Modern engineering components requires highly advanced processing for retaining their strength and endurability and that required new material combinations and advanced manufacturing processes. One very important aspect in manufacturing is the joining processes. Welding is a well-established segment of producing a product and it has several classifications based on the application and the environment. The process technologies for making these sophisticated components require high power consumption, expensive and precision equipment which makes the overall cost of the production very high.
CMT –Cold Metal Transfer Arc welding could be an appropriate choice of fusion welding process which provides many advantages over the conventional arc welding processes in practice. The more interesting and important feature of this process is its arc characteristics. The arc is constricted and highly concentrated so as to produce deep penetration at higher welding speeds and thus high-quality welds can be produced in a lower production time. And this welding process is highly economical since it has different welding modes for welding materials of different thicknesses in which operating current is the only varying parameter. The three modes are CMT welding, CMT Pulse, CMT advanced. The sophistication in these variant modes is that they can utilize the same power source which in turns reduces the overall cost of the equipment. Also, CMT Cycle step can be utilized for the Directed Energy Deposition-DED Arc components.
Joining of dissimilar metallic materials have always been a difficult job to carry out as their physical characteristics and mechanical properties are always distinct. In general, this issue can be minimized by using a filler material addition during welding, optimizing the process parameters and mainly by increasing the heat inputs in the case of high strength material welding. The arc temperature during plasma arc welding is around 30,000 ºC which is very high when compared to conventional GTAW process in which the arc temperature is 15,000ºC. Arc intensity is the measure of depth of penetration and higher arc intensity leads to deeper penetrations and aids good quality welds at higher speeds. The key areas where these high strength dissimilar joints are applied are the petrochemical industries where a combination of high specific strength and high corrosion resistance is required and the Geo-thermal power plants where the same components operating at different temperatures in the range of very high temperatures to subzero temperatures. We hereby aim at welding dissimilar material combinations such as coated steel, Aluminum, DED Arc Component of Titanium Alloys/Inconel/Duplex stainless steel and the more appropriate welding process for producing high quality components with CMT Process. Also, different geometries of the materials are intended to be joined because of the flexibility of the CMT equipment as it has three different modes under same single power source.
Aerospace industry estimates requirements of about 20 million tons of billet material over the next 20 years. With 90% machining rates and ever-increasing material costs especially in titanium, Inconel alloys, conventional manufacturing strategies need reconsideration. New sustainable, cost and time efficient, and environmentally friendly manufacturing processes are required by the modern industry. New Additive Manufacturing (AM) technologies are currently the subject of significant interest. Among the different AM processes, Arc wire based Additive Manufacturing DED Arc technologies provide new routes to manufacture near net shape metal parts. In the DED process, 3D metallic components are built by depositing beads of weld metal in a layer-by-layer fashion. Standard welding processes, such as Gas Metal Arc Welding (GMAW) and Gas Tungsten Arc Welding (GTAW), can be utilized in Metal Additive Manufacturing-MAM which provide high deposition rates. Modern automation technologies enable high geometric flexibility. With the local shielding technique, highly reactive metallic components can be fabricated in an out-of-chamber environment various materials can be applied in the Metal Additive Manufacturing MAM process, such as steel, aluminum alloy and titanium alloy.
To achieve an integrated process that utilizes the full power of the AM technique, each process step must be set up and linked optimally. Design for DED identifies workpiece geometries that are most suitable for the final real-world applications. For example, in aerospace new light weight stiffeners are used which need to satisfy specific mechanical constraints. AM is an ideal way of manufacturing and testing innovative designs because AM removes many of the constraints that one typically encounters in conventional manufacturing. The final quality of the components depends on the deposition strategy which needs to be explored with different design plans.
The wire-based welding techniques used in the DED process can provide high deposition rates. However, the large heat input of these processes also brings significant residual stresses and distortions. These issues can badly impact the accuracy of the final shape of the parts and their mechanical performance. Therefore, it is important to take the thermo-mechanical behavior of the MAM process into consideration during the design stage. Design for MAM also tackles the issues of how to efficiently transfer the design into the real-world manufacture. In the actual WAAM process, the welding paths are executed by a robotic system. The conventional robot programming with a teach pendant is very time-consuming especially for complex paths. To generate a robot Programme efficiently, some researchers “mirror” milling tool paths generated from commercial CAD/CAM software or use sliced routines from Rapid Prototyping software. However, both these ways are not flexible because of software constraints.
Therefore, researchers often develop their own tools to achieve specific part designs. An automatic robot path generation tool has been generated in this research to generate robot code directly from CAD models. This tool can significantly reduce the time on robot programming from hours with a teach pendant to a couple of minutes. Moreover, the optimal deposition parameters process can be easily integrated in the deposition using this tool.
The DED Arc process is an innovative concept that opens a vast space of options for manufacturing large light structures. This MAM process is especially useful e.g. in manufacturing or repairing parts for aerospace industry where complex light weight structures are required. Due to the high flexibility of the MAM process, these parts can be tailor made. The arc welding process COLD METAL TRANSFER provides very favorable material properties yielding ready-to-use parts.
It can be demonstrated that DED Arc-MAM is a cost-effective alternative to machining. At up to 4 kg/h, the deposition rate is very high compared to other additive processes. Stable welding processes are needed that ensure a consistent build-up of weld layers without errors and with just a low heat input. In recent years the number of process variants of reversing welding processes has increased while more characteristics have been launched that are also optimized for MAM. The examples have shown that in both thin-walled special applications and high-strength constructions, a sufficiently homogeneous level of quality can be achieved. The potential of this manufacturing process has not yet been exploited and many new and exciting applications can be expected in the future. For more details regarding DED Arc Wire Additive Manufacturing Technology, please visit – https://www.fronius.com/en-in/india/welding-technology/info-centre/press/3d-printing
Considering the development and Industrialization of this DED Arc Technology, we at Fronius India have planned to schedule a 3-day Basic Training & Awareness Course on Arc Wire additive manufacturing during the month of September 2022.This program will be conducted in Fronius Innovation & Skill Center at Pune, Bengaluru and Gurugram along with a certification from IIW-India to create an awareness and emerging opportunities in this field.