Powder coating application issues (2 of 6)

Poor Penetration of Powder into Faraday Cage Areas

This can be a tricky issue to get your head around. Basically, when parts have internal corners or an odd geometry, due to how the electrostatics travel through the metal, the powder will not apply to these areas easily. This is called a Faraday Cage. The powder is, in a word, stubborn, and will want to pull away from the corners towards the flat areas or edges. This results in areas of a surface that are left bare of powder – usually the corners or recesses and once cured, leave such areas vulnerable to corrosion.

The Problem

Most of us who have worked with powder have come across the Faraday Cage effect! They are difficult and frustrating to deal with, but what causes them? As it turns out, a whole lot of things can be the cause. Grounding and gun settings, like we covered above, but also not enough powder flow, gun to part distance, poor spray pattern, and too fine powder can produce a Faraday Cage effect.

The Fix

There are some methods to preventing and working around a Faraday Cage effect, and we will start with powder flow. If you do not have enough powder coming out of the gun itself, it is going to make it even harder to get the powder into those internal corners. If this is the case, adjust your flow and increase the amount of powder leaving the gun.

You need to mind how much time you spend with the gun, especially so with automatic systems, and where it is positioned with respect to the part. You cannot just push a part through the application and expect the Faraday Cage areas to be filled. What it boils down to is pay attention to your gun. The tip can wear out, or a clot can form on the end – both issues can spoil how the powder will exit the gun. Again, if your reclaimed powder is too fine, it will not carry a charge as well, meaning the risk of a Faraday Cage is increased. Check your mix of virgin to reclaim powder.

Top Tip: This is not an end all solution to beating a Faraday Cage, but heating the substrate before spraying can help the powder disperse more evenly into those tough areas. Doing this increases the overall film build and how well powder grips to the internal corners.

Nanjing Powder New Material Co., Ltd. is specialized in producing various epoxy powder coating, epoxy polyester powder coating, polyester powder coating, flat powder coating, texture powder coating, functional powder coating, polyurethane powder coating, acrylic powder coating and other powder coating products.Powder New strictly implements ISO9001, ROHS Pb-free test, and SGS test report, certificate for safe transport, color fastness test and other Test reports and certificates of export related qualifications. Powder New offers a wide range of products to meet all of your order fulfillment needs.