Process Capability Study Research Articles

Process capability study of domestic organic waste composting process - a pilot scale case study in rural India

Process capability study of domestic organic waste composting process - a pilot scale case study in rural India

Proposed Capability Indices Based on Robust Estimation Compared with Classical Capability Indices

A process capability study is a scientific and systematic procedure that uses control charts to detect and eliminate the unnatural causes of variation until a state of statistical control is reached. On the other hand, in order to meet the quality requirements of the final product, quality should be achieved at every stage of production. Another way of achieving good quality during production is to use statistical techniques at every stage of production. The purpose of this research is to apply it to process capacity indices in replace of the standard deviation estimator. The information, which is taken from the Coca-Cola/Erbil production process, illustrates the qualities of the beverage (750 ml). A Coca-Cola product's 100 observations are divided into 25 models. Employed both the standard deviation estimator-based and the robust Downton estimation-based process capability indices. It was determined that in this inquiry, the robust Downton estimation had better qualities than the standard division estimator because the robust Downton estimation process capacity index values were greater.

Design of a new adaptive MEWMA chart to monitor the mean

The adaptive MEWMA (AMEWMA) charts have been broadly perceived as an effective process monitoring instrument due to the efficient detection of the mean shifts of diverse sizes. This study proposes an AMEWMA control chart to observe the irregular variations in the mean vector of the process which follows the multivariate normal distribution. The idea is to assess the mean shift by using an unbiased estimator and after that adapt the smoothing constant of plotting EWMA statistic through a continuous function. As an evaluation tool, the run-length profiles are computed by using the Monte Carlo simulation method. The proposed AMEWMA chart is proved to be efficient in shift detection as compared to the MEWMA and existing AMEWMA charts. The application of the proposed chart is shown by utilizing a real-life dataset from a case study of process capability for turning aluminum pins where six quality characteristics are to be observed.

Process capability study of domestic organic waste composting process a pilot scale case study in rural India

Process capability study of domestic organic waste composting process a pilot scale case study in rural India

THE IMPORTANCE OF MEASURING SYSTEM ANALYSIS IN PROCESS CAPABILITY ASSESSMENT

The implementation of statistical methods in the product development phases has become an unavoidable part of engineering practice. Monitoring of the condition of the process or production equipment is performed using established methodologies, which include the analysis of process capabilities. This analysis involves identifying the need to evaluate the production process or system, data collection, analysis, and interpretation of data. Data acquisition is performed using a measuring system, which with its characteristics in terms of accuracy and precision must meet certain criteria. This paper aims to determine the capability of the process, calculating the capability indices Cp and Cpk, with special reference to the measurement system. Before using the data in the analysis of abilities, an analysis of the measurement system was previously performed to determine its variation in the total variation of the study. The variation of the measuring system proved to be acceptable, which gave the author a sufficient reason to further exploit that measuring system. The process capability study was conducted on a sample of 125 parts, where it was concluded that the observed process is within the statistical control limits and can produce most of the workpieces within the specification limits.

A framework of tolerance specification for freeform point clouds and capability analysis for reverse engineering processes

The combination of reverse engineering (RE) with additive manufacturing (AM) is widely used for solid freeform fabrication and overcomes limitations with the current capabilities of designers and CAD packages that are restricted to classical model shapes. The shape flexibility offered by RE typically leads to the generated CAD models being represented in point cloud formats or stereolithography files. One resulting challenge is the difficulty with tolerance specification for the RE-generated models, especially for freeform shapes. Geometric metrology for the AM-produced parts to determine their geometric conformation can also be involved. Furthermore, conventional process analyses cannot be performed directly after RE because of the complex geometric data structure. We propose to address all these issues with a new tolerance specification and process analysis framework based on volumetric data analysis. The tolerance zone constructed under our framework, and the corresponding geometric measurements, are consistent with the profile tolerance in geometric dimensioning and tolerancing standards. Reverse engineering's process capability is assessed under our methodology via a parametric bootstrap procedure in the size-and-shape space. The performance and utility of the proposed framework are validated via a process capability study on RE-generated CAD models of multiple, additively manufactured freeform objects.

Synthesis of an arginine-functionalized polyaniline@FeOOH composite with high removal performance of hexavalent chromium ions from water: Adsorption behavior, regeneration and process capability studies

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.

