Skateboard wheels are typically mass-produced in an industrial setting. They are made of polyurethane, a versatile and durable synthetic material. According to 1skates.com, Frank Nasworthy invented polyurethane skateboard wheels in 1970. With their rubber-like grip on the pavement, polyurethane wheels expanded the potential of ways that skateboards could be used. Different types of polyurethane skateboard wheels vary mainly in terms of their durometer, diameter, color, and shape. The durometer is a measure of how hard the wheel is. Soft wheels, best for cruising on hard surfaces, have low durometers, such as 87A. Hard wheels, which absorb little shock, have a higher durometer, like 100A. The diameter is the height of the wheel. Making polyurethane skateboard wheels involves the use of specialized chemicals and machinery. This process is indicative of the basic industrial processes by which polyurethane wheels are made.

1）Mix a batch of polyurethane. Combine the chemical components of the polyurethane in the appropriate proportions in a metering machine. A metering machine is a machine that heats, mixes and dispenses polyurethane

2）Add color. When the polyurethane in the metering machine is a liquid, add dye or some other type of pigment to the batch. This is only necessary if you want your skateboard wheels to have a color.

3）Pour polyurethane into molds. The molds should be made of aluminum and reflect the shape and size you want your wheels to be.

4）Remove the polyurethane "slugs" from the mold after the polyurethane has solidified. Slugs are the basic, unfinished form of your polyurethane skateboard wheels. Place the slugs on a flat surface to fully cure.

5）Shape the wheel. Use a lathe to cut the slug into shape. The sides and riding surface of the wheels should be cut to match each other exactly. A lathe is a piece of machinery that turns an object as it shapes it. In this case the lathe turns the slug as it cuts away excess polyurethane.

Pneumatic Casters Vs. Polyurethane Casters

A caster is a special type of wheel. Small and compact, they are normally used under heavy objects, such as furniture, to allow movement of the item, as well as swiveling abilities to aid that motion.

There are two popular types of casters, including pneumatic and polyurethane. Pneumatic casters are typically rubber filled with air, whereas the polyurethane casters are solid polyurethane material.

Advantages to the pneumatic casters are that they can be filled with air if they get low, and they have better traction than polyurethane casters do. A drawback to pneumatic casters is that if a load is extremely heavy, the weight can flatten the casters out, making motion more difficult.

On the other hand, polyurethane casters are extremely durable due to their solid construction. They can handle heavy loads, for example, the casters on a bed frame holding a mattress, with no flattening of the casters. However, their traction is not as good as the pneumatic casters.

Types of Casters

When selecting casters, consider capacity, the maximum weight the caster will need to support, size, fastening, flooring and environmental conditions. Size matters: The larger the wheel of the caster in diameter and width, the easier the caster will roll. A mismatch of caster to flooring will damage the floor. Dirt at the caster location is an example of an environmental condition that can impede the movement of casters.

Light Duty

The capacities of light duty multipurpose casters range from 50 to 300 pounds. Their wheel sizes are from 2 to 5 inches in diameter, and their tread widths are from 0.75 to 1.5 inches. Plate, threaded stem, square stem and round post mountings are available. Wheel materials are semistreet, solid rubber (hard or soft), polyolefin, mold-on and polyurethane. Side brakes and thread guards are options. Typical uses for light duty casters are in computer rooms, libraries, laboratories, laundries, bakeries and light-duty warehouses.

Medium Duty

The capacities of medium duty industrial casters range from 200 to 800 pounds. Their wheel sizes are from 3 to 8 inches in diameter, and their tread widths are from 0.69 to 2 inches. Plate and threaded stem mountings are available. Wheel materials are semistreet, solid rubber (hard or soft), polyolefin, mold-on, polyurethane, V-groove and phenolic/canvas. Side brakes, foot brakes, wing brakes, 4-position locks, wheel grease seals, ball race dust seals and thread guards are options. Typical uses for medium duty casters are in bakery equipment, hospital equipment, floor trucks, warehouse trucks, display racks, chair trucks and shelf trucks.

Heavy Duty

The capacities of standard heavy duty industrial casters range from 300 to 1,400 pounds. Their wheel sizes are from 4 to 10 inches in diameter, and their tread widths are from 2 to 2.5 inches. Mountings are plate. Wheel materials are semistreet, solid rubber (hard or soft), polyolefin, mold-on, polyurethane, V-groove and phenolic/canvas. Side brakes, foot brakes, wing brakes, 4-position locks, wheel grease seals, ball race dust seals and thread guards are options. Typical uses for heavy duty casters are in assembly line dollies, maintenance trucks, heavy duty platform trucks, transport trailers, ice trucks and frame trucks. Special order heavy duty casters can support weights up to 17,000 pounds.