How to choose between different Polyurethane hardness levels?

How to choose between different Polyurethane hardness levels?

Polyurethane (PU) is an incredibly elastic and versatile material, with a hardness range spanning from soft like gel to rigid like hard plastic. Choosing the right hardness isn’t just about feel; it directly affects the product’s performance, durability, and user experience. So how do you make the right choice? Here’s a quick guide to the key points in PU hardness selection.

Basic Principles of Hardness Selection

Generally speaking, PU hardness is expressed using the Shore A and Shore D scales. Low-hardness PU (Shore A 30–60) feels soft and offers good elasticity and shock absorption. It is very suitable for components that require cushioning, vibration resistance, or human contact, such as protective gear, polyurethane roller wheels, grips, and seals. In contrast, higher-hardness PU (above Shore A 70 and up to Shore D) can withstand greater pressure and prolonged friction, and is commonly used in structural components like plastic gears, plastic pulleys, and bushings.

For example, components that come into contact with the human body are recommended to use Shore A 20–50 to ensure comfort and safety. For structural or mechanical parts, Shore D 40–70 is recommended for better durability and stability.

Balancing Abrasion Resistance and Durability

Polyurethane is known for its abrasion resistance, especially in the mid-to-high hardness range (Shore A 85–D 60), making it ideal for parts exposed to long-term friction, such as industrial polyurethane roller wheels, plastic pulleys, and transmission components like plastic gears. To further improve abrasion resistance, additives such as graphite or glass fiber can be added to enhance strength.

However, it should be noted that while harder PU offers better wear resistance, it may also generate more noise. Therefore, material selection should be based on the application scenario; do you need more abrasion resistance or lower noise?

Noise and Shock Absorption Requirements

For products that require low-noise operation, such as office furniture, fitness equipment polyurethane roller wheels, or mobile devices, it is recommended to use medium-to-low hardness PU (Shore A 30–70). This material can effectively absorb vibrations and impact sound, reduce resonance, and achieve a quiet effect. If the hardness is too high, it may instead create knocking sounds and structural resonance, with a noticeable negative impact.

Testing Is Still Key

Although the above hardness ranges serve as general guidelines, every application environment and requirement is different. Even a one-grade difference in hardness (such as Shore A 85 vs. A 95) can lead to vastly different actual performance. Therefore, it is recommended to create samples and perform real-world testing before mass production. This can greatly reduce subsequent adjustment costs and help the product get closer to the ideal from the very beginning.

Summary: How to Choose the Right Polyurethane Hardness? Get It Right for a Better Product

The hardness of Polyurethane directly affects the product’s feel, performance, and durability. Common hardness levels are indicated from Shore A (soft) to Shore D (hard):

Soft (Shore A20–A60): Excellent elasticity, suitable for skin contact, shock absorption, and anti-slip applications (e.g., Polyurethane roller wheels for fitness equipment, handles, protective gear).

Low to Medium Hardness (Shore A30–A70): Effectively absorbs shocks and reduces noise, offering silent operation; suitable for fitness equipment and furniture plastic pulleys.

Medium to High Hardness (Shore A70–D60): Provides better wear resistance and shock absorption, but may produce more noise; ideal for heavy-duty industrial polyurethane roller wheels.

Hard (Shore A90–D80): Offers higher pressure and wear resistance; suitable for mechanical parts, plastic pulleys, and plastic gears.

Final material selection should be based on actual application and sample testing. It is not recommended to rely solely on hardness values for judgment.

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