Today, goudsmit Netherlands received a request from a French company producing nougat. (Nougat from Montélimar!) They wanted to measure the goudsmit magnets in their production facility, in their own words, to meet quality standards and ensure the magnets were still working optimally. This was also necessary to continue meeting the HACCP (Hazard Analysis and Critical Control Points) quality assurance standards.

This quality label applies to all food manufacturers, whether they produce chocolate, sugar, milk powder, flour, or soup.

MagnetsMeasurement: How is it done, and what are the standards?

Guy Mutsaerts is an expert in magnets for the food industry and has been since 1992. He regularly measures magnets himself and explains all the ins and outs: "In principle, permanent magnets retain their magnetic value for life, so there is little risk of reduced field strength. The only factors that can cause a magnet to lose strength are: breakage, corrosion, or heating (temperature >80 °C). In the food industry, exposure to high temperatures is naturally expected. For example, when cleaning with hot water or placing in a pasteurizer. See his explanation in this video."

goudsmit Gaussmeter

Magnetic field strength is measured with a gaussmeter, but this does not always provide an accurate indication, nor does it tell us about effectiveness! It really only tells you that the magnet's strength has not decreased. The only true way to test magnet operation is using test particles. Because this is difficult to do in practice, flux measurement is the best option.

HACCP Specifications

Guy continues: "The problem is that HACCP specifications do not address magnet operation and implementation. They only mention Gauss values or magnetic flux density. These may be correct, but operation and implementation are also important criteria. Take, for example, the case where there are no stainless steel tubes around the magnets; they will rust, and bacteria will grow between the magnets."

Distance between magnetic bars

Operation is also affected by the distance between the bars. These are often placed further apart to achieve high capacity. This creates gaps in the magnetic field, preventing the capture of all ferrous particles. To overcome this defect, I advocate including a minimum flux density in the HACCP specifications. After all, it is the minimum flux value that determines whether it is possible to capture ferrous particles. During measurements, we also encounter situations where very large magnetic grids are installed. This size makes cleaning hazardous; it exposes operators to the risk of crushing injuries during cleaning. Conclusion: Quality standards must do more than just specify flux density ('Gauss values')."

Variations in magnetic values

"Furthermore, in practice, we find that gaussmeters do not always display the same values. Although these gaussmeters are calibrated, you can obtain different readings. If you have three people perform the same measurement, you will get three different results. This leads to confusion and unease among quality assurance managers. From experience, I have learned that it is best not to measure directly on the bar, but at a slight distance, such as 5 mm. The flux density there is stable. Our white paper (PDF) explains this."

goudsmit Internal Service

goudsmit currently has hundreds of customers in the food industry,goudsmitfor whom we measure magnets. Our customers in the food industry consider it important to have an experienced person do this for them once a year. After all, they do not have calibrated gaussmeters, nor do they have the experience to perform the measurements. We are happy to do this for them!"