A Practical Method of Checking Magnet Power
Regularly checking that a Magnetic Separator has not lost any magnetic strength is good practice and is a key part of many companies’ annual equipment checks, but how easily can it be done?
A Magnetic Field can be measured by using a gauss meter, but due to the design of Magnetic Separators and the variable shapes of the fields, taking accurate and meaningful measures can be extremely difficult. Training and regular use is needed to use a Gauss Meter correctly and get meaningful measurements.
The best meaningful method of measuring and recording the strength of a Magnetic Separator is relatively simple. Magnetic strength can be measured by testing the force required to remove a steel object from the magnet surface. The technique has been used by Bunting Magnetics for many years and provides information that is easily understood and recordable. The force (in kgs) required to detach a specified steel object from the Magnetic Separator can be recorded and then checked as frequently as required. Unlike measurements of gauss, no interpretation of the data is needed as it is a simple physical test.
The Bunting Magnetic Test kit includes a Spring Balance, 3 sizes of steel ball, a steel plate and a non-magnetic spacer plate. When conducting a test, the steel ball or plate is attached to the hook on the end of the Spring Balance and then placed on the surface of the Magnetic Separator. Simple physics takes over as the steel is attracted to the strongest magnetic point or points (i.e. the magnetic poles). Force is then applied to the other end of the Spring Balance to remove the steel from the surface of the Magnetic Separator, with the amount of kg force being applied being measured by the Spring Balance. When enough force is applied, the steel becomes detached from the magnetic field, with the amount of force being recorded on the side of the Spring Balance. This test is repeated 3 times and an average fo
rce reading (in kgs) is calculated to give the recorded reading.
Where the Magnetic Separator has several high points of magnetic force (i.e. magnetic poles), tests at recorded points are taken to check the uniformity of the field.
For many companies, Bunting conduct the tests on a regular annual or twice-yearly basis, providing an independent analysis of their Magnetic Separators. The tests are not limited to Bunting equipment and are summarised in a report that is kept for reference, often as part of the quality or health & safety management system. It provides companies with the knowledge that the Magnetic Separators installed are operating to the best of their ability, protecting product quality, delicate processing equipment, and the company’s reputation.
This simple and yet effective method of testing the strength of a Magnetic Separator is used by companies in a wide range of industries including food production, pharmaceuticals, plastics and recycling. The technique can also be used when assessing different suppliers of Magnetic Separators by asking for the Magnetic Detachment Force to be stated along with the Gauss figure. As Gauss is often difficult to quantify (how does a customer check if a Tube Magnet actually has 12,000 gauss on the surface?), asking for a physical figure that can be easily checked when the Magnetic Separator is delivered ensures that what has been supplied meets the same specification as that quoted and ordered.
Further information on the Bunting Magnetic Test Kit and the Spring Balance test can be found on our website as are details of a Free Magnetic Separation Audit. You can also contact us on: