Reducing Electrocoat Rejects

Quesiton: How can we reduce our e-coat rejects?


How can we reduce our e-coat rejects? We coat large quantities of sheet metal parts for the appliance, lawn and garden and other industries. Thanks in advance for any advice. M.R.


Your question raises several other questions that can help you reduce your rejects: Are the “rejects” really rejects? (Who determines what is a reject?) If your customers and/or internal quality control personnel do not have good definitions of what is a reject, it makes it very difficult for production personnel to make a decision as parts come off the line. An ongoing dialog with your customers and internal QC personnel is essential to reduce having a “moving target” as quality criteria. Regularly scheduled meetings between the parties can establish a better definition of part quality requirements. Product knowledge is also essential, since the visual position and function of the coating on the part in the end-use product can determine quality surfaces. Taking production personnel to the customer can provide a much better appreciation of the quality requirements.

Do you have good definitions of your rejects? It is important to have agreement between QC and production as to what a reject is called and whether it can be tied to a cause. As an example “dirt” is a typical reject that can be abused as a “catch-all” for various causes. The “dirt” can be under, in or on top of the coating. Each of these locations can have different causes, so better descriptions are necessary. A sample board of visual samples used for definitions can be very helpful in training personnel that are reporting rejects. Too few categories of rejects can be more difficult than too many categories. If too few categories are used they become “catch-all” with identification of sources being difficult. Too many categories also can be a problem if consistency between personnel and shifts is not maintained.

Do you have good record keeping of reject quantities? The first two questions need to be answered before this one can be useful. In order to investigate and eventually solve the cause of the rejects prioritizing based on quantity is important. Quantities of rejects by month, week, day and sometimes by hour is necessary to concentrate efforts on finding and correcting the causes of the most prevalent rejects. Once quantities are segregated (remember that definition is important), the time and frequency of rejects is important. If rejects come in “bunches,” the time is important to identify production batch and/or process criteria at that point in time as possible causes.

Are you in agreement as to the cause(s) of each type of reject? Production, quality and engineering need to “be on the same page” in solving problems. Therefore they need to be in agreement as to the possible causes of each type reject. Then a priority list can be established for reducing/eliminating the cause of each reject. “Finger-pointing” between departments or within the finishing department will not solve the problem. Force agreement between all parties so that you can move on to solving the cause of the rejects.