•Inappropriate plan parameter derivation for variables sampling plans is addressed.•The actual α‐risk might be larger than the maximum one desired by the producer.•Correct plan parameters are ...recalculated to overwrite those in the original papers.•Two applicative examples show practical consequences of the proposed corrections.
In this short note, we prove that the derivation of the required sample size and critical acceptance value under the normality assumption of the quality characteristic proposed by Wu, C. W., Aslam, M., & Jun, C. H. (2012). Variables sampling inspection scheme for resubmitted lots based on the process capability index Cpk. European Journal of Operational Research, 217(3), 560–566, is inappropriate. In fact, it leads to a lower probability of acceptance than the one desired by the producer. The same issue also occurs in the case of a variables single sampling plan described in a previous paper by Pearn, W. L., & Wu, C. W. (2007). An effective decision making method for product acceptance. Omega, 35(1), 12–21. Nevertheless, a similar yet less severe inaccuracy is also noticed in Wu, C. W., & Pearn, W. L. (2008). A variables sampling plan based on Cpmk for product acceptance determination. European Journal of Operational Research, 184(2), 549–560.
This research aims to identify one of the methods of statistical quality control, which is represented in the indicators of the Capability Process and explains its importance and how to use it for ...knowing the extension of the process to fulfill the specifications through several indicators with a statement that through practical application on one of the pharmaceutical products (Paramol Tablets Weights) one of the products of Yemeni Drug Company for Industry and Commerce (YEDCO). Hence, the results showed that the permits of process specifications of the tablet weight are equal to about 5 standard deviations, which is less than the standard practices, which are 8 standard deviations. Therefore, the capacity of the process for tablet weight is Cp<1, which is an undesirable state; because the production process is unable to satisfy the specifications. The CPK indicator shows that the process is decentralized and hence the inability of the process to fulfill the specifications; therefore, the company has to revise the limits of Paramol tablet weights specifications and to expand it as the company adopts numerous pharmacopeias in its operations. It must select the pharmacopeia that gives specifications which can make the process capability indicator and the index of process concentration in their standard state (Cp, Cpk=1.33mg).
The energetic and environmental crisis currently being experienced around the world has brought an exponential growth on the demand for wind energy, and, consequently, real challenges for companies ...in this sector. Since this industry is relatively new, its production processes require a significant amount of human intervention and have a high variability in the process and high lead times. Therefore, there is a need to focus on the quality of the processes and their improvement. This paper presents the use of the Six Sigma DMAIC approach integrated with Business Process Management, to reduce the number of defects and the repair time in a leading wind blade manufacturing company in Portugal. During the measurement and analysis phases, data was collected to understand the performance of the process and to identify the main problems and their causes. The data was analysed through several graphical and statistical techniques. In the analysis phase, process modeling was also utilized, using Business Process Model and Notation, to identify the critical steps that are responsible for producing the majority of defects. One month after beginning to use this approach, it was possible to notice a reduction in the number of defects by more than 30%, in the repair time by 14%, and an increase in the process sigma level by more than 100%. Thus, this hybrid approach has allowed the company to become more competitive and responsive to the constant growth in demand.
Process capability indices such as C
p
, C
pL
, C
pU
, and C
pk
have been used for evaluating the performance of a manufacturing process in statistical quality control and statistical process control ...fields. In this paper, a Bayes estimator of C
pk
is constructed such that the prior mean is set to be equal to a specified value while the prior distribution is weakly informative. This estimator is compared with conventional Bayes and non Bayes estimators.
•We propose a fuzzy-inference-based decision-making method for PCA.•The method enables users to select optimal PCIs using fuzzy logic for K and Zshift.•The PCA results are reported via the dashboard ...of our decision-making system.•The proposed method was applied to a manufacturing process for home gas boilers.
This paper proposes a decision-making method based on fuzzy inference to facilitate process capability analysis based on the knowledge and experience of experts, and implement systematized statistical process capability control. Data screening is implemented in the form of a rule-based decision-making tree to perform normality testing, R- or s-control chart testing, and x-bar control chart testing on process data to determine whether a process is in a state of statistical control. After setting the improvement direction of the process using a four-block diagram, the processes with a high probability of defect leakage due to large dispersion compared to the specification are reexamined after the fundamental improvement is completed by reinforcing the technology. Additionally, an optimal process capability index is selected using fuzzy inference by considering the degree of bias in a distribution and the differences between short- and long-term process capabilities. The feasibility of the proposed method was verified by applying it to a process for manufacturing home gas boilers. The method enables process control engineers to examine the results of the statistical analysis and the priority of the process to be improved, which are visualized in real time using a dashboard. These results are subsequently used for decision-making.
