Process Capability and Six Sigma Methodology Including Fuzzy and Lean Approaches

Şenvar, Özlem; Tozan, Hakan

doi:10.5772/10389

Cited by 16 publications

(17 citation statements)

References 45 publications

(43 reference statements)

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“…Surprisingly, the mean MBP, DBP max, SBP max and MBP max, min were not significantly different between the groups. Searching for a more inclusive analytical technique to overcome the possible inaccuracies of these comparisons, we found computing of PCIs[1112] very useful and advantageous. As an indicator of how closely a process is able to match the output to its overall specifications and to predefined targets, it is widely employed as a statistical tool to assess production, quality and process improvement efforts in engineering design.…”

Section: Discussionmentioning

confidence: 99%

Isoflurane versus sevoflurane with interscalene block for shoulder arthroscopic procedures: Value of process capability indices as an additional tool for data analysis

et al. 2016

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Background and Aims:Hypotensive anaesthesia reduces intra-articular bleed and promotes visualisation during arthroscopy. The haemodynamic effects of inhalational agents isoflurane and sevoflurane were studied extensively, and both were found to reduce mean arterial pressures (MBP) to an equivalent magnitude. We investigated the relative ability of isoflurane vis-a-vis sevoflurane to maintain the target systolic blood pressure (SBP) in patients undergoing shoulder arthroscopic procedures.Methods:In a prospective randomised study, 59 patients in two groups of 30 and 29 patients each received concomitant general anaesthesia (1.2–1.5 MAC of isoflurane and sevoflurane) and interscalene brachial plexus block. Nitrous oxide was used in both groups. Intraoperatively, serial blood pressure recordings of SBP, diastolic blood pressure (DBP), MBP and heart rates were done at every 3rd min intervals. The manipulations needed to achieve target SBP (T = 90 mmHg) for optimal arthroscopic visualisation and treat unacceptable hypotensive episodes were noted. Conventional statistical tests and process capability index (PCI) evaluation were both deployed for data analysis.Results:Lower mean SBP and DBPs were recorded for isoflurane patients as compared to sevoflurane (P < 0.05, for mean, maximum and minimum recordings). Higher mean heart rates were recorded for isoflurane (P < 0.05). PCIs indicated that isoflurane was superior to sevoflurane in the ease of achieving target SBP of 90 mmHg as well as maintaining blood pressures in the range of 80–100 mmHg.Conclusion:Isoflurane provides better intraoperative haemodynamic status vis-a-vis sevoflurane in patients undergoing shoulder arthroscopic surgery with preliminary interscalene blockade. The PCI can be a useful additional medical data analysis tool.

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Section: Discussionmentioning

confidence: 99%

Isoflurane versus sevoflurane with interscalene block for shoulder arthroscopic procedures: Value of process capability indices as an additional tool for data analysis

et al. 2016

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“…PCA involves statistical techniques (Senvar & Tozan, 2010). PCA is used to estimate the process capability and evaluate how well the process will hold the customer tolerance.…”

Section: Process Capability Analysis (Pca)mentioning

confidence: 99%

Comparing performances of clements, box-cox, Johnson methods with weibull distributions for assessing process capability

