With the increasingly fierce market competition and the approach of joining WTO, many enterprises have realized that product quality is the key to their survival and competitive advantage, thus putting forward higher requirements for quality management. This requires the use of advanced and effective quality management technology for quality management. SPC(Statistical Process Control, Chinese name "Statistical Process Control"), as an internationally accepted quality management technology, is being paid attention to and adopted by more and more enterprises, and it is regarded as an important tool for enterprises to reduce rejection rate, improve product quality, increase enterprise efficiency and fully implement ISO9000 and QS9000 quality management systems, and has achieved good results. However, due to the short application time of SPC in domestic enterprises, the quality managers of many enterprises need to further understand and master how to apply SPC to quality management. This paper aims to discuss how to apply SPC to enterprise quality management.
1. What is SPC?
SPC (Static Process Control) Statistical process control is an effective method to improve the quality management level of enterprises. Based on the principle of mathematical statistics, through the collection and analysis of test data, the effect of "prevention in advance" is achieved, so as to effectively control the production process and continuously improve the quality.
Second, the development of program-controlled switches
SPC was first put forward by W.A.Shewhart, a quality management expert at Bell Laboratories, in the 1920s. Later, it was widely adopted by European and American enterprises. After World War II, Japan, whose economy was severely damaged, fully implemented SPC in enterprises. After 30 years of hard work, Japan has leapt to the leading position in the world in terms of quality and efficiency. Roger. W.Berger, a famous American quality management expert, thinks SPC is one of the cornerstones of Japanese industrial success. After 1980s, with the development of computer technology, professional SPC software began to appear. With the help of SPC software, SPC has been applied unprecedentedly. At present, SPC has been widely used in manufacturing enterprises in Europe and America, including Hongkong and Taiwan Province.
Because of the importance of SPC in quality management, the International Organization for Standardization (ISO) also regards it as an element of ISO9000 quality system certification. The QS9000 certification of the three major American automobile industry groups also lists SPC as an important content;
At present, there is a big gap between China and foreign developed countries, both in theory popularization and implementation of SPC. At present, except for foreign capital and joint ventures in China, there are not many domestic enterprises that implement SPC application, and the understanding and application of statistical methods are still superficial. Experts pointed out that this situation is extremely disproportionate to the level of economic development in China and will be greatly changed.
Third, the core tools of SPC
SPC mainly achieves the purpose of quality analysis, quality control and quality improvement through various control charts. The core tool of SPC is control chart, which includes measurement control chart (Xbar-R chart, Xbar-S chart, etc. ) and counting control chart (p chart, c chart, u chart, etc. ). Used to directly control the production process, carry out quality diagnosis and quality improvement, and play a preventive role in the production process. As the saying goes, inspection is a waste, and only prevention can create value. In addition to the control chart, SPC also includes histogram, Pareto chart, scatter chart and hierarchical chart, which constitute the seven technologies of QC.
Fourth, the steps for enterprises to implement SPC
Understanding and mastering SPC theory is the premise of implementing SPC. Enterprises in different industries have different methods and steps to implement SPC due to different production processes, but basically there are the following steps:
1, the management's understanding and attention
Zhu Lan, a famous quality management expert, has a famous 8020 principle on quality issues. He believes that enterprise leaders can solve 80% quality problems, while grass-roots workers can only solve 20% quality problems. In the statistical process control (SPC) reference manual of QS9000 standard, the principle of 85 15 is defined, which further emphasizes the importance of leadership in solving quality problems. Many business leaders believe that poor product quality is caused by poor quality or irresponsibility of relevant staff. In fact, if advanced quality management technology and tools are adopted, the quality can be obviously improved under the same original conditions, and SPC is such an effective tool. Therefore, in order to implement SPC, senior managers of enterprises must first recognize the important role of SPC and lead all employees of enterprises to devote themselves to the application of SPC.
2. Make SPC implementation plan.
It is very important to make a complete plan for the smooth implementation of SPC. In the plan, it is necessary to clarify the contents of each stage of SPC implementation and the relevant responsible persons, and set clear objectives and time for SPC implementation.
3. Conduct SPC training.
Training relevant personnel in advance is the key to implement SPC. Training can be carried out by sending relevant personnel to external training units. If possible, please invite training institutions to the factory for training. One of the advantages of training in the factory is that it can increase the number of trainees, on the other hand, it can make the training content more in line with the actual situation of the factory and enhance the training effect. In addition, training in the factory can also create a good atmosphere for the implementation of SPC. At present, there are not many institutions that can carry out SPC training in China. Guangzhou Zhao Jin Technology Co., Ltd. has been engaged in the development and training of SPC software for a long time, and is a leader in the industry. SPC training for many large and medium-sized enterprises at home and abroad has achieved good results.
