Arc welding technology

Additive manufacturing with arc welding processes such as GMAW, TIG or plasma processes represents a resource-efficient and economical option for the production of complex 3D components. The use of filler materials in wire or powder form enables buildup rates of several kg/h, which means that the production of large-volume components can be addressed. The Production Technology Group is mainly focused on the control of energy input and the resulting process-material interactions. The WAAM process (Wire Arc Additive Manufacturing) can be used to process almost all metallic materials in the form of wire.

In additive manufacturing, three-dimensional structures with varying complexity are manufactured. For the production of the components it is necessary a to create a path planning strategy for the weld beads to be applied. The component is in vertical plane sections broken down (sliced), in order to subsequently be applied layer by layer using the appropriate manufacturing process. The strategy not only takes into account the geometric conditions of the component, but also the heat transfer within the part. This can influence both productivity and the mechanical-technological properties.

Additive manufacturing with arc welding processes enables the targeted use of different materials within a component. The layer-by-layer build-up process allows specific alloys to be placed at functionally relevant positions within the workpiece. Thus, for example, multi-material structures with integrated wear protection or ductile intermediate layers to absorb residual stresses or to reduce distortion are implemented at the Production Technology Group.

Delicate, material-saving, strength- and stiffness-adapted load-bearing structures made of metal are becoming increasingly important. Through such structures, it is not only possible to incorporate individual aesthetics into buildings or to create iconic architectural masterpieces, but also to generate stress-optimized technical solutions based on nature (bionics). The motivation to produce a lightweight structure with maximum stability is often paired with the desire for minimal and adapted material use as well as low manufacturing costs.

Deposition welding describes a form of coating and is used for hardfacing, cladding or buffering components. In particular, the refurbishment of worn components with wear-protective or corrosion-resistant alloys represents an economical way of extending the product life cycle of stressed components. The metal inert gas and plasma powder cladding processes used in the Production Engineering Group are plasma powder deposition welding are characterized by high productivity and very good automation. The research focus is on the correlation between process control and coating properties, such as wear resistance, using different alloy systems.

Hot wire technology is a process extension of conventional gas metal arc welding (GMAW) in which one or more additional wires are introduced into the molten pool of the GMAW process. On the one hand, a significant increase in deposition rate is achieved by the additionally introduced wire. On the other hand, the energy input of the GMAW can be decoupled from the filler wire, allowing thermally unstable materials to be processed efficiently. Hot wire technology represents an essential mainstay in the field of arc welding technology at the Production Technology Group.

Arc welding processes - such as gas metal arc welding - are widely used in many areas, such as automotive and power plant construction. Research at the Production Technology Group focuses on the development of joining strategies for highly productive welding using hot wires, but also for delicate welded joints on thin sheets with thicknesses of less than 1 mm, which are some of the most demanding tasks in joining joining technology with arc belong to.

The development and opening up of new fields of application is a major focus in the field of arc technology at the Production Technology Group. Here, process developments, analysis methods, automation solutions or material developments are implemented in publicly funded research projects or bilateral contract research. The competence in the areas of additive manufacturing, buildup or joint welding enables the specific or individual realization of special applications.

The structural welding simulation is used at the Production Technology Group as a process-accompanying tool for the clarification of technical welding questions such as microstructural transformationsresidual stresses or component distortion.. The welding simulation on the numerical solution of a model and is validated by comparison with experimental tests. The comparison of different process variations, materials or clamping conditions makes it possible to an optimized approach for the selected welding task. Structure welding simulation is used in addition to additive manufacturing welding, it is also used in joint and buildup welding.

The acoustic process diagnostics is in the the field of arc processes for decades a applied methodology, which, however, is mainly based on the experience of the welders and welders. With the help of the most modern methods of signal processing as well as artificial intelligence approaches the automated acquisition and processing of the corresponding data is being developed at the Production Technology Group. This approach results in the development of a real-time capable online quality assurance for additively manufactured components. Thus both the manual inspection effort as well as the resource-intensive rework can be reduced in the future.

A compact, cost-effective and fully integrated system for additive manufacturing using Wire Arc Additive Manufacturing (WAAM) was developed at the Production Technology Group. The focus of the development was on the further development of sensor-based measurement data acquisition and processing. With external dimensions of approx. 2000x1200x1200 mm (HxWxD), the overall design is so compact that the system can be used as a mobile unit for presenting the WAAM manufacturing process at trade fairs. The welding system allows the production of components with dimensions of up to 800x750x300 mm³ by means of a three-axis CNC gantry system. The path planning and the adjustment with sensor data is carried out by means of a 3D CAD/CAM system.