Polyurethane Key Properties
Urethanes have better abrasion and tear resistance than rubbers, while offering higher load bearing capacity. When compared to plastics, urethanes offer superior impact resistance, while offering excellent wear properties and elastic memory. Urethanes have replaced metals in sleeve bearings, wear plates, sprockets, rollers and various other parts, with benefits such as weight reduction, noise abatement and improved wear resistance. Polyurethane is available in polyester and polyether formulations. Depending on your application it is important to consider the strengths of these formulations. Polyester offers outstanding sliding abrasion resistance for bulk material handling applications like chute liners, while Polyether has excellent cutting abrasion resistance for applications like sandblast curtains. Polyether will perform better in wet applications due to its hydrolytic stability and has better low temperature performance. Polyester offers better overall chemical resistant than Polyether. Polyester offers higher tensile strength, better cut and tear resistance and is ideal for shock absorption and vibration dampening applications.
Polyurethane Key Properties
- Abrasion resistance - Polyurethanes often outwear other materials (rubber, plastics and metal) by many times in many applications when severe abrasion is a factor.
- Oil and solvent resistance - Polyurethane has excellent resistance to oils, solvents, fats, greases and gasoline.
- Load bearing capacity - Polyurethane has a higher load-bearing capacity than any conventional rubber. Because of this characteristic, it is an ideal material for load wheels, heavy duty couplings, metal-forming pads, shock pads, expansion joints and machine mounts
- Tear resistance - The tear-strengths of various Polyurethanes range from 100 to 1000 lbs./linear inch, which is far superior to rubbers. As a result, urethane is often used as drive belts, diaphragms, roll covers, cutting pads, gaskets and chute liners.
- Weather resistance - Polyurethane has outstanding resistance to oxygen, ozone, sunlight and general weather conditions.
- Noise abatement/reduction - Hard urethanes are now being used as gears in products where sound reduction is desired. The soft urethanes are used to replace rubbers for improved sound/vibration dampening.
- Flex-Life - Most formulations offer extremely high flex-life and can be expected to outlast other elastomer materials where this feature is an important requirement. Dust boots, bellows, diaphragms, belts, couplings and similar products are made from urethane for this reason.
Polyurethane Limitations
- Polyester Base not recommended below -40F
- Polyether Base not recommended below -100F
- Polyester Base will not perform as well as Polyether in Wet Applications
- Polyester Base is more chemical resistant than Polyether Base
Machining Polyurethanes
Machining is challenging due to the elastic nature of the material. For more information on machining polyurethane download our polyurethane machining guidelines.
Polyurethane Parts
Polyurethanes can be cast to finished part geometries with relatively low-cost tooling. With the difficulty in machining urethanes casting is a very common way to produce polyurethane parts. Contact Us for to evaluate your part for casting.
