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.
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
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
5. Lub-X® C
- Reduces friction with a dry lubricant dispersed throughout the plastic
- Color: Light Blue
- FDA Compliant? Yes
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
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
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.
