Quality Magazine

Other Dimensions: Carefully Consider Calibration

September 1, 2004
Take a hard look at the reasons to move calibration in house.

Editor's note: This is the first installment in a multipart series regarding manufacturers doing their own calibration. The series will look at the reasons why a manufacturer might make this choice, as well as some of the considerations that must be taken into account when embarking on this course of action.

Why would a manufacturer want to do his calibration in house?

The answer to such a question may be as simple as, "I don't trust outside labs." Or, an outside lab may be trustworthy, but they're too expensive. High costs from outside labs may be because a manufacturer requests a great amount of detail on calibration reports, some of which is not required by standards. An example of this is requiring a laboratory to list all the equipment and masters they used in the calibration process and their recall dates. I'll be dealing with the cost elements of a laboratory in a future column. Doing it yourself may end up costing more than what is currently being spent on calibration.

There are many operating matters to consider in making the decision to bring calibration in house, but one that is not so obvious, and is often overlooked, is fighting another set of battles like those many manufacturers currently may fight. I'm referring to a situation where the quality department rejects product and production is ready to run your inspection people through their computer numerical control (CNC) mill. What will happen when quality starts rejecting the gages and tools that production uses, in addition to the products being made?

Another, not-so-obvious, situation that may develop when a manufacturer moves calibration in house deals with accreditation. If a manufacturer wants "authority" backing the in-house calibration program, accreditation by an outside agency is important. In some industry sectors it may be mandated so there will be no choice.

It will have to be determined what standards will be used to operate an in-house facility. ISO 9000 is not appropriate for calibration and testing labs because it allows a manufacturer to get away with all sorts of mayhem, as long as it's done consistently. The appropriate standard is ISO 17025 or ANSI/NCSL Z-540. A manufacturer needs to get a copy of these documents and read them thoroughly to understand what will be required.

One reason used to justify in-house calibration is delivery times. Many companies only have one of a particular kind of measurement tool and can't afford to send it out for calibration. This can be a frightening situation. I wonder what happens when someone drops that one-of-a kind tool on the floor and the forklift runs over it. They either get another one or get it repaired. In either case, they won't have one to work with for a while. It may be cheaper to have backup equipment rather than incur the expense of an in-house calibration facility. If this approach is taken, a manufacturer can afford the time to send tools out for calibration or repairs without crippling measurement capabilities.

If a manufacturer has many custom gages, he may be reluctant to send them outside for calibration for fear of loss or damage. This could justify in-house calibration if those custom tools are difficult to replace in a timely manner.

Many companies decide to do their own calibration because they do not trust the numbers that come back from outside calibration facilities. This is often a byproduct of measurement disputes when several laboratories calibrate the same gage or tool and all of them report different sizes for the tool. A manufacturer in such a predicament may decide that it can do better with its own facility. This may be so when considering some of the operations out there calling themselves calibration laboratories. If a manufacturer really knows calibration procedures, he could be correct in making a decision to bring calibration in house, but it may be cheaper and simpler to shop for a better outside calibration source. There are many from which to choose.

The decision for a manufacturer to do his own calibration must be carefully considered, along with all of the not-so-obvious ramifications that go along with it. As this series of columns will point out, there are many elements to be considered. And, while there may be only one or two factors that drive a manufacturer in such a direction, it's important to know what lies ahead in costs and operations. If you don't, your in-house calibration facility could become your in-house calamity.