What Does Welding Quality Control Rely On?

With the rapid development of modern welding technology, the continuous improvement of welding production level and the increasing international trade of welding products, in order to ensure the quality of welding products, effectively use resources, and protect the interests of users, the quality management of welding products has gradually embarked on the Standardized and standardized road.

In March 1987, the International Organization for Standardization (ISO) officially released the ISO9000-9004 standard series on quality management and quality assurance.

In 1994 and 2000, the International Organization for Standardization revised the ISO9000 family of standards twice to make them more simplified, more focused, more scientific and universal, and to raise the quality assurance system to the level of the quality management system.

Correspondingly, in 2000, my country released the GB/T19000:2000 "Quality Management System" standard series equivalent to this international standard series.

Modern quality management believes that in order to make the product meet the required quality indicators, it should start from each production process and ensure it by controlling and adjusting the factors that affect the quality of the process. The quality of the process must be achieved through the quality of work and various management methods.

Therefore, in the quality management work, the quality of the process must be guaranteed by the quality of the work, and the quality of the product must be guaranteed by the quality of the process.

It can be seen that in order to achieve the quality goal, it is necessary to establish an effective and easy-to-operate quality management system in the management system. And apply this system to the entire manufacturing process of the product.

Knowledge point 1: Influencing factors and countermeasures of welding process quality

Table of contents

1. People ----- Welding operator factors

2. Machine ----- Welding machine equipment factor

3. Material ----- welding raw material factors

4. Method ----- welding process method factors

5. Ring -----environmental factors

Process quality refers to the degree of assurance that the processing process can guarantee the quality of the product in the production process. In other words, product quality is based on process quality, and only excellent process quality can produce excellent products.

The quality of the product is not only achieved after the completion of all processing and assembly work, but also through the measurement of certain technical parameters by full-time inspectors and the approval of users, but it exists at the very beginning of the processing process and runs through the entire production process. 

Whether the final product is qualified or not depends on the cumulative result of all process errors. Therefore, the process is the basic link of the production process and also the basic link of inspection.

The production of welded structures includes many processes, such as decontamination and rust removal of metal materials, straightening when preparing materials, scribing, blanking, processing and forming of groove edges, assembly of welded structures, welding, heat treatment, etc. Each process has certain quality requirements, and there are factors that affect its quality.

Since the quality of the process will ultimately determine the quality of the product, it is necessary to analyze various factors that affect the quality of the process and take effective control measures to ensure the quality of welding products.

The factors affecting the quality of the process can be summed up in five aspects: personnel, equipment, materials, process methods and production environment, referred to as "human, machine, material, method and environment" for short. The degree of influence of each factor on the quality of different processes is very different, and it should be analyzed in detail on a case-by-case basis.

Welding is an important process in the production of welded structures, and the factors affecting its quality are also the above five aspects.

1. People ----- Welding operator factors

The various welding methods depend on the operator in different degrees.

For manual arc welding, the welder's operational skills and careful working attitude are very important to ensure the welding quality.

For submerged arc automatic welding, the adjustment of welding process parameters and welding are also inseparable from human operation.

For various semi-automatic welding, the movement of the arc along the welding joint is also controlled by the welder. If the welder has poor quality awareness during welding, careless operation, non-compliance with welding procedure regulations, or low operating skills and unskilled techniques, the quality of direct welding will be affected.

Control measures for welding personnel are as follows:

(1) Strengthen the quality awareness education of welders "quality first, user first, and the next process is the user", improve their sense of responsibility and meticulous work style, and establish a quality responsibility system.

(2) Conduct on-the-job training for welders on a regular basis, master the process regulations theoretically, and improve operational skills in practice.

(3) Welders are required to strictly implement the welding process regulations during production, and strengthen the self-inspection of the welding process and the inspection of full-time inspectors. the

(4) Conscientiously implement the welder examination system, insist that welders hold certificates to work, and establish welder technical files. For the production of important or major welded structures, more detailed considerations are required for welders. For example, the length of welder training, production experience, current technical status, age, length of service, physical strength, eyesight, attention, etc., should all be included in the scope of assessment.

2. Machine ----- Welding machine equipment factor

The performance and stability and reliability of various welding equipment directly affect the welding quality. The more complex the equipment structure, the higher the degree of mechanization and automation, the higher the dependence of welding quality on it.

Therefore, such devices are required to have better performance and stability. Welding equipment must be inspected and tested before use, and a regular inspection system must be implemented for various in-service welding equipment.

In the welding quality assurance system, from the perspective of ensuring the quality of the welding process, the following points should be done for welding equipment:

(1) Regular maintenance, maintenance and overhaul of welding equipment, and trial use of important welding structures before production.

