1. The evolution of quality control

1. Operator control stage: The quality of the product is controlled by the operator alone.

2. Team leader control stage: The team leader is responsible for the entire Product quality control of the team.

3. Inspector control stage: Set up full-time quality inspectors to be responsible for product quality control.

4. Statistical control stage: Use statistical methods to control products Quality is a major breakthrough in quality control technology, creating a new situation in quality control.

5. Total quality management (TQC): quality control of the entire process.

6. Total quality control CWQC: All staff quality control, all staff participation.

2. Quality inspection methods

1. Full inspection: All products or materials submitted for inspection will be inspected Inspection method without omissions. Applicable to the following situations:

① The batch size is small, the inspection is simple and the cost is low;

② The product must be qualified;

< p> ③ If there is a small amount of failure in the product, it may cause the product to have fatal effects.

2. Sampling inspection: Select some individuals from all individuals of a batch of products for inspection, and conduct inspection based on the samples It is a typical statistical inference work to use the inspection results to judge whether the entire batch of products is qualified.

① Applicable to the following situations: a. Destructive testing is required for product performance inspection;

b. The batch size is too large to allow full inspection;

c. It requires a longer inspection time and higher inspection costs;

d. A certain level is allowed There are defective products.

② Relevant terms in sampling inspection:

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 an inspection batch cannot contain multiple production batches, nor can inspection batches be combined at will.

b. Batch size: the number of units contained in the batch;

c. Sampling number: the number of products sampled from the batch;

d. Unqualified determination number (Re): the abbreviation of Refuse means rejection;

e. Qualification number (Ac): The abbreviation of Accept is acceptance;

f. Qualification quality level (AQL): The abbreviation of Acceptable Quality Level. In layman’s terms, it is the acceptable rate of non-conforming products. .

3. Determination of the sampling plan: The sampling plan adopted by our factory is designed according to the national standard GB2828 "Batch-by-Batch Inspection Count Sampling Procedure and Sampling Table". The specific application steps are as follows:

① Determine the quality judgment standard of the product:

② Select the inspection level: general inspection level is divided into Ⅰ, Ⅱ, Ⅲ; special inspection level is divided into S-1, S-2, S-3, S -4. Under normal circumstances, the general level II is adopted.

③Select qualified quality level (AQL): AQL is the main basis for selecting the sampling plan and should be agreed upon by the producer and the user.

④ Determine the sample size code, that is, the number of samples.

⑤ Select the type of sampling plan: such as a normal sampling plan, a strict sampling plan, or a multiple sampling plan.

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⑥Check the table to determine the number of qualified judgments (AC) and the number of failed judgments (Re).

3. Inspection operation control

1. Incoming materials (goods) Inspection (IQC): It is the primary control point for the factory to prevent unqualified materials from entering the production process. (Incoming Quality Control)

① Incoming material inspection items and methods:

a Appearance: General Use visual inspection, hand feeling, and comparison samples to verify;

b Dimensions: generally verified with calipers, micrometers and other measuring tools;

c characteristics: such as physical, chemical, and mechanical characteristics , generally verified by testing instruments and specific methods.

②Incoming material inspection method: a full inspection, b sampling inspection

③Processing of inspection results: a. Acceptance; b. Rejection (

(i.e. return); c Concession acceptance; d Full inspection (single out unqualified products for return)

e Re-inspection after rework

④Based standards: "Raw materials, purchased parts technology Standards", "Incoming Inspection and Test Control Procedures", "Physical and Chemical Inspection Procedures", etc.

2. Production process inspection (IPQC): generally refers to the inspection of materials after entering the warehouse and before the finished products are placed in the warehouse. The quality control of production activities at this stage is called Inprocess Quality Control. The quality inspection at this stage is called FQC (Final Quality Control).

①The main methods of process inspection are:

a. Combination of first article self-inspection, mutual inspection and special inspection; b. Combination of process control with random inspection and patrol inspection;

c. Centralized inspection of multiple processes; d. Process by process Inspection during the process;

e. Inspection after product completion; f. Combination of sampling and full inspection;

② In-process quality control (IPQC): It is a patrol inspection of the production process.

a. First article inspection; b. Material verification; c. Inspection: Ensure appropriate inspection time and frequency, and strictly inspect according to inspection standards or work instructions. Including product quality, process procedures, Inspection of machine operating parameters, material placement, logos, environment, etc.; d inspection records should be filled in truthfully.

③ Process product quality inspection (FQC): It is a quality verification after the product is completed to determine the Whether a batch of products can flow into the next process is a fixed point

Inspection or acceptance inspection. a. Inspection items: appearance, size, physical and chemical properties, etc.; b. Inspection method: sampling inspection is generally used; c. Unqualified treatment ; d. Record;

④Standards based on: "Work Instructions", "Process Inspection Standards", "Process Inspection and Test Procedures", etc.

3. Final inspection Control: that is, finished product shipping inspection. (Outgoing Q.C)

4. Feedback and handling of quality abnormalities:

① If you can determine it yourself, directly notify the operator or workshop to handle it immediately;

② If you cannot determine by yourself, submit the bad sample to the supervisor for confirmation, and then notify the correction or handling;

③ Abnormal situations should be recorded truthfully;

④ Confirm corrective or improvement measures and track the results;

⑤ Clear status identification should be made for inspection of semi-finished products and finished products, and relevant departments should be supervised for isolation and storage.

5. Quality records: Provide objective evidence for completed quality work activities and results.

Must be: accurate, timely, clear, complete, and stamped with an inspection seal or signature.

It is also necessary to: organize and archive in a timely manner and store it in a suitable environment.

4. Introduction to statistical technology (see "Statistical Technology Application Guide")

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.

