Quality Magazine

Don't ‘Shop' Calibration

May 1, 2004

In the effort to save costs, manufacturers may end up paying for poor calibration decisions.

Many gage and measurement tool users put their product quality at considerable risk in their efforts to save money. Senior managers often issue cost-cutting edicts without fully realizing what effect it might have on the gages that help them make money. Too many companies treat calibration as an exercise in updating paperwork.

Cost cutting can often result in laying off a skilled and knowledgeable person and replacing him with someone cheaper, who typically has less knowledge and skills. The main task for the new person is to coordinate sending equipment outside for calibration. Or, the manufacturer may decide to implement an in-house calibration program to save spending money on an outside laboratory.

Manufacturers unfamiliar with calibration procedures may try to insist that their calibration providers "certify" a tool or that a gage meets a specification with which the manufacturer is unfamiliar. However, those same manufacturers are only willing to pay for calibration of a single feature on a gage and not the calibration of other features, which may have a direct effect on the functional size of the gage in question. Some manufacturers get quite upset when outside calibration laboratories refuse to certify what day it is, let alone a gage on such a basis.

It is possible to save money by doing calibration in-house, if the appropriate equipment, environment and skilled people are available. Often, the volume of tools to be calibrated is not enough to justify the purchase of the appropriate calibration equipment. It is not uncommon for a tool worth $10,000 to be purchased for the purpose of calibration. Such a purchase is not questioned as to the tool's accuracy, when the model used by a professional calibration laboratory costs $30,000 or more. You can bet the sales representative for the cheaper model is not going to enlighten the manufacturer that there is a difference in cost and accuracy between the tools, even if he is aware of a difference.

Another move to lower calibration costs is the "one-stop shopping" myth. The theory is that if a manufacturer gives all his calibration work to one lab, he will save on internal costs and the outside lab will deliver a juicy discount for being selected as the sole supplier of calibration services. This may make sense, or even dollars. But, if a manufacturer has different tools with different technologies that require calibration, such as electronics and dimensional metrology, the calibration laboratory may need to subcontract the work and markups on the work may result in little or no savings to the manufacturer.

No matter how much money may be saved, the calibration still has to be done correctly, and that may not be possible when an outside laboratory is set up primarily for dimensional work and dabbles in electronic instrument calibration. The environmental requirements are different for each field, as is the knowledge base and skill set. It is safer to split the work up into various disciplines to reduce the risk of receiving less than needed calibration work. More importantly, when a manufacturer has technical questions about a report or device that has been calibrated, he will be able to discuss those issues with specialists.

Another reason to send gages and tools directly to specialists is to avoid the costs and delays involved when there is a rejected tool or gage. In using a laboratory that specializes in one type of calibration, a manufacturer can take advantage of the on-site repair facilities that many such laboratories have available. Such repair services can get a manufacturer operational in a short time and at reasonable cost. In the case of fixed-limit gages, specialty laboratories may have an inventory of replacement gage members so the gage can be quickly returned "in tolerance."

Even if a manufacturer uses an accredited calibration lab, there are risks involved, because while the laboratory may pass muster in calibrating a tool, an insufficient knowledge base could cause problems. This happens many times when it comes to thread gages. Some laboratories use software to generate specifications, but the software doesn't agree with the standards. What's the chance of this happening? About 15% when standard gages are involved. Other calibration labs use incorrect markings from a gage handle as the basic dimensions for the gage. Usually they are right, but not always.

There are savings to be had in calibration costs, but supermarket logic is risky. Technical thinking, not accounting, is required if you want to save costs and obtain dependable calibration results. When the wheels start falling off a manufacturer's measurements, or barrels of rejected parts appear on the loading dock, the damage control costs usually put the savings resulting from a misguided calibration strategy in the petty cash category.

Hill Cox is chair of the technical committee for The American Measuring Tool Manufacturers Association (AMTMA). He is also president of Frank J. Cox Sales Ltd. (Brampton, Ontario, Canada.) He may be reached at askquality@bnpmedia.com.