Process Control in Plating

Q. I have worked in the plating industry for a number of years and recently starting a new job. I do know how to plate, but my new position requires me to put in place process control procedures for all of our plating lines. Can you give me any suggestions? –J.J.

A. I certainly can! I was trained as a chemist and learned from the "getgo" that you must have reproducible processes to get reproducible results. Here are some of my thoughts on process control.

What is process control? Wikipedia gives a reasonably simple, straightforward definition: “Process control is a statistical and engineering discipline the deals with architectures, mechanisms, and algorithms for controlling the output of a specific process.” The typical electroplating operation may not approach this level of sophistication, but, there are plating operations that come close to this definition.

If we take the idea of process control at the simplest level, which I define as keeping process variables within set values, process control plays a very important role to the modern electroplater.

Why is process control critical? The answer is a no brainer! The electroplater must have reproducible results from batch to batch. This can include such elements as thickness, hardness or solderability of the deposit and so forth. If we don't have controls in place to obtain reproducibility, we end up with failed, rejected parts that have to be stripped and reprocessed, or worse, junked. This costs money and time, and generates additional waste. Having to redo parts because they don't meet required specifications greatly affects the bottom line.

Process control in the plating industry has historically been approached with lukewarm acceptance—another cost center, and if you could get by without it, all the better. For many shops it consists of testing process tanks on some irregular basis, usually when something goes wrong. For other shops, process control consists of visual inspection of finished parts or the tanks themselves, and then determining that an addition should be made to the process tank or tanks.

In some cases, rather than looking at the process, the plater blames the base material, or the manufacturing process before electroplating, which, although resulting in reduced recordkeeping and testing costs, is very shortsighted. Limitations include increased processing costs, dissatisfied customers and non-reproducible results.

Process control methods do vary with the type of plating operation a company performs. For example, a captive plating operation that plates thousands of widgets each day can use more sophisticated process control methods than a job shop that has a number of plating processes and plates hundreds of different parts in a given period of time. The large captive operation can use statistical methods to help improve the processes, whereas a job shop that plates many different types of parts with different plating baths has a more difficult time using statistics.

There are commonalities for all types of plating and finishing operations, however. The things I look for are written procedures for each type of plating, record keeping for each process tank (testing results, history of additions, history of tank dumps, etc.). I prefer to see the day-to-day testing performed at the plating facility rather than sent out to a distant laboratory. Testing should be done on a regularly scheduled basis, not just when something is wrong with a process, and results should be recorded in a computer program or spreadsheet. The information must be readily available.

Another aspect of process control that is very important is daily monitoring of the functionality of the various pieces of equipment used on the process line. Are the pumps used for circulation working? Are the tanks properly agitated? Are your rinses functioning? What about your filtration systems? This is common sense and certainly not rocket science!

In my experience, many plating operations may think that they are following strict process control because they monitor a few parameters of a particular plating process, but in reality have missed the most important aspect: people.

Where should a shop start? Perform an audit on your process control measures. An unbiased individual, usually an outsider, should perform this audit. It may cost some money, but the shop may discover that they have all the elements in place, but just don’t have them implemented properly.

And what about people? I think the biggest strides in process control will be in the area of management techniques. In my experience, a large number of screw-ups and rejects are due to the humans involved. Management quite often does not really work to get the operators to buy-in and adapt the procedures used in a modern plating facility. Operators are undertrained, and in many cases do not understand what they are doing. The solution to this problem is better training of operators and getting them to be owners of what they are doing.

No doubt we have better process control hardware and software today, but if the humans who monitor this technology are not well trained, process control will still very much be a hit or miss proposition.

I think the most important thing people in our industry should be aware of is that good process control doesn’t necessarily mean you have all sorts of computers, bells and whistles, and automated testing methods. It means you truly understand your process and follow procedure on a daily and continuous basis. This means doing the chemical tests as required, confirming that operators are following the written procedures for each type of part/process, and most importantly, demonstrating that senior management believes in and is supportive of good process control.