Powder coating is a popular choice for metalwork as it is a less expensive way of coating metal, and offers a durable finish. . The powder is applied then baked onto a mild steel or aluminium frame and offers a durable finish that can be glossy or matt. The aesthetic is a flatter colour that can look pleasing when a metalic colour is used. There are a variety of standard powder coated colours to choose from (white, black, bronze, taupe, silver and gun metal) and possibility of custom colors as well, all available in matt or gloss.
Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint.
Removal of oil, dirt, lubrication greases, metal oxides, welding scale etc. is essential prior to the powder coating process. It can be done by a variety of chemical and mechanical methods. The selection of the method depends on the size and the material of the part to be powder coated, the type of impurities to be removed and the performance requirement of the finished product. Some heat sensitive plastics and composites have low surface tensions and plasma treating can be necessary to improve powder adhesion.
Another method of preparing the surface prior to coating is known as abrasive blasting or sandblasting and shot blasting. Blast media and blasting abrasives are used to provide surface texturing and preparation, etching, finishing, and degreasing for products made of wood, plastic, or glass. The most important properties to consider are chemical composition and density; particle shape and size; and impact resistance.
When a thermosetting powder is exposed to elevated temperature, it begins to melt, flows out, and then chemically reacts to form a higher molecular weight polymer in a network-like structure. This cure process, called crosslinking , requires a certain temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed.
Ultraviolet (UV)-cured powder coatings have been in commercial use since the 1990s. They were initially developed to finish heat sensitive medium density fiberboard (MDF) furniture components. UV-cured powder coatings use less heat energy and cure significantly faster than thermally-cured powder coatings. The use of UV LED curing systems, which are highly energy efficient and do not generate IR energy from the lamp head, make UV-cured powder coating even more desirable for finishing a variety of heat-sensitive materials and assemblies. An additional benefit for UV-cured powder coatings is that the total process cycle, application to cure, is exceptionally fast.
28 January 2022