Casters are a general term, including movable casters, fixed casters and movable casters with brakes. The movable caster is also called the universal wheel, its structure allows 360-degree rotation; the fixed caster is also called the directional caster, it has no rotating structure and cannot be rotated. Usually two kinds of casters are used in combination. For example, the structure of the trolley is two directional wheels in the front, and two universal wheels in the back near the push armrest. There are casters of various materials, such as pp casters, PVC casters, PU casters, cast iron casters, nylon casters, TPR casters, iron core nylon casters, iron core PU casters, etc. Ergonomic casters are designed with consideration for the operating environment and the task to be performed so that any injurious effects on the operator are minimized. Long-term repetitive actions involving resisting casters can contribute to strain injuries. Improper specifications can also contribute to reduced service life of casters. Many parameters play a role in how well the caster performs. Parameters such as tire hardness, tread width and shape, the length of the trailing offset (the 'caster') and wheel diameter all affect the effort required to start the platform moving. Harder wheels will make the caster easier to roll by reducing deformation resistance. A less inflated tire offers more deformation resistance and thus more effort is required to move the attached platform. Turning effort is affected by the amount of caster and by the wheel diameter. Enhancements to traditional caster design include toe guards, track wipers, reinforced legs, steering tubes, swivel locks and brakes, all implemented in an effort to reduce operator injuries in the workplace.

PU wheel is also called PU perfusion wheel. Strictly speaking, PU is also a kind of plastic, but additives are added in the production process, so the performance is more superior, and of course the production cost also increases. Features of PU perfusion wheels: Elasticity can play a certain shock absorption effect (even better than inflatable wheels), good grip, not easy to slip, more wear-resistant, and good comfort. PU material can be applied to the fabric or weight-bearing parts of footwear, such as high-end inline wheels, skateboard wheels, PU pads, luggage wheels, shopping cart wheels and other purpose wheels, in sports products such as drift boards, vitality boards In some sports and leisure products favored by teenagers, such as ice skates, twisting shoes, etc., the wheels are generally PU wheels.

Rollers, cylindrical parts, are divided into driving and driven rollers, and are used in various transmission and conveying systems such as printing machines, digital printers and other conveying equipment, papermaking and packaging machinery. Most of them are made of stainless steel, steel castings, and solid forged alloy steel cores. According to the lagging material, there are natural rubber rollers, nitrile rubber rollers, polyurethane rollers and so on. Equipment roller printing, like newspaper printing, is a high-speed process that can produce more than 6,000 yards of printed fabric per hour. This method is also called mechanical printing. In roller printing, the pattern is printed on the fabric by an engraved copper drum (or roller). The copper cylinder can be engraved with very delicate fine lines arranged closely, so that very fine and soft patterns can be printed. For example, the fine, dense Paelizli tweed print is one type of pattern printed by roller printing. Fountain engraving should be exactly the same as the pattern designer's design drawings, and each color needs an engraving roller. Roller printing is the least used method of high-volume printing production, and production volumes continue to decline each year. This method is not economical if the batch size of each pattern is not very large. In most cases, roller preparation and equipment adjustments are costly and time-consuming, making printing with this method less economical. However, roller printing is often used for prints with very fine line patterns such as paisley tweed prints and major prints that are printed in large quantities for many seasons. The size of the engraving fountain depends on the printing machine and the printing pattern. Most printers can be configured with fountains with a maximum circumference of 16 inches, which means that the size of the printed pattern loop cannot exceed 16 inches. The width of the fountain should be slightly larger than the width of the printed fabric so that the fabric, including the selvage, can be fully printed with the pattern. Once ready, the printing cylinder can be used almost unlimitedly, generally printing millions of yards of fabric with no problem.