1 Overview

       In order to obtain excellent coating film and excellent product quality, the preparatory work on the surface of industrial aluminum profiles prior to painting is referred to as surface treatment before coating, referred to as pretreatment for short. The pre-processing work mainly includes the following three aspects.

      (1) Remove all kinds of dirt, such as degreasing (also called degreasing), and derusting, from the surface of coated aluminium profiles to ensure the physical and chemical properties of the coating and the quality of the product. The common dirt is metal corrosion products (such as rust, oxide scale), welding slag, dust, alkali stains, oil stains, and old paint films. If these stains are not completely removed before painting, not only the adhesion, corrosion resistance, moisture resistance, and product appearance of the coating film are affected, but also the rust will continue to spread within the coating film. In severe cases, the coating film will fall off into pieces.

      (2) The surface of the cleaned industrial aluminum profile is chemically treated to improve the corrosion resistance of the coating film and the adhesion of the coating film to the profile surface. For example, phosphating steel and oxidizing aluminum parts.

      (3) The use of mechanical methods to eliminate defects in the machining of industrial aluminum profiles, adjust the surface roughness of profiles to improve the appearance of the product quality and adhesion. Such as flat aluminum profile uneven and burrs, with the sandblasting method to increase the surface roughness.