Welding is a necessary process in modern machinery manufacturing industry, which is widely used in automobile manufacturing. The application of welding technology is indispensable for the six assemblies of automobile engine, gearbox, axle, frame, body and carriage. In the manufacturing of auto parts, there are various welding methods, such as spot welding, projection welding, seam welding, roll projection welding, electrode arc welding, gas shielded welding, argon arc welding, gas welding, brazing, friction welding, ultrasonic welding, electron beam welding and laser welding. Because spot welding, gas shielded welding and brazing have large production capacity, high degree of automation, high speed, low consumption, small welding deformation Easy to operate, so it is especially suitable for auto parts, so it is most used in auto production.

        From the beginning of its establishment, VANROAD has closely followed the needs of customers to develop welding process and process, invested in the purchase of KUKA welding robot, gas shielded welding, resistance welding and other welding equipment, and qualified and experienced welding engineers to check the process and technology. From the review of welding requirements, the production of welding DFM, the determination of welding process, the development of welding tooling, the training of welding personnel, the control of welding process, to the inspection and judgment of welding quality, the welding system is reviewed and controlled in strict accordance with the requirements of cqi-15 standard, so as to ensure the stability and reliability of the welding system and ensure the stable welding of high-quality products.

       With the development of the company and the change of customer demand, the company has added laser welding, ultrasonic welding and other equipment to enrich the company's welding process and provide customers with more welding solutions.

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CQI-15：What is a welding quality system?

        Welding process is a special process (procedure). After the parts are welded, the internal quality characteristics of the welded joint, such as penetration and mechanical properties, cannot be detected intact. Whether the quality is good or bad can only be found by the customer during use. It can be seen that the welding process has higher risks than the general process! This first reflects the non detectability of its failure mode!

         Since we can't know through the inspection after welding, how can we ensure the quality of welded products? Most people will answer: monitor the factors in the welding process!

This answer is correct, but there is an obvious "jump"!

        What factors are monitored? What is the standard range of each factor? What method and frequency monitoring is used? How did these requirements come about? And these factors are quite many! For example, for a mechanical property index, for arc welding, there can be more than a dozen influencing factors, including current, voltage, welding speed, gas flow, etc., and there are interactions between them, some of which are difficult to control (such as pair gap, arc length, etc.)!

        Therefore, before monitoring the process, we need to determine the characteristic items and standards to be monitored, as well as the control methods and frequency, work flow when out of control and problems occur. This work is called process planning, which is the first thing we need to do, and then we can implement control (monitoring) in the formal production process.

For the welding process, there is a quality assurance model as shown in Figure 1 below:

The above is the planning of welding process (level). In the automotive industry, the ideal process planning includes the steps shown in Figure 2:

Figure 2 shows the welding process planning based on the design requirements, but the factors that determine the welding quality come from a wider range of sources!

Imagine: if there are fatal problems in the design, manufacturability and weldability problems, for example, the designed structural space is limited and welding cannot be carried out, the use of low plastic materials with poor weldability, dense cross welds in the structure, etc., it is difficult to meet the design requirements from the welding process measures!

Therefore, we should first review the manufacturability of the design, that is, DFM, where m should include welding. It is necessary to explicitly include a DFM step in the design and R & D process, and define the review points related to welding in the DFM.

If the materials and structures without mature welding process in the whole industry are intended to be used, or the materials used need post weld heat treatment during welding are not considered in the evaluation of product profit and price, it will be difficult to ensure the expected quality level and profit level in the later work no matter how to do it!

Therefore, the review points of welding shall be included in the feasibility assessment of the project.

The above two examples show that welding quality should be considered at the whole project (level), including project planning (before project approval), product design (manufacturability DFM) and welding process planning.

A crucial question is: who should do this from project feasibility study, design manufacturability study to welding process planning? Who will implement and be responsible for the planned requirements in the future? For example, training and qualification management of welding personnel, handling of abnormalities during monitoring, solution of welding problems, rework / repair, etc.

Of course, they are proficient in welding professional knowledge / skills! Not just those who are proficient in these planning tools (such as PFMEA)!

We define the responsibility of planning, process control and welding problem solving after formal production in a documented form. This work is the planning of management responsibility (level)!

To sum up, the planning results at the process level, project level and management responsibility level constitute a quality system. For the welding process, it is called the welding quality system. The planning of these three levels has clear requirements in cqi-15 standard.

For the process that is difficult to guarantee through post inspection, its quality must be guaranteed by a quality system!

Many people are paying attention to visible and touchable intuitive things, such as equipment, materials and products, and despise abstract things such as systems and planning! What's more, the setting of welding parameters depends entirely on the welding equipment supplier for debugging. If the products change in the future, they will not move or move!

In the final analysis, this is a conceptual problem!