Powder Coating Metals: The Most Common Issues

Powder coatings have been the preferred finish in industries ranging from heavy machinery to gadgets, active adventure products to appliances. Powder coatings have several advantages over liquid coatings, including a solvent-free workplace, cheaper total line expenses, and simplicity of clean-up.

Powder coatings can also aid finishers with their sustainable practices because they have 0 to very low VOCs and offer overspray recovery and product wastage that can be handled of in ordinary landfills (appropriate guidelines should be checked for suitable clearance methods).

When it comes to making the most of powder coating, the challenges listed below are obviously not the only ones that must be addressed, but they are some of the most prevalent. Identifying possible problems ahead of time can save time and money.

A Well-Grounded Recommendation

The majority of electrically sprayed powder coatings are supplied a negative charge from the powder gun, while the part is grounded. This ground supplies the opposite polarity and attracts the powder to the component, but only if the part is properly grounded. A bad ground reduces transfer efficiency and resulting in an incorrect film build. Proper maintenance methods can aid in preventing this from happening.

Poor film build, for instance, could be caused by “dirty” hooks, which have been protected by powder build-up over time. The hook must be properly cleaned — or replaced if they can no longer be cleaned. The amount of passes a hook may make after being cleaned varies.

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More is Less

The secret to producing high-quality powder coating is to spray just the proper quantity of materials with the least amount of air possible. Excessive feed atmospheric pressure and powdered volume will not produce in faster or better coated parts, and the finishing, spray guns, and booth may suffer as a result.

If there is so much powder being blasted that the far end of the spraying booth cannot be seen, it is likely that the gun is conveying too much powder. A conventional powder pistol has an electrode at the tip that emits negative ions into the air.

The powdered coating is then shot through the resulting ion cloud, creating a negative charge. If too much powder is injected into the ion cloud, or at too high a speed, the powder doesn’t really pick up the charges as quickly, and uncharged powder drifts around the booth. A powder gun works best when an even, gentle spray of powder is released from the gun nozzle, allowing the powders to pick up the right charge and cling to the part.

Particle Size Matters

The capacity to recover and recycle spray that does not cling to objects is one of the key advantages of powder coating. Attempting to coat with exclusively recovered material, on the other hand, is both inefficient and costly.

Every powdered coating is made to a certain size range. Irrespective of whether the powder is virgin or recycled, the same range must be maintained to provide optimal coating thickness, finishing quality, and transfer efficiency. Particles shrink as they are retrieved and reused, preventing them from adequately fluidizing and retaining the right charge.

Transfer efficiency can be reduced to 50% or less as a result of this. Larger recycled particles, but at the other hand, can cascade off the coated components, landing on the booth floor and result in a transfer efficiency of 30% or less.


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