Manufacturing technologies comparability testing

The choice of test equipment and methods has become extremely wide and, apart from large, integrated, electronic colorimetric and spectrophotometric instrumentation, field personnel can choose from miniburettes, direct-reading titrators (modified syringes), digital titrators, drop tests, tablet tests, permanent color standard comparators, indicator papers, portable colorimeters, immunoassays, etc. Today, field-test methods tend to be tailored by equipment manufacturers to their own analytical systems, and consequently the specified use of particular standard methods for the examination of water, from any one technology or official body, is probably not realistic. Rather it is the fitness-for-purpose rule that is more relevant. 

In the first phase of this research, a comparative analysis study was carried out on yams from the back panel of the vest that had failed in the field (manufactured in November 2002, hereinafter referred to as the officer s vest), a new, non-deployed vest of the same model and constmction as the officer s vest (manufactured in September 2003, hereinafter referred to as the new vest), and a vest from the National Law Enforcement and Corrections Technology Center (NLECTC) Compliance Test Program Archive, of the same model and constmction as the officer s vest (manufactured in March 2001 and submitted for compliance testing in May 2001, hereinafter referred to as the archive vest). 

Reproducibility is the precision obtained when samples are prepared and compared between different testing sites. Method reproducibility is often assessed during collaborative studies at the time of technology or method transfer (e.g., from a research facility to quality control of a manufacturing plant). 

The most important tests on bonded joints are targeted at the determination of the strength under precisely defined conditions. In order to obtain comparable results from such tests on different test stations, for example, at the adhesive manufacturer and the adhesive user, the test conditions have to be stipulated in detail and must be binding. For this purpose, test standards have been issued by the German Institute for Standardization (DIN) and the European Standards (EN) in cooperation with interested technical groups. The standards for tests in the held of adhesive technology, for example, contain indications regarding material and dimensions of test pieces, the test method to be applied (test equipment, test speed), if required even surface pretreatment of test pieces and other test criteria to be taken into account. 

The first sign of a problem was noticed in September of 2002. A board manufactured in August 2002 and exposed in the weathering box for only 860 h, showed cracks on the surface. Similar boards made in September 2002 showed cracks at the surface after 830 h in the box. These were isolated effects, and they were attributed to some technological deviations at the plant in Green Bay. However, based on those observations, in November of 2002 the amount of antioxidants was almost doubled compared to the original manufacturer s recommendations, and these boards with increased amount of the antioxidant were produced from November 2002 to January 2003. These boards were tested in the weathering box for 2000 h and were found quite satisfactory. 

---