How to determine if a caster material has good brittle resistance?

Key Methods for Determining the Brittle Resistance of Caster Materials

Brittle resistance refers to a material's ability to maintain toughness and resist fracture under low temperatures, stress, or impact. The key criteria are as follows:

 

Preferred Materials:

High Brittle Resistance: Cold-Resistant Modified PU (especially polyether types, with a Tg as low as -60°C), Toughened Modified PA (e.g., with added elastomers), and Cold-Resistant Rubber (nitrile, silicone rubber).

 

Avoid: Ordinary unmodified plastics (PA6, PVC, PP, PE), and hard and brittle resins (phenolic, unmodified ABS), which are prone to brittle fracture at low temperatures.

 

Key Tests and Parameters:

Low-Temperature Impact Test: Require the manufacturer to provide a low-temperature impact test report (e.g., ASTM D256, ISO 179). Key Parameter: Notched impact strength > 5 kJ/m² at the target low temperature is considered good (e.g., -30°C data for -30°C use).

 

Glass Transition Temperature (Tg): The critical temperature at which a material becomes brittle. Requirements: Material Tg < minimum operating temperature (e.g., for a -30°C environment, select a material with a Tg < -30°C).

 

Low-Temperature Hardness Change: Test the hardness (Shore A) at room temperature and low temperature. Judgment: A change of ≤ 10% is considered good (e.g., 85A → ≤ 94A); a change > 20% indicates a high risk of embrittlement.

 

Structure and Appearance:

Wheel Design: Stress concentration areas (edges, spokes) should have rounded corners and avoid sharp angles. Prefer one-piece molded wheels to avoid spliced structures.

Material Uniformity: The wheel surface should be free of bubbles, impurities, or localized hard spots, as these defects can easily cause brittle cracking.

 

Verification and Reference:

Available for field testing: After 24 hours of low-temperature stabilization, perform load-bearing rolling and edge impact tests to observe for cracks and chipping, and check dimensional stability (shrinkage ≤ 1%).

 

Manufacturer Endorsement: Prioritize brands that offer low-temperature performance certification (such as cold storage equipment certification) and have similar low-temperature application success cases.

 

Summary of the Judgment Process:

Initial Materials: Cold-Resistant PU, Toughened PA, Cold-Resistant Rubber.

 

Key Data: Ensure low-temperature impact strength >5 kJ/m², Tg < operating temperature, and hardness change ≤10%.

 

Structure: Ensure rounded corners, integrated molding, and no defects.

 

Reference Certification Cases: Select products with proven low-temperature application experience.

 

The above methods can effectively assess the caster material's resistance to embrittlement and ensure reliable operation in low-temperature environments.