Advantageous for manufacturing large parts of automobiles, ships, and aircraft
Due to the nature of the manufacturing industry in which most of the various parts are made of metal materials, metal 3D printing is in the spotlight as a core technology that will lead to manufacturing innovation. Metal 3D printers can effectively reduce product life-cycle costs from prototype development to mass production because any mold of a complex shape can be customized with high precision. In particular, it is considered as the most efficient alternative when it has high added value like parts of mid-to-large-sized transportation equipment such as ships and aircraft but requires small-scale production of multiple varieties.
The Korea Institute of Industrial Technology (hereinafter referred to as'Biowon') has developed a technology that can manufacture medium and large-sized parts or die-casting * molds more quickly and inexpensively by incorporating the latest welding technology into the field of metal 3D printing.
* Precision casting method in which the metal used as the material in the mold is melted and forced into the mold with high pressure
The existing PBF (Powder Bed Fusion) * method of 3D printing technology has the disadvantage that the larger the mold, the higher the manufacturing cost and the lower the productivity, as the high-power laser equipment and expensive powder materials have to be stacked one layer for a long time. In addition, the price per large metal 3D printer is more than 1 billion won, so it is financially burdensome even for small and medium-sized enterprises to adopt and operate it.
* A method of laminating by sintering or melting by laying powder flat and selectively firing a laser
In order to overcome these shortcomings, Dr. Chang-wook Ji of the Advanced Orthopedic Engineering Research Group at Vio-won has developed a'Wire+Arc 3D additive manufacturing method' that rapidly laminates metal wires with the latest push-pull welding technique. Devised and optimized the related process.
This method is similar to Directed Energy Deposition (DED) *, another method of 3D printing, but instead of using a laser as a heat source, a high-temperature electric flame'Arc' is used, and a wire is used instead of a metal powder. It is differentiated in that it is melted and laminated.
* A method that instantaneously melts when a high-power laser beam is shot on the metal surface, while also supplying metal powder to laminate in real-time.
The research team integrated the welding machine, robot, and stacking path setting software into one system, and built a database of various process variables such as wire material, gas flow rate, and working temperature, and optimized it to be suitable for 3D printing.
Production speed is more than twice as fast as the existing casting method, and the introduction cost is about 1/10 of a commercial 3D printer.
The developed technology is an automated method in which, when CAD drawings of parts and products to be manufactured are entered into the system, the path setting software selects the optimal stacking path, and the welding torch attached to the robot arm melts the wires along with the path and stacks layers. This method is more than twice as fast as the conventional casting method, and in particular, in the case of die-casting mold manufacturing, the manufacturing cost is about 20% compared to the CNC machining method *, a technique that makes the mold by cutting the base material with an automated machine tool. The material loss rate is also 80% lower. The equipment construction cost is also economical as it is only a tenth of that of a large 3D printer.
* computer numerical control
In addition, the cladding method, which is a welding technique that bonds different materials during the lamination process, can be applied. Through this, it is possible to increase the mold life and increase the dimensional stability of the product by improving the cooling speed and abrasion resistance of the mold. Using this technology, the research team produced a large ship propeller with a size of 2m, which normally takes about 2 months, in 3 weeks. I even got certified.
Dr. Chang-wook Ji said, the developed technology is a high-speed, low-cost 3D printing technology that can be easily introduced by small and medium-sized manufacturers with only an automated welding system and CAD drawings. So, we plan to use it for manufacturing aviation parts.
On the other hand, this technology development was carried out through the Ministry of Trade, Industry and Energy's industrial technology innovation project and the New Market Creation Support Project, which is a major institutional project.