QA and best practice for the correct selection of calibrated samples for testing control systems in accordance with BRC, EFSIS and HACCP.
Is the test part just a test part?
Not exactly - just like control systems, one size really doesn’t fit all. In the end, you did not invest time and resources in capital equipment to detect the presence of a trial part. You need to confirm the fact that the control system will keep your products without contaminating foreign bodies.
Type and form of pollutant
If you look at the samples you are using now, you will notice that the nested pollution is a sphere, and the diameter is shown in mm. Most metal detectors work on the principle of a balanced coil, since contaminants and products pass through the system, which leads to an imbalance of this arrangement. It is this imbalance that determines whether contamination will be detected. As with the type of material, the cross-sectional area of the pollutant plays the most significant role. That is why we use spheres - no matter what orientation of the test sample enters the metal detector, the cross-sectional area will not change.
The most common materials used to test control systems are iron (Fe) iron, non-native (NFe), usually brass, and stainless steel (SS), as a rule, non-magnetic grade 316.
Unfortunately, in the real world, the most common pollutants will not be spherical, the metal is more likely to be in the form of wire or shaving. Remember that the metal detector works on the cross-sectional area? You could theoretically get a long, thin “needle” type of contamination - if it was only 1 mm in diameter, and the detection limit of metal detectors was 2.0 mm, it could be 12 inches, and you still could not detect it .
X-ray systems work differently, they work for density, the amount of energy absorbed by the pollutant along with the form determines detectability. You may have a blade with a thickness of 1 mm, and if your X-ray is set to detect 2.0 mm, you can skip pollution, even if it was 1 "in diameter, if it was to be flat perpendicular to the beam in the form of an X-ray. For sample samples - care should be taken to understand what type of glass sphere is used.The density varies greatly from one glass to the next known lime (SLG) because it provides a semi-standard. Your product in glass jars is likely to be The knowledge of glass will probably be your glass from a can, after breaking, etc. It might be worth considering to make samples that use your type of glass.
The size of pollutants used for testing
Most commercially available test samples use calibrated spheres from different materials. When you choose your size specification for testing, it is important to choose one that is reliably and repeatedly detected. Too little, and the control system may miss it, too much is not a representative test. As a rough rule, if you have a wet or salty product (reactive), and your metal detector detects 2 mm of iron, it will be about 1.5 times more for Non Ferrous than 3 mm. Double black for stainless steel (both non-magnetic and non-conductive), therefore 4 mm approx.
If you have a dry product — for example, a grain or a deep-frozen product, then black and non-native will be the same, and stainless steel is about 1.5 times larger.
The x-ray systems are not affected by the frozen / thawing state of the product, working on the density (X-ray absorption), so black, color and stainless steels will be the same size. Most x-ray systems are only tested using stainless steel and glass. As mentioned earlier, different glasses have different densities, so make sure you know the type of glass in the test sample.
Your product and application will affect the size of the pollutants found. When you write your HACCP procedure, be sure to use suitable sizes. Your metal detector or x-ray system supplier will be able to help determine the sensitivity of your system. Thereby setting a realistic specification. Your sample supplier should also be able to help you establish sensitivity and organize routine testing and annual calibration.
Calibrated sample test sample
As mentioned earlier, the purpose of your inspection system is to detect unwanted foreign bodies in your products - to ensure the final quality of products for your customers. Laying a test sample on a metal detector tape can be a repeatable test, but do you know how this relates to metal detection in the real world? Consider your type of deviation and make sure the contaminated product responds positively, so consider the position of the test sample.
You should consider the format of the test section, which allows you to test your system in a repeatable, representative form. For example, if it is a free product, the sample must be moved with your product. If it is a conveyor system with pneumatic or mechanical rejection, make sure that contamination can be located anywhere in the package and is still detected and rejected. As for location, the product itself can protect the effects of pollution. A 2 mm sample of iron, which is easily detected outside the cheese block, cannot be detected inside at all. Consider inserting a sample so that the contaminating sphere is embedded in the product.
Do not use plastic samples for testing on x-ray systems - as polluted spheres are introduced, x-rays allow them to “see” them. Image analysis software looks for differences in density, and a high absorption area (contaminated) surrounded by low absorption (plastic test piece) makes it very removable, even if it is built into the product. Damage to the real world is likely to be surrounded by a product with a higher density. Use flat x-ray test cards to test x-ray systems that come in the form of a flat card to minimize the effect of the contaminant “holder”.
Upper of the metal detector is the least sensitive part, closer to the lining (top, bottom and sides) is more sensitive. Consider this when you determine where to place the contamination for your routine testing. Make sure that you can restore the test part after the test, you do not want to cause a contamination problem when testing. If you are compiling test bags, make sure they are clearly labeled and do not mix with a good product.
