Smart Machining Module for Wire-Based Laser Deposition Welding
When economic or safety considerations rule out the use of powder materials in additive manufacturing, wire-based laser deposition welding becomes an option. The Fraunhofer Institute for Production Technology IPT in Aachen has now developed a smart laser module that can be combined with industrial robot systems in the medium term.
Powder bed 3D printing is currently the most well-known additive manufacturing process for filigree and complex metallic parts. However, there are two other less known additive processes which are particularly suitable for repairing or modifying larger-scale parts: powder-based and wire-based laser deposition welding. Compared to powder-based laser deposition welding in which the material flows in the form of tiny particles at high pressure out of a nozzle and onto the component to be melted there by the laser, deposition welding performed using the local infeed of solid wire material is significantly more material efficient and environmentally friendly.
Wire-based deposition welding, also known as Laser Metal Deposition-Wire (or LMD-W) is highly suitable for integration into existing production lines due to the easy to handle additive material. However, the process is considerably more complex to control and therefore more fault-prone than powder-based deposition welding, so that it has previously been used mainly for rough pre-machining operations. The "LMD-W-20-L" laser machining head, developed by the Fraunhofer IPT in Aachen, is a retrofit solution, whose sturdy construction and smart sensor system equip it for combination with industrial robot systems in the medium term.
Integration into conventional process chains
The cost-effective welding head works with commercially available laser optics and does not require complex custom-made beam guidance systems. In future, using the built-in sensor system, it will be possible to record typical faults as they arise in the course of an on-going process, permitting the causes to be analysed during operation and to be offset by the control system. Lateral wire infeed at a steep angle of 20 degrees to the optical axis ensures stable processes with high fusing efficiency. The range of wire materials available already includes various types of steel, nickel and titanium-based alloys along with numerous special purpose materials. The Fraunhofer IPT is currently exploring the suitability of other alloys as part of a number of research projects.
Material efficiency of 100 percent
The stand-out characteristic of wire-based laser deposition welding is its quasi 100 percent material efficiency. This is because the material fed in is melted completely and applied layer-by-layer to the surface of the part. Given the CAM support required and multi-axis process control, additional functional elements can be added to existing parts to produce a hybrid construction and permit repairs or modifications to be undertaken. A wide range of wire-based additional materials can be processed not only very cost-efficiently but also in near net shape, ensuring that the parts turned out are of premium quality.