Other Dimensions: Dazzled by the Digits
August 1, 2011
The digital display has become so much a part of our life, I wonder what the world would do without it. First it was watches. Everyone had to have a digital model even though you can get a faster indication of the time with a fleeting glance at an analog model because you actually have to read and process the numbers on a digital display. What’s in is not necessarily what’s best.
Metrology is one of many fields that has felt the impact of digital displays and measuring systems-for better or worse.
Anyone can use an instrument and get a reading up on the display. Unfortunately, too many people assume that reading is correct because they’ve never been taught the basics of measurement. It wasn’t that long ago that people worked their way up in a manufacturing company after serving time in various related departments along the way. When they had the opportunity to go into the inspection department, they had a pretty good grounding in the basics and an appreciation of what a ten-thousandth of an inch or a micron meant in practical terms. They also had experience in knowing where some manufacturing processes could go off the rails dimensionally, and knew what to look for to prevent such things coming at them out of the blue.
That background and training rarely seems to happen much any more. Today, the emphasis is on whether or not the person is computer savvy, rather than skilled or experienced in measurement. The result is a group of people who are instrument readers but have no idea what the numbers mean. In a worst case scenario, they are essentially data collectors, pushing buttons to send data to a software package in a central computer. The result of all of this is a dazzling display of pretty charts and printouts that indicate everything is okay-but sometimes it’s not.
We often see examples of digital blindness when customers get a calibration report that indicates something may not be right, but it goes straight into the files so they can prove they had the item calibrated. The piece of paper is more important than what is on it.
Of course, there are some quality auditors out there who do not suffer from digital blindness and actually look at the reports and understand what the digits mean. And then they start asking those embarrassing questions.
In a reversal of this situation, we have folks that question why this year’s report on their gage blocks differs from the one issued last year by a millionth or two here and there. They’re not blind; they see the digits but just don’t know what they mean. In such cases the report is questioned because the blocks have rarely been used and only by a heavenly entity so the changes couldn’t be the result of wear, or so it is claimed. Discussions of measurement uncertainty and block stability will go nowhere.
Adding a couple of digits to a digital display is done relatively cheaply and is one of the curses of the technology. Too often the improved resolution is meaningless but it does help to sell instruments, irrespective of how good or bad they are from an accuracy point of view.
When you get down to the last digit, metrology knowledge will overcome digital blindness. But getting it is not easy in today’s workplace. This is particularly so when folks believe that massaging numbers with computer programs will keep everything on the straight and narrow. Long forgotten is the old rule, garbage in-garbage out, which means if you don’t know your metrology, you could be loading up an impressive data bank based on dicey measurements.
What’s the answer? Training is the obvious answer, but training comes in many forms. For many companies, showing employees how to use the equipment is the gold standard. Unfortunately, this type of training doesn’t answer the “What went wrong?” question when things come unstuck. “I dunno...” will be the usual answer. Someone with some good training will be able to point to a couple of areas, but more likely than not, they’ll sense something not being right before the digits trigger panic stations in the quality department.
In the absence of training, the only advice I can offer for everyone involved in the process is never believe the last digit.
Hill Cox president of Frank J. Cox Sales Ltd. (Brampton, Ontario, Canada). He may be reached at firstname.lastname@example.org