Laser welding is an advanced welding technique that uses a focused laser beam to join materials with high precision and minimal distortion. This method is highly efficient, providing faster welding speeds and reducing the need for post-weld treatment due to its narrow heat-affected zone. One of the key benefits of laser welding is its ability to produce strong, high-quality welds, even in complex or hard-to-reach areas. Additionally, it allows for greater automation, making it ideal for industries requiring consistent and repeatable welds, such as automotive and aerospace manufacturing.

However, the weld quality depends significantly on the used laser parameters and involved materials. A minor change in reflectivity can lead to changing weld properties which might not be detectable without destructible testing methods. Therefore, we focus on both in-situ real-time monitoring to detect changing process conditions, and on understanding the fundamental processes within laser welding. The combination of both fields then allows the design of fully automated AI-controlled laser welding setups which automatically detect the most suitable laser parameters for the current process window without human intervention.

Using lasers for material cutting allows fast, precise and contactless material separation. Depending on the laser parameters, different types of material can be cut with minimal burr, smooth cutting edges and a significantly reduced thermally affected zone, compared to "traditional" cutting methods, such as saws.

In our work, we strive not only to achieve the best process quality, but also to understand the fundamental processes of laser cutting. This is achieved by combining existing knowledge of involved physical and chemical processes with data acquired from in-situ real-time monitoring of process emissions.

The combination of both, in-situ real-time monitoring and fundamental knowledge of involved processes, allows the group to achieve perfect cut qualities independent of target material and laser type.

Additive manufacturing (AM) enables the fabrication of monolithic metallic parts with intricate geometries, increasing product value. With significant design freedom and layer accessibility, AM allows the creation of parts with complex mechanisms and tailored functionalities. In addition to our work in alloy design and powder engineering, we are committed to advancing the understanding of Laser Powder Bed Fusion (LPBF), an important sector in metal AM, where a laser selectively fuses powdered material layer by layer, enabling the creation of highly complex and precise metal parts. We investigate the process through cutting-edge characterization, in-situ monitoring, and mechanistic modeling. Our goal is to reduce defects, optimize processing parameters, and achieve superior mechanical properties in printed part.

Laser powder bed fusion process

Our research activities also include Directed Energy Deposition (DED), another additive manufacturing process that utilizes a focused energy source, such as a laser or electron beam, to melt material as it is being deposited, allowing for the efficient production or repair of large and intricate components.

Microstructured surfaces have a wide range of applications in fields such as optics, electronics, biotechnology, energy, transportation and more. Through careful control of surface topology substrates can be imparted with novel functionalities not present in bulk materials that can be exploited for innovative and efficient micro-devices as well as macro-scale products.

Mask projection, step-and-repeat laser direct ablation enables the surface structuring at high throughputs for features at the 1 um – 1 mm scale. A high-powered excimer 248nm DUV laser is pulsed through a stencil-like photomask to transfer the pattern into a flexible, cheap polymeric foil by directly ejecting the substrate material through photothermal and photochemical interactions. The Laser Center group of EMPA's Laboratory for Advanced Materials Processing (Prof. Dr. Patrik Hoffmann) has developed and optimized a unique processing tool capable of structuring areas up to multiple square meters, providing unique fabrication capabilities for industry applications and research partnerships.

Large-scale laser microprocessing examples

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