Tread plate is the name given to sheet metal stock that bears the distinctive diamond patterns of raised marks on its surface (which also gives it its name of ‘diamond plate’). Other names include Durbar floor plate and checker plate.
Tread plate is typically made from Aluminum or stainless steel and comes in a range of thicknesses. It is lightweight but robust, easy to clean and non-skid, as well as being highly resistant to corrosion. This combination of properties makes it popular for applications such as industrial walkways, ramps and stairs – hence the name of Tread Plate – as well as work surfaces and wall coverings where hygiene is an issue (such as in dairy processing plants and ambulances). It is often used domestically for truck beds and kick plates, as well as for smaller applications such as tool boxes, because it is visually attractive as well as tough.
There are many variations of tread plate. Common materials include Aluminum alloy and stainless steel, which each have different advantages. However, veneer sheets are also available. These are sometimes known as ‘cosmetic’ sheets and are much thinner and less robust than the thicker plate typically used for industrial and other hard-wearing application. They are often just 0.025 inches thick (0.6mm). Their chief use is to provide the look of tread plate and some protection to a surface, but without the expense and weight. They are also used for craft projects since they can very easily be bent and cut. These sheets are occasionally made of plastic, as well as Aluminum, and are designed to be highly malleable. The diamond pattern is often embossed (imprinted into the surface), instead of being raised. They still have the same non-slip properties, though their flimsier nature means they are not generally used for flooring.
Materials and properties
Aluminum 3003. Tread plate is most commonly made from a kind of Aluminum alloy known as Aluminum 3003, consisting of Aluminum with a small proportion of Manganese (1.2 percent) as well as traces of other materials. This gives the Aluminum improved strength over the pure metal, whilst not impairing its machinability. The sheets are typically cold-pressed to create the raised diamond pattern that gives them their distinctive look and non-slip characteristics. The most common form is 0.063-inch plate (1.5mm thick), though heavy-duty 0.125-inch (3mm) plate is also available where additional durability is required.
The sheets are strain-hardened and partially annealed in the manufacturing process. This gives them an additional degree of wear-resistance, but means they cannot be further heat-treated. Finally, the sheets are hot-dipped to give them their bright finish, or else another finish is applied.
Stainless Steel tread plate is used for applications where corrosion resistance and hygiene are paramount, since stainless steel is extremely tough and will not rust. Tread plate is usually made from an alloy called 304 stainless steel, which comprises mainly iron, with a proportion of Chromium (around 18 percent) and Nickel (generally 8 percent). These give it its common name of 18/8 stainless steel. It also contains traces of Manganese, Silicon, Carbon and sometimes Molybdenum.
304 stainless steel is, like Aluminum, non-magnetic. It is fairly resistant to both thermal and electrical conductivity, compared to other metals, and is also exceptionally resistant to corrosion, because the Chromium ‘passivates’ and provides a protective layer on the surface of the metal. This prevents any corrosion from spreading to the inside of the stock. There are a few exceptions, such as in highly saline or low-oxygen environments, but on the whole it is easy to maintain and clean. Stainless steel tread plate can be finished in a range of ways, the most common being 2B (milled finish) and #4 (brushed finish), though there is a wide range of finishes depending on use. These will be suitable for different applications due to the level of smoothness and the ‘grain’ that can be felt on the surface. Stainless steel does not need to be painted to protect it, which makes stainless tread plate suitable for applications where hygiene is paramount, such as on food preparation surfaces, dairy processing plants, and medical equipment. (In fact, it should not be painted, because the surface does not allow paint to adhere easily and it can flake off, leaving an unattractive finish and a hazard to hygiene from small particles of paint.) It is also resistant to staining and picking up odors.
Tread plate is designed to be easily cut, shaped, formed and drilled. Aluminum is a highly machinable material, and the most common thickness of tread plate (0.063-inch) can be cut and moulded with normal DIY tools. It can be cut with tin snips or a hacksaw, drilled with ordinary drill bits and bent without issue. This makes it a popular solution for truck beds, kick plates for doors, and other domestic applications. It can be ordered in pre-cut sizes for simplicity. The thicker 0.125-inch tread plate is harder to work with, but can still be cut and shaped with ordinary tools.
Stainless steel tread plate is harder to work with, especially for thicker sheets. Standard thicknesses range from 0.024-inch right up to 1-inch plate. Obviously these thicker plates require specialised industrial tools to form, but the thinner sheets can still be worked with regular DIY tools and are surprisingly machinable given the toughness of the metal.
In general tread plate requires very little maintenance. Neither Aluminum nor Stainless steel rust or corrode under normal conditions. In most cases, it is enough to brush off any dry dirt and wipe away any stains or mud with a damp cloth. Surfaces can be hosed down if needs be. More stubborn stains can usually be removed with a mild detergent and a soft cloth. The only conditions in which you need to clean and check them regularly is if they come into contact with corrosive chemicals or salt water, such as in marine applications. In these situations a thorough clean and check is recommended at least once a year, in addition to routine maintenance.
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by Eric Lee