ASTM A1070:16 pdf download

ASTM A1070:16 pdf download.Standard Specification for Cast and Sintered Alnico Permanent Magnets.
7.2 Physical density values are given for information purposes oniy and are not mandatory.
7.3 Alnico magnets are used for their magnetic characteristics. The end-use application should not rely on them for structural purposes due to low tensile and flexural strength. These materials are brittle and can chip or break easily. Magnetic properties may also he affected by physical stress.
8. Magnetic Property Requirements
8.1 Magnetic properties are listed in Table I.
8.2 The values of essential magnetic properties listed in the table are specified minimum values at +20 ± 2 °C (+68 ± 4 °F), determined after magnetizing to saturation in closed magnetic circuit.
8.3 The specified values of magnetic properties arc valid only for magnet test specimens with a uniform cross-section along the axis of magnetization. Properties for anisotropic (magnetically oriented) magnets are measured along the axis of preferred orientation.
8.4 Because of the nature of permanent magnet production, magnetic testing of each lot is strongly recommended, especially for applications where the magnet performance is closely specified. Such magnetic property evaluations shall be conducted in the manner described below. Where the magnet shape is not suitable for magnetic testing. a specimen shall he cut from the magnet using appropriate slicing and grinding techniques, paying attention to any magnetic orientation within the magnet.
8.4.1 The magnetic properties shall be determined in accordance with Test Method A977/A977M, or by using a suitable, mutually agreed upon magnetometric method.
8.4.2 When magnets are being purchased in the fully magnetized condition, the testing shall determine the magnetic properties from the as-received magnetization state, followed by magnetization to saturation and testing of the magnetic properties from the fully magnetized condition.
8.4.3 When magnets are being purchased in the unmagnetized condition or in an unknown state of magnetization, the test laboratory shall magnetize the test specimen(s) to saturation in the same orientation as the received specimens’ indicated direction of magnetization and measure the magnetic properties from this fully magnetized condition.
8.4.4 When magnets are being purchased in a calibrated, stabilized, or bknockeddown condition, magnets should be handled with care to prevent exposure to externally applied fields. Refer to Appendix X3 for an explanation of these terms. During testing using Test Method A977/A977M and to avoid changing the magnetization state of the material prior to test, the measurement should proceed in the second quadrant only without attempting to saturate the magnet specimen.
8.4.5 Other test methods may be utilized as agreed to between producer and user. Such tests may include open circuit magnetization Helmholtz test (refer to Appendix X3), field strength measurements in a defined magnetic circuit or magnetic flux density measurements adjacent to the magnet surface.