The profitability of a plating line depends on the line’s reject rate. The higher the reject rate, the lower the profitability.
Most plating lines have multiple steps to achieve the final finish. In general, the steps involve cleaning and activating the metal to be plated, plating the desired finish, and post plate rinsing and drying. A formalized approach to reject prevention requires establishing standard operating procedures (SOPs) for each plating line and “walking the line” before startup to assess whether the plating line meets the SOPs and is ready to run.
The ABCs of SOPsSOPs should be prepared for each tank on the plating line and should contain the following information:
- Purpose and description of each tank
- Makeup procedure and quantities used
- Concentration ranges
- Safety precautions
- Operating conditions - temperature, pH, current/voltage, time, filter flow rate and change frequency, agitation
- Maintenance procedures and frequency
- Control procedures
- Troubleshooting procedures
- Other comments
Walking the LineAfter the SOPs are prepared, the line should be “walked” (audited) on a routine schedule. Walking the line is especially important after a shutdown has occurred. It is too easy to start the line on Monday morning because production needs to run, without regard for whether the process solutions are up to temperature or whether the rinses are flowing correctly. But out-of-spec conditions lead to rejects. When walking the line, you should compare the actual condition of each tank to the SOPs that have been developed for that tank. Inspect the overall plating line, as well as the mechanical/electrical system, operating conditions and tank chemistry.
General Plating Line Observations: Look for overall cleanliness and any line maintenance that might be required. Check to make sure all safety procedures are being followed correctly.
Mechanical/Electrical Systems: Check the hoist, rectifier, filters and bussing to make sure everything is well maintained and working correctly. Also check the condition of racks and rack coatings, the flight bar and tank saddles.
Operating Conditions: Check the condition of the anode bags and make sure the anode baskets aren’t too full or too low. Also make sure that the solution levels are correct. Check the accuracy of the temperature controller by verifying the temperature with a thermometer. Make sure the solution agitation equipment is on and that the agitation is uniform. Also check to make sure the rinses are on and flowing, with no turbidity.
Chemistry: Check the lab analysis prior to startup to verify that all of the tanks meet the required specifications.
Improving ProfitabilityBy establishing standard operating procedures and using them to assess whether the plating line is ready to run, you can reduce reject rates and improve profits.
For more information about plating, visit www.atotech.com.
Editor's note: A variation of this article originally appeared in Southern Metal Finishing (www.southernmetalfinishing.com). Reprinted with permission.