How Long Do Cards Last?

by Dr. Brad Paulson, Thor Engineering, ICMA Standards Representative

You find yourself poring over the requirements included in a request for proposal, and find a specification detailing that the cards last a particular term of issue. No problem, you have a plethora of potential constructions, and one of them must certainly meet the requirement, right?

Unfortunately, as we all know, no design or material selection can guarantee that the entire population will survive any pre-determined term; nothing is indestructible, and some number of any manufactured item can be expected to fail before the end of the anticipated useful life. Ultimately, the expected life of any card population is the point at which the issuer or user feels that the number of returned, defective, or malfunctioning cards has become excessive. Therefore, it is not so much an issue of the expected term the entire card population is expected to survive, but the point at which an unacceptable number of cards are deemed to fail or be defective.

There are multitudes of laboratory tests that can be used to compare the relative robustness of card constructions. Card Durability Test Methods, ANSI/INCITS 322, is a compilation of such test methods published as an American National Standard by American National Standards Institute (ANSI), and similar test method documents are currently under development in France, by Association Francaise de Normalisation (AFNOR), and in Germany, by Deutsches Institut fur Normung (DIN). These documents provide generally destructive methods for testing the strength, flexibility, abrasion resistance, and general durability of cards by flexing, rubbing, stretching, heating, freezing, and generally abusing them. In theory, by comparing the test results of different card types, it is possible to identify card structures that are more robust and those that are less robust.

However, regardless of the attention to detail, confidence level of the test results, or tolerance of the test methods, the test results are in units of force, cycles, pressure, or torque, and not in years of functional use; even when the test results are in units of time, the result is time under test conditions, not time of functional use of the card. Presently, there is no algorithm or accepted method to correlate any of the properties of the manufactured cards with expected life of the card when in use; that is, surviving a given number of flexure cycles does not equate to a specific number of years the card can be expected to be used without breaking. Likewise, surviving a given number of abrasive test cycles does not imply that the card magnetic stripe could be expected to function for any number of years in use. Too many extraneous factors occur while carrying and using the cards that make predictions of individual card life difficult.

As pointed out previously, AFNOR, ANSI, and DIN technical committees to International Organization for Standardization (ISO) Working Group 1 (WG1) are actively working on making the correlation between test results and expected life of cards in use; the goal of WG1 is to arrive at a method to predict, or project, the failure rates of cards, prior to manufacture and issuance. Generally, the philosophy of the French and German technical committees to AFNOR and DIN is to accelerate the aging of cards through pre-conditioning in order to measure the failure rates expected during card usage. On the other hand the ANSI technical committee, INCITS B10.3, is working to correlate results of standardized tests with failure rates of issued cards. To support the project, B10.3 has modeled the survival, and failure, rates of four card types issued at Xavier University, Cincinnati, Ohio in 2000 and 2001. Although the models change depending on card constructions, modeling the survival of any card type will provide curves similar to those shown in the chart. B10.3 is now working to correlate test results with the survival rates of the card types.