Process Capability Studies in an Automated Flexible Assembly Process: A Case Study in an Automotive Industry

Statistical Process Control (SPC) methods can significantly increase organizational efficiency if appropriately used. The primary goal of process capability studies is to obtain critical information about processes to render them even more effective. This paper proposes a comprehensive framework for proper implementation of SPC studies, including the design of the sampling procedure and intervals as well as process capability indices. Some of the most essential process capability indices in the literature were reviewed to develop a methodology to utilize process capability indices within the SPC framework. The current study presents an efficiency-oriented criterion designed for measuring SPC implementation productivity. The framework is applied to the windshield installation process of an Iranian automobile assembly line. The process was sampled in various sessions. Results verify that the implemented SPC framework could successfully improve the process and that the proposed framework could significantly address bottleneck in the process and enhance the quality level of the process from satisfactory to excellent according to the reference values of process capability indices. Managerial insights are also drawn from results.

Investigation of production parameters for process capability analysis: A case study

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.

Transportation time reliability appraisal in maritime context

Transportation time information plays an important role in transportation and logistics. Variability in transportation time is obvious in any mode of transport due to unpredictable system parameters and their dynamic behavior. Significant work has been done in transportation on road and rail modes but the area is still open and hot for maritime being less explored so far. This paper, in maritime perspective, defines the transportation time as time taken for all the activities from loading at source harbor till it’s unloading at the destination and so the return path. As uncertainties can be handled effectively by statistical methods, it is used for transportation time appraisal. The paper presents the methodology for maritime transportation reliability assessment and illustrates the same with an application to a case of Stena Baltica ferry operation in Europe. This paper uniquely combines quality and reliability tools in maritime studies and the obtained results are validated through the simulation. Further a leading link is taken to resolve the problem reducing the uncertainty level in the voyage by bringing process capability study into the investigation. Appropriate investigation and analyses with respect to transportation time variance reduction is also carried out in the paper.

Application of Six Sigma methodology in an Indian chemical company

PurposeThe aim of this paper is to deploy Six Sigma (SS) methodology for addressing the customer complaints pertaining to Chemical-X in an Indian chemical company.Design/methodology/approachThe study followed a structured Define, Measure, Analyze, Improve, Control (DMAIC) approach to address the customer complaints. The complaints have been classified into different categories along with a project charter in the define phase. In the measure phase, measurement system analysis (MSA) and supplier, input, process, output and control (SIPOC) have been applied. In the analyze and improve phase, why–why analysis, process capability study, how–how analysis, Gage repeatability and reproducibility and Taguchi design have been applied to optimize the manufacturing process parameters for Chemical-X. Lastly, in the control phase, validation of 20 batches has been piloted to validate the optimized parameters.FindingsThe findings of this study highlight the optimization and prioritization of the process parameters. It shows that humidity has the least impact on the manufacturing of Chemical-X, whereas shift type has the maximum impact. The experimental output indicates that the 1st Shift, the holding time after grinding should be twenty-four hours, and the temperature after grinding should be 40 °C to reduce the customer complaints concerning lumps formation in Chemical-X.Research limitations/implicationsThe study is performed for a single product (Chemical-X). It has focused only from the manufacturing process view and not from the transportation, suppliers and downstream supply chain view.Originality/valueA systematic and data-driven approach of the SS methodology ensured that the customer complaints due to lumps formation reduced from 5% (approx.) to 1% (approx.) which resulted in the cost saving of INR 4 million (approx.) annually.

Performance analysis in WEDM of titanium grade 6 through process capability index

Purpose The purpose of this study aims to obtain excellent products, consistent investigation and manufacturing process control which are the preconditions that organizations have to consider. Nowadays, manufacturing industry apprise process capability index (Cpi) to evaluate the nature of their things with an expect to enhance quality and also to improve the productivity by cutting down the operating cost. In this paper, process capability analysis was applied during wire electrical discharge machining (WEDM) of titanium grade 6, to study the process performance within specific limits. Design/methodology/approach Four machine input parameters, namely, pulse ON time, pulse OFF time, wire feed and wire tension, were chosen for process capability study. Experiments were carried out according to Taguchi’s L27 orthogonal array. The value of Cpi was evaluated for two machining attributes, namely, average surface roughness and material removal rate (MRR). For these two machining qualities, single response optimization was executed to explore the input settings, which could optimize WEDM process ability. Findings Optimum parameter settings for average surface roughness and MRR were found to be TON: 115 µs, TOFF: 55 µs, WF: 4 m/min and WT: 6 kg−F and TON: 105 µs, TOFF: 60 µs, WF: 4 m/min and WT: 5 kg−F. Originality/value Process capability analysis constantly checks the process quality through the capability index keep in mind the end goal to guarantee that the items made are complying with the particulars, providing data for product plan and process quality enhancement for designer and engineers, giving the support to decrease the cost of item failures.

