Quality management has a complete system, which is gradually produced and improved with the development of production and science and technology. Its management content includes all activities that determine the quality policy, objectives and responsibilities, and achieve them through quality planning, control, assurance and improvement in the quality system. We often talk about quality management, but we have rarely introduced it from the perspective of the party, and this article will focus on the means of quality management, that is, tools and methods.
01 Five tools
1) Statistical Process Control (SPC).
The statistical analysis technology is used to monitor the production process in a timely manner, and scientifically distinguish the random fluctuations and abnormal fluctuations of product quality in the production process, so as to provide early warning of the abnormal trend of the production process, so that the production management personnel can take timely measures to eliminate the abnormality and restore the stability of the process, so as to achieve the purpose of improving and controlling the quality.
2) Measure System Analysis (MSA)
The error output of the measurement system is analyzed using mathematical statistics and graphing methods to evaluate the suitability of the measurement system for the parameters to be measured, and to determine the main components of the error of the measurement system. Commonly used methods include quantitative analysis (range method, mean range method, etc.), counting analysis (cross method), and destructive analysis (nesting method).
3) Failure Mode & Effect Analysis (FMEA).
In the planning and design stage of products, processes and services, the subsystems, components, and procedures that make up the products are analyzed one by one, and the potential failure modes are identified, the possible consequences are analyzed, and the risks are assessed, so as to take measures in advance to reduce the serious procedures of the failure modes and reduce the probability of their possible occurrence, so as to effectively improve the quality and reliability and ensure the systematic activities of customer satisfaction.
4) Advanced Product Quality Planning (APQP).
A structured approach to identifying and developing the steps required to ensure that a product satisfies customers. The goal of product quality planning is to facilitate contact with everyone involved to ensure that the required steps are completed on time. Effective product quality planning relies on the commitment of the company's top management to the purpose of striving to achieve customer satisfaction. The benefits of its implementation are directing resources to customer satisfaction, facilitating early identification of needed changes, avoiding late changes, providing quality products in a timely manner and at the lowest cost, etc.
5) Production part approval process (PPAP).
The general requirements for the approval of production parts, including production materials and bulk materials, are specified. The purpose of PPAP is to determine whether the supplier has correctly understood all the requirements of the customer's engineering design records and specifications, and whether its production process has the potential to meet the customer's requirements according to the specified production cycle in the actual production process. It is a practical technique used to verify that the products manufactured by the production tooling and process meet the technical requirements through the product approval and recognition procedures before the first batch of products are shipped.
02 Seven methods
1) Checklist
The checklist is a method of listing the contents or items that need to be checked one by one, and then checking them one by one on a regular or irregular basis, and recording the problem points, sometimes called a checklist or checklist. For example:Check form, diagnosis form, work improvement checklist, satisfaction survey form, assessment form, audit form, 5S activity checklist, engineering anomaly analysis form, etc.
Implementation Steps:Determine who to inspect;Develop a checklist;Check and record according to the checklist itemsThe responsible unit is required to improve the problems in a timely mannerThe inspector confirms the improvement effect within the specified timeSummarize regularly and make continuous improvements.
2) Layered approach
The hierarchical approach is to classify a large number of views, opinions or ideas on a particular topic into groups, and to group and layer a large amount of data or information collected according to their interrelationships. The layer method is generally used in combination with the other seven major techniques such as Plato and histogram, and can also be used alone. For example:Sampling statistics table, bad category statistics table, ranking list, etc.
Implementation Steps:Determine the topic of the study;Make ** and collect data;Group the collected data;Comparative analysis, analysis of this data, finding out its internal causes, and identifying improvement projects.
3) Plato
Plato's use is premised on the hierarchical method, which arranges the items identified by the hierarchical method from largest to smallest, plus a graph of the cumulative values. It can help us to identify the key problems, grasp the important minority and the useful majority, and is suitable for remembering numerical statistics, some people call it ABC chart, and because Plato's order is from large to small, it is also called a permutation chart.
Implementation Steps:Collect data, classify them by layer, and calculate the percentage of each level item in the overall projectSummarize the data that are divided into categories, arrange them from more to less, and calculate the cumulative percentageDraw horizontal and vertical scales;Draw a histogram;Draw a cumulative curve;Record the necessary analysis of PlatoKey points:a Plato has two ordinates, the left ordinate generally represents the quantity or amount, and the right ordinate generally represents the cumulative percentage of the quantity or amount;b Plato's abscissa generally indicates the inspection items, arranged from left to right according to the degree of influence;c When drawing Plato, draw a rectangular square corresponding to the left ordinate according to the frequency of the occurrence of the number or amount of each item, and trace the points corresponding to the right ordinate according to the cumulative frequency of each item, and connect these points into a line in order.
4) Cause and effect diagrams
Causal diagram, also known as characteristic causal diagram, is mainly used to analyze the causal relationship between quality characteristics and possible causes affecting quality characteristics, and to promote the solution of problems by grasping the current situation, analyzing the causes, and finding measures. Also known as a fishbone diagram.
Implementation Steps:
Set up a causal diagram analysis team, 3 or 6 people are preferred, preferably representatives of various departments;Identify the problem points;Draw the main bone, middle bone, and small bone of the trunk line and determine the major causes (generally find out the causes from the six aspects of 5m1e, i.e., man, machine, material, method, measure, and environment).The participants had a heated discussion, analyzed according to the major causes, found the medium or small causes, and drew them into the cause and effect diagramThe causal diagram team should reach a consensus to identify the items that are most likely to be the source of the problem with a red pen or special markWrite down the necessary items.
5) Scatter Chart
The data corresponding to the change of cause and effect is depicted on the x-y coordinate system to grasp whether the two variables are related and how relevant they are, this kind of graph is called a "scatter map", also known as a "correlation map".
Implementation Steps:Identify the two variables to be investigated, collect relevant and up-to-date data, at least 30 groups or more;Find the maximum and minimum values of the two variables, and map the two variables to the x-axis and y-axisThe corresponding two variables are marked with the coordinate system in the form of pointsItems such as the title, maker, and production time are countedInterpret the relevance and degree of relevance of scatter charts.
6) Histogram
The histogram is based on the characteristic value of a product or process, using the principle of normal distribution (also called normal distribution), grouping more than 50 data, and calculating the number of occurrences of each group, and then depicting it on the horizontal axis with a similar histogram.
Implementation Steps:Collect the same type of data;Calculate the range (full range) r=xmax-xmin;Set the number of groups k:k=1+323logn determines the smallest unit of measurement, i.e., when the number of decimal places is n, the smallest unit is 10-n;Calculate the group spacing h, and the group spacing h = range r and the number of groups k;Find the upper and lower limit values of each group, the first group of lower limit values = x min - the minimum unit of measurement 10-n 27, the second group of lower limit values (the upper limit of the first group) = the lower limit of the first group + the group distance h;Calculate the central value of each group, and the central value of the group = (lower limit value of the group + upper limit of the group) 2;Make frequency tables;Draw a histogram by frequency table.
7) Control charts
The control chart method is such a prevention-oriented quality control method, which uses the quality characteristic values collected on site to draw a control chart, and judges the quality status of the product production process by observing the graph. Control charts can provide a lot of useful information and are one of the important methods of quality management.
Implementation Steps:The following steps are generally required to make a control chart: a sample is drawn according to the specified sampling interval and sample size;b Measure the mass characteristic values of the samples and calculate their statistical values;c Trace on the chart;d Determine whether the production process is parallel.
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