Other Dimensions: Write It the Right Way
Editor's note: Columnist Hill Cox is beginning a multipart 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.
There's a computer program for everything these days, and if you have enough knowledge to fill in the blanks, you can prepare all types of quality-related documents-from quality manuals to calibration procedures. The problem with boiler-plate software programs is that despite what they promise, if someone using it doesn't know the subject being documented well enough, e.g., calibration, gage management, etc., all the software and graphics in the world won't make a difference-the end result will be of little value. And, if it's a well-known brand of software being used, there may be flaws in it that auditors know about that the user doesn't, at least until they are written up by the auditor because of the erroneous procedures derived from those flaws.
Often, software purporting to comply with a particular standard is little more than carte blanche plagiarism from the standard, using similar or the same language. Auditors who may not be up to speed regarding the technical aspects of the standard are then comfortable with the way the software-generated procedures read.
Some software companies have a "specialist" write the technical details of calibration procedures. If you're lucky, the results of this method will actually make sense. However, the specialist's details may not be as good as a manufacturer needs in compiling documented procedures, writing the manufacturer into corners. Further problems arise if the specialist has a background in electronics while the manufacturer's needs are for dimensional metrology procedures.
The solution to all of this is to write one's own calibration procedures. There are some basics one must consider, so put the brakes on the computer hard drive for the moment while those basics are reviewed.
The first assumption on my part is that you are interested in dimensional metrology. My examples will relate to this discipline. However, this exercise in creating calibration procedures will be useful to those in other areas of metrology who face the same task.
My second assumption is that you will be writing or revising procedures related to equipment calibration for your company.
I make no claim that the resulting procedures comply with any particular standard-most standards are vaguely written. Everything I'll pass along has been subjected to audits and assessments, and a variety of standards during the past 30 years, so I think it's safe ground here.
What is a calibration procedure? It's a document that gives all the instructions necessary for a competent person to carry out the calibration of a measurement tool with consistent results adequate to verify the state of the calibrated item, i.e., suitable or not for its intended use.
The final calibration procedure can be a few lines, paragraphs or pages, depending on how much is required of the calibration process. The length of the calibration procedure will vary depending on the skill and knowledge level for which one is writing. Each procedure should be self-contained, detailing everything someone needs to know to carry out the calibration. Some manufacturers may create an overriding page that covers the details that apply to every procedure.
A quality manual should outline how the procedures are developed but should not contain the procedures themselves. Keep the procedures in a separate, three-ring binder. If they are placed in the quality manual, every time you make a change to the procedure, the changes will have to be copied to everyone who has the manual.
Now that we've got the hard part over with, my next column will outline the detail level that a calibration procedure should have and how it should be organized.