Inspecting Magnet Strength
Bunting engineers have conducted a thorough review of all the Magnetic Separators installed at the Jordans Dorset Ryvita plant in Poole, Dorset. The audit was completed over three days, including attending site on Saturday to prevent any loss in production.
Jordans Dorset Ryvita has a strong heritage of making whole grain foods and working with farmers to protect the countryside. Ever since the brands first came together, they have continued to act on these values.
A Magnetic Separator Audit involves the inspection and test of Magnetic Separators to confirm their magnetic and physical integrity. Commonly, such tests are conducted annually, with the final report forming part of the company’s quality audit process.
The tests in a Magnetic Separator Audit are conducted in two stages. Stage one involved the inspection of the physical integrity of the Magnetic Separator. This includes checking welds, and assessing any wear and damage to the surface.
Stage two involves testing the magnetic strength of the Magnetic Separator. These tests are conducted by placed a magnetic ball or plate into the magnetic field and then measuring the force (in kgs) needed to remove that object from the surface of the magnetic separator. The actual ‘gauss’ reading of a Magnetic Separator is not checked as measurement is difficult and often inaccurate. Gauss is the is the cgs unit of measurement of magnetic flux density (or “magnetic induction”, but can be difficult to measure accurately.
The metal test piece is attached to the end of the Spring Balance and then placed into the magnetic field, being attracted to the magnetic pole. The metal test piece is then pulled off the surface of the magnetic separator whilst holding the other end of the spring balance. The amount of force needed to remove the metal test piece from the surface is recorded (in kgs). The test is repeated three times and an average reading taken. Similar techniques are used to test other designs of Magnetic Separators such as Plate Magnets.
There were a wide range of designs, strengths and ages of Magnetic Separators in the production process at Jordans Dorset Ryvita. The company had not experienced any problems due to metal contamination and requested the audit as part of their continued improvement plan.
Day one was spent assessing the location and recording the customer identity numbers of all the Magnetic Separators. Checking the location also highlighted any health and safety issues that needed to be considered for the audit, such as working at heights. The review identified 52 Magnetic Separators.
The physical checks of the Magnetic Separators were conducted on day two and three, on the weekend to minimise any production downtime. Each Magnetic Separator was removed from its location and visually inspected. Then the magnetic strength was checked using the pull test technique. The data was recorded and presented in a detailed report with recommendations following the audit. This report can then be used as part of the quality management system. It also provides base data for comparison on future audits.
Following the audit, the engineering team at Jordans Dorset Ryvita have made several changes to improve the removal of metal during the production process.
“Having an external review of the Magnetic Separators really helps the client,” explained Mark Harris, Bunting’s Engineer. “We conducted the audit without any assumptions and this freedom enabled us to highlight the areas where protection was good and also focus attention where they could be improvements. We are looking forward to working with the team at Jordans Dorset Ryvita for the long-term and providing our technical support when needed.”
For further information on measuring the strength of a Magnetic Separator, please visit our website or contact us on:
Photographs taken and videos produced by Paul Fears Photography