Machine capability sigma level evaluation and allocation method

Sheng Yong Zhang, Gen Bao Zhang, Yan Ran*, Adrian Murphy

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The concept of process capability has been widely used in production management and quality control. However, applying traditional process capability evaluation method to machine capability cannot eliminate the influence of other process factors other than machine. To solve the problem, we propose the sigma machine capability evaluation method in this paper. First, multivariate statistical analysis methods are used to analyze the influence of all factors. Second, we deleted the non-normal data through sample fitting. Then, on the basis of normal distribution, we used the sample variance as the evaluation index to calculate the sigma levels of single characteristic and multiple characteristic parts. Last, we applied the sigma evaluation method and the traditional one to conduct a case study and compare their results, which proves the feasibility and superiority of the sigma level evaluation method.

Original languageEnglish
JournalProceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
Early online date27 Dec 2019
Publication statusEarly online date - 27 Dec 2019


  • allocation method
  • compensation coefficient
  • Machine capability
  • multi-characteristic
  • sigma level

ASJC Scopus subject areas

  • Mechanical Engineering


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