Calibrating for Product Integrity

This week I heard one of my favorite all-time words used in the context of having the proper reference to achieve a credible measurement. That word was "calibrate." This word has so many connotations that have to do with accuracy, reliability, credibility, etc. The Merriam-Webster dictionary defines calibrate as:

To standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors or to adjust precisely for a particular function to measure precisely; especially: to measure against a standard.

Every engineer knows that a design is only as good as the actual measurements can confirm. That being said, the integrity of the measurement depends upon not just the operator's ability to perform the measurement but also the integrity of the equipment used.

I was the 24th employee at what became a 1,200 person company. We were pioneers in the point-to-point digital microwave telecommunications industry. We had expanded to several buildings in a campus-type environment. The R&D engineering was separate from the manufacturing operations so electronic test equipment was spread out between two buildings as well. Customer service also had a dedicated lab for repairing returns. This scenario translates into a rather interesting asset management challenge. To make things even more interesting, 80 percent of the test equipment was leased or rented.

There was no single person assigned to manage the equipment. Each department rented their own gear as needed and when a company grew as fast as we had, the perspective was to keep pressing forward in terms of daily demands and priorities. As a result, some of the rented equipment was "lost" in time and space. When we tried to find the equipment to return it to the rental company, we could not locate it because it moved from lab to lab and into private offices without transport records. We were spending thousands of dollars on rental equipment each month and did not have the ability to justify the ongoing rental fees because we did not know if the equipment we were renting was still needed or not. So a day of playing "find the test gear" was mandated by management.

What we found was most disturbing: 70 percent of the equipment used in manufacturing operations was beyond the calibration date. We had no way of knowing that the measurements taken over the last X months were accurate. We found rental gear in cabinets that had not been used in two years because we were no longer making the products that required that equipment.

So, here is the best-practice when dealing with test equipment, rented or owned. As soon as the equipment arrives on site, a designated person assigned to asset management records the make and model number of the incoming gear. Also, the last calibration date is recorded and the name of the person responsible for the equipment is also noted in the record. The anticipated rental period is entered into a database cross referenced with the make and model, equipment location, and calibration date. The database includes a feature for real-time reminders indicating both calibration due dates and rental status payments.

Part of the procedure for managing the test equipment includes a travel log that details any movement of the gear from one lab to another or from one person to another. The borrowing lab or individual must sign a receipt for the equipment to be followed by the database update.

It is an excellent idea to have the rental company track the calibration dates as well. Setting this up requires an agreement with the rental firm that they will call a week in advance to allow time for any internal adjustments that would accommodate the absence of the equipment while it is out for calibration.

As a final comment, I would like to remind everyone that part of a quality audit should be the examination of all test equipment calibration dates. If you are using a contract manufacturer, by all means look at those dates. Ask the contractor how frequently the equipment needs calibration as stated by the manufacturer and if they have a calibration management system in place. If you are a manufacturer with test equipment, the only way you know your product is meeting spec is if your measurements are made with up-to-date calibrated equipment.

Don't run the risk of losing key customers or prospects by discovering too late that your data has not been reliable. Also, you may want to do a physical audit periodically to make sure that you are not paying for equipment that is not being used. Money is one thing. Design and performance integrity is everything.