Polyurethane (PU) is used in a wide variety of wheel surfaces, including medical and industrial casters, due to its excellent durability and high loading capacity. Our PU casters also feature precision ball bearings, ensuring perfectly smooth, silent movement. These casters will not leaving marks on floor surfaces, even under heavy loading.
However, PU has weaker hydrolytic stability. As a result, the durability of PU wheels may be affected by humid environments, along with the cleaning chemicals and high temperature steam sterilization processes regularly used in hospitals. In addition, a PU surfaces will gradually harden and degrade if kept in a cold environment (<0° Celsius) for long periods of time.
Thermoplastic Rubber (TPR) is another material commonly used in wheel surfaces, including medical and industrial casters. The main advantage of a TPR wheel surface is tis elasticity, which gives it good shock-absorbing properties while in motion. This makes TPR the ideal material for medical equipment caster wheels.
However, due to a softer wheel surfaces, TPR has a slightly lower loading capacity than PU. In addition, TPR wheel surfaces may gradually deform and consequently affect caster function if left stationary for prolonged periods under heavy loading.
Nylon is generally used in industrial casters, due to its hardness, high loading capacity and long life. However, nylon wheels create noise while moving on floor surfaces, making them unsuitable for using in hospitals and other environments where quiet is required.
Electric Conductive Wheels
Electric conductive wheels are mainly used in advanced medical equipment and the technology industry. Available in PU and TPR, Electric conductive wheels comply with international standards (Resistance<104 Ω). These wheels are ideal for medical devices, trolleys and hospital beds which are fitted with precision electronic instruments and frequently moved. Electric conductive wheels conduct electricity emanating from electronic devices to the floor, ensuring patient safety and protecting equipment.
Antistatic wheels are also available in both PU and TPR, and comply with international standard (Resistance< 108 Ω). Normally, static electricity is generated as a wheel moves in a dry environment – as a result, dust, hair, etc. on the floor is attracted to the wheel surface. Antistatic wheels are the perfect solution to this problem.
Roller – raceway contact is theoretically linear.
Furthermore, there are several different types of rollers:
Theoretically, ball – raceway contact is limited to occasional.
Ball bearings are the most widely used in industry because they feature the best performance / price ratio.
They are found in wheels, car transmissions, farming machinery, machine tool spindles, etc.
If the gap clearance is increased, angular contact is obtained; the bearing can now bear increased axial loads* and performance levels are enhanced.
Cylindrical roller bearings are used in car gearboxes, on bearing block 4 of the Boeing and Airbus CFM56 engine, in the rail sector. The cylindrical bearing is almost always used with a ball bearing to support axial loads.
The advantage of the taper roller bearing is that it can withstand combined loads*, while it has a very small outside dimension footprint. It is notably used in car wheels, train sparkplugs etc.
However, the drawback is that it is difficult to manufacture and is therefore more expensive.
Contact pressure between rolling bodies and raceway is distributed along a line in roller bearings. In ball bearings, it is concentrated on a single point. It is for this reason that, for comparable outside dimension footprint, roller bearings withstand higher loads* and lower limit speeds.