4, determine the key variables
The first is to find out all controllable quality indicators and related parameters, including control points, control contents, data types and applicable control charts of each process.
Secondly, from the most common problems in the production process as a breakthrough, this process is analyzed and controlled to make its production process reach a stable state.
Thirdly, this method is applied to the whole production process after the process as a breakthrough reaches a stable state, so that the production process of the whole enterprise reaches a stable state.
Step 5 collect information
Collecting data here mainly refers to using reasonable sampling methods to ensure the integrity and accuracy of data required by SPC. Including sampling time interval, sample size, random sampling arrangement, sampling distribution, etc.
6. Statistical analysis
At present, enterprises can implement statistical process control by adopting version 3.0 of statistical process control software of Guangzhou Zhao Jin Technology Co., Ltd.. The software is developed according to the latest version of ISO9000/QS9000 standard, and many powerful functions are added on the basis of the original version 2.0. It is the representative of similar software, and has a very powerful statistical analysis function, which has been adopted by many large and medium-sized enterprises at home and abroad. The software has the following characteristics: first, it is simple to operate, easy to learn and use; Second, it can automatically collect data and monitor the production process in real time; Third, it has a unique early warning function, which can find problems before quality accidents appear and prevent them before they happen; Fourth, it has strong data and chart processing ability, and can provide 13 statistical charts including Xbar-S chart and 20 statistical data including CPK; Fifth, its unique decision support function can help managers automatically find out the causes of problems and the measures to be taken, and easily achieve the goal of continuous quality improvement. TodaySPC3.0 software is a rare and excellent quality management software, which makes the implementation of SPC simple and easy.
7. Take measures to improve quality
Quality managers can take measures to continuously improve quality according to the statistical analysis results of SPC software and the actual situation of enterprises.
8. Announce the implementation results.
In the process of implementing SPC, enterprises should publish the results of using SPC in time to enhance the confidence and determination of employees and accelerate the progress and depth of SPC implementation.
Verb (abbreviation of verb) SPC implementation effect example
A food company whose main product is candy. Before SPC was adopted, in order to prevent complaints and claims caused by not reaching the standard weight, the weight of each candy was set to be 0. 1-0.2g higher than the standard weight, and the waste of raw materials in one year was as high as 6.5438+0 million yuan. After quality management with TodaySPC software, the weight of each candy can be kept consistent with the standard weight by controlling the stability of the process, so the cost of each candy can be reduced by 0.002 yuan. The company produces 40 million pieces per month, saving 80,000 yuan per month and 960,000 yuan a year. The effect is very obvious.
Spc Statistics —— Eight Steps of Implementing SPC Control Chart
1, identify key processes
The formation of a product quality requires many processes (working procedures), some of which play a vital role in product quality. Such a process is called key process, and SPC control chart should be used for key process first, not all processes. Therefore, the first step in implementing SPC is to identify key processes.
Then, the key process is analyzed and studied, and the structure of the process (input, output, resources, activities, etc.) is analyzed. ) is recognized.
2, determine the process key variables (characteristics)
Analyze key processes (causal diagram, Pareto diagram, etc.). ) and find out the variables (characteristics) that have the greatest influence on product quality.
3. Make process control plans and specifications.
This step is often the most difficult and time-consuming, and some experimental methods can be adopted with reference to relevant standards.
4. Collection and arrangement of process data
5. Preliminary analysis of process controlled state
Use the control chart to analyze whether the process is controlled and stable, and take measures if the special reasons for uncontrolled or worse are found.
Note: At this time, the distribution center (x), mean deviation σ and control chart boundary of the process may be unknown.
6. Process capability analysis
Only when the process is controlled and stable, it is necessary to analyze the process capability, and when it is found that the process capability is insufficient, measures should be taken.
7. Control chart monitoring
Only when the process is controlled and stable, and the process capacity is sufficient, can the control chart for monitoring be adopted and enter the SPC implementation stage.
8. Monitoring, diagnosis and improvement
In the process of monitoring, when abnormal conditions are found, the reasons should be analyzed in time and measures should be taken to restore the process to normal. For the controlled and stable process, continuous improvement should be made to reduce the common causes of deterioration, improve the quality and reduce the cost.