Predict and Assure the Matchable Degree in Selective Assembly via PCI-based Tolerance

1999 ◽  
Vol 121 (3) ◽  
pp. 494-500 ◽  
Author(s):  
Yu Zhang ◽  
X. Daniel Fang
Keyword(s):  
Diesel Engine ◽  
Process Model ◽  
Process Capability Indices ◽  
Manufacturing Processes ◽  
Process Performance ◽  
Selective Assembly ◽  
Statistical Process ◽  
Quality Requirements ◽  
Capability Indices

Selective assembly is a method to achieve high precision fit using low precision parts. The current practices in selective assembly lack a physical process model to guide the design and process of mating parts, consequently, selective assembly is often a nightmare for manufacturing people and historically an event to be avoided. Process capability indices (PCIs) are the widely accepted process parameters, functioning as a measure of process performance, such as process centering, process spread, process bias, etc. In this paper, the concept of PCI-based tolerance is proposed as an interface between quality requirements and statistical process control (SPC) parameters. An analytical model involving PCI-based tolerance is developed to predict and assure the matchable degree in selective assembly. A detailed case study of the fit of dry liners and cylinder blocks in a diesel engine is presented. As matchable degree and other process quality requirements can be assured at the stage of design by introducing PCI-based tolerance, the process of selective assembly can be improved significantly as an effective way to achieve precision assembly with economical manufacturing processes.

scholarly journals Performance Evaluation Using Multivariate Non-Normal Process Capability

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 833 ◽  
Author(s):  
Alatefi ◽  
Ahmad ◽  
Alkahtani
Keyword(s):  
Manufacturing Industry ◽  
Process Capability ◽  
Quality Characteristic ◽  
Process Capability Indices ◽  
Manufacturing Processes ◽  
Capability Indices ◽  
Skewness Reduction ◽  
Quality Of Products

Process capability indices (PCIs) have always been used to improve the quality of products and services. Traditional PCIs are based on the assumption that the data obtained from the quality characteristic (QC) under consideration are normally distributed. However, most data on manufacturing processes violate this assumption. Furthermore, the products and services of the manufacturing industry usually have more than one QC; these QCs are functionally correlated and, thus, should be evaluated together to evaluate the overall quality of a product. This study investigates and extends the existing multivariate non-normal PCIs. First, a multivariate non-normal PCI model from the literature is modeled and validated. An algorithm to generate non-normal multivariate data with the desired correlations is also modeled. Then, this model is extended using two different approaches that depend on the well-known Box–Cox and Johnson transformations. The skewness reduction is further improved by applying heuristics algorithms. These two approaches outperform the investigated model from the literature because they can provide more precise results regardless of the skewness type. The comparison is made based on the generated data and a case study from the literature.

scholarly journals Design of evaluation tool used to improve the production process

2019 ◽  
Vol 9 (1) ◽  
pp. 641-649
Author(s):  
Hlatká Martina ◽  
Korec Karel ◽  
Kampf Rudolf
Keyword(s):  
Production Process ◽  
Visual Basic ◽  
Process Capability Indices ◽  
Evaluation Tool ◽  
Statistical Parameters ◽  
Important Data ◽  
Statistical Process ◽  
Capability Indices ◽  
Application Programming ◽  
Visual Basic For Application

AbstractThis paper is devoted to the use of statistical methods to ensure the highest quality processes. Specifically, it deals with creating an application in MS Excel which evaluates standard statistical parameters and if the required process capability indices are complied with, then it is possible to proceed to SPC (statistical process control). The application was created in MS Excel using the Visual Basic for Application programming language. In addition to the required calculations, the application also generates forms with all important data. This application was designed to reduce reject rate and improve the production process in a contracting company.

scholarly journals Concept of process capability indices as a tool for process performance measures and its pharmaceutical application

2020 ◽  
Vol 10 (5) ◽  
pp. 333-344
Author(s):  
Abikesh Prasada Kumar Mahapatra ◽  
Jianwu Song ◽  
Zhibo Shao ◽  
Tang Dong ◽  
Zihong Gong ◽  
...  
Keyword(s):  
Control Charts ◽  
Manufacturing Industry ◽  
Drug Product ◽  
Control Process ◽  
Process Capability ◽  
Process Capability Indices ◽  
Process Performance ◽  
Process Robustness ◽  
Capability Indices ◽  
Pharmaceutical Industries

The main objective of the present study is to present the concept of process capability and to focus its significance in pharmaceutical industries. From a practical view point, the control charts (such as X and R hart) sometimes are not convenient summary statistics when hundreds of characteristics in a plant or supply base are considered. In many situations, capability indices can be used to relate the process parameters. The resulting indices are unit less and provide a common, easily understood language for quantifying the performance of a process. Process capability indices (PCIs) are powerful means of studying the process ability for manufacturing a product that meets specifications. Several capability indices including Cp, Cpu, Cpl and Cpk have been widely used in manufacturing industry to provide common quantitative measures on process potential and performance. The formulas for these indices are easily understood and can be directly implemented. A process capability analysis compares the distribution of output from an in-control process to its specifications limits to determine the consistency with which the specifications can be met. The process capability is also having a significant role in pharmaceutical industry. Process capability indices can be a powerful tool by which to ensure drug product quality and process robustness. Determining process capability provides far more insight into any pharmaceutical process performance than simply computing the percentage of batches that pass or fail each year. Keywords: Process capability; Cp/Cpk; Pp/Ppk; Pharmaceutical quality, process robustness, specification

