Direct Energy Deposition (DED), also known as metal laser cladding, is one of the methods used to fabricate metal workpieces by additive manufacturing technology.
In recent years, various industries have developed many new types of processing technologies in response to the processing needs of the new era. Among them, laser-related processing types, such as welding, cutting, repairing, anti-wear coating, and laminate manufacturing, are widely used in engineering fields, including aerospace, automotive, shipbuilding, mold, and biomedical industries. After the continuous evolution and improvement of laser technology, the current high-energy laser technology can quickly and accurately heat the powder particles in flight, and at the same time melt the surface of the substrate to form a molten pool, which can be quickly stacked to form the desired stacking layer or three-dimensional shape. The production technology of the three-dimensional shape of Laser Deposition belongs to a kind of laminated manufacturing technology. Laminated manufacturing technology is also known as 3D printing technology. 3D metal components manufactured with this technology provide the feasibility of industrially producing more complex parts; this technology gradually stacks complex parts by stacking layers. The 3D elements of the structural form can be combined with a unique combination of practical and aesthetic properties.
The direct laser deposition (DLD) manufacturing method is a processing method that uses laser light to directly heat and melt materials, and stack them into the desired surface layer or component shape. This manufacturing method belongs to a direct energy deposition (DED) technology.
What is Direct Energy Deposition Technology (DED)?
The molten pool is generated in the deposition area by the laser and moves at a high speed. The material is directly fed into the high-temperature melting area in the form of powder or filament, and then deposited layer by layer after melting, which is called laser direct energy deposition additive manufacturing technology.
The principle of the direct energy deposition process is to output the powder flow and the laser beam coaxially on the surface of the workpiece to be processed, and the laser photothermal effect acts on the sprinkled powder flow and the molten pool on the surface of the workpiece. The metallurgical change occurs on the surface of the workpiece by melting the metal powder at a high temperature, to achieve the purpose of increasing the height of the surface layer of the workpiece. 3D objects can be formed by continuous layer-by-layer fusion.
Direct laser deposition (DLD) technology can form coatings or desired three-dimensional shapes by laser melting metal, alloy, or ceramic gold powder materials. This technology is one of the methods of direct energy deposition. The high-energy laser heating source of the direct laser deposition technology can not only heat the powder material but also heat the surface of the substrate to form a molten pool. Direct laser deposition technology can be used as a kind of three-dimensional printing, which is classified as a powder-spraying three-dimensional printing method, which has the advantages of rapid prototyping, can quickly produce large-scale coatings or components, and the utilization rate of materials High, so it has the advantage of constructing large-scale components or coating in various industrial fields.
Direct Energy Deposition (DED) Technology Principle and Processing Method:
- Machine technology:
The DED machine needs to integrate the machine tool and the laser system, and both the laser system and the machine tool are equipped with independent controllers. Trigger the laser controller through external contacts to control the related functions of the laser system. After confirming the functions of the laser equipment, confirm the IO interface of the PLC and write the PLC program, develop the PLC ladder diagram in the simulator and establish the man-machine interface of the laser system. Finally, after planning the circuit wiring, practice combining the laser system, power supply system, ice water machine, and installing the laser head in a five-axis CNC machine tool. By rewriting the control program of the controller in the machine tool, a machine tool with a direct energy deposition function is produced. Furthermore, the developed man-machine interface monitors the status of the machine, and commands the controller to control the DED process processing path, while outputting lasers and metal powders on the processing plane to produce workpieces.
- Process molding technology:
This technology integrates and optimizes the process parameters of the DED machine, determines the setting value or range of each process parameter by regression analysis, and conducts a factor experiment for three significant control factors: laser power, scanning speed, and powder supply amount. And carry out gas path optimization to find the best process parameters, and observe the results of each path covered by path planning. Finally, through the optimization of the path, it is written into the CAM path planning software to improve the appearance flatness, and mechanical properties of the finished product, and achieve the goal of predictable process parameters, microstructure, and mechanical properties.
Due to the use of metal powders, it has great applicability in workpieces that require many material removals, such as aerospace, automotive, and other industries. In addition, the DED process is a type of 3D printing technology that can produce very complex workpieces. If the workpiece can be integrated and designed, the workpiece that originally required many parts will only need a small number of parts to meet the demand, which has a great advantage in cost. Since DED uses powder spraying to make workpieces, DED can be used to develop various new alloy materials, especially materials such as gradient materials that are not easy to manufacture by other methods are very suitable for using DED, so the future application of DED is very promising. and economy.
What are the Technical Advantages of Direct Energy Deposition (DED)?
The method of direct laser deposition is to melt the material and attach it to the substrate, so the utilization rate of the material is high. Compared with the traditional machining production method, the traditional manufacturing method may waste more than 50% of the material in the production process, while the direct laser deposition method can be produced in a way that saves expensive material costs and avoids material waste. For example, in aerospace, semiconductor, LCD, mold, power generation, and biomedical industries, the materials and manufacturing costs of their components are high. Therefore, if the cost of materials can be reduced, or repairs can be performed when components are partially damaged, the cost of manufacturing or operation can be reduced.
Direct laser deposition equipment can be individually designed for customers to create a customized system. This system is generally composed of a powder feeder, laser source, shielding gas, powder nozzle, and mobile control system. The mobile control system Parts of the system can be adjusted to suit the needs, including mobile beds, robots, or rotary tables, etc.
Integrate machine tool and a laser system to produce machine tool with man-machine interface and integrated laser control function, which can command and control the cladding processing path. In addition, the process parameters of the DED machine are integrated and optimized to determine the setting value or range of each process parameter. Through the optimization of the path, it is written into CAM software, so that the process parameters, microstructure, and mechanical properties can be predicted.
What is the Industrial Applicability of Direct Energy Deposition (DED)?
The application of direct laser deposition technology can be simply divided into 3D printing of new components and coating stacking or repairing the surface of components. When direct laser deposition technology manufactures new components by 3D printing, a carrier substrate is required as the carrier for 3D component production. After the 3D component is produced, part of the carrier can be cut off. If not, the carrier itself will also be cut off. can be part of a component. Therefore, direct laser deposition technology can add 3D printed components of other shapes to other components, or add additional functions to existing components, and can also be used for overlay coatings and repair components.
Direct laser deposition technology can be applied to high-value components that require expensive production, assembly, or maintenance costs, etc., to avoid material loss caused by excessive machining. Industries that have applied direct laser deposition technology for manufacturing, including applications in marine, marine, power generation, petrochemical, aviation or automotive industries, etc., more specific applications include repair and manufacturing of aero-engine components, turbine engine blade repair, sintering Repair with molds, hard facing layer stacking of components related to oil drilling, biomedical implants, fabrication of complex components, development of new synthetic materials and rapid prototyping, etc.
DED uses powder spraying to make workpieces, and it has great applicability in workpieces that require a lot of material removals, such as aerospace, automobile, and other industries. In addition, DED can make very complex workpieces, and only a small number of parts can be required after the workpiece is integrated and designed. It is very suitable to develop new alloy materials, especially materials such as gradient materials that are not easy to manufacture by other methods, so DED technology has the future and economy.