Powder coating is an advanced method of applying a decorative and protective finish to a wide range of materials and products that are used by both industries and consumers. The powder used for the process is a mixture of finely ground particles of pigment and resin, which is sprayed onto a surface to be coated. The charged powder particles adhere to the electrically grounded surfaces until heated and fused into a smooth coating in a curing oven. The result is a uniform, durable, high-quality, and attractive finish
What is Pretreatment for Powder Coating?
Pretreatment means surface preparation. Here by pretreatment, we mean metal pretreatment as the powder coating is predominantly applied to metals.
Surface Preparation Includes:
Mechanical cleaning includes for (Applied Powder Coatings) aluminum oxide blasting. This by abrasive action not only removes the surface impurities but also eliminates scratches and surface irregularities. Cleaning is very good, however, coating must be done immediately because the cleaned surface is in a highly reactive state and corrosion occurs very soon. Chemical cleaning includes removal of dirt, oil and grease, and the oxidation products present on the surface by means of chemicals. The chemicals may be applied by wiping, spraying or dipping. The nature of chemicals used depends upon the base metal and will be discussed later in detail.
Application of Conversion Coating
Conversion coating. – These are applied for three purposes: 1) provide temporary in process corrosion protection before application of powder coating. 2) promote good adhesion of the powder coating to the substrate. 3) impart under paint corrosion & thereby improve the life of the powder coating. The type of the conversion coating used also depends upon the base metal and will be discussed later.