Companies engaged in powder coating face issues of coating build-up removal from hooks, racks, hangers and rejected parts. The techniques used for stripping cured powder coating can include cold chemicals, mechanical methods or thermal (uses heat) or thermo-chemicals.
MECHANICAL STRIPPING utilizes blasting media such as CO2 pellets, glass beads, steel shots, etc. These are blasted at the coated surface and remove the coating by abrasion. Aggressive media will remove the coating but can leave a rough profile on the metal surface of parts that have been stripped and will need to be repaired.
THERMAL CLEANING uses heat to break down the coating but creates ash residue which requires removal by water blast. Thermal cleaning can be done by baking the coating, burning off or by fluidized bed. The key to this technique requires the parts to be resistant to the high temperatures employed, which can reach 1200°F/648°C.
BAKE OFF is a technique utilizing an oven with temperatures about 700°F/370°C. This temperature will eventually ignite the powder coating. Such ovens have a water mist system which slows the burning and reduces equipment damage. The left over ash residue must be completely cleaned off.
BURN-OFF / FLUID BED requires 1100°F/590°C temperatures. The coating burns quickly and water is then used to stop the burning and remove the excess ash. Fluid bed stripping uses sand for heat transfer. The parts are placed in the fluidized tank where the hot sand, 800°F/426°C, removes the coating. No additional cleaning will be needed, the sand provides the scrubbing action.
THERMO-CHEMICAL stripping uses a combination of heat and chemical reaction. This is also known as “molten salt stripping”. The working temperature is 850°F/454°C.
ROOM TEMPERATURE STRIPPING some suppliers’ “cold” chemicals perform at room temperature or low heat of 135°F/57°C. In general, the chemicals are environmentally preferred and are safer for the operator. The chemicals dissolve the powder coat binders requiring an easy rinse after immersion. Room temperature powder coat strippers are used to strip parts as well as hangers, racks and hooks. This technique is very cost effective using an immersion tank. Exhaust ventilation is highly recommended.
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Abrasive Cleaning Media & Equipment
