Discussion on the most popular international advan

2022-09-21
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Discussion on international advanced quality management technology and methods

I. CUSUM (cumulative sum) control chart and EWMA (exponential weighted moving average) control chart

with the widespread use of conventional control chart in SPC control theory, its shortcomings gradually appear, one of which is insensitive to small deviation in the process. CUSUM and EWMA can solve similar problems

1. The design idea of CUSUM control chart is to accumulate data information. CUSUM control chart can be used for Metrological Data (normal distribution), number of unqualified products (Poisson distribution variable), and unqualified product rate (binomial distribution variable). The theoretical basis of CUSUM control chart is the sequential probability ratio test in the principle of sequential analysis, which is a basic sequential test method. The control chart accumulates the small deviation of the process through the accumulation of information, so as to achieve the effect of amplification and improve the sensitivity of detecting the small deviation of the process

2. The control statistics in the EWMA control chart also use historical data, and the control chart can take different weights for the data in different stages. The closer the data is, the greater the weight is. The farther it is, the smaller the weight is. The essence of EWMA control chart design is to find the optimal parameters( λ, K) The principle of the combined process is: for a given steady-state ARL (0), make the process have the minimum runaway ARL when the offset of the set offset occurs

II. Robust design technology

the robust design method of product/process and the robust technology development method in the technology development stage are collectively referred to as robust design technology. It is the most effective way to develop high-quality and low-cost products. In actual production, the existence of noise factors (small changes in raw materials, differences in the level of operators, smile fluctuations of machinery and equipment, etc.), and the resulting fluctuations are inevitable? quot; Reduce fluctuations endlessly, make products, technological processes and technical functions insensitive to various noise factors, and continue to move towards the goal of zero fluctuations. (i.e. wave theory, the theoretical pillar of Quality Engineering). If the method of source control is adopted, the robust technical design is used to find a group of horizontal combinations of controllable factors, so as to minimize the fluctuation of the output quality characteristics of product/process performance or technical functions around the design target value

the robust performance of basic functions depends on two points: first, the fluctuation of output quality characteristics is small; Second, the quality characteristics should be as close to the design target value as possible. S/n can accurately reflect these two goals

implementation process of robust technology development:

1. Carry out initial design and confirm ideal functions

2. Identify controllable factors and noise factors

3. Implement one-step optimization, that is, optimize the robustness of the system

4. Implement two-step optimization to determine adjustable factors that have a significant impact on sensitivity

3 Quality Function Deployment (QFD) (also known as house of quality)

Quality Function Deployment is a powerful comprehensive planning technology, especially suitable for large products (such as aircraft, automobiles and large equipment). It is an overall concept, providing a way to transform customer needs into appropriate technical requirements corresponding to each stage of product development and production (i.e., market strategy, planning, product design and engineering design, prototype production, production process development, production and sales). It is a systematic method that aims to implement the whole process and all-round quality assurance of product applicability in the development and design stage. Starting from the information required by the market, it transforms it into design language, and then expands vertically through components and parts to processes; Carry out reliability deployment of quality deployment, technology deployment and cost deployment horizontally. Formally, it is characterized by a large number of system expansion tables and matrix diagrams, and try to reveal the possible problems in production in advance, so as to achieve the purpose of multiple design, multiple improvement and multiple assurance

the purpose of quality function deployment: from the perspective of total quality management, quality elements include physical and chemical characteristics and appearance elements, mechanical elements, human elements, time elements, economic elements, production elements, market and environmental elements. These elements are combined into an organic system, and the quality functions of each step in the whole process of product from design and development to final scrap are clarified, so that each quality function can be effectively completed

Quality deployment

basic composition of Quality Function Deployment (as shown in the figure below) technical deployment

comprehensive quality deployment reliability deployment quality function deployment

quality function deployment cost deployment

narrow quality deployment quality function deployment

the most commonly used quality function deployment documents are:

1, customer requirements planning matrix

2, design matrix

3, final product characteristics deployment matrix

4 Production/procurement matrix

5, process planning and quality control table

6, work instructions

IV. Concurrent Engineering (CE) has become the main topic faced by Synchronous Engineering

modern enterprises is how to do well in innovation, but innovation 2.3 LFT materials face two risks: market uncertainty and technical uncertainty. The change of competitive situation caused by the change of customer needs and technological progress in the market requires the shortening of product life cycle and the acceleration of renewal; Technically, due to the complexity of product structure and the adoption of new principles, the development cycle has been extended. Concurrent engineering provides solutions and methods for enterprises to launch products needed by customers and society in the shortest possible development cycle

definition of concurrent engineering: it is a systematic method to implement concurrent and integrated design of products and manufacturing and auxiliary processes, and urge developers to always consider all factors (including quality, cost, schedule and use requirements) in the whole life cycle of products from concept formation to post-use disposal

the key to the implementation of concurrent engineering: how to promote the communication between functions is the key to the implementation of concurrent engineering, and organization and structure are one of the main factors affecting the functional communication. According to the characteristics of project management, it becomes very important to establish a multi-functional cross departmental scientific group and a matrix organization

