Polyurethane Material Guide: Understanding the Advantages and Comparing the Different Types
Polyurethane is a polymer material that absorbs impact from the workpiece and helps prevent damage to equipment or surfaces.
Polyurethane is commonly used with pushers, stoppers, or bumpers, but is also used with certain bolts and conveyor rollers. Plates and sheets of raw polyurethane material are also available.
Advantages of Polyurethane Material
Excellent mechanical strength and abrasion resistance are the two main properties of polyurethane that most grades of polyurethane provide. It's known for its durability, flexibility, wear resistance, and weather resistance.
1. Hardness
Polyurethane has a wide range of hardness. It can be formulated to be soft and flexible or hard and rigid.
The most common category of hardness is indicated by Shore A. This scale generally ranges from Shore A30 to Shore A90, measured by using a type-A Durometer. Another way to quantify hardness is by using the Asker C scale. With both indications, the larger value means a harder material. Generally, as the hardness increases, impact resilience increases while elongation percentage decreases.
2. Load Bearing Capacity
Polyurethane is a much softer and lighter material than most metals, which makes it a great candidate to use in shock-absorbing applications. Polyurethane is strong enough to withstand high forces but is resilient and compressible compared to other materials.
3. Abrasion Resistance
Materials with high abrasion resistance are important when withstanding surface wear over long periods of time. One of the most common properties of most types of polyurethane is its great abrasion resistance.
For general polyurethane, MISUMI has performed abrasion tests using the Taber Method and found an abraded volume of 197.3 mm3. Note: these values are not guaranteed but measured from our testing.
4. Adhesion to Materials and Plastics
When polyurethane is used in combination with metals or plastics, there are many ways they can be assembled. When used with metals, polyurethane is either bonded to the metal piece or baked directly onto the metal.
Certain products may have the option to come with adhesive tape on one side of the polyurethane for easy adhesion to plastics.
Comparison of Polyurethane Material Types
General polyurethane is commonly used across all industries, but it may not be best suited for the job depending on your application. Luckily, there are several different types of polyurethane to choose from:
General (Ether & Ester Polyurethane)
General polyurethane is commonly used across many different industries due to its excellent mechanical strength and great abrasion resistance. Ether polyurethanes are Shore A95 and A90, while Ester polyurethanes are Shore A70, A50, and A30. These materials are both suitable for sealing or shock-absorbing applications.
The table below shows which type of Ether vs. Ester polyurethane has superior properties.
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Antistatic
Antistatic polyurethane has similar properties to general polyurethane, except with surface resistivity properties. This is commonly used in systems directly exposed to electronics.
If your application does not specifically need to be protected with antistatic properties, then general polyurethane would likely be better suited.
Characteristic values for antistatic polyurethane can be found below.
Low Rebound
Low-rebound polyurethane excels in compression resistance, which makes it difficult to deform over time. In compression set tests, low-rebound polyurethane was found to have a compression set of 1% compared to the 25% from general polyurethane.
Due to this, this type of material is best suited for shock-absorbing applications with high loads. Low rebound polyurethane is not suited for large impact applications due to its weaker tensile strength and elongation.
Heat Resistant
If your application is under high temperatures, heat-resistant polyurethane would be the best option. This polyurethane is designed to maintain its high material strength up to temperatures as high as 120°C.
Like antistatic urethane, if your application does not specifically need to run in a high temperature environment, then you are likely better off using a general polyurethane instead.
Abrasion Resistant
Abrasion-resistant polyurethane offers additional protection to abrasion resistance. This unique material composition allows for 2.5x higher abrasion resistance than general polyurethane, which helps reduce exchange frequency.
This material works great in high-friction, high-cycle applications while allowing longer replacement intervals.
Super Abrasion Resistant (Vulkollan?)
Vulkollan? is a super abrasion-resistant polyurethane that is far superior to general polyurethane in abrasion resistance and load bearing. The abrasion resistance is about 6x higher, and the material strength is about 1.5x higher than general polyurethane.
Similar to abrasion resistant polyurethane, Vulkollan? is a great option to combat surface wear from high usage. Over time, this material may discolor, but this does not affect the physical properties.
Ceramic
Ceramic polyurethane excels in abrasion resistance and has a smooth machined surface despite its low hardness. While abrasion resistant and Vulkollan? polyurethanes are resistant to “surface” abrasion, ceramic polyurethane is resistant to “line” abrasion.
Ceramic polyurethane will also compress more than general polyurethane under the same loads, while also being about 2x more abrasion resistant than general polyurethane. If this type of polyurethane gets damaged or scraped from contact, it may produce some dust.
Configurable Bolts, Pushers, and Stoppers
MISUMI offers a wide range of rubbers, bolts, and stoppers with different material options. Explore our products:
This article was first published here.