WCA November 2013

Long-lasting Rapid Coat

loops’ or hooks should be attached at suitable locations, for ease of handling the item, so as not to mark the product appearance. These are later cut off or removed. 2. Preheating: The bare item is heated in the oven at 250-300°C (480-570°F) for 5-10 minutes. The heating time and temperature depends on the mass of the item and the loading of the oven. This has to be practically ascertained to provide the desired production rates and coating thickness. 3. Coating: The heated item can be coated in two ways: Spray coating, the powder can be sprayed onto the item using electrostatic spray guns. The air velocity and amount of powder should be suitably adjusted so as to prevent overspray or bouncing back of the powder spray, or Dip/fluidised bed coating: The heated item is dipped in a tray containing the powder and the powder is splashed on it, or the item is dipped in a fluidised bed of the powder for 2-5 seconds. The powder will stick to the hot item. Once the item is coated, care should be taken to ensure it does not rub or come into contact with any surface to prevent damage. A rough, powdery, but uniform coating on the item is obtained. The excess un-melted powder is shaken off with a slight jerky motion or light tapping. The coating thickness increases with the pre-heating temperature and dipping time. To smoothen out the powder and provide a glossy surface, the item is re-heated in the oven for 2-3 minutes. The suggested temperature varies between 120-140°C. This causes the powder to melt, sinter and flow out. Excessive heating may cause the coating to discolour or sag. The item should be carefully taken out of the oven, without the coating coming into contact with any other surface, and allowed to cool in a clean, dust-free atmosphere. Sometimes water quenching is also resorted to for wire products. The thin ‘wire loops’ attached earlier for handling the item are carefully snipped off at the base so as not to mar the appearance. The item is inspected for pinholes or blemishes. These can be filled or repaired with a little powder with a small soldering iron or hot air gun. Rapid Engineering Co Pvt Ltd – India Website : www.rapidcoat.com

Rapid Coat powder coatings are manufactured by Rapid Engineering Co Pvt Ltd (RECPL). Located at a two-acre site in New Delhi, India, Rapid Coat manufactures both thermoplastic and thermosetting powder coatings, which are sold globally. HAPA stands for high adhesion polymer alloy. As the name suggests, it is a thermoplastic polyethylene alloy. These plastic coating powders have been specifically designed to provide a long lasting, chemically and mechanically tough coating for both exterior and interior applications. The HAPA coating has excellent adhesion to the base metal and is almost impossible to peel off. HAPA powders are available in a variety of grades: HAPA SC (spray coating): The powder item size is very fine and designed to be sprayed onto the item using electrostatic spray guns. The air velocity and powder flow should be suitably adjusted so as to prevent overspray or bouncing back of the powder spray. HAPA DC (dip coating): This grade of powder is designed for coating by the dip/fluidised bed coating method. In this method, the heated item is dipped into a fluidised bath containing the powder for 2-5 seconds. HAPA granules: These granules possess the same properties as the other grades but are designed for coating using the extrusion coating method. HAPA powders find many applications given the tough and durable coating properties along with the flexibility available in methods of coating. Some of the most common applications of HAPA are: playground equipment, garden furniture, outdoor benches, welded wire mesh, wire mesh rolls, chain link fences, security fences, fence posts, pipelines, automotive clamps, automotive fuel tank filler pipes, fire extinguishers, battery boxes, submersibles, fan guards and lamp posts. The coating methods include: 1. Fabrication: The metal plate is de-greased, de-rusted, de-scaled, passivated and cleaned. Thin ‘wire

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Wire & Cable ASIA – November/December 2013