In a perfect world, the Kaser team would perform quality control at every step of the powder coating process, every day. Hanging, pretreatment, spraying, curing, and packaging – mistakes can (and do) occur at each of these stages, impacting the quality of the finished product. We pay as close attention as we’re able.
When the workload is high and team members are absent, however, we have to focus our quality control measures on the stages that matter most: pre- and post-curing.
You’ve likely seen videos of Wills in a dark booth, checking an uncured part with a high-powered flashlight. He’s looking for:
- Missed areas, particularly on welds or in recesses;
- Thin areas, where the substrate may be showing through the powder;
- Thick areas, where the powder looks like cottage cheese, indicating back ionization.
Because the powder has not yet cured, there’s still time for Wills to fix any issues he catches in this phase. He adds some passes to missed or thin areas, adjusting his gun settings if necessary. He uses a low-pressure air blower (or even a vacuum) to thin out any powder that’s too thick.
Above all, he takes his time. This pre-cure inspection is Wills’s best shot at preventing rework. The more thorough he is now, the fewer parts we’ll have to re-spray later.
Once the part has cured, we do another inspection. We start aesthetically: how does the part look? Are there any bare areas? Is the coating smooth? Are there pinholes or fish eyes? Is there debris in the coating? What is the customer’s first impression going to be when they pick up?
Next, we check mil thickness. The part can look amazing coming out of the oven, but if the coating isn’t thick enough, corrosion will set in sooner than expected.
Most of the time, when we catch problems, they’re of our own making. Every once in a while, they’re due to malfunctioning equipment or the powder itself. Either way, knowing what to look for takes time and practice. Give your QC team members plenty of opportunity to observe powder before and after it cures. That’s the only way to learn how it’ll behave in the oven.