specifications. These parts can be used in a wide range of fields as they are heat resistance, chemical resistance, and non-stick characteristics parts.
&#; Injection molding products
These are Injection molding products made from various functional engineering plastics, including fluoroplastic. With our extensive know-how, we can propose the appropriate molded product shape from the design stage onwards.
Representative examples of our achievements include fluoroplastic (PFA, ETFE, PVDF, ETCFE), engineering plastics/super engineering plastics (PEEK, PSU, 4-6PA, PPS, PEI, etc.), and general-purpose resins (PP, PE, PS, PVC, PBT, etc.).
Ultra-high molecular weight polyethylene is an engineering plastic with excellent characteristics.
Its main features are its excellent lowest friction, abrasion resistance and impact resistance.
Although it is not suitable for use in high temperature environments of 100°C or higher, it is a recommended material for sliding applications in usable temperature environments and for applications requiring resistance to wear and impact.
In addition, our ultra-high molecular weight polyethylene tape is recommended for applications that require partial lowest friction, high abrasion resistance, and impact resistance. If you would like to try it out, please feel free to contact us.
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