Everything You Need to Know About Powder Coating Pre-Treatment Process

30 May 2022

Powder coating maximises a free-flowing, dry powder in coating a given workpiece. The powder is normally applied electrostatically before curing the workpiece under heat or ultraviolet light.

What makes powder coating beneficial compared to other coating processes is that it can provide a durable and wear-resistant finish to the workpiece. The same finish can likewise protect the material underneath from outdoor air and moisture, preventing corrosion and other types of damage. Powder coating can also make the workpiece easy to maintain, cost-effective, and sustainable.

These benefits, however, cannot be fully attained if the workpiece does not undergo the powder coating pre-treatment process. Pre-treatment process is necessary to ensure that the workpiece can fully keep the powder coating finish. Here are some of the vital steps of the powder coating pre-treatment process.

Choose the Pre-Treatment Type

The pre-treatment of workpieces may differ according to their material composition. Choosing one that fits the qualities of the materials can help make the powder coating successful.

For instance, workpieces made from steel and cast iron must acquire special corrosion and rust protection through an iron phosphate sealer. Aluminium workpieces, on the other hand, must be pre-treated based on whether they are cast or extruded. The oxide layer of their surfaces must also be removed to allow the adhesion of powder coating. A duplex coating is needed for galvanised workpieces, while additional pre-baking or heat-drying is necessary for hot-dip galvanised workpieces.

Clean the Workpieces’ Surfaces

After choosing the type of pre-treatment for the workpieces, the next step that must be done is to clean their surfaces. Cleaning the surfaces of the workpieces is crucial since it removes any dirt, grease, grime, and soil. Failure to conduct this step will only make the powder coating difficult to adhere to the surfaces of the workpieces. This step can be done through washing, media blasting, and chemical cleaning.

Washing the surfaces can help de-grease them altogether. During this type of cleaning, the surfaces are subjected to clean, reverse osmosis or deionised water to effectively eradicate dirty elements. Surfaces with tougher soils can then utilise a pressure cleaner to remove them effectively. Media blasting, alternatively, is done by shooting tiny solid particles at high velocity towards the workpieces. These particles can help in removing surface soils. Chemical cleaning, ultimately, can remove organic soils like mill oils, machining coolants, and forming lubricants from the workpieces through an acid cleaner.

Remove the Cleaning Remnants

Once the surfaces have been cleaned, they must be rinsed to remove any remnants of chemicals or cleaning solutions. Failure to remove these remnants or cleaning solutions will only contaminate the powder coating, which makes the whole process ineffective.

Removing the cleaning remnants can be done by rinsing the surfaces with deionised or reverse osmosis filtered water. After rinsing them, manufacturers can let them dry through air drying or oven drying. Oven drying is recommended for ferrous workpieces to prevent corrosion and rusting.

To know more about the powder coating pre-treatment process, you can call us at Epac Productions.

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