Şenvar

Şennaroğlu

2016

JIEM

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Abstract:Purpose: This study examines Clements' Approach (CA), Box-Cox transformation (BCT), and Johnson transformation (JT) methods for process capability assessments through Weibull-distributed data with different parameters to figure out the effects of the tail behaviours on process capability and compares their estimation performances in terms of accuracy and precision.Design/methodology/approach: Usage of process performance index (PPI) P pu is handled for process capability analysis (PCA) because the comparison issues are performed through generating Weibull data without subgroups. Box plots, descriptive statistics, the root-mean-square deviation (RMSD), which is used as a measure of error, and a radar chart are utilized all together for evaluating the performances of the methods. In addition, the bias of the estimated values is important as the efficiency measured by the mean square error. In this regard, Relative Bias (RB) and the Relative Root Mean Square Error (RRMSE) are also considered. Findings:The results reveal that the performance of a method is dependent on its capability to fit the tail behavior of the Weibull distribution and on targeted values of the PPIs. It is observed that the effect of tail behavior is more significant when the process is more capable.-634-Journal of Industrial Engineering and Management -http://dx.doi.org/10.3926/jiem.1703Research limitations/implications: Some other methods such as Weighted Variance method, which also give good results, were also conducted. However, we later realized that it would be confusing in terms of comparison issues between the methods for consistent interpretations. Practical implications:Weibull distribution covers a wide class of non-normal processes due to its capability to yield a variety of distinct curves based on its parameters. Weibull distributions are known to have significantly different tail behaviors, which greatly affects the process capability. In quality and reliability applications, they are widely used for the analyses of failure data in order to understand how items are failing or failures being occurred. Many academicians prefer the estimation of long term variation for process capability calculations although Process Capability Indices (PCIs) C p and C pk are widely used in literature. On the other hand, in industry, especially in automotive industry, the PPIs P p and P pk are used for the second type of estimations.Originality/value: Performance comparisons are performed through generating Weibull data without subgroups and for this reason, process performance indices (PPIs) are executed for computing process capability rather than process capability indices (PCIs). Box plots, descriptive statistics, the root-mean-square deviation (RMSD), which is used as a measure of error, and a radar chart are utilized all together for evaluating the performances of the methods. In addition, the bias of the estimated values is important as the efficiency measured by the mean square error.In this regard, Relative Bias (RB) and the Relativ...

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“…In order to gain deep insight of the optimized parameters predicted by the DoE array, DPMO was calculated by using the following formula [12]:…”

Section: Defect Per Million Opportunities (Dpmo) Modelmentioning

confidence: 99%

“…An important method to determine the reproducibility of the process is defect per million opportunities model (DPMO). DPMO evaluates the reproducibility of the process to relatively high sensitivity such as parts per million (PPM) [11,12]. The "Six Sigma" approach can help in achieving the highly reproducibility of the industrial process.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design of Experiment Approach in the Industrial Gas Carburizing Process

Rehman¹,

Munawar²,

QaisarNawaz³

et al. 2018

Statistical Approaches With Emphasis on Design of Experiments Applied to Chemical Processes

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Carburized samples were prepared under different sets of conditions at Millat Equipment Limited, Lahore, Pakistan, using continuous carburizing furnace under a reducing atmosphere. The gas carburizing process parameters were determined by the Taguchi design of experiment (DoE), an orthogonal array of L9 type with the mixed level of control factors. The key process parameters in gas carburizing process such as delay quenching interval, hardening temperature, and soaking time in oil were optimized in terms of core hardness, effective case depth (ECD), and surface hardness. DoE approach elucidated that the best results in terms of core hardness are A2 (delay quenching for 60 seconds), B2 (hardening temperature of 800°C), and C2 (soaking in quenching oil for 300 seconds). However, the best results in terms of ECD were A1 (delay quenching for 45 seconds), B3 (hardening temperature of 820°C), and C1 (soaking in quenching oil for 180 seconds). In order to choose the optimized parameters from the results given by DoE, microscopic analysis was conducted. Microscopic analysis showed coarse bainitic structure in core and tempered martensite at the surface of the samples processed at A2 (delay quenching for 60 seconds), B2 (hardening temperature of 800°C), and C1 (soaking in quenching oil for 180 seconds) compared to the other process conditions (A1, B3, and C1), which shows fine bainitic structure at core and relatively higher amount of retained austenite at the surface. Finally, defect per million opportunities (DPMO) model exhibited that the samples produced from the optimized set of parameters (A2, B2, and C1) are highly reproducible, gaining DPMO of 83 parts per million (PPM).

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Process Capability and Six Sigma Methodology Including Fuzzy and Lean Approaches

Cited by 16 publications

References 45 publications

Isoflurane versus sevoflurane with interscalene block for shoulder arthroscopic procedures: Value of process capability indices as an additional tool for data analysis

Isoflurane versus sevoflurane with interscalene block for shoulder arthroscopic procedures: Value of process capability indices as an additional tool for data analysis

Comparing performances of clements, box-cox, Johnson methods with weibull distributions for assessing process capability

Design of Experiment Approach in the Industrial Gas Carburizing Process

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