The plant has a drying oven for a product line that is basically made from plastic sheets. The operations supervisor over the process has complained that the oven is leaving scorch marks on the plastic.
Upon inspection of products that have gone through the oven, you do see dark streaks that look like scorch marks. You point out to the supervisor that the plastic doesn’t look melted. You calibrated the controller so you know it’s working properly. You also know the heating elements have the correct supply voltage.
Yet he insists this is an electrical problem. How might you find the likely culprit?
Since you’ve already determined that excess temperature is an unlikely cause, contact the manufacturer to see at what temperature, if any, the material might scorch. Or if the drying temperature is anywhere near the material’s melting point.
Perhaps undesired current flow due to improper bonding is causing scorch marks. But if the system checks out against Art. 250, Part V, then you can rule that out too.
Maybe now you can put this monkey on someone else’s back. Probably, an impurity is in the process equipment. Maybe it’s from excessive lubrication (or wrong lubricant) on the oven drive system, or just dirt from the plant environment. Pass this to the mechanics to see if they can solve the problem.