Application of Density Functional Theory computation (DFT) and Process Capability Study for performance evaluation of Orthophosphate removal process using Polyaniline@Hematite-titaniferous sand composite (PANI@HTS) as a substrate

A new approach is adopted in this study to eliminate orthophosphates in the aqueous medium. It is about synthesizing a composite from a conductive polymer (Polyaniline) and a sandy material (Hematite-titaniferous sand). The synthesized composite (PANI@HTS) and its components were characterized with (XRD) X-ray diffraction, (XRF) X-ray fluorescence, (SEM) scanning electron microscopy coupled with (EDS) energy dispersive X-ray spectroscopy, (FTIR) Fourier-transform infrared spectroscopy and laser diffraction particle size analysis. The phenomenon of adsorption of orthophosphates on PANI@HTS has found to be dependent on several factors, such as adsorbent dose, pH, contact time and pollutant concentration. From the study of adsorption kinetics and the effect of pollutant concentration, the Langmuir model and the pseudo second order model were the most suited for explaining adsorption phenomena with a highest correlation (R2 > 0.98). The adsorbed amount that was found in this study reaches 16.15 mg/g. The adsorption mechanism of orthophosphate ions onto PANI@HTS composite was computationally investigated using Density Functional Theory (DFT). The adsorbate-adsorbent interfacial interactions are assumed to be physisorption in nature due to the low values of binding energy and electronic charge transfer. This DFT simulation result is in good adequacy with the experiment. The capability study of the present process has shown that our method is capable, satisfactory and can be applied on a large scale.

Investigations for In-house prepared Biocompatible Feed Stock Filament of Fused Deposition Modelling: A Process Capability study

Fused deposition modelling (FDM) is one of the low cost additive manufacturing (AM) process. The feed stock filament of FDM is the only consumable in the process and by preparing (in-house) bio compatible feed stock filament the application domain can be increased. Some studies have reported the use of twin screw extrusion (TSE) process for preparation of bio compatible feed stock filament (comprising of polyvinyl chloride (PVC) and polypropylene (PP) and hydroxyapatite (HAp) particles) with improved mechanical, dimensional and thermal properties, for commercial FDM setup. But hitherto very less has been reported on process capability of in-house prepared biocompatible feed stock filament. In the present work statistical analysis (for tensile strength, hardness and dimensional accuracy) has been performed for investigations of process capability. The results have been also supported by control charts (X-chart and R-chart) based upon the best feedstock filament wire.

Improving Process Capability of Cutting and Drilling Processes of Elevator Assembly Parts

Statistical process control (SPC) technique has become more and more often used for manufacturing process improvement with understanding the process and detecting the process variation. This paper presents a study from a small enterprise classified as OEM supply elevator assembly parts. A process capability study is performed for cutting and drilling processes in order to verify the process capable of consistently meeting the required specification and delivering quality products since increasing a number of rework parts. Why-why analysis was used to identify the root cause and the principles of Poka Yoke and jig & fixture design were then applied by design a measure gauge for cutting and drilling processes. After improvement, the result shows that the Cpk of cutting process increase from 0.19 to 2.72 while Cpk of drilling process also increase from 0.36 to 4.50. Since the Cpk is greater than 1.3 this means that both two processes have a capable to produce the output meet specification.

Hematite–titaniferous sand as a new low-cost adsorbent for orthophosphates removal: Adsorption, mechanism and Process Capability study

Abstract In this work, a new natural performing material Hematite–titaniferous sand (HTS) is used to study the adsorption of Orthophosphates, and to obtain the optimum conditions for maximum removal. The adsorbent used was characterized and inspected employing (XRD) X-ray diffraction, (XRF) X-ray fluorescence, (SEM) scanning electron microscopy coupled with (EDS) energy dispersive X-ray spectroscopy and (FTIR) Fourier-transform infrared spectroscopy. The adsorption of Orthophosphates on Hematite–titaniferous sand has found to be dependent on different variables such as contact time, solution pH, solution temperature and initial concentration. These variables were investigated using Batch Method. According to the results of the experiments in this research, adsorption kinetic was found to adopt the pseudo-second order kinetic model, which was the best appropriate model to describe the adsorption process. It was found that the Langmuir isotherm model fitted the adsorption data with the highest correlation ( R 2 > 0,99) at various temperatures. The adsorbed amount was found to be 0,612 mg/g. The thermodynamic parameters explain that the adsorption is spontaneous and favorable. Moreover, the optimum conditions were found to be pH = 5 , 1500 mg of adsorbent and a contact time of 120 min at adsorption temperature T = 45 ° C ± 1 . The process capability study demonstrated that the adsorption process was capable, and was stable for large-scale application.

