Metal Detection: Testing Metal Detectors

Regardless of how sophisticated or reliable a metal detection system may be, it is essential that a frequent and thorough test and recording program be established. This is an essential component if any quality or HACCP (Hazard Analysis & Critical Control Points) system. In the absence of any industry standards for detector testing each company must establish their own test criteria. To date many of the standards adopted have been defined by the major retailers

Historically, metal detectors have been tested with a ferrous and non‐ferrous, and sometimes a stainless steel test sample.
More recently there has been a trend towards using a single, (preferably stainless steel), test sample in order to simplify the test process.

Every application will be different and therefore the samples should be tailored to each detector. If the sample is too small for the application, it will cause unnecessary test failures and create a high frustration level with the test operators. If the sample is too large, it will not accurately test the performance of the detector. Using a selection of test sample sizes, establish a realistic and repeatable operating performance level. Then a detectable test sample(s) can be chosen.The size of the test sample must be established so that it can be reliably detected inside the product passing through the centerline of the detector ‐ least sensitive point.