Challenges facing pure copper manufacturing

Copper processing is an important part of my country's nonferrous metal industry. After years of rapid development, my country has become the world's largest copper producer and consumer. Copper parts are usually manufactured using metal powder injection molding (MIM) and traditional processes such as forging, machining, extrusion, and casting. Simple geometries can be produced, but complex structural components are difficult to produce or require other processes such as welding. Enable complex manufacturing. As the demand for complex structural components increases on the application side, the traditional process of preparing pure copper components can no longer meet all the needs of the rapid development of the application market. The advantages of additive manufacturing (AM) technology that can realize the integrated forming of complex parts are gradually emerging, showing huge application potential in the production of copper parts.

Particularly in subtractive manufacturing processes, pure copper is notoriously difficult to work with, and its ductility often results in deformation during subtractive manufacturing operations. Therefore, subtractive manufacturing often requires the use of copper alloys with lower electrical and thermal conductivities. In additive manufacturing, although the application of pure copper materials started late, it has shown a trend of rapid development in recent years. Especially in the field of national defense and military industry, the application of copper additive manufacturing has continued to make important progress, which has also promoted the development of copper. Developments in materials additive manufacturing.

Different processes for pure copper additive manufacturing

The most typical processes for metal additive manufacturing are selective laser melting (SLM) and electron beam melting (EBM) technology, and pure copper materials can also be printed. However, due to the high reflection, high electrical conductivity, and high thermal conductivity of copper metal, the SLM process has a low absorption rate during the laser melting of copper, and it is difficult for the laser to continuously melt the copper metal powder, resulting in low forming efficiency and difficulty in controlling the metallurgical quality. In addition, copper's high ductility makes post-processing tasks such as removing excess powder more difficult. Since EBM uses electron beam as the heat source, it will not be affected by the high reflection factor of SLM laser, so it has a slight advantage. However, because copper has high electrical conductivity, the EBM printing process will be very short; and because of copper’s high thermal conductivity, the dimensional accuracy and mechanical properties of the printed model will be poor in controllability, so the surface quality of the printed copper parts will be poor. Good, which in turn brings inconvenience to the post-processing of applications such as copper induction coils.

However, the challenges existing in the pure copper laser additive manufacturing process are also being gradually overcome. For example, the mechanical properties and electrical conductivity of pure copper parts using the green laser selective laser melting system (green SLM) are greatly improved, and the reduction in reflectivity can make the processing process more stable and efficient. In addition, the copper 3D printing process of material extrusion, photopolymerization and binder jetting has also been commercialized. Among them, the powder extrusion printing (PEP) technology based on sintering cleverly avoids the problems of high thermal conductivity and high reflection in the pure copper printing process. By first printing the green body, and then going through the mature powder metallurgy degreasing and sintering process, the structure is obtained. Excellent high performance pure copper components. It is expected to bring more diversified solutions to the manufacturing of next-generation thermal and electrically conductive parts.

Advantages of PEP technology for manufacturing copper

PEP technology is a metal/ceramic indirect 3D printing process that combines "3D printing + powder metallurgy" launched by Shenghua 3D. It takes advantage of the complex structure, integration, lightweight and other technical characteristics of 3D printing technology, and then gives full play to the capabilities of powder metallurgy. Technical advantages such as a wide range of processing materials and low processing costs empower the digitalization of traditional manufacturing.

3D printing of pure copper based on PEP technology does not require high-energy laser beams, and cleverly avoids the problems of high thermal conductivity and high reflectivity in the pure copper printing process. Pure copper is obtained by first printing the green body, and then degreasing and sintering. part. It transfers the thermal processing process to the sintering step, making it easier to manage thermal stress; and the sintering temperature is lower than the full melting temperature required in other types of direct 3D printing processes, allowing the heat to be applied more evenly, thus ensuring the product Performance consistency.

During the printing process, if you want to obtain pure copper parts with high density or high electrical and thermal conductivity, the pure copper printing material formula and degreasing sintering process requirements are also very high. Sublimation three-dimensional pure copper granular material UPGM-CU is very suitable. For pure copper 3D printing, it maintains high purity of raw materials while also making it easier to achieve densification, which can meet the printing needs of different pure copper parts. The 3D printing equipment independently developed by Shenghua 3D can process pure copper and its alloy materials to manufacture dense components. It has been widely used in the product development of heat exchangers, radiators and electric inductors.

PEP technology has a simple forming process, does not require laser devices, and has the characteristics of low-temperature forming and high-temperature forming. It can solve the problem of high-reflective metals such as copper having low absorption rate in the laser band, and solve the manufacturing and processing problems of fine and complex geometric structures and high-performance pure copper at the same time; the printing material is easy to prepare, and there are no strict requirements on the sphericity and fluidity of the original powder, so it is suitable for Powder materials used in powder metallurgy processes, and printing materials can be recycled. It provides an effective way for pure copper materials that are difficult to manufacture and process.

Empowering copper processing and manufacturing, sublimating the three-dimensional battle without slacking off

In recent years, in the face of complex and ever-changing domestic and international macroeconomic situations and development environments, my country's copper processing industry has actively promoted mode changes, structural adjustments, and transformation, maintaining the sustained and rapid development of the industry. At present, the processing capacity of my country's copper industry continues to improve, the application fields continue to expand, the level of localization continues to improve, and the entire industry shows a good trend of vigorous development. Pure copper additive manufacturing can greatly reduce manufacturing cycle and cost. Secondly, parts with more complex structures can also be manufactured, which not only improves the accuracy of the product, but also enables customized production. These advantages make pure copper additive manufacturing have broad application prospects in various industries.