Today the part of an engineer is compelled to perform manufacturing, and in addition to survey whether the product is fit for conveying the same parametric results or convey insufficient defective ...parts. This can be an expert by process capability considerations. However, there is an unusual impact on process capability on production expenses for any manufacturing areas. An engineer is constrained to perform generation assignment, as well as to examine whether the procedure is fit for delivering the same parametric results or create blemished segments. This can be accomplished by a statistical process capability study. In this paper, an endeavor has been made to highlight the procedure of factual resistance breaking points and its appropriateness for evaluating the process capability of Y9T caliper. The Y9T caliper influenced by different cutting parameters, for example, speed of machine; feed rate and length of cut and so on. By considering the above parameters for ordinary running conditions, the process capability indices (Cp and Cpk) for a few Cases were gotten. The procedure for ordinary conditions is in measurable control however, there is an extension for improvement of process expenses by enhancing the capability indices. There might be a possibility for enhancing process capability records of the same process through changing the process parameters likes the speed of machine, feed rate, and length of cut. The outcomes got from further cases demonstrate the change in process capability indices. The outcomes likewise demonstrate that there is a change in the manufacturing rate per batch by enhancing process capability.
Purpose
The purpose of this paper is to establish mechanisms for process improvement so that production efficiency and product quality can be expected, and create a sustainable development in terms ...of circular economy.
Design/methodology/approach
The authors obtain a critical value from statistical hypothesis testing, and thereby construct a process capability indices chart, which both lowers the chance of quality level misjudgment caused by sampling error and provides reference for the processes improvement in poor quality levels. The authors used the bottom bracket of bicycles as an example to demonstrate the model and methods proposed in this study.
Findings
This approach enables us to plot multiple quality characteristics, despite varying attributes and specifications, onto the same process capability analysis chart. And it therefore increases accuracy and precision to reduce rework and scrap rates (reduce), increase product availability, reduce maintenance frequency and increase reuse (reuse), increase the recycle rates of components (recycle) and lengthen service life, which will delay recovery time (recovery).
Originality/value
Parts manufacturers in the industry chain can upload their production data to the cloud platform. The quality control center of the bicycle manufacturer can utilized the production data analysis model to identify critical-to-quality characteristics. The platform also offers reference for improvement and adds the improvement achievements and experience to its knowledge management to provide the entire industry chain. Feedback is also given to the R&D department of the bicycle manufacturer as reference for more robust product designs, more reasonable tolerance designs, and selection criteria for better parts suppliers, thereby forming an intelligent manufacturing loop system.
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•A novel arginine-functionalized polyaniline@FeOOH composite was synthesized.•The as-developed composite provides superior cleanup ability and selectivity for Cr(VI) ions from ...water.•Electrostatic attractions controlled the Cr(VI) adsorption process.•The process capability study reveals the suitability of Cr(VI) adsorption for large scale application.•Arg-PANI@FeOOH exhibits excellent re-generability and reusability for Cr(VI) ions removal.
In this study, the synthesis of a novel arginine-functionalized polyaniline/FeOOH (Arg-PANI@FeOOH) composite for hazardous Hexavalent chromium ions (Cr(VI)) removal from wastewater was reported. The SEM, EDS, FTIR, XRD, and PZC measurements were used to characterize the as-developed Arg-PANI@FeOOH composite. Batch adsorption experiments were used to investigate the influence of pH, temperature, contact time, Arg-PANI@FeOOH amount, initial Cr(VI) concentration and coexisting ions on the efficiency of Cr(VI) removal. The Cr(VI) adsorption was much more advantageous at lower pH values, reflecting that the electrostatic interactions were the main driving forces that govern Cr(VI) binding mechanism on the Arg-PANI@FeOOH surface. The experimental data showed good fitness to the pseudo-second-order kinetics and Langmuir isotherm. The Cr(VI) species highest monolayer coverage capacity onto Arg-PANI@FeOOH was 682.30 mg g−1. The adsorption of Cr(VI) onto the Arg-PANI@FeOOH is spontaneous via an endothermic reaction. The competing anions were not affected the Cr(VI) adsorption, demonstrating that the Arg-PANI@FeOOH selectively adsorb Cr(VI) ions. The developed Arg-PANI@FeOOH material demonstrated good reusability up to five regeneration cycles. The process capability to predict the practical aptitude of Arg-PANI@FeOOH adsorbent to remove Cr(VI) from aqueous solutions was successfully applied. As a result, the adsorption of Cr(VI) onto Arg-PANI@FeOOH composite is a capable process for full-scale wastewater purification purposes. This paper provides relevant findings for a polyaniline-based adsorbent for the efficient removal of Cr(VI) from wastewater.
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