September, 2024: Face Time
Q: What is laser wire additive (LWA) manufacturing?
A: LWA uses a laser and standard MIG wire stock to deposit material along a predefined path—in either a single layer or multiple layers. This process continues until the finished size and shape of the part is completed. Using a welding power supply to resistively heat the wire without an arc, before entering the laser-created melt pool, increases the deposition rates to levels not achieved by any other additive process. Benefits of LWA include quick build times, unlimited part size and raw material cost reduction. Lasers offer high processing speeds, especially at higher powers and with precise control of the focused energy. LWA is similar to laser welding and laser cladding, fot which there exists a substantial knowledge base, making the implementation predictable and reliable. The process also fully consumes the wire stock. Some materials, such as titanium and other aerospace alloys, realize huge cost savings when printing near net shape versus machining from a billet.
Q: How does LWA compare to other additive processes, and what materials are typically used?
A: Other additive processes use metal powders, either in a powder bed, which limits the part size to the size of the bed, or by deposition similar to LWA. Powder deposition, however, results in excess powder that needs to be collected and contained. Powder metal also presents health and safety hazards from inhalation that are avoided with wire deposition. A main difference between wire and powder is layer thickness. A wire layer is often measured in millimeters, while powder layers are measured in microns. The larger layer thickness of wire results in faster build times. Powder, while having a longer build time, can create a finished (net shape) surface and features that are more intricate. LWA achieves near net shapes that require post machining. But even with adding the post machine time, it may still result in a part that’s made faster. Nearly every type of metal can be used, including those that are difficult to machine. The process is also applicable with non-metals, such as polymers and ceramics.
Q: How do you ensure that a part’s desired mechanical properties and structural integrity are maintained when using LWA?
A: Properties and integrity are gained through constant monitoring of the process, including laser parameters, process speed, temperature, build height and wire feed rate. Inspection systems can help users look at the pre-, post-, and in-process sections of the part and self-correct.
Q: Can you give a little bit of detail about Laser Mechanisms’ experience with LWA technology?
A: We have developed three sophisticated processing heads for laser wire additive that are designated as DH, DHc (compact) and DHμ (micro). The micro unit weighs about 10 kg and is rated for up to 6 kW laser power. The compact weighs 18 kg and is rated up to 6 kW and the DH weighs approximately 35 kg and is rated for up to 30 kW. Within these units, a laser is directed into the device where it is split into three beams of equal power positioned around the center. The wire is fed coaxially into the center, eliminating all issues with side-fed wire and directionality. The head is omnidirectional, or independent of the direction of travel.
Q: What should companies consider when evaluating the LWA process?
A: If they already have experience in laser welding and/or laser cladding, they may have a good understanding of the energy source and concepts such as seam tracking, process monitoring, data tracking, data logging and laser safety. They will also need expertise in robot/machine programming. Since a part run can last for numerous hours or even days, companies must constantly monitor all parameters. Every material has its ideal print/weld speed and deposition rate. There will be a learning curve, especially as the need to print faster is always present.
Q: How do you see the technology continuing to develop in the future?
A: Many of the current applications are in defense, aerospace and large equipment manufacturing. As processes get refined, I see it being used more and more for part repair, mold repair and printing large obsolete parts that previously required casting. Other industries, such as commercial aircraft, automotive, shipbuilding, construction and energy, are already considering and developing applications for the LWA process due to its high build rate and ability to make large components.
MARK ROBINSON has been with Laser Mechanisms (http://lasermech.com/) for over 28 years. He works directly with machine tool builders and specializes in advanced applications for aerospace customers.