2. Questionnaire: commonly used in quality management activities Questionnaires are used to collect data. Such as defective project questionnaires, non-conformity reason questionnaires, etc.

3. Pareto chart: An effective method to find out the main issues affecting product quality. It is based on the "key It is made by the principle of "minority, secondary majority" (i.e., the 28 principle). The permutation chart has two ordinates, an abscissa, several rectangles and a curve. The ordinate on the left represents frequency, and the ordinate on the right Indicates the frequency (expressed as a percentage). The abscissa indicates the various factors that affect quality, arranged from left to right according to the degree of influence.

4. Cause-and-effect analysis diagram: used to analyze the causes of quality problems. A kind of chart, generally analyzed from six aspects: human, machine, material, method, environment and measurement.

5. Histogram: (omitted)

6. Control chart: (omitted)

5. Commonly used working methods and analysis methods of quality management

1. PDCA management cycle

The PDCA management cycle is the basic working method of quality management (program),

Divide the whole process of quality management into four stages: P (plan),

D (do), C (check), and A (action summary).

The first is the P (planning) stage, which is divided into four steps

(1) Analyze the current situation and find out the main quality problems

(2) Analyze the causes of quality problems Various influencing factors

(3) Identify the main factors affecting quality

(4) Develop measures, propose improvement plans, and set goals for the main factors affecting quality

The second is the D (implementation) stage: execute according to the planned goals

The third is the C (inspection) stage: check the actual implementation results to see whether the expected results of the plan are achieved.

The fourth is the A (summary processing) stage, which is divided into two steps:

⑴ Summarize mature experience and incorporate it into standard systems and regulations to consolidate achievements and prevent mistakes

⑵ Incorporate the unresolved problems in this round of PDCA cycle into the next round of PDCA cycle to solve.

2. 5W2H method: Why: Why----Why should we do this?

What: What to do? What to prepare?

Where: Where to do it best?

When: When - ---When will it start? When will it be completed?

Who: Who----who will do it?

How: How--how to do it?

How much: How much does it cost?

3. Brainstorming method

Brainstorming method, also known as brain stimulation method, can effectively identify possible solutions to problems and potential quality Improvement opportunities. Generally used in analysis discussion meetings, especially QC group meetings, quality analysis meetings, etc.

The following issues should be paid attention to when using the brainstorming method:

1 .Criticism is prohibited: criticizing and opposing the opinions of others is not allowed;

2. Free and unrestrained: imagine freely, speak freely, and truly say everything you know;

3. Welcome to put forward more opinions: the more opinions you put forward, the better;

4. Combine and improve: combine with other people’s opinions to continuously inspire and improve your own ideas;

5. Record truthfully: Anyone’s speeches, including opposing opinions, must be recorded truthfully. 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.

6. How to carry out QC group activities

1. Formation of QC group

①Definition of QC group: QC group (abbreviation of Quality Control) is the quality management group. It refers to the group at the production site Or employees at work positions are voluntarily organized to use 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 integral part of quality management. An effective organizational form.

②The role of QC group activities: A. Conducive to developing intellectual resources and improving people's quality; B. Preventing quality problems and continuously improving;

C. It is conducive to improving interpersonal relationships, strengthening team awareness and quality awareness, thereby improving the team's work efficiency.

③Principles for forming a QC team: A. Voluntary participation and voluntary combination are the basic principles for forming a QC team. Principle; B. Top-down, top-down combination is the basis for forming a QC team; C. The combination of leaders, technicians and workers is a good form of forming a QC team; D. Seeking truth from facts and combining it with reality.

< p> ④ Number of people in the QC team: The QC team should not have too many people, generally 3-10 people are appropriate.

⑤ Responsibilities of the QC team leader: A. Organize team members to formulate activity plans, divide work, and take the lead Carry out activities as planned; B. Responsible for liaison and coordination work, promptly report group activities to superior authorities, and strive for support and help; C. Do a good job in quality education, organize group members to learn relevant business knowledge,

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 and hold group meetings frequently to study and solve various problems, and do a good job Record group activities, and be responsible for organizing and publishing results.

2 QC group activity steps

① Selection of activity topics: Topic scope: topics to improve product quality; topics to reduce losses Topics; Topics to optimize the environment; Topics to improve management; Topics to improve the quality of employees.

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 selection should be specific and clear; the topic selection should be a short-term, quick-result topic. A topic should generally be completed in 3-6 months, and no more than one year at most.

② Investigation of the current situation: Through questionnaires or other forms, use data to clarify the problems to be solved, and determine the main direction of solving the problems, providing a basis for setting goals.

③Setting goals: The goals should be set It can be achieved through everyone's efforts.

④Cause analysis: Use appropriate tools to classify the main issues of the current situation investigation into six major factors: man, machine, material, method, environment, and measurement, and use a questionnaire ,

Analyze with appropriate tools such as cause-and-effect diagrams and Pareto charts to find out the specific causes of quality problems and determine the main causes. Note: During cause analysis, a group meeting should be held and brainstorming should be used Method, use the wisdom of the team to find out the reasons one by one as much as possible.

⑤ Formulate countermeasures: Generally, specific items are listed in the form of a countermeasure table. When formulating the countermeasure table, the 5W1H method should be used. Ask a few whys. So the countermeasures

The strategy list should include: why the countermeasures should be formulated (Why), what goal to achieve (What), where to implement it (WHere), who will implement it (Who), and when Completion (When) and how to execute (How), etc.

⑥Implement countermeasures: execute according to the formulated countermeasures or plans.

⑦Effect inspection and verification.

⑧Consolidation measures: Summarize the results of the inspection and incorporate them into relevant standards, work instructions, systems and regulations to consolidate the achievements achieved and prevent similar problems from happening again.