The Study of Relationship between Multivariate Capability Indices and Sampling Number

2015 ◽  
Vol 713-715 ◽  
pp. 362-368
Author(s):  
Qi Yuan An ◽  
Shao Xi Wang
Keyword(s):  
High Reliability ◽  
Process Capability ◽  
Process Capability Indices ◽  
Statistical Process ◽  
Multivariate Process ◽  
Sample Number ◽  
Capability Indices ◽  
Calculation Results ◽  
Important Means ◽  
The Impact

ultivariate process capability indices (MPCI), as an important means of statistical process control (SPC), can be used to ensure the high reliability of semiconductors manufacturing process. However, the reasonable sampling number is an important factor when considering MPCI values. As general, the large sample number requires much effort and time, or even cannot be achieved. In this paper, we evaluated the impact of different sample size on the calculations of multivariate process capability indices using simulation and analyses. After getting enough data and choosing disparate sample numbers, corresponding multivariate process capability indices can be obtained, which demonstrate the relationship between sampling numbers and calculation results. The conclusions have critical guiding significance for manufacturing semiconductors with high reliability requirement.

scholarly journals Process Capability Indices as Fuzzy Numbers

2016 ◽  
Vol 34 (4) ◽  
Author(s):  
Abbas Parchami ◽  
Mashaallah Mashinchi ◽  
Ali Reza Yavari ◽  
Hamid Reza Maleki
Keyword(s):  
Fuzzy Numbers ◽  
Process Capability ◽  
Process Capability Indices ◽  
Manufacturing Processes ◽  
Membership Functions ◽  
Specification Limits ◽  
Fuzzy Process ◽  
Capability Indices ◽  
Fuzzy Specification Limits ◽  
Fuzzy Process Capability

Most of the traditional methods for assessing the capability of manufacturing processes are dealing with crisp quality. In this paper we discuss the fuzzy quality and introduce fuzzy process capability indices, where instead of precise quality we have two membership functions for specification limits. These indices are necessary when the specification limits are fuzzy and they are helpful for comparing manufacturing processes with fuzzy specification limits. Some interesting relations among the introduced indices are obtained. Numerical examples are given to clarify the method.

Advanced Quality Planning of Manufacturing Products - APQP

2013 ◽  
Vol 371 ◽  
pp. 777-781 ◽  
Author(s):  
Doina Valentina Ciobanu ◽  
Adela Eliza Dumitrascu ◽  
Catalin Tudosoiu ◽  
Stelian Alexandru Borz
Keyword(s):  
Quality Assurance ◽  
Quality Management ◽  
Manufacturing Processes ◽  
Approval Process ◽  
Statistical Process ◽  
Quality Planning ◽  
Process Duration ◽  
Quality Process ◽  
Production Part

Implementation of management by processes in Romania it is a problem if we consider its effects: improving performances of organizations expressed in terms of quality, process duration, cost, etc. Taking into account the sequence of steps corresponding to the specific managerial process and quality management, it is considered that its functions are: planning, organizing, coordinating, controlling, quality assurance and improvement. This paper presents a detailed approach of advanced product quality planning (APQP) of technological products and the case study regarding the analysis of industrial product defects implementing statistical process control (SPC). The Production Part Approval Process (PPAP) purpose continues to be to provide the evidence that the specification requirements are clearly understood by the organization and the manufacturing processes are the designed capability. Implementing the APQP technique permits us to define and establish the steps necessary to ensure that a product satisfies the customers requirements.

The Use of Capability Indices in Process Evaluation of Ceramic Materials

2006 ◽  
Vol 45 ◽  
pp. 578-583
Author(s):  
S. Papargyri ◽  
D.N. Tsipas ◽  
A. Botis ◽  
A. Papargyris
Keyword(s):  
Process Evaluation ◽  
Bending Strength ◽  
Slip Casting ◽  
Ceramic Materials ◽  
Process Capability Indices ◽  
Statistical Control ◽  
Statistical Process ◽  
Three Point Bending ◽  
Acceptable Quality ◽  
Capability Indices

In order to manufacture products of acceptable quality within predetermined specification limits, an evaluation of the manufacturing process through the use of capability indices is necessary. Capability indices are used in order to evaluate a process and to monitor the product characteristics and the results of quality improvement cycles. The three point bending strength of kaolin ceramic specimens produced by two different production processes (slip casting and hydroplastic extrusion) were investigated. It was found that under statistical control and normal distribution of strength values, the process capability indices Cp, Cpk, regardless of any disadvantages and the fact that they have limitations, can be combined with other techniques in the field of statistical process control and become valuable tools in process evaluation of ceramic products.

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