Measuring Up On Coating Thickness

Management guru W. Edwards Deming might have had surface coatings in mind when he was once asked to summarize his thoughts on the best industry practices.
 

“If I had to reduce my message for management to just a few words, I’d say it all had to do with reducing variation,” Deming was quoted as saying, and many in the finishing industry would agree.
With many OEMs specifying to shops and custom coaters exactly where, when and how to test the variance levels of finishes, it often can be confusing and labor intensive to measure coating quality on a line.
 

What’s even worse is to find out hours and even days later that a coating line or spray gun was out of tolerance, causing inconsistencies in finishes and often catching grief from a customer.
Fischer Technology, Inc. hopes to end that daily struggle for finishers with the introduction of equipment and a software suite that takes testing specifications from customers and makes it easy to check measurements and complete the necessary paperwork, all at one time.

Expanding Functionality
“The Fischer DataCenter software significantly expands the functionality of our measuring instruments,” says Paul Lomax, marketing director for the Windsor, Conn., company.” Finishers can now quickly and easily take measurement data and transfer it to their PCs, where inspection reports can be created and printed.”
 

What’s even better: unique forms and reports created by customers can be scanned into the Fischer software, so that measurement data can be placed into specific areas of the customer’s reporting documents.
 

“It really tailors the system to the finisher’s customers, who will want their own documents and reports filled out,” Lomax says.
 

The system starts with the Fischer DataCenter “Inspection Plan,” which is generally a step-by-step listing of what is to be measured, how often and where, based off a set of presets that Fischer has already installed in the software.
 

The inspection plans are generated on the PC and loaded onto Fischer’s “smart” hand-held instruments, the Dualscope FMP100 or the FMP150. Step-by-step, on-screen guidance leads the operator through the measurement acquisition procedure.
 

Mobile Data Terminals
“Essentially, the DataCenter IP turns the FMP100 and FMP150 into data terminals,” Lomax says. “Since the software can be used to implement customer internal inspection regulations in inspection plans, it knows where to tell the operator to take measurements.”
 

The measurement data then can be transferred easily and quickly to the Fischer DataCenter using USB, Bluetooth or RS232 ports, thus eliminating pen and paper.
 

The DataCenter software can provide immediate evaluation of the measurement results and a quick overview of the finishing process. The software displays a histogram, sum frequency chart and the statistical process control chart. The measurement results and evaluations are linked to attributes such as measurement location, name of operator, date and time, or any other parameter required.
 

The software also includes a powerful tool for quality control called the Factory Diagnosis Diagram (FDD), which was developed and patented by Fischer.
 

“The FDD presents visual processing of measurement data or of characteristic data derived from measurement groups, or mean values,” Lomax says. “It enables, in the form of so-called rank lines, monitoring and optimization of production processes in the simplest way.”

Recognizing Interference Factors
Lomax says the tool enables users not familiar with the fundamentals of statistical quality management to recognize interference factors and avoidable causes of process variations quickly, and, more importantly, then eliminate them, if need be.
 

The FDD can show the operator the following data using graphical means:

• What is the overall distribution of the mean values of measurement data, such as coating thickness values?
• How large is the variation of individual readings around their respective mean value?
• Are there significant (i.e., more than just random) differences between mean values?
• What is the location of the mean values and variation bars relative to a specified tolerance?
   

“It is possible to notice at one glance whether the observed production process meets potential tolerance specifications or not,” Lomax says.

As an example, a finisher is coating sheet metal, and the same coating thickness is required across the entire surface area. The sheet is divided into 20 measurement zones, or blocks. Several coating thickness measurements are performed for each measurement zone, and the mean value and variation are computed from the measurement data. The mean values are sorted in the FDD in ascending order (ranking) and projected onto a straight line in the graph according to their size.
 

Systematic Difference
“The measurement zones, identified by points of the same color, do not contain systematic differences of the coating thickness,” Lomax says. “Systematic difference between the coating thicknesses of the measurement zones exist if the FDD shows points of different colors. This indicates the need for process improvement measures.”
 

He says an operator can recognize points with three different colors. For example, the red points of blocks 1 and 6 are even above the upper limit value, so to optimize this production process, initially the coating thickness in measurement zones 1 and 6 must be reduced.
 

The other enticing feature of the Fischer DataCenter software is its ability to generate reports based on the customer’s own forms and paperwork. A report that includes the results, statistical evaluations and graphs according to the customer’s specifications can be generated immediately with a click of the mouse following the transfer of the measurement data.
 

“The inspection reports are generated automatically based on custom-created report templates,” Lomax says. “Report templates are created only once and can be used as often as desired to ensure the consistency of the inspection reports.”
 

Even Fischer’s entry level units, such the Dualscope MP0R, are capable of downloading readings directly into any custom-created report template using the DataCenter software.

Create Report Templates
The DataCenter does offer a text editor for creating report templates. Using the drag and drop function, placeholders can be placed at the desired location in the document, which could include the customer’s own graphics, logos or images.
 

Lomax says special evaluations also can be created using selection and filter functions. For example, if in an automotive paint plant only the paint coating thickness of all hoods of a specific car model need to be examined, it is easy to exclude all other measurement data.
 

“Only the measurement data of the hood of this car model are then taken into account in all graphs and in the inspection report,” he says. n
 

For information on Fischer Technology products, please call 1-860-683-0781, or visit Fischer-Technology.com.