Web coaters and roll coaters are used to rapidly apply controlled layers of paint, protective films, adhesives, and other types of coatings onto a moving surface of paper, plastic film, coil stock, metal foils, or other sheet materials. The coating is often metered onto a roll and then transferred onto the moving web. Web coaters and roll coaters can include extrusion or slot die coaters, spray coaters, curtain coaters, dip spin coaters, and immersion coaters. After the web and roll coaters apply the protective coating (either a liquid or mastic composition) to a substrate, the coating converts into a solid film that is protective, decorative, or functional. Web and roll coaters and roll coating machinery are used in many industries to apply different types of coatings, including varnishes, glues, inks and paints.
Types of Web and Roll Coaters
There are many types of web coaters and roll coaters available. One coater in the web coaters and roll coaters category is a dip spin coater. A dip spin coater is used to paint large batches of small parts, such as fasteners. With dip spin coating, parts are placed in a wire basket that is immersed into a coating reservoir. The dip spin coating process is automated and has a high production rate. An immersion coater is similar to a dip spin coater in that the substrate or parts are dipped into a coating bath. The coating generally has a low viscosity to allow it to return to the bath as the substrate is removed. This process is often used for porous substrates. A curtain coater, however, releases a continuous sheet of liquid onto a substrate or object traveling on a conveyor. Curtain coaters have been used for many years and allow for controlled speeds and reduced physical defects. Coil coating is a continuous and automated process for metal coating. With coil coating, a metal coil is unwound at a constant speed and passes through various treatment and coating processes before being rewound for shipment. Advances in coil coating have resulting in a much faster production rates. Thin film coating is often used to apply dopants and sealants to electronic devices, chips, and microelectronic parts. Most thin film coating techniques allow layer thickness to be controlled within a few tens of nanometers. Thin film coating is often used in optics, electronics, and packaging.