What factors determine the load capacity of a caster?

Factors Determining Caster Load Capacity
The load capacity of a caster isn't determined by a single parameter; rather, it's the result of a combination of core structural component performance, material properties, design techniques, and usage scenarios. The key factors are as follows:

First, the structural strength of the core load-bearing components. The wheel frame serves as the "skeleton" of the caster's load-bearing structure. The thickness of its material (such as cold-rolled steel or stainless steel) and the welding/stamping process directly impact the load capacity. Thicker thickness and stronger welds, along with greater deformation resistance and a higher load capacity limit, contribute to a higher axle diameter. As the core force transmitter, the axle's larger diameter and higher material hardness (such as quenched 45# steel) help prevent breakage or bending. For example, the axle diameter of industrial-grade casters is often 2-3mm larger than that of consumer casters, increasing load capacity by over 50%.

Second, the wheel's material and specifications are important. Wheel materials vary significantly in their load-bearing capacity: Rubber wheels offer excellent elasticity but lower load capacities (typically 50-100kg per wheel), making them suitable for lightweight equipment. Nylon and polyurethane wheels are hard and wear-resistant, capable of carrying loads of 100-300kg per wheel. Cast iron wheels offer the highest load capacities (over 300kg), but are only suitable for heavy-duty industrial applications. Wheel diameter and width also affect load capacity. For the same material, larger diameters (for greater ground contact area) and wider widths (for more distributed pressure) increase load capacity. For example, a 100mm diameter wheel can carry approximately 30% more load than a 50mm diameter wheel.

Another factor is the installation and fit of the caster. The method of attaching the caster to the equipment (e.g., screw fastening or plug-in mounting) must match the strength of the equipment base. If the base plate is too thin or the screw spacing is too small, even if the caster itself has a high load capacity, it may break due to uneven force at the mounting point. Furthermore, the number of casters will also distribute the load. For example, when using four casters, the total load capacity should be calculated as "single caster load x 4 x safety factor (usually 0.7-0.8)" to avoid damage due to overloading a single wheel.

Finally, the operating environment has an impact. Floor flatness is crucial. Rough surfaces can cause localized force concentration on the caster, requiring a 20%-30% reduction in the actual load capacity. If the caster is used in a humid or corrosive environment for a long time, and the frame or wheel material is not treated with rust/corrosion protection, rust will weaken the structure and indirectly reduce the load capacity.