Technology Center
Measuring principle magnetic characters of residual induction£¨Br£©, coercive force (Hc), intrinsic coercive force (iHc) and maximum energy product ((BH)max) by plotting B-H curve (demagnetization curve), conducted under IEC 60404-5:1993, is the scientific way for evaluating magnet property. For some magnets such as radially oriented ring, diametrically oriented ring, segment type and other irregular geometries what are not able to be directly measured, then standard sample what is molded with same lot material and sintered together or cut from the inspected object will be measured. Property evaluation of measuring flux density (surface gauss) by gauss meter is not recommended due to its limit of sensitivity. To briefly evaluate magnets what are not suitable for being plotted with hysteresis graph, flux test by Helmholtz coil connecting with flux meter is also a good suggestion.
Except visual characteristics, dimension and principle magnetic characters, other physical and mechanical properties shall not be as criteria for acceptance or reject unless otherwise specified in the drawing or contract. The definition of defect appearance, dimensional tolerance and magnetic property should be described in the drawing or as per IEC 60404-8-2 standard if it is in absence. Generally we carry out sampling inspection on magnet appearance, dimension and property. The sampling procedure is determined according to ISO 2859-4:2002. AQL4.0, AQL1.5 and AQL0.65 of inspection level¢ñare respectively adopted for judgment on magnet appearance, dimension and property. If customer has special requirements on sampling plan, inspecting item, process capability control of dimensional tolerance Cpk¨R1.33 and others, please kindly discuss with us in advance.