Dairy inspection sensitivity gets smarter
Food safety specialist Fortress Technology addresses the main metal detection challenges that arise when inspecting dairy applications for contaminants , reviewing how the latest technology is smarter and overcomes a number of sensitivity challenges .
Applying the company ’ s longstanding metal detection expertise , European Sales Director Phil Brown explains how changing characteristics , product and orientation effect can disrupt product signals and affect detection sensitivity if not addressed . The food inspection specialist also touches on how digital technologies and machine learning are pushing the innovation boundaries and streamlining inspection processes .
PASSING UNDER THE RADAR
Due to high levels of automated processing machinery , the use of tools for maintenance , and other mixing equipment , metal remains the most prevalent contaminant risk in food manufacturing , potentially causing product quality and consumer safety issues . Metal detectors can be deployed to reduce this food safety risk . However , due to the physics of disturbing the electromagnetic field , the orientation of a metal contaminant can affect whether a contaminant is effectively detected .
This phenomenon is known as orientation effect . It occurs most noticeably when long , thin wiretype metal contaminants are more easily detected if they pass through the metal inspection system in one orientation rather than another . However , this orientation effect is exhibited by any non-spherical contaminant , not just wires .
A typical occurrence could be when equipment is calibrated to detect a stainless-steel sphere measuring 2mm in diameter . While it may identify and reject this contaminant , the machine may fail to detect a stainless-steel wire that is slightly smaller in diameter , but longer than 2mm . It does depend on the orientation of the wire as it travels through the detector .
Often , it can be easier to detect stainless steel and non-ferrous wires when they pass through the aperture
Reducing the aperture size in relation to the product size can be a simple and effective way to increase metal detector sensitivity
space sideways or upright , rather than in alignment with the conveyor . This is because of the magnetic permeability of the metal , which is much lower for stainless steel than ferrous metals .
Reducing the aperture size in relation to the product size can be a simple and effective way to increase metal detector sensitivity . This is because sensitivity is expressed as the smallest detectable spherical contaminant travelling through the geometric centre of the aperture . The centre of aperture is always the least sensitive position in the aperture . The idea is to challenge the worst-case scenario . So , if the contaminant is detectable in this position , then it will be more easily detected closer to the aperture walls .
Features like single pass product learning and automatic calibration can also help , as operators are easily able to overcome a potentially changing product effect which will result in maintaining the highest performance levels and lowest levels of false detections .
Keeping the aperture opening no larger than required in relation to the product size is considered best practice
74 FDPP - www . fdpp . co . uk
SENSITIVITY SIGNATURES
Dairy product applications are typically wet and conductive , which can present an additional challenge for metal detectors . Cheese , for example , with its high moisture content , combined with salt , can be highly conductive and cause a reaction like metal being present . This product effect can result in the product being rejected and good food being discarded .