Editor's note: Columnist Hill Cox has put together a series that focuses on developing custom calibration procedures particular to an individual manufacturer's circumstances. Accurately written calibration procedures are critical in today's manufacturing environment, especially as new standards require detailed documentation.
Calibration procedures can be thin on description if the staff is knowledgeable. However, despite your operators' knowledge, calibration procedures must be written with the idea that a new employee or trainee may have to use them. Striking a balance between being too descriptive and relying on the in-house knowledge base to fill in the details of calibration procedures is a judgment call based on the individual circumstances of each manufacturer.
The first rule in knowing how much detail to include in calibration procedures is to keep them simple and make them step-by-step instructions. Use plain language and make sure all operators understand them. Telling someone to "tweak the knob" to obtain a measurement reading may result in the knob being ripped off with pliers.
Another rule is, "Don't reinvent the wheel." Many manufacturers write lengthy procedures that duplicate those in the equipment maker's manual. Makers of calibration tools usually provide excellent instructions on how to use their tools. They have the benefit of having answered many of the same questions from manufacturers using their tools, and so there is some assurance all the bases have been covered. If these "frequently asked questions" about calibration match an existing manufacturing situation, they can be copied in the written calibration procedure. Or, a manufacturer may decide to have his written calibration refer to the equipment maker's manual for the step-by-step details. Of course, a copy of that manual must be available to those using the procedure.
New product standards, such as those produced by the American National Standards Institute, often contain calibration information that can be used as a starting point in developing written calibration procedures, or those standards-making bodies will have documents that outline, in great detail, how to calibrate different tools. Use pictures and sketches if they will help provide a clear understanding of the calibration requirements.
Don't add detail that is marginal to the task at hand, or those calibrating might become confused. Everything written should reflect the reality of the manufacturing and calibration environments. Stick to the basics required for the job. It's the content that counts, not the word count.
Include "cautionary" notes, suitably highlighted to prevent mistakes or damage to the tools. Also include "hints" that can make the job easier or more effective.
Make sure operators understand that it is not a sin to have the calibration procedure manual open in front of them while they work. However, continually using the calibration procedure manual for the same simple procedure may signal a problem. Continually reinforce to those doing the calibrations that they cannot depart from the procedures without authorization. If an operator has an idea for a better way to do the calibration, they should first let their superiors know. By doing that, the recommendation may be correctly assessed, and the procedures can be correctly amended.
There are several ways to determine if the effort to create written calibration procedures has been successful. A radical method is to have a staff review of the procedures before they are carved in stone. Or, monitor the operators as they do the calibration to determine whether they are following the details.
Another way to test a newly written calibration procedure is by having someone who doesn't normally work in the laboratory try to perform the procedure. They must, of course, know the basics before doing so. An expert from outside the company can also be used to review a procedure. And, because the operators are supposed to thoroughly understand the calibration procedures, give them a written test on them from time to time. A copy of their results should be put in their employment file.
Now that the calibration writing process has been covered, the overriding rule in developing procedures should be evident: "Document what you do, do what you document." After you accomplish writing a successful set of calibration procedures, you may be ready to broaden your literary endeavors. Try your hand at cookbooks. Cookbooks are the biggest sellers. And guess what? Recipes are also step-by-step procedures.
The basic rule in writing is, "Write about what you know." So if you can't boil water without burning it, stick with writing calibration procedures instead of cookbooks.