Dip coating the metal in plastic (Plastic Coating)

Plastic coating is the process of applying a thermoplastic to the surface of metal items to provide long-term corrosion, impact and chemical resistance whilst offering an attractive decorative finish. Plastics tend to be applied a little thicker than standard paints and are generally impermeable to water or aggressive chemicals. As a result thermoplastics are ideal for very long term protection of metal in the construction and automotive industries or for the coating of welded items such as wire baskets, fencing mesh and cylinders.

The materials used are in powder (or liquid) form and are usually applied in the factory by standard fluid-bed (fluidised bed) or electrostatic spray techniques.

Thermoplastic powders can be coated using either the fluidised bed dip coating process or by electrostatic spraying.

At this stage in the manufacture of the project the metal needs to be bent and the edges are all finished so that they will not cut anyone. The metal is placed in the oven at a temperature between 350 and 400 degrees C, for 4 minutes. At this temperature the metal becomes very hot and will burn you if it is touched. You need to wear protective heat proof gloves.

Note the position of the metal, it is slightly overhanging the edge of the oven, this is to make it easly removed. When the 4 minutes are up the metal is removed, an ‘S’ shaped hook is used to lift the metal and it is then taken to be dipped into the plastc powder. It is dipped twice, each time for 1 second, this allows the plastic powder to stick to the metal and start to melt. The hook with the lever attached is hung up on a rail to allow it to cool down, there is an extractor fan located close by to all any fumes created by this process to be taken away from the room. The metal is hung on this rail for at least 10 minutes, after this the plastic is still a bit soft and should be handelled carefully.