Process capability control procedure for electrical machines by using a six‐sigma process for achieving six‐sigma quality level

Abstract

An overall six‐sigma process (SSP) that includes a novel process capability control (PCC) procedure is presented for satisfying a six‐sigma level for a Z‐value as well as a mean value of target performance. An example of this process is present for the efficiency and torque ripple in a spoke‐type permanent magnet motor considering the manufacturing tolerances of five rotor dimensions. In this context, six‐sigma means that the probability of failure of the product or system is 0.00034%. A novel SSP with a PCC procedure is suggested for designing electrical machines. In this procedure, three possible PCC methods were determined based on the definition of the Z‐value. Next, each method was carried out to achieve the target Z‐value and to illustrate the advantages and possible issues associated with each method. Finally, the authors showed that the suggested PCC procedure effectively achieves the target Z‐value of the motor and can be widely used for the design of electrical machines.

Tolerance Sensitivity Analysis and Robust Optimal Design Method of a Surface-Mounted Permanent Magnet Motor by Using a Hybrid Response Surface Method Considering Manufacturing Tolerances

“…R ls and R rc are ignored due to their relatively small effects on the OCAF. The effect of R mg can be included in the PM model by Equations (1) and 2:…”

“…In order to compensate for the demerits of SNR, this paper presents the H-RSM which is the hybrid of response surface method (RSM) and Taguchi robust design and directly finds the optimal point in terms of Z-value instead of SNR by using the regression equation because the target POF can be directly estimated by its corresponding Z-value [1]. Table 3 shows some important characteristics of the Z-value and SNR.…”

“…In Figure 7a, the LSL is used for the Z-value. It can be said that the robust optimal design has been successfully performed when Z-value is larger than 6.0 in the six-sigma process [1]. Figure 7b shows the difference between the conventional RSM and H-RSM, in which the H-RSM considers the variation of design variables and response caused by those of uncontrollable noise factors.…”

“…In addition, motor engineers should carry out the robust optimal design which is needed to satisfy the required probability of failure (POF) caused by the variations of the uncontrollable noise factors such as the manufacturing tolerances, the operating temperature, etc., as well as the mean value of the target performance [1].…”

“…Therefore, this paper presents the robust optimal design method using a hybrid response surface method (H-RSM) which directly finds an optimal point satisfying a target Z-value or a probability of failure through three steps. The objective of the method is to achieve the six-sigma level of Z-value of the OCAF; the six-sigma level of Z-value corresponds to 0.00034% of the POF [1].…”