Laser Metal Deposition (LMD-w) with wire
Clean, cheap and 100% efficient: Why wire lasers often outperform powder blowing.
1. Introduction: Wire instead of powder
When it comes to Directed Energy Deposition (laser deposition welding), most people think of lasers that blow metal powder into a molten pool (LMD-P / DED-P). But powder conveying has its pitfalls: some of the expensive powder bounces off (overspray) and spreads throughout the machine, which often reduces the powder usage efficiency to below 60%.
A highly efficient alternative is wire-based laser deposition welding (Laser Metal Deposition Wire – LMD-w or DED-w for short). Instead of powder, a solid welding wire is guided laterally into the laser focus.
Why LMD-w instead of electric arc (WAAM)?
In Wire Arc Additive Manufacturing (WAAM), the wire is melted using an electric arc. This is incredibly fast, but it brings enormous, uncontrolled heat into the component. The laser in the LMD-w works much more precisely, the melt pool is smaller and the heat input is strictly focused. This means: Better surfaces, more precise geometries and less thermal distortion than with WAAM.
2. The unbeatable advantages of the wire
Laser processing of wire offers massive economic and ecological advantages in heavy industry.
- 100% material utilization: In contrast to powder (overspray), every centimeter of the wire supplied is melted and becomes a component. There is no waste and no contamination of the machine.
- Wire costs: Welding wire is a standard industrial product. It only costs a fraction (often times 5 to 10 cheaper) of high-purity, atomized AM metal powders.
- Cleanliness and Safety (HSE): There is no dangerous respirable particulate matter. Machine operators do not need complex breathing masks or special explosion protection (ATEX) vacuum cleaners as in powder handling.
3. The technological challenge: “Dripping”
LMD-w is demanding in terms of control technology. If the laser energy, the wire feed and the traversing speed of the robot are not perfectly coordinated, errors will occur.
If too much heat hits too little wire feed, a drop will form at the end of the wire and fall off ("dripping"). The melt pool breaks off and the process gets out of control. Modern systems (e.g. Meltio or TRUMPF) use coaxial wire feeds and camera systems (closed-loop control) that monitor the melting process thousands of times per second and adjust the laser power in real time to guarantee an even transition (smooth transfer).
4. Applications in industry
Due to the slightly lower resolution compared to the powder bed, but the very high speed, LMD-w shines in large format.
- Coating (Cladding): The hard and wear-resistant coating of large shafts, drill bits or hydraulic cylinders.
- Free-form manufacturing: The 3D printing of medium-sized to huge structural components (e.g. made of titanium) for aviation, which are then CNC milled (near-net shape).
5. Conclusion: The rise of wire laser systems
LMD-w combines the enormous material efficiency and low raw material costs of the welding wire industry with the unsurpassed precision of the laser. Particularly hybrid systems that integrate a Meltio wire laser head into an existing 5-axis CNC milling machine enable companies to seamlessly print huge components and immediately mill them to the final size.