IPT vs Round Robin

Historically, the Nadcap Materials Testing Laboratory Task Group has referred to all types of interlaboratory and intralaboratory tests as “round robins."  A true round robin, however, only occurs in the specific case of all participants actually evaluating or testing the exact same test object. Except in the case of some metallographic cross-tests where the set of mounts passed from one laboratory to the next, none of these activities meet this definition.

Even cross-testing and interlaboratory tests are not the best descriptions for the job at hand, because they are such general terms. Interlaboratory tests may be carried out for many purposes: to evaluate reproductivity of a producedure, to valuate standards etc.

The purpose of the interlaboratory tests required by Nadcap is to establish that the laboratory is not only good on paper but does, in fact, carry out testing well enough to meet the needs of the users. Then, on an ongoing basis, Nadcap watches to see that the laboratory’s testing processes are in control.

This forms the basis for maintaining accreditations not by constant inspection (ie on-site audits) but rather through the observation of metrics (proficiency test results) on an ongoing basis. This provides better special process control to the users and economy to the suppliers.

The Nadcap-sponsored proficiency testing program was implemented due to a lack of aerospace-orientated commercial or technical-society based interlaboratory programs available to meet the documented requirements. Commercial programs often include all different types of laboratories, using multiple testing methods, which do not necessarily provide a fair standard of judgement for high quality aerospace laboratories.

Voluntarily hosted ad-hoc programs are a lot of work and difficult to maintain from year to year. They are costly in time and money to buy and qualify materials. Most laboratories have been meeting requirements through heavy reliance on in-house programs, which are useful, but not as statistically sound and effective as a program with a large number of participants representing the best of the industry.

Fairness is greatly improved, as having an official program levels the playing field and assures that all suppliers are meeting the same minimum standard of participation and performance. A truly open access is guaranteed to all laboratories, not just the largest, best known, or most skilled at networking.

Economy is served as the basic cost of the program is amortized over the maximum number of participants. Perhaps, also, seeing the value of a solid program, the users and/or the large supplier captive laboratories will help carry the program through donations of materials or services.

Institution of an effective proficiency testing program also moves toward and supports further reduction in audit frequency, whilst making a Nadcap accreditation more credible, meaningful and valuable to everyone – suppliers, users, customers and the public who rely on us for their safety.