1. Structure
1. Wheel
Bears and produces a rolling core part. Common materials include rubber (ER), polyurethane (PU), nylon (PA), cast iron (CI), stainless steel (SS), etc.
2. Mounting bracket / Swivel plate
The bearing parts that connect equipment to wheels are divided into two types: swivel and rigid.
3. Swivel bearing
Components that enable 360° horizontal rotation of the support, often ball bearings or flat bearings.
4. Bushing
The friction reduction element between the axle and the hub is commonly made of copper alloy or engineering plastic.
5. Brake
It is divided into directional lock and wheel brake, which is used to lock rotation or roll.
2. Types
1. Swivel caster
Horizontal swivel for equipment that requires frequent turning.
2. Rigid caster
Straight rolling is only available for applications where trajectory stability is required.
3. Omni wheel / Mecanum wheel
Multi-directional sliding is achieved through oblique rollers, which is mostly used in AGVs and robots.
4. Kingpin-less caster
The center rivet is eliminated, and the swivel part is forged as a whole, which has better impact resistance and maintenance performance, and is suitable for heavy load or high-frequency use scenarios.
3. Materials
1. Nylon (PA6 / PA66)
Wear-resistant, impact-resistant, can be used both indoors and outdoors, and is cost-effective.
2. Polyurethane (PU)
With a wide hardness range, low rolling resistance, and low noise, it is suitable for occasions where the ground is protected and silence is required.
3. Rubber (NR / SBR / NBR)
Good elasticity and excellent shock absorption performance, but average aging resistance.
4. Cast Iron (CI)
High load-bearing capacity, high temperature resistance, high requirements for the ground, mostly used in high-temperature or heavy-duty industrial environments.
5. Stainless steel (SS304 / SS316)
Corrosion-resistant, easy to clean, meet food-grade and cleanroom requirements.
4. Performance parameters
1. Load capacity
The large static and dynamic loads allowed for a single wheel should be calculated according to the safety factor of × total equipment weight (usually 1.25–1.5).
2. Temperature resistance
The material can operate in an ambient temperature range of -30 °C ~ +80 °C for a long time.
3. Rolling resistance
The horizontal thrust required to start and maintain movement is related to tire hardness, ground roughness and bearing type.
4. Impact resistance
The material's ability to resist instantaneous impact without cracking or permanent deformation.
5. Installation method
1. Plate mount
The four-hole or five-hole bottom plate should be fixed with bolts to the equipment base plate, and the mounting surface should ensure flatness.
2. Stem mount
The threaded rod is inserted into the equipment foot and locked with a nut, suitable for occasions where quick disassembly and replacement are required.
3. Expanding sleeve
It is fixed in a tubular foot base using a tapered sleeve radial expansion, without welding or tapping.
6. Functional expansion
1. Silent caster
The choice of elastomer tread and precision bearings reduces operating noise to ≤45 dB.
2. Anti-static casters
The tread resistance is ≤10⁴ Ω, which can conduct static electricity in time and meet the requirements of electronic assembly and explosion-proof areas.
3. Corrosion-resistant casters
The brackets and fasteners are made of stainless steel or galvanized nickel and have passed the 720 h neutral salt spray test.
4. Heavy-duty casters
A single wheel carries 1 t–20 t, usually with a double raceway structure, forged brackets and high-strength hubs.
7. Standards and certification
1. DIN EN 12532 / EN 12533
European standards for casters and wheels, covering dimensional, static load, fatigue and brake test methods.
2. DIN 4102 / EN 13501
Fire rating of floor paving materials is used to evaluate the flame retardant properties of wheel surface materials.
3. FDA 21 CFR §177 vs. EU 10/2011
Food-grade material requirements, suitable for food processing and pharmaceutical industries.
4. RoHS & REACH
Limit hazardous substances and chemical registration requirements to ensure products comply with environmental regulations.
8. Geometry and Detail
1. Swivel radius
The horizontal distance from the center of rotation to the outside determines the small turning space required by the equipment.
2. Offset
The horizontal distance between the wheel centerline and the slewing centerline affects steering flexibility and stability.
3. Dual wheel design
The load is shared by two wheels in parallel, reducing the specific pressure of ground on a single wheel, and improving stability and passability.
epilogue
Familiarity with and correct use of the above terms can reduce ambiguity and improve communication efficiency in technical communication, specification confirmation and quality acceptance. It is recommended to describe the requirements in the seven-paragraph format of "structure-type-material-size-load-function-standard" in the inquiry or technical agreement to ensure that both supply and demand have a consistent understanding of the product.