Case Study – Trouble Curing Powder Coated Parts on an Automatic Line
This was a standard Datapaq check on a powder coater’s main powder line. The powder coater mentioned that they had some trouble curing on the handlebars for ATV’s on the lower side of racks that hold 22 parts. The oven set point was 490F but the oven was reading 394F. On the graph, the air temp did reach 400F but only in the middle of the oven. The lowest probe on the outside only reached 325 for 55 seconds. It appeared like some of the baffling needed to be reworked in the oven. It also looked like the oven could be insulated a little better to keep the heat from escaping out the top. This could have helped the difference in the lower temp on the bottom of the rack. The electronics should have also been looked at due to the difference in the set point and the actual oven temp. Another possible solution was to slow the line a bit so that the metal temp could climb further up the cure curve.
The dwell time was only 31’32” in the oven. This was a hard dwell time for structural tube steel to achieve 375F for 15 minutes. By incorporating a few of these changes, they were able to successfully cure the ATV handlebars and pass the required MEK rub tests their customer required. They replaced the temperature controller, increased the set point, changed some of the baffling in order to push the air down, and slowed the line slightly to get a 45 minute dwell time in the oven.