Process Capability Analysis in a Polypropylene Bag Manufacturing Company

Process capability analysis combines statistical tools and control charts with good engineering judgment to interpret and analyze the data representing a process. This work analyzes the process capability of a polypropylene bag producing company. The case study organization uses two plants for production and data was collected over a period of nine months for this study. Analysis showed that the output spread of plant 1 was greater than the specification interval spread which implies poor capability. There are non-conforming parts below the Lower Specification Limit (LSL: 500,000 metres) and above the Upper Specification Limit (USL: 600,000 metres) and that the output requires improvement. Similarly, the capability analysis of plant 2 shows that the overall output spread is greater than the specification interval spread (poor capability). The output centre in the specification and overall interval are vertically aligned, thus specifying that the output from plant 2 is also process centered and requires improvement. Recommendations were made to improve the outputs from each production plant.

Modelling dimensional change of machined parts and optimizing replacement time and initial position of cutting tool

In a manufacturing process, a key quality characteristic such as a certain dimension of machined parts can have a systematic shift toward the upper or lower specification limit due to the cutting tool wear. That is, the quality characteristic is a stochastic process with trend. As a result, the process capability and quality loss vary with time and depend on the initial position of the cutting tool. In this setting, decision problems that need to be solved are optimization of replacement time and initial position of the cutting tool. This paper proposes a non-homogenous Wiener process to model the dimensional change of machined parts; and the above-mentioned decision problems are solved through combining this model with a cost model that involves Taguchi quality loss. A real-world example is included to illustrate the appropriateness of the proposed models. The results are useful for both reliability researchers and manufacturing engineers.

Decision-Making for the Lifetime Performance Index

The purpose of this research is to develop a maximum likelihood estimator (MLE) for lifetime performance index CL for the parameter of mixture Rayleigh-Half Normal distribution (RHN) under progressively type-II right-censored samples under the constraint of knowing the lower specification limit (L). Additionally, we suggest an asymptotic normal distribution for the MLE for CL in order to construct a mechanism for evaluating products’ lifespan efficiency. We have specified all the steps to carry out the test. Additionally, not only does hypothesis testing successfully assess the lifetime performance of items, but it also functions as a supplier selection criterion for the consumer. Finally, we have added two real data examples as illustration examples. These two applications are provided to demonstrate how the results can be applied.

The Evaluation on the Process Capability Index CL for Exponentiated Frech’et Lifetime Product under Progressive Type I Interval Censoring

We present the likelihood inferences on the lifetime performance index CL to evaluate the performance of lifetimes of products following the skewed Exponentiated Frech’et distribution in many manufacturing industries. This research is related to the topic of skewed Probability Distributions and Applications across Disciplines. Exponentiated Frech’et distribution is a generalization of some lifetime distributions. The maximum likelihood estimator for CL for lifetimes with exponentiated Frech’et distribution is derived to develop a computational testing procedure so that experimenters can implement it to test whether the lifetime performance reached the pre-assigned level of significance with a given lower specification limit under progressive type I interval censoring. At the end, two examples are provided to demonstrate the implementation on the algorithm for our proposed computational testing procedure.

Hybrid censoring samples in assessment the lifetime performance index of Chen distributed products

The performance and potential of a process of industrial products is assessed under lower specification limit L by lifetime performance index (CL). In this paper, under consideration the independent lifetimes Chen products with known one shape parameters the CL of the performance of a process is evaluated. For the hybrid censoring scheme the maximum likelihood (ML) estimate of CL is constructed as well as confidence interval for CL is developing. Also, Bayesian approach is adopted to estimates CL and credibly interval is constructed. Some theoretical results of hypothesis tests of CL is adopted. Finally, our obtaining results will be assessed and compared through Monte Carlo simulation study and numerical example.

PENGENDALIAN KUALITAS PEMOTONGAN KAIN SATEN PADA PROSES PEMBUATAN TAS DI HOME INDUSTRI X DI KABUPATEN SIDOARJO

purchasing power, making a number of craftsmen home industry in Sidoarjo either small,medium or produced in homes facing bankruptcy. Their products are not only competingwith a medium or large industrial products that use semi-modern machinery, but alsoimported products, especially from China and Vietnam which relying on cheaper productprices. Ironically, consumers now also its orientation, to model and quality. It which notowned by the craftsman home industry, because their manual production. With thiscondition, resulted in the emergence difficulties for home craftsmen in the industry toimprove and expand its business.With the variety of backgrounds, as described above, the purpose of this researchare to provide recommendations about the quality control, cutting sateen in the process ofmaking bags in the Home Industries X.Solving problems in this research using the method to determine the source ofvariation of the process, that is using the Control Chart of X-bar (average) and R(Range). The results showed that the value of Process Capability Index (Cp) in the HomeIndustry X has a value of Cp = 0.525 <1.00. This means that the process has a lowcapability to meet the specifications of the expected measurement. As well as with size ofKane Performance Index (Cpk = 0.367) were the criteria CPL = 0.367, or CPU = 0.682<1.00, which means that the process is not able to meet the lower specification limit(LSL) and upper (USL). With this condition, it is necessary to control the use of controlchart from the X-bar and R to monitor the ongoing process from time to time, to soquickly take corrective action, if any changes which not desirable in the process ofmaking bags at Home industrial X.Kata Kunci : Pengendalian Kualitas, Indek Kapabilitas Proses (Cp), Indeks Kinerja Kane(Cpk)

UNIVARIATE PROCESS CAPABILITY INDICES FOR UNILATERAL SPECIFICATION REGION — A REVIEW AND SOME MODIFICATIONS

In a manufacturing industry, often the quality characteristic under study is found to have only one of the two specification limits viz., upper specification limit (USL) or lower specification limit (LSL). In such cases the process capability indices (PCI) designed for bilateral specifications become inappropriate. However, in the literature only a few indices are available to address this problem. In the present paper, we have made an extensive study of the PCI's for unilateral specifications with a brief discussion of their possible fields of applications and drawbacks, if any. We have also proposed a logical formulation of a parameter of one of these indices which reduces the subjectivity of the index and hence makes it more suitable for practical application. An example, with the computed values of the various PCI's, is discussed to make a comparative study of the performance and inter-relationship between these PCI's. We have concluded the paper with a discussion on the future scope of study in this field.

Bayesian Estimation of Generalized Process Capability Indices

Process capability indices (PCIs) aim to quantify the capability of a process of quality characteristic (X) to meet some specifications that are related to a measurable characteristic of its produced items. One such quality characteristic is life time of items. The specifications are determined through the lower specification limit (L), the upper specification limit (U), and the target value (T). Maiti et al. (2010) have proposed a generalized process capability index that is the ratio of proportion of specification conformance to proportion of desired conformance. Bayesian estimation of the index has been considered under squared error loss function. Normal, exponential (nonnormal), and Poisson (discrete) processes have been taken into account. Bayes estimates of the index have been compared with the frequentist counterparts. Data sets have been analyzed.