Casters are made of different components, and not every caster is created equal. There are many things to consider in the caster construction and choice of wheel that will mean the difference between having a solution that works well for the task or one that is a disappointment. Knowing some of the considerations for proper caster and wheel decisions will help prevent you from making a costly mistake.
What to Consider When Choosing a Caster
Many things need to be considered when choosing the right caster for your task, and these considerations depend on where you'll be using the caster. The application that your caster will undergo determines the caster qualities that you'll need. Here are a few of the most important things to know before choosing the proper caster and wheel:
Wheel Diameter: Since larger wheels will roll more easily, you will want a wheel as large as possible, but you do not want a wheel that is so large that it will raise the center of gravity of your load that can lead to tipping.
Swivel Radius: If you are choosing a fixed caster this is not a concern, but if you need your caster to swivel you need to know how much clearance is required to attain a 360-degree swivel with the mounted caster.
Dynamic Load & Load Capacity: Each caster is designed and built to support a certain maximum load while in use, and exceeding this maximum can cause damage and deterioration of the caster, which can potentially lead to catastrophic failure. For this reason it is important to know the maximum load you will have so that you can divide this evenly among the casters you will use; more casters can mean more load capacity for a cart or trolley.
Rollability: Choosing the right bearing is critical in determining how well your caster will roll in application. To reduce the effort to initiate and sustain rolling, a good precision ball bearing is a wise investment.
Brakes: There are many braking options if needed, and each has pros and cons. Side and friction brakes are very economical while tread locks and top locks offer a more positive locking wheel. There is also the consideration of locking the swivel if this is needed for the job.
Mounting Considerations: How do you want to mount your caster? Options include top plates, which are bolted into place and screw threads, or press threads that are inserted into a hole in your cart or trolley are also available.
Different Wheels for Different Needs
In general, it is best to use hard wheel materials on soft floor surfaces and soft wheel materials on hard floor surfaces to prevent damage to the wheels and marking of the floors. Choosing the right type of wheel material the first time can save you a lot of problems and anguish later, especially when it's time to change your casters.
Here are some of the softer caster wheel materials available:
Poly II Rubber: A light gray Polypropylene core that has a dark gray thermoplastic rubber tread molded onto it. This is a soft tread wheel, which rolls easily and quietly.
Soft Rubber: While these provide lower load capacities to their hard rubber cousins they offer quiet movement, added floor protection, and a cushioned ride for the load you are moving. These are resistant to most chemicals and oils.
Thermoplastic Rubber: This wheel material is often a better choice than soft rubber while still providing non-marking floor protection. The soft tread is bonded to the core and is resistant to oils, chemicals and is ideal for applications where the caster will be washed down.
Glass Filled Nylon: These wheels can handle heavy loads, are extremely durable, and have high impact resistance.
And for alternate usage, here are some of the harder caster wheel materials available:
Polyolefin: One of the most economical hard tread solutions these non-marking treads are resistant to frequent wash-downs, grease, cleaning solutions, chemicals and oil. They have high impact strength in a lightweight molded construction.
MoldOn Polyurethane: A Polyurethane tread, which is permanently molded onto an aluminum hub. These provide easy rolling with long service life, good floor protection and high load capacity.
Ploy II Urethane: A light gray Polypropylene core wheel with a dark blue Polyurethane tread molded onto the surface. Hard tread provides excellent floor protection and resists nicks and marks in the wheel. The wheel is also resistant to acids, oils and most chemicals.
Cast Iron: One very popular hard wheel material is cast iron as it is durable and strong, and does not chip or wear easily. One concern is the problem of water resistance, so caution is warranted.
Expert Advice When Choosing the Best Caster & Wheel for Your Needs