Testing Magnetic Separators in Food Processing Plants
In one week, we have conducted Magnetic Separation Audits at three separate UK food processing plants. The audits form part of the quality management system of each company and are used for both internal and external food quality and safety assessments.
A Magnetic Separation Audit involves the physical testing and inspection of all Magnetic Separators.
Physically Testing the Magnetic Strength
The first part of the inspection assesses the magnetic strength. This involves using a Pull Test Kit which includes a spring balance and various sizes and shapes of magnetically susceptible steel test pieces. A Gauss Meter is not used as the readings can be inaccurate and variable. The physical test involves placing the steel test piece on the surface of the magnet (on a magnetic pole) and measuring the amount of force (in kgs) that is needed to remove the item from the surface of the magnet. This is then repeated and an average reading recorded.
Visually Assessing the Magnet
The second set of tests involve the visual inspection of the Magnetic Separators and we are checking for:
- The amount of metal contamination captured by the Magnet;
- Signs of damage or wear;
- Weld integrity;
- Fixings and any related safety issues (e.g. missing restraining nuts);
- Cleaning regimes and ease of cleaning;
In the three recent audits there were a number of findings including:
- Magnetic Separators were in locations where it was extremely difficult to clean and may be considered a safety risk;
- Welds on a Magnetic Separator had been eaten away by the acidic product resulting in liquid penetrating the Tube Magnet. This caused the magnets to expand within the stainless steel casing and also destroyed the magnetic field;
- The magnetic strength of some Magnetic Separators (especially those that had been installed for some time) was very poor and the level of separation would be minimal;
- In some locations, Magnetic Separators had been removed from the process but were still registered in the system;
- The positioning of some Magnetic Separators could be changed to improve the metal separation performance;
Following the Magnetic Separation Audit, a full report, with all the test results, is written and submitted with recommendations. This then forms part of the food processing company’s internal quality audit system and is refereed to when there are inspections from external third parties and customers. Commonly the audit is repeated on a annual basis using the same test parameters.
Similar audits are also undertaken in other industries including Plastics Production and Recycling. An annual health check ensures that the Magnetic Separators are performing to their maximum potential and achieving the separation goals for which they were originally installed.
For more information on the issue of Metal Contamination and Metal Separation, or to arrange a free onsite survey and audit of a particular plant or process, please contact the Bunting team on:
Phone: +44 (0) 1442 875081