Basic knowledge of quality control 2009-11-07 1. The evolution of quality control\x0d\1. Operator control stage: the quality of the product is controlled by the operator alone.\x0d\2. Team leader control stage: The team leader is responsible for the product quality control of the entire team.\x0d\3. Inspector control stage: Set up full-time quality inspectors to be responsible for product quality control.\x0d\4. Statistical control stage: Use statistical methods Controlling product quality is a major breakthrough in quality control technology and creates a new situation in quality control.\x0d\5. Total quality management (TQC): quality control of the entire process.\x0d\6. Total quality management (CWQC) : Full quality control, full participation. \x0d\ 2. Quality inspection method \x0d\ 1. Full inspection: An inspection method that inspects all products or materials submitted for inspection without omission. Applicable to the following situations: \ x0d\①The batch size is small, the inspection is simple and the cost is low; \x0d\②The product must be qualified;\x0d\③If there is a small amount of failure in the product, it may cause the product to have a fatal impact.\x0d\2. Sampling inspection: The activity of selecting some individuals from all individuals of a batch of products for inspection, and judging whether the entire batch of products is qualified based on the inspection results of the samples, is a typical statistical inference work. \x0d\① Applicable to the following situations : a. Destructive testing is required for product performance inspection;\x0d\b. The batch size is too large to be fully inspected;\x0d\c. Long inspection time and high inspection costs are required;\x0d\d. A certain degree of defective products is allowed. \x0d\② Relevant terms in sampling inspection: \x0d\a. Inspection batch: The same products are gathered together as sampling inspection objects; generally speaking, a production batch is an inspection batch. A production batch can be divided into several inspection batches, but one inspection batch cannot contain multiple production batches, and inspection batches cannot be combined at will.\x0d\b. Batch size: the number of units contained in the batch; \x0d\c. Sampling number: The number of products extracted from the batch; \x0d\d. The number of unqualified determinations (Re): the abbreviation of Refuse is rejection; R*e. The number of qualified determinations (Ac): the abbreviation of Accept is acceptance; \x0d\f. Acceptable Quality Level (AQL): The abbreviation of Acceptable Quality Level. In layman’s terms, it is the acceptable rate of defective products. \x0d\3. Determination of the sampling plan: MIL-STD-105E. The specific application steps are as follows: \x0d\ ① Determine the quality judgment standard of the product: \x0d\ ② Select the inspection level: general inspection levels are divided into I, II, and III; special inspection levels are divided into S-1, S-2, S-3, and S-4. Under normal circumstances, Adopt the general level II. \x0d\③Select the qualified quality level (AQL): AQL is the main basis for selecting the sampling plan, which should be agreed upon by the producer and the user.\x0d\④Determine the sample size code, that is Sampling number.\x0d\⑤Select the type of sampling plan: such as a normal sampling plan, a strict sampling plan, or a multiple sampling plan.\x0d\⑥Check the table to determine the number of qualified judgments (AC) and the number of unqualified judgments (Re\ x0d\3. Inspection operation control\x0d\1. Incoming material (goods) inspection (IQC): It is the primary control point for the factory to prevent unqualified materials from entering the production process. (Incoming Quality Control)\x0d\①Incoming material inspection items and Methods: \x0d\a Appearance: Generally verified by visual inspection, hand feel, and comparison samples; \x0d\b Dimensions: Generally verified by measuring tools such as calipers and micrometers; \x0d\c Characteristics: such as physical, chemical, and mechanical Characteristics are generally verified by testing instruments and specific methods. \x0d\ ② Incoming material inspection method: a full inspection, b random inspection ③ processing of inspection results: a acceptance; b rejection (i.e. return); c concession acceptance; d full inspection Inspection (picking out unqualified products for return) \x0d\e Re-inspection after rework ④ Standards based on: "Technical Standards for Raw Materials and Purchased Parts"

, "Incoming Inspection and Test Control Procedures", "Physical and Chemical Inspection Procedures", etc.