Which caster material has the highest load-bearing capacity?

Among caster materials, high-strength engineering plastics (such as reinforced nylon PA) and metal alloys (such as cast iron and steel) have significantly higher load-bearing capacities and are particularly suitable for heavy-load applications (a single wheel often carries over 500kg, and some specialty materials can exceed 1000kg). The following analysis is categorized by "load-bearing capacity gradient," combining material characteristics and applicable scenarios to help you choose the right caster:

1. For ultra-heavy loads: Metal alloys (cast iron, steel)
Metal casters currently offer the highest load-bearing capacity. Their compact molecular structure and exceptional rigidity allow them to withstand extreme loads. Core representatives include cast iron and steel casters:
Cast iron casters:
A single wheel can carry up to 800-2000kg, or even higher (such as heavy-duty industrial cast iron wheels). They offer excellent impact and compression resistance and resist deformation under prolonged heavy loads. However, they are heavy (density approximately 7.2g/cm³), have low corrosion resistance (prone to rust, requiring galvanizing or painting), are noisy when pushed, and can easily scratch the floor. Therefore, they are only suitable for applications where weight, noise, and floor protection are not critical, such as for securing heavy-duty equipment (such as large machine tool bases) or for outdoor use on rough surfaces (such as construction sites and freight yards). Steel casters (such as carbon steel and stainless steel):
They have a load-bearing capacity comparable to cast iron (800-1800kg per wheel), but offer greater strength and corrosion resistance than cast iron (stainless steel is suitable for heavy-load applications in humid or mildly corrosive environments). Their disadvantages are similar to those of cast iron, including increased weight, noise, and cost. They are suitable for applications such as heavy-duty equipment in the food industry (stainless steel is corrosion-resistant) and heavy-duty handling in the chemical industry (where corrosion resistance is required).

2. Mainstream for Heavy-Duty Vehicles: Reinforced Engineering Plastics (Reinforced Nylon PA)
Ordinary nylon (PA) already has a good load-bearing capacity (300-500kg per wheel). However, glass fiber-reinforced nylon (PA + glass fiber) significantly increases its load-bearing capacity by adding glass fiber to enhance molecular chain strength, making it the optimal solution for the "heavy-duty + lightweight" requirement.
Load-bearing Performance: A single wheel can carry 500-1200kg. Some specially reinforced models (such as PA with carbon fiber) can approach metal levels. With a density of only 1.3-1.5g/cm³, it's over 60% lighter than metal, reducing the effort required to push.
Core Advantages: It offers both wear resistance (good self-lubrication and low friction coefficient), oil resistance (resistance to mineral and vegetable oils), and mild corrosion resistance (reinforcement reduces water absorption and ensures stable performance in humid environments). Furthermore, it produces quieter propulsion than metal (approximately 50-60 spm). decibels), will not scratch floors (such as epoxy floors and ceramic tiles).

Applicable scenarios: Heavy-duty equipment in industrial workshops (such as heavy-duty shelves and large logistics carts), and heavy-duty tool carts in auto repair shops (exposed to oil and heavy loads). Combining "heavy-duty, durable, and floor-protecting" characteristics, it is currently the most widely used material in heavy-duty applications.

3. Medium- and heavy-duty alternative: High-strength polyurethane (PU, such as MDI-based PU).

Ordinary PU casters typically have a load capacity of 100-500kg, while high-strength modified PU (such as MDI-based PU and PU with added reinforcements) can increase this to 500-800kg, making them suitable for applications requiring "heavy load, quiet operation, and floor protection."

Balance of load capacity and properties: Higher load capacity than ordinary plastics (such as PP) but lower than reinforced nylon and metal; yet, they offer excellent elasticity and extremely low noise levels (40-50 psi). decibels), and the wheel tread has a moderate softness, protecting floors (such as marble and wood floors) while also conforming to uneven surfaces (such as slightly potholed concrete) to reduce bumps.
Limitations: Long-term exposure to high temperatures (>80°C) can soften the wheel, reducing its load-bearing capacity. Its resistance to strong solvents (such as gasoline) is weaker than that of reinforced nylon. It is suitable for heavy-duty indoor applications that require quietness and floor protection, such as heavy-duty cleaning vehicles in shopping malls and heavy-duty turnover vehicles in pharmaceutical workshops.

4. Comparison of Low-Load-Bearing Materials (Preferred for Non-Heavy-Load Applications)
The following materials have low load-bearing capacity (mostly less than 300kg per wheel) and are only suitable for light/medium-light load applications. They should be explicitly excluded from heavy-load applications:
Polypropylene (PP): 50-300kg per wheel. Cost-effective for light-load applications in wet conditions, but prone to deformation under heavy loads.
Nitrile-Butadiene Rubber (NBR): 50-200kg per wheel. Excellent elasticity but poor wear resistance, suitable only for light equipment.
Ordinary Nylon (Unreinforced): 300-500kg per wheel. Lower load-bearing capacity than reinforced nylon. Susceptible to wheel wear under prolonged heavy loads. Summary: Load-Bearing Capacity Ranking and Selection Recommendations
Load-Bearing Capacity Gradient (from high to low):
Metal Alloy (Cast Iron/Steel) > Reinforced Nylon PA (Glass Fiber/Carbon Fiber Modified) > High-Strength Polyurethane (PU) > Standard Nylon PA > PP/Nitrile Rubber;

Key Selection Logic:
Extremely heavy loads (single wheel > 1000kg) + no quietness/ground protection requirements: Choose cast iron/steel casters;
Heavy loads (500-1000kg) + lightweight/wear-resistant/ground protection requirements: Choose reinforced nylon PA casters;
Medium-heavy loads (300-500kg) + quietness/ground protection requirements: Choose high-strength polyurethane casters;
A high-strength bracket (such as thickened galvanized steel or stainless steel) is also required to avoid the safety hazard of "the wheel meets the load-bearing requirements but the bracket breaks."