Curing oven are used for melting, film formation and curing: dead-ends and electric-through passageways. The furnace consists of insulating panels, one or two double-door door blocks, one to eight heating units with air recirculation systems, control panels and cabinets. The insulating panel consists of the outer and inner bearing profiled panels of galvanized and painted steel and insulation of basalt slabs 100 mm thick.
Inside the furnace are placed heating blocks, air distribution systems and suspension system.
Sealing of doors is carried out by means of silicone heat-resistant seals fixed on the perimeter of the door.
The dimensions of the camera, the number of doors, the location of the control panel and the cabinets are selected by the customer at the stage of writing the technical task.
To control the polymerization process, the furnace is equipped with an electric cabinet with a thermostat, a timer and a ring-end ring.
The main requirement for Furnaces to ensure the quality of the coating is the ability to evenly heat the product with powder paint at a given temperature for a given powder paint for a certain period of time sufficient to solidify the powder paint. The speed of raising the temperature is also of great importance for the stoves. This requirement is to the greatest extent possible by air-recirculating furnaces. Manufacturers of powder paint in the accompanying technical documentation indicate, as a rule, several possible modes of curing, ensuring the quality of the coating for each specific material.
The most common powder paints polymerize at a temperature of 160-180C with an accuracy of support in volume and time within a maximum of +/- 5oC for 10-20 minutes. It should be emphasized that the polymerization temperature refers to the temperature of the surface of the product being painted, not the temperature of the furnace. When heated in the furnace particles of powder paint melt, merging into a continuous film of a viscous melt, wetting the surface of the product. The air contained in the layer of powder paint is displaced. However, some of the air remains in the film, creating pores that impair the protective and mechanical characteristics of the final coating.
The best conditions for creating a film with a minimum of air pores are to paint products heated to a temperature above the melting point of powder paint, and to apply thin layers of coating. In normal practice, a layer of powder paint is applied at the normal temperature of the product.
With the further heating and warming of the product, the melt of the PF penetrates into the micro-roughness of the surface, providing sufficient adhesion of the coating, and hardens.
At this stage of curing it is possible to obtain a coating with the desired characteristics: appearance (level of gloss, structure), adhesion, mechanical strength, hardness, protective properties, etc.
It is very important to understand that these characteristics will only meet the specified ones when the curing modes meet the recommended ones (it should be recalled again that the curing temperature is the temperature on the surface of the product when forming the coating). In practice, when painting massive metal parts, the surface temperature of which rises much slower than that of thin-walled products and does not meet the readings of the device, measured the temperature in the furnace, the coating does not have time to completely harden, which reduces the mechanical strength of the film and adhesion. In this case, preheating of the products is applied or the curing time is increased taking into account the need to reach the curing temperature by the surface.