To remove surface pollutants such as dirt, oil, greases, rust from steel, galvanized steel, aluminum or plastic parts, the surfaces should be chemically pretreated in order to guarantee the adhesiveness of coating. We can provide various types of pretreatment to meet different applications:
Spraying pretreatment Suitable for single shape and bulk production, fully automatic painting line.
Dipping pretreatment Suitable for various shapes, materials and sizes of products and inner surface pretreatment.
Rolling wash pretreatment Suitable for sheet metal.
Waterfall pretreatment Suitable for aluminum profile pretreatment in fully automatic vertical line.
Powder Recovery System
By collecting the powder, which passes by the job, and filtering it, the efficiency of the process can be increased to 95% material usage.
The powder will remain attached to the part as long as some of the electrostatic charge remains on the powder. To obtain the final solid, tough, abrasion resistant coating the powder coated items are placed in an oven and heated to temperatures that range from 180 to 220 degrees C (depending on the powder). Under the influence of heat, a thermosetting powder goes through 4 stages to full cure.
MELT, FLOW, GEL, CURE
The final finish depends on accurate control of the oven temperature and on the following factors: The volume of circulating air is dependent on the required temperature, heat consumption and the temperature difference between the forward and return air. The temperature tolerance is ±5 °C. Heating – up and holding times are influenced by the mass of the internal oven components, such as intermediate walls, reinforcements and heat insulation. However, the nature of the work pieces, its density on the suspension system and the thickness of the material are also important criteria in designing the oven. Considerable care is therefore needed in the design of all detailed components of the oven.
Various oven structures have been developed , and the overall plant design and the space available will determine whether a continuous oven, a reverse oven or one of the many other types is advisable. Our experienced designer will always make his plant design flexible to conform to specific requirements. Another factor which also determines the surface quality is the amount of time the work piece is in the curing oven. When using a continuous oven with set production throughout rates, the temperature must be controlled within prescribed limits. Depending on the powder type, hardening is carried out at up to 250 °C.