One of the most popular materials used for sealing and gasketing is polyurethane. It is very cost-effective and has many useful properties. Be careful not to use urethane foam gasketing foam when you require a polyurethane seal. A polyurethane gasket is not the same as a polyurethane seal.
Reacting isocyanate and polyol creates polyurethane. Polyols are made from oxygen, carbon, and hydrogen. Isocyanate is a compound that contains only nitrogen oxygen and carbon. Combine them and you have materials that can be used to make gaskets and seals.
The polyurethane seals are good from -65 to 210 degrees F. Below this temperature, they will become brittle and melt at higher temperatures. Polyurethane has good load bearing and impact resistance. It is also resistant to petroleum and hydraulic oil attacks.
There are many hardnesses for polyurethane, but the majority of it is 95 Shore A. This material is tough and more durable than natural rubber.
Foaming polyurethane makes it much more flexible. To make gas, you need to add a foaming agent or isocyanate/polyol reactant. The liquid solidifies, leaving bubbles throughout the material. This gives the material a springy resilience.
Polyurethane foam applications
The most important application is cushioning. The most common use of polyurethane foam in furniture and shoes is for its compliance and high recovery. Another common application is gasketing. Its compressibility provides protection against impacts and allows for manufacturing tolerances.
Sealing is the only time you should not use polyurethane foam. Polyurethane foams are open-cell structures, which allow fluids to pass through.
Polyurethane seal applications
Polyurethane’s outstanding abrasion resistance makes it a popular choice for situations that involve relative movement. The oil resistance helps to ensure a long life for seals around hydraulic cylinder rods. Another common use is pipe seals, along with shaft seals and wipers.
Make sure you get the right polyurethane
For many sealing and gasket applications, polyurethane or simply urethane is a great choice. It’s important to remember that it can be difficult to seal in its foamed form.
Sh Winman – PU gasket sealing machine
PU gasket sealing machine developed by Sh Winman for FIPFG/gasketing. The dynamic mixing system uses polymeric reaction material to produce PU gaskets with high precision and consistent quality. The gaskets can also be applied directly to the component by using a linear robot. An industrial robot can also be used to position the component underneath the permanently installed mixing head and then apply the foam beads. The gasket will then be set at room temperature. The required time depends on many factors such as the material, mix ratio, temperature, humidity, and room temperature. The control unit can store different metering or positioning programs. You can change many parameters easily. You can choose different materials or components, or different discharge capacities, with different gasket heights and widths.