Material Guide: Cast Polyurethane Rubber

Our Guide To AU & EU – Cast Polyurethane Rubber (PU)

Cast Polyurethane rubber (PU) can be divided into two very distinct classes. These are Polyester, also known as AU, and Polyether Urethanes, also known as EU. These cast PU products are known for their outstanding tensile strength and their tear and abrasion resistance. This is what makes them great for use in custom polyurethane moulded products such as gaskets and diaphragms. Here at DLR Elastomer Engineering, our polyurethane moulded solutions are based on diphenylmethane diisocyanate, also known as MDI. 

What Are The Advantages Of PU Rubber?

PU Rubber is a useful, versatile rubber material due to its high levels of durability and resistance to oxidation, ozone and petroleum-based fuels and oils. This makes it a great solution as custom polyurethane moulded products for oil and gas applications. Polyesters have similar physical properties to those of polyethers but tend to be more superior. 

Additionally, PU rubber features good electrical properties, making it suitable for a broad array of applications, particularly as a coating to protect electrical products. Also, as these materials are liquid cast, tooling prices tend to be lower than for heat and pressure moulded rubbers. 

What Are The Disadvantages Of Cast PU Rubber?

Unlike polyethers, polyesters can be affected by not only hot water but also high levels of humidity. With this in mind, PU moulded parts are often unsuitable for use in areas that come into contact with hot water or warmer, more humid environments. 

Furthermore, another disadvantage of cast PU rubber is that the compression set and creep properties are only deemed to be fair. With this in mind, these products may not be suitable for applications that demand high compression sets. Additionally, cast polyurethane has a low resistance to acids and alkali. 

Another consideration to take into account is that, given the high hysteresis, also known as damping, of most cast PU rubbers, care must be taken for applications that involve high-frequency deformation, as well as tyre speeds of over 8mph. 

What Are The Typical Applications Of PU Rubber?

Cast PU rubber suits a wide array of applications, particularly those in oil applications. With this in mind, the typical applications for PU include:

• Abrasion-resistant Coatings and Lining
• Moulded Rubber Diaphragms
• Gaskets
• Haul-off Pads
• Hoses 
• Seals. 

What Temperatures Does Cast PU Rubber Operate Under?

PU moulded products suit environments with a typical working temperature range of -40°C to +90°C.

Looking for more detailed information on the different types of rubbers and polymers we work with? Then check out our material guides where you can find FAQ’s and more guides like this one detailing all you need to know. If you are looking for rubber or polymer products get in touch with DLR Elastomer today via our contact page or via LinkedIn and we can chat over your requirements.