(2) Regularly check the ammeter, voltmeter, gas flow meter and other instruments on the welding equipment to ensure accurate measurement during production.

(3) Establish technical files of welding equipment status to provide ideas for analyzing and solving problems that arise.

(4) Establish a responsibility system for welding equipment users to ensure the timeliness and continuity of equipment maintenance.

In addition, the use conditions of welding equipment, such as requirements for water, electricity, environment, etc., the adjustability of welding equipment, space required for operation, error adjustment, etc. also need to be fully paid attention to, so as to ensure the normal use of welding equipment.

3. Material ----- welding raw material factors

The raw materials used in welding production include base metal, welding materials (electrode, welding wire, flux, shielding gas), etc. The quality of these materials is the basis and premise to ensure the quality of welding products.

In order to ensure the welding quality, the quality inspection of raw materials is very important. In the initial stage of production, that is, before feeding materials, it is necessary to check the materials in order to stabilize production and stabilize the quality of welding products.

In the welding quality management system, the quality control of welding raw materials mainly includes the following measures:

(1) Strengthen the acceptance and inspection of welding raw materials, and re-inspect their physical and chemical indicators and mechanical properties when necessary.

(2) Establish a strict management system for welding raw materials to prevent contamination of welding raw materials during storage.

(3) Implement the marking operation system of welding raw materials in production to realize the tracking and control of the quality of welding raw materials.

(4) Select welding raw material suppliers and cooperative factories with high reputation and good product quality for ordering and processing, so as to fundamentally prevent welding quality accidents.

In short, the welding raw materials should be checked on the basis of welding specifications and national standards, and their quality should be tracked and controlled in time, instead of just entering the factory for acceptance and ignoring the marking and inspection in the production process.

4. Method ----- welding process method factors

The welding quality has a strong dependence on the process method, and occupies a very prominent position among the factors affecting the quality of the welding process.

The influence of the process method on the welding quality mainly comes from two aspects, one is the rationality of the process formulation; the other is the strictness of the execution process.

First of all, it is necessary to conduct process qualification for the welding process of a certain product or a certain material, and then formulate the welding procedure specification according to the process assessment report and drawing technical requirements, and compile the welding process specification or welding process card. These various process parameters expressed in written form It is the basis for guiding welding. It is compiled based on the test of simulating similar production conditions, long-term accumulated experience and specific technical requirements of the product. It is an important basis for ensuring welding quality. It has regulations and seriousness. , prudence and continuity. It is usually compiled by experienced welding technicians to ensure its correctness and rationality.

On this basis, ensure the strictness of the implementation of the process method, and do not change the process parameters arbitrarily without sufficient grounds. Even if it is really necessary to change, certain procedures and procedures must be performed.

An unreasonable welding process cannot guarantee a qualified weld, but with a correct and reasonable process specification that has been verified through assessment, if it is not strictly implemented, a qualified weld cannot be welded either. The two complement each other and depend on each other, and neither aspect can be ignored or neglected.

In the welding quality management system, the effective control of the factors affecting the welding process method is:

(1) Welding procedures must be evaluated in accordance with relevant regulations or national standards.

(2) Select experienced welding technicians to compile the required process documents, and the process documents should be complete and continuous.

(3) Strengthen on-site management and supervision during the welding process in accordance with the regulations of the welding procedure specification. the

(4) Before production, the welding product test plate and the welding process inspection test plate should be made according to the welding process regulations to verify the correctness and rationality of the process method.

What's more, the formulation of welding procedure regulations is not detailed, and there must be a remedial plan for quality accidents for important welding structures to minimize losses.

5. Ring -----environmental factors

In a specific environment, the dependence of welding quality on the environment is also greater. Welding operations are often carried out outdoors in the open air, which is bound to be affected by external natural conditions (such as temperature, humidity, wind, rain and snow). Under certain other factors, welding quality problems may also be caused by environmental factors alone.

Therefore, some attention should also be drawn. In the welding quality management system, the control measures of environmental factors are relatively simple. When the environmental conditions do not meet the specified requirements, such as strong wind, wind speed greater than level 4, or rainy and snowy weather, relative humidity greater than 90%, the welding work can be temporarily stopped , or take measures against wind, rain and snow before welding;

When welding at low temperature, the low carbon steel should not be lower than -20°C, and the ordinary alloy steel should not be lower than -10°C. If this temperature limit is exceeded, the workpiece can be properly preheated.

Through the above analysis of the five factors affecting the quality of the welding process and their control measures and principles, it can be seen that the five factors are interrelated and cross each other, and the consideration must be systematic and continuous.


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