It is often found in the Food Processing Industry that the Castors and Wheels used on the Handling Equipment are troublesome, with failures, regular replacement & maintenance, and excessive noise being commonly complained of. Generally these “Problems” are caused by incorrect selection of the Castor Wheels.
Within this article we want to address some of the issues experienced with Food Industry Castor Wheels, look at the typical application environment and discuss how to solve some of these potential issues, including which are best types of Food Industry Castors and Wheels.
Quite Simply, a Company or Facility that is producing, handling, or preparing food. These may include, Food Processing Plants, Food Hospitality Services (Schools, Hospitals, Hotels), Bakery and Cooking Facilities, Slaughter Houses, Fisheries & Seafood Processing Plants. In addition, there are the associated industries such as Storage, Transportation, Packaging, Bottling & Labeling companies.
It is common within the Food Industry that the equipment used to handle the food (Racks, Trolleys, Cages) has to cope with extremes of temperature. This includes any Castors and Wheels that are used on the equipment to allow the food to be easily moved around the production facilities.
In the Food Industry environment it is common for Temperatures to range from -21ᵒC (typical for Commercial Freezers), to around 260ᵒC (Typical for Commercial Bakery Rack Ovens). This in itself is an issue for Wheel manufacturers, as the extremes of temperature, particularly the high temperatures can have a considerable impact on a Castor Wheels mechanical properties, such as Roll Resistance, Load Capacity, Impact Resistance and ultimately their life span.
The extreme temperature resistance that is demanded of the Equipment, including the Castors and Wheels has meant that over recent years new composite materials have been developed to cope with the high demands.
However the main problem occurs due to what’s called “Thermal Shock”. This is where the Castor Wheels are subjected to a rapid change in extremes of temperature, for example a Bakery Rack being removed from a walk-in freezer and shortly put into an oven.
This “Thermal Shock” is a major cause for the wear, tear and ultimate failure of the Castor Wheels. (It should be noted that a “failure” may not necessarily be a catastrophic failure, and can also be considered a major change in mechanical properties making the wheel unsuitable for the environment).
Thermal Shock can cause Brittleness of the Wheels Material, Change in stiffness, Corrosion, Excessive Noise, Increased Roll Resistance, and Wear on the Wheel Bearings.
Cast Iron Wheels were common many years ago in the Food Industry environment, and are still found on many old pieces of equipment today. Castor Iron Wheels offer a highly robust wheel that does not easily damage or deteriorate and provides a reasonable level of performance; however they were not ideal for the typical flooring surfaces used in food processing plants, resulting in floor wear and damage, and are generally noisy when used.
Since the rise of Complex Plastics, Composites and Resins, specially Engineered Wheels have been developed that can cope with the Temperature demands, and to some extent the Thermal Shock. These include Phenolic Wheels, Thermosetting Plastic Wheels and Epoxy Resin Wheels, which can cope well with the Extremes of Temperatures of between -40ᵒC up to 350ᵒC, with only minor changes to their mechanical properties throughout the temperature range and during Thermal Shock.
There are also Thermoplastic Wheels with High Temperature Rubber Treads, which offer reduce noise and increased protection of the flooring surfaces, however these typically have a reduced maximum temperature range, in the order of 150ᵒC
Each type of High Temperature Wheels has slightly different properties, generally speaking, and in the case of Bulldog Castors Ltd there are 6 different types of High temperature Wheels suitable for the Food Industry. Properties range from extreme high maximum temperature, thermal shock resistance, water/fluid resistance and several other factors. If you wish to read in detail about the 6 different High Temperature Castor Wheels, please read our Blog “ High Temperature Wheels” – Click Here
Looking at the Castor Fork (Bracket), it is common to find Mild Steel Zinc Plated materials, however to extend life and increase performance the use of Stainless Steel materials (such as AISI304 Castors and also AISI420) to combat the excessive corrosion that would be caused by Thermal Shock, Wear, and Wash-Down, where standard Mild Steel Zinc Plated Castors would Rust and Corrode, causing both increased roll resistance of the equipment and hence increasing operator fatigue, but also critically the potential for contamination into the food processing environment.
When using swivel Castors it is also important that high temperature grease is used to lubricate the bearings and swivel head to ensure wear of the bearings is controlled to a minimum. Certain Castors are available with a grease nipple to reapply grease periodically.
Apart from Temperature, Food Handling Equipment has to endure continuous day to day heavy use and heavy loads applied to them. Equipment may be pushed and pulled around different areas of the production line, having food and goods added and removed throughout the process. This may be a 24 hour production facility where the castors and equipment are used to their extreme. Food Industry Castor Wheels must therefore be carefully selected considering the environment and demand of the wheels.
Regular maintenance schedules should be in place where the Castors are inspected for excessive tread wear, damage, chips or cracks to the wheels and also checks on the bearings and grease. As a general rule of thumb, a wheel should not swivel more than two times when pushed by hand (at room temperature), otherwise this signifies either loss of lubrication or worn out bearings.
Check out the video on youtube for details on a quick check of Castor Wheel Swivel Bearing Performance, https://www.youtube.com/watch?v=S7kWMMCAclM
Another challenge for Food Industry Castor Wheels is that in most processing environments they must be able to accommodate regularly cleaning, including High Temperature Steam Sterilisation, Cleaning Fluids and Water. These cleaning methods can causes various issues including corrosion, loss of grease, and retention of fluids in the wheel material.
As with all material handling equipment the larger the Castor wheel the easier the manoeuvrability of the equipment. It’s much easier to push a trolley with 100mm Castors, as it is with 50mm Castors. In addition, larger wheels handle obstacles, uneven floors and steps much easier and result in reduced likeliness of damage to the wheel. Therefore the size of the equipment and flooring surface should be considered when selecting the size of wheel.
Bulldog Castors Ltd offer a range of Food Industry Castor Wheels. Our Technical department are available to provide advice and wheel selection, and have a great knowledge of the Food Industry and requirements that are necessary for the Industry. Contact sales@bulldogcastors.co.uk or call +44 (0)116 2970521
