3rd ICAI 2024

International Conference on Automotive Industry 2024

Mladá Boleslav, Czech Republic

Substituting into the formula

The calculations show that the proposed meter is not able to fully detect the variability of the process at the level of the expected Cp indicator. It is important to know that measurements carried out with a measuring instrument with a resolution or accuracy class selected according to the guidelines presented above will not provide us with the required value of the Cp index – it depends mainly on the variability of the process in relation to the tolerance area. A properly selected device will not “mask” this variability by its insufficient resolution. From the presented analyses one should not draw conclusions such as that the use of a very high-resolution instrument will allow to take a sample of a small number and on this basis determine the value of the Cp index. It is the “high” sample size (variety) that allows to determine the variability of the process, and not a very accurate measurement of a sample with a low number. The influence of sample size on the value of the Cp index can be read in electronic publication [8]. 3. Conclusion The presented recommendations regarding the selection of the instrument’s resolution can be used at the initial stage, in which we design a measurement system for a specific purpose. Of course, in order to properly implement the SPC principles, preliminary control tests are often carried out to determine, for example, the values of Cg and Cgk indicators. Nevertheless, these studies also require the use of measurement systems with previously defined parameters, such as resolution. It is also possible to check the resolution of existing measurement systems and see if any quality problems are due to its insufficient resolution of gauge . It should also be remembered that a measuring system is usually not only an instrument (gauge), but also an operator and a measurement procedure. In industrial practice, it is assumed that errors in the measuring system can be divided into two categories related to the measuring instrument and the work of the operator, often forgotten about the measurement procedure, which can affect the work of the operator and the use of the instrument. Once you have determined the variability of the process, the appropriate resolution of the instrument, examined the variability of a given data set, and all the factors that can affect the measurement of a specific characteristic, you can proceed to perform a proper analysis of the measurement system. The proposed approach is intended to be helpful in determining the initial requirements for measuring instruments used in statistical process control.

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