Types of Coating Machines
Types of Coating Machines
A coating machine is a device that applies adhesive or other types of coatings to paper, plastic, metal, and other materials. This equipment is used in a variety of applications, from food packaging to manufacturing devices. Some machines are designed to apply a single layer of coating, while others are used to coat multiple layers. The type of coating that is applied to the product can vary from simple glues to complex, high-performance sealants and coatings. The size and shape of the product will determine the type of coating that is applied to it.
When a product requires a protective or barrier coating, a coating machine is an ideal choice. These machines are capable of applying a wide variety of protective coatings, including polymer films, epoxy resin, and aluminum oxide (AlOx). These systems can also be used to coat thin metallic sheets, which are often used in electronics and aerospace applications.
The type of adhesive or coating that is applied by a coating machine will determine the type of equipment that is required. Generally, a roll coater is best for products that require a full surface coating, while ribbon or extrusion applicators are best for wide, ribbon-type coating patterns. There are also specialty machines available for coating a specific pattern, such as stripes or other shapes.
In general, a roller or drum-type coating machine is appropriate for all substrates, from very thin flexible materials such as paper to very thick rigid or semi-rigid materials such as plywood or fiberboard. The substrate thickness and other characteristics will determine the type of feed roller configuration that is necessary to ensure a proper coating. A dual-feed roller arrangement may be necessary to force the material to come into contact with the coating roller. For stiffer materials, a soft-faced coating roller may be needed to prevent the material from bridge over the coating roller and create voids in the coating.
A single-feed roller configuration is also possible for some materials, particularly if the coating being applied is very viscous and does not flow well across the surface of the substrate. This arrangement allows the part to be fed into the machine crooked, and the coating will still be evenly applied over the entire surface.
Another type of coating machine, shown in Figure 11, is used to coat very thin and fragile materials such as foam, non-woven fabric, and thin rubber. The pressure rolls in this machine are designed to force a traveling strip of material directly against the coating roller, so that it is forced to cling to the coating. This arrangement is usually used with a liquid adhesive, and it is sometimes combined with stripper fingers. In some cases, the pressure rolls are not driven, since some types of adhesive generate sufficient drive force to pull the web through the machine. However, the use of a single pressure roll is not recommended for extremely flexible substrates, because they are more likely to fold or bunch up as they pass through the coating point.