Urethane wheels are wheels that are made from molded urethane, alternatively referred to as polyurethane. Urethane contains urethane carbamate links, and is an elastomer, which is a portmanteau term of "elastic polymer." Urethane wheels have all of the beneficial characteristics of metal, plastic and rubber wheels combined. They are more flexible, more cost effective, have higher resilience, better noise reduction, and are more resistant to impact, corrosion, and abrasion than metal. Urethane is better than plastic in terms of resistance to impact, low temperatures, cold flow, abrasion, and radiation. Furthermore, they can reduce noise, have greater resilience, have better elastic memory, and cost less than plastic. Finally, urethane outperforms rubber due to its broader range of hardness, easy customizability, and higher resistance to impact. Polyurethane wheels can also be recoated and retooled, avoiding expensive fine tuning costs in the process.
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Advantages of Urethane Wheels
Molded urethane possesses other advantageous qualities such as durability, chemical and heat resistance, noise reduction, and elastic memory. Urethane wheels can vary in levels of hardness. They can be sponge soft, iron-hard, or any level of hardness in between. In addition to hardness, they can also be fabricated in a wide variety of colors, sizes, and shapes.
Urethane Wheel Fabrication Processes
Two main processes can be implemented to fabricate urethane wheels.
- Liquid Casting
- Involves the melting down of urethane to liquid state and pouring it into a wheel shaped mold to cool and solidify. Synthetic resins can also be utilized in this process. The liquid casting process is typically used for prototyping and smaller scale production processes.
- Injection Molding
- Involves melting the urethane down to a liquid form and using a low-pressure pneumatic injection gun to inject the liquid material into a wheel shaped mold through fill holes. Injection molding machines consist of a network of heaters, motors, and other moving components, which require a large amount of energy to operate. Fortunately, research has been done to make this process more energy efficient. Regardless, injection molding makes up roughly 32% of all plastic processing applications, and is one of the most popular forms of plastic processing today.
- Secondary Fabrication Processes
- Urethane wheels can be formed from molded urethane through secondary processes as well. Urethane wheels can either be made from solid urethane, or a combination of urethane bonded to metals such as cast iron, aluminum, and steel. These wheels are preferable to more heavy-duty applications. Within a bonded-to-metal wheel, the core of the wheel is made of metal, while the tread of the wheel is made from urethane. The fabrication of urethane wheels is highly cost-effective, and urethane is approved by the FDA to be used in clean rooms and other sterilized environments.
Types of Urethane Wheels
A multitude of different types of urethane wheels are available. Some of these types include:
- Crowned Wheels
- Typically used for turns in conveyor systems.
- Engraved Wheels
- Feature engraved patterns such as identification marks, brand names, or serial numbers.
- Desk Wheels
- Can be found in document processing equipment.
- Drive Wheels
- Assists in making industrial machines more resistant to abrasion.
- Compliant Wheels
- Used for the processing of documents of varying degrees of thickness.
Urethane Wheel Applications
Urethane wheels can be used for a multitude of applications including carrying case wheels, grocery carts, conveyor bearings, skateboard wheels, roller coaster wheels, and forklift drive and load wheels. Industries that benefit from urethane wheels include medical, athletic equipment, transportation, retail, industrial manufacturing, and material handling.
In addition to these applications, a new use for urethane wheels that has recently become popular is the use for rotating buildings. Structures such as the Five Sixty restaurant in Dallas, TX, and the Space Needle rotate, but do not use urethane wheels. Instead, buildings such as small restaurants or bed and breakfasts utilize urethane wheels to move the buildings along. These buildings have a simple traditional structure and are built on a steel frame, which is supported by a set of heavy urethane wheels that help the building rotate. These massive wheels weigh around 300 pounds each. In addition to the urethane wheels, the rotating buildings feature a non-rotating centralized area which houses the buildings’ electrical and plumbing lines. The rotating buildings can be controlled through software apps. Throughout the world, there are currently more than 10 rotating buildings, each varying from a house to a public attraction. The current cost of building one of these rotating buildings is around $400,000, which is significantly lower than the cost of building them when they were first introduced. Rotating buildings were inspired by the Everingham rotating house in Australia, and are continuing to become more popular.