\x0d\2. Production Process Inspection (IPQC): Generally refers to the quality of production activities at each stage after the materials are put into the warehouse and before the finished products are put into the warehouse. Control, that is, Inprocess Quality Control. Compared with the quality inspection at this stage, it is called FQC (Final Quality Control) \x0d\①The main methods of process inspection are:\x0d\a. First article self-inspection, mutual inspection, and special inspection Combined; b. Combining process control with sampling and inspection;\x0d\c. Centralized inspection of multiple processes; d. Inspection step by step; \x0d\e. Inspection after product completion; f. Sampling and full inspection Combined; \x0d\② In-process quality control (IPQC): It is a patrol inspection of the production process. \x0d\a. First article inspection; b. Material verification; c. Patrol inspection: ensure appropriate inspection time and frequency, Strictly inspect according to inspection standards or work instructions. Including inspection of product quality, process procedures, machine operating parameters, material placement, marking, environment, etc.; d Inspection records should be filled in truthfully. \x0d\③ Process product quality inspection ( FQC): It is a quality verification after the product is completed to determine whether the batch of products can flow into the next process. It is a fixed-point inspection or acceptance inspection. a. Inspection items: appearance, size, physical and chemical properties, etc.; b. Inspection method: sampling is generally used Inspection; c. Unqualified handling; d. Recording;\x0d\④Standards based on: "Work Instructions", "Process Inspection Standards", "Process Inspection and Test Procedures", etc.\x0d\3. Final inspection control : That is, finished product shipping inspection. (Outgoing Q.C) \x0d\4. Feedback and handling of quality abnormalities: \x0d\ ① If you can judge by yourself, directly notify the operator or workshop to handle it immediately; \x0d\ ② If you cannot judge by yourself, Then submit the defective sample to the supervisor for confirmation, and then notify the correction or processing; \x0d\③ Abnormal situations should be recorded truthfully; \x0d\④ Confirm the corrective or improvement measures, and track the results; \x0d\⑤ Semi-finished products, semi-finished products, etc. The inspection of finished products should be clearly marked with status, and relevant departments should be supervised for isolation and storage. \x0d\5. Quality records: Provide objective evidence for completed quality work activities and results.\x0d\ Must be: accurate, Timely, legible, complete, and stamped with an inspection seal or signature. \x0d\ It is also necessary to: organize and file in a timely manner, and store it in a suitable environment. \x0d\ 4. Introduction to statistical technology (see "Statistical Technology Application Guide" 》) \x0d\1. Hierarchical method: It is the use of statistical methods as the most basic tool of management. The purpose is to summarize and make statistics of messy and disordered data.\x0d\2. Questionnaire: in quality management activities Questionnaires are commonly used to collect data. Such as defective project questionnaires, non-conformity reason questionnaires, etc.\x0d\3. Pareto chart: An effective method to find out the main problems affecting product quality. It is based on the "critical few, minor It is made by the principle of "the most important" (i.e. the 28 principle). The arrangement chart has two ordinates, an abscissa, several rectangles and a curve. The ordinate on the left represents frequency, and the ordinate on the right represents frequency ( Expressed as a percentage) The abscissa represents the various factors that affect quality, arranged from left to right according to the degree of influence.\x0d\4. Cause-and-effect analysis chart: It is a chart used to analyze the causes of quality problems, generally from people , machine, material, method, environment, measurement and other 6 aspects of analysis. 5. Histogram omitted)\x0d\6. Control chart omitted)\x0d\ 5. Commonly used working methods and analysis methods for quality management\x0d\1. PDCA management cycle\x0d\PDCA management cycle is the basic working method (program) of quality management. The whole process of quality management is divided into P (plan), \x0d\D (Do implementation), C (Check inspection), A (Action summary processing) four stages. \x0d\The first is the P (planning) stage, which is divided into four steps\x0d\(1

) Analyze the current situation and find out the main quality problems\x0d\(2) Analyze various influencing factors that cause quality problems\x0d\(3) Find out the main factors affecting quality\x0d\(4) Target the main factors affecting quality Factors formulate measures, propose improvement plans, and set goals. The second stage is D (implementation): implement the planned goals according to the formulation. The third stage is C (inspection): check the actual implementation results to see whether the expected results of the plan are achieved.\x0d\ The fourth is the A (summary processing) stage, which is divided into two steps: \x0d\⑴ Summarize mature experience and incorporate it into standard systems and regulations to consolidate achievements and prevent mistakes; ⑵ Incorporate the unresolved problems of this round of PDCA cycle into the next Solve it in the PDCA cycle. \x0d\2, 5W2H method: Why: Why----Why do you do this? \x0d\What: What ---- do? What to prepare? \x0d\Where：Where----Where is the best place to do it? \x0d\When: When----when does it start? When will it be completed? \x0d\Who: Who----Who will do it? \x0d\How: How----How to do it? \x0d\How much: How much does it cost? \x0d\3. Brainstorming method Brainstorming method, also known as brain stimulation method, can effectively identify possible solutions to problems and potential quality improvement opportunities. It is generally used in analysis and discussion meetings, especially QC group meetings and quality analysis meetings. Etc.