OBRABOTKAMETALLOV Vol. 26 No. 1 2024 TECHNOLOGY From the results obtained it follows (see fi g. 6) that the overall dimensions of the specimens, consisting of fi ve layers surfaced without applying a magnet, have a statistically signifi cant diff erence from the dimensions of the specimens, surfaced under the infl uence of a magnetic fi eld; namely, the width of the specimens increased by 11.2 %, with a calculated t-criterion equal to −3.22 and a signifi cance index of 4.3×10−3, and the height of the samples decreased by 10.3 %, with a calculated t-criterion equal to 5.36 and a signifi cance index of 6.3×10−5. The results of the calculation of F-criterion (see fi g. 6, a) showed that the variances of the overall dimensions of the surfaced specimens are statistically insignifi cant and the calculated signifi cance indices exceed the accepted signifi cance level of 0.05. The change in the geometric error of the surfaced layers was assessed by the value of defl ection from straightness of the specimen’s side walls in vertical direction for a given section as well as the defl ection in the width of the specimen. Fig. 7 shows a diagram for measuring the value of defl ection from straightness, which was carried out for the left wall (EFL1) and the right wall (EFL2) of the specimen, and in further calculations the defl ection from straightness having the largest value was used: EFL = max (EFL1, EFL2). The results of measuring defl ection from straightness are presented in Table 3. Fig. 8 shows the results of a statistical comparison of the value of the defl ection from straightness using t-test. From the obtained results (see fi g. 8) it follows that defl ections from straightness in vertical direction for the side walls of the specimens surfaced without a magnet do not have a statistically signifi cant diff erence from the specimens surfaced under the infl uence of a magnetic fi eld, with the calculated t-test criterion equal to −1.0097 and a signifi cance index of 0.3277, which exceeds the accepted signifi cance level of 0.05. Based on the value of the calculated F-criterion, the variance of the defl ection from straightness of the side walls of the surfaced specimens is also statistically insignifi cant, with a calculated signifi cance index of 0.3496. To compare the defl ection values of the specimens’ wall width, for each specimen the width was measured at seven points of diff erent heights, according to the diagram presented in fi g. 9. Table 4 shows the results of measuring the width of the surfaced specimens. a b Fig. 7. Scheme for measuring the deviation from straightness of the specimens surfaced: a – without the infl uence of a longitudinal magnetic fi eld; b – under the infl uence of a longitudinal magnetic fi eld
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