APPLICATION OF I / MR AND CUSUM CONTROL CHARTS TO EVALUATE THE QUALITY OF CAST STEEL IN INDUCTION FURNACES

This article is a result of research carried out in foundry casting steel castings for the railway industry.The smelting process (smelting) in induction furnaces, in terms of the compatibility of the actual chemical elements in the metal with the composition laid down in the technological instructions, was included in the study program.In practice, the actual content of elements is determined by the static spectral analysis method and recorded in the documentation created by the traditional record.Entries are evaluated only in terms of compliance with technological instructions, which does not translate into improvement in the quality of the melt as a function of the duration of the production process.The introduction of time analysis in the melting range allows to take into account the variability of a number of factors affecting the actual (final) content of the elements and thus the quality of the cast.An example of time analysis presented in the article is the ability to use I / MR control cards for individual (single) observations composed of smelting processes and CUSUM cards that enable the detection of factor variability based on cumulative sums.Cards of this type can be helpful in achieving the quality of alloys in real time of the melting process.