\x0d\ The following issues should be paid attention to when using brainstorming: \x0d\1. Criticism is prohibited: criticizing and opposing other people's opinions is not allowed; \x0d\2. Free and unrestrained: imagine as much as you want and speak freely , truly speak everything you know; \x0d\3. Welcome to raise more opinions: the more opinions you put forward, the better; \x0d\4. Combining improvements: combine with other people’s opinions to continuously inspire and improve yourself Thoughts; \x0d\5. Record truthfully: Anyone’s speeches, including opposing opinions, must be truthfully recorded. The first is to obtain comprehensive information, and the second is to give people a sense of importance and psychologically inspire others to express more opinions. \x0d\ 6. How to carry out QC group activities\x0d\1 Formation of QC group ① Definition of QC group: QC group (abbreviation of Quality Control) is the quality management group. It refers to the voluntary organization of employees at the production site or work station , a group that uses the basic theories and methods of quality management to carry out mass quality management activities to solve problems in the workplace to achieve the purpose of quality improvement. The QC group is an effective organizational form of quality management.\x0d\ ②The role of QC group activities: A. Conducive to developing intellectual resources and improving people's quality; B. Preventing quality problems and making continuous improvements; C. Conducive to improving interpersonal relationships, strengthening team awareness and quality awareness, thereby improving the team's Work efficiency.\x0d\③Principles for forming a QC team: A. Voluntary participation and voluntary combination are the basic principles for forming a QC team; B. Top-down, top-down combination is the basis for forming a QC team; C. Leaders and technical personnel Combining with workers is a good way to form a QC team; D. Seek truth from facts and combine it with reality.?\x0d\④Number of QC team members: The QC team should not have too many people, generally 3-10 people are appropriate. \x0d\⑤QC Team Group Responsibilities of the leader: A. Organize team members to formulate activity plans, divide work, and take the lead in carrying out activities according to the plan; B. Responsible for liaison and coordination, promptly report the group activities to superior authorities, and strive for support and help; C. Do a good job Quality education, organize team members to learn relevant business knowledge, and continuously improve the quality awareness and professional level of team members; D. Unite team members, fully promote democracy, create a relaxed environment for team members, and enhance the cohesion of the team; E. Organize regular meetings Group meetings, research and solve various problems, keep records of group activities, and be responsible for organizing and publishing results. \x0d\2 QC group activity steps ① Selection of activity topics: Topic selection scope: topics to improve product quality; reduce losses

topics of consumption; topics of optimizing the environment; topics of improving management; topics of improving the quality of employees.\x0d\Requirements for topic selection: Adhere to seek truth from facts, first easy and then difficult; advocate a combination of large and small topics, focusing on small topics; The topic should be specific and clear; the topic should be selected with a short cycle and quick results. A topic should generally be completed in 3-6 months, no more than one year at most.\x0d\② Investigation of the current situation: through questionnaires or other forms , use data to speak the way to clarify the problems to be solved, and determine the main direction of solving the problems, providing a basis for setting goals. \x0d\③ Setting goals: The goals set should be achievable through everyone's efforts.\x0d \④ Cause analysis: Use appropriate tools to analyze the main issues of the current situation investigation according to the six major factors of human, machine, material, method, environment, and measurement, using appropriate tools such as questionnaires, cause-and-effect diagrams, and Pareto charts. Find out the specific causes of quality problems and determine the main reasons. Note: During cause analysis, a group meeting should be held, brainstorming method should be used, the team's wisdom should be used, and the causes should be found out one by one as much as possible.\x0d\⑤ Formulated Countermeasures: Specific items are generally listed in the form of a countermeasure list. When formulating the countermeasure list, the 5W1H method should be used and ask a few more whys. Therefore, the countermeasure list should include: Why should the countermeasure be formulated (Why), and what goal should be achieved (What) , where to execute (WHere), who will execute (Who), when to complete (When) and how to execute (How), etc. \x0d\⑥ Implement countermeasures: execute according to the formulated countermeasures or plans. \x0d\⑦ Effect inspection Verification.\x0d\⑧Consolidation measures: Make a summary based on the inspection results and incorporate them into relevant standards, work instructions, systems and regulations to consolidate the achievements achieved and prevent similar problems from happening again