The statistical control of the measuring process capability of vertical displacement of the head restraint - The second part: Case study

In the paper, two techniques of the statistical process control, namely: histogram and process capability are applied to examine whether a process is statistically controllable and to identify disturbances that occur in the process. The objective is to evaluate the capability of the measuring process of vertical displacement of the head restraint. In the measuring process, forces that are used to displace the head restraint up and down are recorded. The analysis consists of checking whether the lifting and lowering forces of the head restraint belong to the required ranges of forces. The processes of displacement of the head restraint up and down are characterised by a high potential, but a poor centering. In order to improve the centering of the process, causes of defects are identified.