179 weckenmann

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Unformatted text preview: the calculation of averages, standard deviations, tests for equal variances and the construction of boxplots and control charts with individual values. These control charts reveal whether production is under control or not, and all observed out-of-control values have been investigated in detail to decide whether they represent outliers. 3.3. Error analysis of the influencing factors The statistical characteristics of the factors related to material input, including sheet thickness, initial length, springback, and bend allowance, are presented in Table 1, with the nominal value, the range, the mean, and the standard deviation of the samples. Table 1: Factors related to input material. Nominal Max M in Mean Stdev Sample size Thickness [mm] 2 1.948 1.935 1.942 0.015 30 Length [mm] 240.96 241.03 240.81 240.89 0.041 30 Springback [o] 4.92 4.46 4.69 0.09 33 Bend allowance [mm] 3.96 4.07 4.01 0.02 36 Since the machine and process related factors, such as gauging and punch positioning errors, are strongly related to the individual production environment, the possible shift of the average values, the rang...
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