Implementation of statistical process control in a bottling line in winnery industry

Introduction: The great demand of the markets has led to situations in which the production systems are characterized by the production of several batches but of small size. This new paradigm requires that adequate techniques be developed, both in terms of planning and in terms of Statistical Process Control (SPC), since there may be situations where it is not possible to collect enough data to properly estimate the parameters of the process (mean and variance). Objectives: Implementation of Statistical Process Control techniques in a wine industry in order to improve its final product. Methods: Whenever there is not enough data to properly estimate the parameters of the process, the suggested approach, is to adopt the developments proposed by Charles Quesenberry. In this case, the statistic of the sample at time i is transformed through the estimations of the process parameters using the information obtained (data) until the instant (i-1). The univariate study of process capability is performed through the capability indices QL and QU. Thus, in this paper, two situations of statistical control are addressed, one in which a univariate study is done, based on Q charts, and another in which the multivariate study is made, based on the MQ charts. Results: This study comprised the implementation of the SPC) of a wine brand that has low production volumes, in the process of bottling wine, which is considered a critical step since some care is needed, such as avoiding the occurrence of microbiological contaminations or oxidation of the wine. Conclusions: Whenever it is not possible to apply traditional control charts the use of the control Q charts (univariate analysis) and the control MQ charts (multivariate analysis) are the most appropriate choice not only for the control of one or more products but also for several sets of quality characteristics.

Retrospective analysis for phase I statistical process control and process capability study using revised sample entropy

This study explored a new nonparametric analytical method for identifying heterogeneous segments in time-series data for data-abundant processes. A sample entropy (SampEn) algorithm often used in signal processing and information theory can also be used in a time series or a signal stream, but the original SampEn is only capable of quantifying process variation changes. The proposed algorithm, the adjusted sample entropy (AdSEn), is capable of identifying process mean shifts, variance changes, or mixture of both. A simulation study showed that the proposed method is capable of identifying heterogeneous segments in a time series. Once segments of change points are identified, any existing change-point algorithms can be used to precisely identify exact locations of potential change points. The proposed method is especially applicable for long time series with many change points. Properties of the proposed AdSEn are provided to demonstrate the algorithm’s multi-scale capability. A table of critical values is also provided to help users accurately interpret entropy results.

Tool life and surface integrity aspects when drilling nickel alloy

Nickel based super alloys manufactured through powder metallurgy (PM) route are required to increase the operational efficiency of gas turbine engines. They are material of choice for high pressure components due to their superior high temperature strength, excellent corrosion, oxidation and creep resistance. This unique combination of mechanical and thermal properties makes them even more difficult-to-machine. In this paper, the hole making process using coated carbide inserts by drilling and plunge milling for a nickel-based powder metallurgy super alloy has been investigated. Tool life and process capability studies were conducted using optimized process parameters using high pressure coolants. The experimental trials were directed towards an assessment of the tendency for surface malformations and detrimental residual stress profiles. Residual stresses in both the radial and circumferential directions have been evaluated as a function of depth from the machined surface using the target strain gauge / center hole drilling method. Circumferential stresses near workpiece surface and at depth of 512 µm in the starting material was primarily circumferential compression which was measured to be average of –404 MPa. However, the radial stresses near workpiece surface was tensile and transformed to be compressive in nature at depth of 512 µm in the starting material (average: -87 Mpa). The magnitude and the depth below the machined surface in both radial and circumferential directions were primarily tensile in nature which increased with hole number due to a rise of temperature at the tool–workpiece interface with increasing tool wear. These profiles are of critical importance for the selection of cutting strategies to ensure avoidance/minimization of tensile residual stresses that can be detrimental to the fatigue performance of the components. These results clearly show a tendency for the circumferential stresses to be more tensile than the radial stresses. Overall the results indicate that the effect of drilling and milling parameters is most marked in terms of surface quality in the circumferential direction. Material removal rates and tool flank wear must be maintained within the control limits to maintain hole integrity.

Utilização da técnica seis sigma para redução de sobrepeso de matéria prima nos produtos em conserva

Devido a um ambiente cada vez mais competitivo, as empresas estão buscando novas formas de aperfeiçoamento de seus processos e produtos. Este artigo tem objetivo de apresentar como a utilização da técnica Seis Sigma pode contribuir para redução de desperdício de matéria prima no processo de envaze de uma empresa de conservas, onde para evitar infrações às normas, as empresas costumam acrescentar legumes além do necessário devido a variabilidade do processo. Por meio da utilização da técnica Seis Sigma, cartas de controle e estudo de capacidade de processo foi possível estabelecer um diagnóstico das perdas de matéria prima no processo de envaze, definir índice atual de capacidade e de gasto com sobrepeso nos produtos. Para análise dos pontos a serem melhorados foi utilizado o diagrama de causa e efeito e por seguinte a implantação das ações corretivas para manter o processo sob controle e atingir uma melhora significativa da capacidade de processo. Os resultados apresentaram uma redução com desperdício de sobrepeso de matéria prima para empresa de aproximadamente 43 ton/ano, uma economia de R$ 107.460,00/ano.