Magnetic Pull Test Kit
It is essential that the test kit user understand the function of the magnetic equipment in question so that appropriate testing procedures may be applied. Magnetic separators must accomplish two separate tasks to effectively remove ferrous tramp from the product stream. The first task, CAPTURE, requires the separator to retrieve ferrous particles from its maximum rated reach out distance and deposit it on the collection area of the magnetic face. The second task, RETENTION requires the separator to magnetically hold the ferrous object against the wiping effect of product flow over the magnet face.
Measurement of a separator’s ability to capture ferrous objects involves performing a pull test at a given distance away from the magnet face. The test kit provides a spacer with gaps of 1/8” and 1/4” to measure attractive force in the typical 1/2” or less separation zone around cylindrical magnetic cartridges. To represent a plate magnet’s capturing ability beyond 1/2” away from the magnetic face, the test kit spacer provides gaps of 1/2” and 1” above the magnet.
A pull test using a metal ball test piece in contact with the separator face represents the magnet’s ability to retain ferrous objects. The test ball size does not necessarily represent the expected tramp metal size because a minimum ball size is required to produce a measurable pull force value on the force gauge. For ceramic separators a 1/2” and 1” ball is provided while the 1/4” and 1/2” balls provided produce sufficient force for rare earth magnetic equipment.
GENERAL PULL TEST PROCEDURE
For the sake of personnel safety, test pieces have been selected which will produce pull forces within the range of the 0-12lb. force
The following illustrations show combinations of test pieces and spacer block orientations which produce repeatable values for ceramic and rare earth magnetic cartridges and plates. Actual values measured may differ between similar equipment due to a wide range of variables such as environment, testing technique and equipment options. The primary objective of an in-field testing program is to establish a base line for a given magnet and, through repeated tests, confirm its continued performance.
Consistency in testing is critical to achieve repeatable results-follow the prescribed guidelines and make note of any deviations.
Documenting your test results with the included Magnetic Inspection Log will provide a record of how the test was performed as well as
a comparison with future tests.
1. Clean and remove any steel objects or dirt from the face of the magnet.
2. Where possible, position the magnet facing up in a horizontal position. In cases where the magnet cannot be removed from the process line, attempt to position it such that the force gauge and test piece can be pulled away from the magnet in a perpendicular (right angle) direction.
3. Calibrate the force gauge. Holding the gauge vertically, pull the latch hook down to the 3# reading and allow it to snap back. Adjust the knurled knob so that the maximum reading pointer is set at zero. Use the 1# test weight to check the accuracy of the scale under load and readjust the force gauge if necessary.
4. Select the appropriate test piece and spacer block orientation for the test to be performed. Attach the test piece to the force gauge and position the spacer block firmly against the magnet face as shown in the following diagrams. Then, firmly holding the test piece, position the test piece on the spacer block (use caution as the magnetic attraction will tend to snap it down).
5. Pull the force gauge SLOWLY and SMOOTHLY in a perpendicular (right angle) direction until the test piece breaks away from the magnet.
6. Read the force measurement as indicated by the “maximum reading pointer”. Repeat the test twice and if the same value is achieved, record it in the Magnetic Inspection Log. If the values are different, an additional test should be performed to achieve two agreeing values, or an average can be developed from the two nearest values.
7. A polarity indicating wand has been included in this test kit which has “N” and “S” marked on opposite ends. It can be useful for identifying the north and south pole positions on a magnet and for locating the strongest zone of a particular pole. Since like poles repel and opposites attract, the polarity of a pole can be identified easily.