Rexroth Tightening System 350 System Documentation - Rhino ...

290/316 Bosch Rexroth AG | Tightening Technology 10 Working with the System10.4 Results storage and statistics(A)20(1)6(B)15(2)5(3)410352101.50 2.5 2.750(m)Figure 10–54: On the Y-axis either the absolute or the relative frequency is given with which the measurement dataoccurred within the random sample(A) Relative frequency(B) Absolute frequency(1) Average value(2) Class(3) Class “width”(m) ClassesDistributionTypical histograms in tightening technology are nearly symmetrical with the maximum in the center andevenly decreasing concentrations on the left and right. A normal distribution (histograms in the form of abell, Gauss graph, see Fig. 10–54) can be used as the statistical model for many distribution graphs intightening technology. The normal distribution can be found wherever a specific set value should be„reached“ (e.g. torque, angle). The deviations of the actual values from the mean or average value arecalled dispersion 1) .The normal distribution is used to estimate the probability of events (e.g. reaching the set value) and todraw conclusions on the distribution of measurement values.From the distribution graph of the normal distribution, the following can be determined for a random sample:– Number of measurement values inside and outside of the given tolerance– Random sample average– Standard deviation σ in the turning point of the distribution graph and its multiple as a measure of thedispersion for the measurement values.1) Causes for this could be: Changes in material batches, thread tolerance, worn tools, influence by personnel,etc.System 350 | 3 608 878 040/05.2008