Quality control in workshop production of NdFeB magnetic materials using an LIBS rare earth magnet instrument

Abstract

NdFeB magnetic materials are the most commonly used rare earth magnets. In the production and processing of the NdFeB magnetic materials, it is necessary to conduct quality control on crude samples of magnetic materials to reduce production costs. Laser induced breakdown spectroscopy (LIBS) is a technique to obtain the spectrum of elements by exciting plasma on the surface of the sample with a high energy laser. An LIBS rare-earth magnet on-line measuring instrument for crude sample detection of magnetic materials is designed and developed. The instrument meets the requirements for product quality control in workshop production. The spectra of 7 kinds of NdFeB crude material samples were obtained by the LIBS instrument. To improve the classification accuracy, the algorithm in the instrument supporting software was used. Appropriate stoichiometric methods were selected, and a sliding window minimum removal base method was independently designed to further optimize the classification accuracy. The optimal ratio was determined by discussing the proportion of data sets, and the accuracy and stability were compared by cross-validation. Finally, stoichiometric method parameters were optimized. The overall optimization improves the classification accuracy from 87.14% to 99.05%. It is verified that the LIBS rare earth magnet online measuring instrument can effectively classify and detect NdFeB rare earth magnets, providing a fast, convenient, accurate and economical testing method for quality control in magnetic material workshops.