In the past 30 years, with China's reform and opening up, and a large number of foreign-funded enterprises have invested and set up factories in China, which has greatly promoted China's manufacturing technology, including welding and steel fabrication technology.

Tooling & jig is a kind of technological device designed to meet the assembly accuracy of welding components. Its main function is to ensure that the relative position tolerance and shape tolerance of the designed weldments can be achieved after assembly and welding, so as to ensure the accuracy of the weldments after steel fabrication. Before designing the Tooling & jig, first of all, it is necessary to study and analyze the structural shape, dimensional accuracy and tolerance of the welding workpiece, calculate the deformation and stress of each welding joint, and then design the structural form of the Tooling & jig according to the obtained data, as well as the guarantee method of dimensional accuracy, dimensional tolerance range,  positioning method, etc. then a set of simple and effective Tooling & jig is designed according to the structural characteristics of the fabrication workpiece. From the perspective of Tooling & jig design, the fixture itself has enough strength and rigidity to control the deformation of workpiece during assembly, clamping and welding. The positioning and positioner of the parts are designed according to the characteristics of the workpiece, the positioning and clamping mechanism can keep the accurate positioning of the components, and prevent the parts from moving due to the force and overturning during the fabrication process. At the same time, the accurate and reliable positioning and clamping of Tooling & jig can reduce or even cancel the marking work, replace the manual operation with equipment, reduce the probability of product deviation, and improve the accuracy and interchangeability of parts.

In terms of the manufacturing characteristics of the Tooling & jig itself, the manufacturing of the Tooling & jig is different from that of the general equipment, and the Tooling & jig needs to have high manufacturing accuracy. When making the welding Tooling & jig, first of all, the parts of the Tooling & jig should be accurately cut and prepared, according to the strength requirements, some parts need to do heat treated, and then do precision machining for the parts. In terms of accuracy, it is necessary to ensure the accuracy of each parts of the jig itself, such as dimensions, flatness, straightness, coaxiality, etc., and then assemble and weld each part during fabrication. During fabrication, the tolerance level shall be improved, and then the dimensional and geometric tolerances controlled by the jig shall be accurately measured and inspected on the platform, and the parts that cannot guarantee the accuracy shall be subject to local repairing and grinding, and the special parts shall be subject to secondary machining to ensure the accuracy of each control part. In this way, the design accuracy and manufacturing accuracy level of the jig are higher than the design accuracy level of the production workpieces. The fabrication tolerance of workpiece can be effectively controlled within the design range by using the assembly jig, which avoids the inaccuracy caused by manual method, and ensures the fabrication accuracy of the final assembly workpiecs. 

With the specialization and upgrading of China machinery manufacturing, many workshops are now mass production. In the mass production, if we still use the traditional method to let the technical workers mark, align, locate and fix one by one, it will consume a lot of working time. If we encounter more complex artifacts, it will consume more time, and the efficiency will be very low. Moreover, it is difficult to ensure the accuracy of assembly and fabrication by human measurement and positioning, because in the continuous repeated work, people will inevitably make all kinds of errors, resulting in workpiece size error and accuracy exceeding the standard. As a result, not only the quality can not be guaranteed, but also a large amount of labor and auxiliary time will be consumed, and finally the production cost will be increased. The use of welding tooling can overcome all kinds of errors caused by human factors, simplify the assembly process, and greatly improve the assembly and fabrication efficiency. However, the design and investment cost of tooling is very low, which is only very small compared with the traditional manual production. From the perspective of economic value, the application of tooling will bring considerable economic effect, which has been fully proved by objective practice in many production workshops.

Although the steel fabrication is not a high-end manufacturing technology, on the contrary, it is a very traditional manufacturing technology, but the steel fabrication technology is very important in the modern manufacturing industry, even for some equipment manufacturing, it occupies a very important position temporarily, For example, ship body, aircraft frame, high-speed rail frame, etc., whether it is workload, cost, or importance, all play a crucial role in the quality and cost of equipment. Therefore, if China wants to become a manufacturing power, it must also pay attention to the manufacturing technology of steel fabrication, and constantly improve and improve the accuracy and quality of welding structure.