About KJS Associates
Since its founding in 1968 by Dr. Karl J. Strnat, KJS Associates, Inc. (KJS) has specialized in all aspects of magnetic materials testing. The two major areas of activity are magnetic measurement services and the design, construction, and sale of high-quality magnetic test instrumentation and fixtures. The company also offers training and seminars on magnetic topics, which can be presented at the customer’s facility or at KJS Associates, Inc.
KJS offers a wide range of reliable and confidential testing services with NIST-traceable certification. For hard magnetic material testing, we can measure the magnetic “B vs. H curves” and unit properties of all types of permanent magnets over a wide range of temperatures. For soft magnetic material testing, we can provide you with quasi-static “DC” magnetic B vs. H curves, coercivity Hc, permeability, core loss and other important material properties over a wide temperature range.
NIST-traceable calibration of fluxmeters, guassmeters, Hall-effect probes, and flux measurement coils.
Soft Magnetic Materials
KJS characterizes the magnetic properties of magnetically soft materials, on a confidential basis, for industrial and government clients. As an independent test laboratory, KJS can provide accurate B vs. H and (B-H) vs. H magnetization curves and core loss characteristics, measured on any type of magnetically soft materials including: Si-Fe, Fe-Co, Fe, stainless steel, Ni-Fe alloys, and others using computer-automated equipment.
Under DC conditions, KJS can test for maximum permeability, saturation magnetization, loop shape, and coercive field. Testing complies with ASTM A-773-96 (Standard Test Method for DC Magnetic Properties of Materials Using Ring and Permeameter Procedures with DC Electronic Hysteresigraphs) or ASTM A341-95 (Standard Test Method for Direct Current Magnetic Properties of Materials Using D-C Permeameters and the Ballistic Test Methods). Under AC conditions, data can be provided on the AC permeability, B vs. H and core loss testing from 10Hz to 50kHz. Specimens can be in the form of rings, Epstein strips, bars with round or rectangular cross-section, and sometimes other physical forms. Testing can comply with ASTM A343-93a (Standard Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame) or ASTM A927-94 (Standard Test Method for Alternating-Current Magnetic Properties of Toroidal Core Specimens Using the Voltmeter-Ammeter-Wattmeter Method). Special tests can also be set up to meet specific customer requirements.
Hard Magnetic Materials
KJS Associates characterizes the magnetic properties of permanent magnets, on a confidential basis, for industrial and government clients. As an independent test laboratory, KJS can provide accurate B vs. H and (B-H) vs. H magnetization curves, measured on any type of permanent magnet material over a temperature range of -150ºC to +350ºC, using computer-automated equipment. Testing is certified traceable to NBS (now NIST) standards.
A large range of sample geometries can be accommodated, and KJS has in-house cutting and grinding equipment for sample preparation, when required. Additional capabilities include measurement of reversible and irreversible losses of flux, magnetic aging of test samples at various temperatures, and determining temperature coefficients of flux and coercivity.