Quality Engineering Technology (such as QFD, Taguchi method, FMEA, etc.) and computer technology (such as CAX Series) are widely used in concurrent engineering

successful implementation method of concurrent engineering:

1. Each function puts forward all feasible schemes within its functional scope according to its own conditions and requirements, and then communicates to form their own schemes that are feasible for each function, thus forming the overall scheme

2. With the continuous progress of the process, the information obtained from other follow-up functions such as development, testing, customers, etc. will gradually reduce the number of schemes. Finally, their respective plans can be determined and implemented

3. Strictly follow the final plan and make continuous improvement as needed

v. level comparison or benchmark comparison (benchmarking)

this method was founded in Xerox company. Its basic idea is to compare and analyze the activities and behaviors of the same and similar processes in different departments or companies within the company, find out the gap and its potential reasons, in order to achieve or exceed the current best practice of the same kind

The idea of level comparison can be thought of as "know yourself and know the enemy"

benchmarking in Sun Tzu's art of war is a systematic and continuous measurement process. This process is to continuously measure and compare leading enterprises and specific leading processes around the world, so as to obtain effective information to help the company take improvement actions

level comparison can be divided into: internal level, competitive level, functional level, general level ratio, that is, Aku ratio

content of level comparison: quality, productivity and time (productivity and time reflect cost issues)

VI. failure mode and effect analysis (FMEA)

FMEA is applied to product design and process development. It is an important analysis tool, which helps to prevent costly failures. It provides the design team with such a combination of high-end characteristics, making torl highly elastic, impact resistant, corrosion-resistant, easy to process, light-weight and other characteristics. On Pai has become an ideal material to successfully replace metals in many precision, reusable, high temperature and load friction and wear occasions. It is an effective way to anticipate and eliminate these failures. Failure mode and consequence analysis is suitable for serialized activities. These activities are aimed at:

1. Measures to recognize and evaluate the potential failure of a product/process and its consequence opportunities

2. Identify measures that can eliminate or reduce the chance of these potential failures

3. Documenting the process is essential to correctly determine how to meet customer needs in the design process

FMEA includes (Design) DFMEA and (process) PFMEA

Design FMEA should start from listing what the design wants to do and what it doesn't want to do, that is, the design intent. Customer requirements determined through QFD, vehicle requirements documents, known product requirements and/or manufacturing/assembly requirements shall be integrated. The clearer the definition of expected characteristics, the easier it is to identify potential failure modes and take corrective measures

Process FMEA should start from the flow chart/risk assessment of the whole process. The flow chart shall determine the product/process characteristic parameters related to each process. If possible, some product impact consequences should also be determined according to the corresponding Design FMEA

VII. Manufacturing design (DFM) and assembly design (DFA)

synchronous engineering process designed to optimize the relationship between design function, manufacturability and easy assembly. Because people often ignore the consideration of product assembly, product manufacturing or the design of the components that make up the product. So it is particularly important

the most important thing is to improve the understanding of the relationship between process variables and product results. On this basis, the designer then determines the product characteristics (and their limitations) that must be controlled in the manufacturing process in the technical specifications, so as to achieve its use requirements. This will help:

1. Improve the production of products

2. Improve the ability of the existing manufacturing process

3. Provide information that can be used for the training of supervisors and workers

it is usually applied by a horizontal functional group. It can prevent the design engineer from designing manufacturing or assembly steps that exceed or exceed the assembly technology or production capacity. The team usually involves experts and customers in other fields (reliability, maintainability and Manufacturability) to solve the designer's lack of knowledge or failure to understand an important design characteristic

VIII. Experimental design (DOE), typical as Taguchi method

an experimental technology used to control process input in order to better understand the impact on process output. A designed test is a test or test sequence, in which the variables that potentially affect the process are systematically changed according to the described design matrix. The reactions concerned are evaluated in the following cases: 1) among the variables of the test, determine the variables that have a significant impact; 2) Quantify the impact of the whole range represented by the variable level; 3) Get a better understanding of the nature of the causes that work in the process; 4) Compare impacts and interactions. The representative methods of experimental design include traditional method and Taguchi method

Taguchi method: its purpose is to ensure quality through design. It achieves its purpose by determining and controlling key variables (or noise) that cause deviations in process/product quality. Its whole concept can

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