Castors not only help move a piece of furniture, but they have an aesthetic function too. But how do you choose the right castor for your furniture?
When choosing a castor you have to think about a few things. The weight of the furniture, the type of flooring you’ll be using it on and the material of the castor itself all affect the type of castor you need.
Castors are a common feature on most office furniture. Having wheels simply makes the furniture easier to move, it’s a practicality. Castor wheels also make office chairs safer, as the wheels will glide better over the floor, and not dig in causing the risk of the chair tipping over and injuring the person sitting down.
Typically, castors are made from chrome, copper, brass plastic and pewter. And with regards to which castor is suited to which floor type there is a general rule:
For hard floors use a soft wheel and for soft floors choose a hard wheel. And the larger the wheel, the easier it will be to move.
Soft wheels are usually made from rubber while harder wheels are made from polyurethane or nylon. There are also castors with pneumatic mechanics available, but these are more often found on furniture that’s being used outside. These might also come as a puncture proof option.
Applications for Castors
You probably won’t notice castors around the home or in the office until you really start to look for them. But they are everywhere:
- Sofas and couches
- Industrial bins
- Large photocopiers
- Hospital equipment
- Supermarket trollies
And that’s just a few applications.
Naturally, the small plastic wheels on an office chair wouldn’t be robust enough for industrial use such as bins or in a hospital or school. These would require an entirely different wheel solution.
Choosing a Castor – Weight
The weight of the furniture or piece of equipment you are moving has a huge bearing on the type of castor you choose.
When the load is heavier the castors will need to move under more extreme conditions and if the ground is uneven the load distribution can change (if a wheel or even two wheels lift off the floor, the remaining two or three wheels will still be carrying the same weight).
It’s crucial to understand the weight the castors must support. Also consider whether there will be any shock forces such as items being dropped onto the equipment that the castors must support.
Castors will have a max load bearing, so to work out the maximum load each castor needs to carry (for a four castor setup) add the unit weight and the extra load and divide this by three.
Equipment weight + maximum extra load / three
So, if the equipment weighs 25kg and the extra load will be a maximum of 5kg then:
25 + 5 = 30
30 / 3 = 10
So, each castor should carry a load bearing of 10kg to be effective.
Types of Castor
Castors come in many types. Brass castors, for example, would be found on furniture that needs an antique feel. It’s an aesthetic thing as well as a functional one. Rubber castors are the most suitable where you need quiet movement or on carpet.
- Rubber offers good grip and control, will protect the floor and are perfect for hard surfaces.
- Polyurethane has good grip and control, is good for heavy duty applications and great for hard surfaces. Floor protection with these is average but polyurethane castors also offer low noise and look good.
- Polypropylene offer easy movability and are suitable for both hard and soft surfaces.
- Nylon castors are similar to polypropylene above, but are also ideal for heavy duty use.
Also consider the swivel radius (if you’ve chosen a swivel castor) and make sure the wheel can turn completely without being stopped throughout its rotation.
Because castors are made from a range of material it’s vital to choose the material that’s right for the environment.
Environmental factors can affect the performance of castors – for example extremes of temperature can affect their use and certain rubbers can leach into the environment as they get older, so are not suitable places that need to be highly hygienic. Hospital equipment can be highly sensitive to some materials so will need the correct castor to prevent this.
If the castors break it’s often less expensive to replace the castor than the whole piece of equipment. And with a little planning and understanding it doesn’t have to be a huge challenge.