In standard working environment, temperature is range from 5°C to 60°C (41°C to 140°F). Within this range the wheels and casters work normally for their full working life. However, there are applications with temperatures outside the above mentioned range. For example, we have casters used in baking ovens.
Waiting room before entering the baking oven
High heat resistant Casters
In a regular basic, oven baking is a highly repetitive process which means that the wheels are used in baking ovens again and again and again. From the table below you see that in a food baking oven we get temperatures from around 150°C up to 260°C with (occasional) water vapour present.
|Type of food||Degree (°C)||Minutes|
|Farm Bread||205||40 moist|
|Crusty Rolls||220||20 moist|
Table of temperatures for producing some popular cakes
For such cases, specialized heat resistant wheels is used for the job to be done. Please keep in mind that as temperatures increase, the wheels become weaker and this lowers the load capacity. Besides, static (non-moving) applications with sustained high temperatures over long periods of time the material will begin to deteriorate, which shortens the working life of the wheel. The most three popular materials here are Glass filled Nylon, Phenolic and Cast iron. And you should follow each material’s specifications listed below to choose the most suitable one.
1. Glass filled Nylon 150 – 210°C (300 to 410°F):
Actually the best options of all three, especially for Hospitality and ‘food baking’ applications. The wheel can endure high temperatures, non marking and OK on most floor surfaces. Fiberglass reinforced nylon wheels are the preferred wheel for extended periods of up to 210°C (410°F) (assuming most of their life is spent outside the oven), and for short periods up to 230°C (446°F) even 260°C (500°F) but not longer than 5 minutes.
Features of SUPO Heat resistant Casters: aluminium double brake. Double ball bearings ensure smooth and convenient movement
2. Phenolic 100 – 300°C (570°F)
Phenolic is less durable than Glass Filled Nylon. Also it has a shorter life cycle due to heat deteriorating. The bright side is that Phenolic is the cheapest wheel and can go up to very high temperatures. So it is widely used in Light duty Industrial applications with very high temperatures such as ovens used for curing paint.
Another weakness of Phenolic is its load capacity can decrease dramatically when rising temperature. For example, a Phenolic wheel that has 125kg load capacity at 100°C (212°F) shall be drop to just 40kg at 300°C (570°F). Therefore it is very important to ensure that the load capacity of the trolley fits within the appropriate temperature and load capacity. Phenolic wheels (with special inorganic fillers and PTFE bushes) are preferred for extended periods up to 280°C (536°F) assuming most of their life is spent outside the oven and for short periods up to 300°C (572°F). These have a thick cross section, but are more brittle than either nylon or ordinary grades of Phenolic.
WARNING: Phenolic wheels are not suitable for medium duty applications or applications where wheels are subjected to impact such as when a trolley is rolled down steps.
3. Cast Iron 200 – 400°C (390 – 725°F):
Cast iron is the best candidate for worse working condition. It has the largest load capacity, longest life time and can endure highest temperature with extended period. As a result, we usually see the Cast iron wheel in Industrial based applications such as ‘paint curing’ ovens and also for use in sustained high temperature environments.
For temperatures that exceed 230°C (446°F) a more exotic grease is required. The Production Manager must be notified of this prior to placing the order and the customers required temperature noted on the picking slip once the order is placed.
WARNING: Cast Iron is heavy, noisy and may damage concrete floors and other floor surfaces.
Low temperature Casters
Below 5°C you must specify temperature of use at the time of ordering. Below 5°C (41°F) wheels begin to stiffen quickly, and will soon freeze the bearings so that neither the castor swivels nor the wheels revolve. In chilling rooms, freezing stores, ordinary greases would be useless. You should use aeronautical grease which is a synthetic oil with a microgel thickener as this compound can last 6 – 12 months with temperature as low as -30°C (-86°F)
For the wheel: As the temperature becomes lower, the softer rubber and polyurethane treads on our wheels become less elastic and can be broken. Nylon wheel is OK but may not last long. At such times we recommend fiberglass reinforced wheel, which can be used down to -30°C (-86°F).