Hybrid manufacturing: CNC and 3D printing merge
The combination of additive and subtractive manufacturing in one machine.
1. Introduction: The limits of pure AM and pure CNC
The machining (CNC milling/turning) is precise, fast and delivers perfect surfaces. However, it fails due to cavities and extreme component complexity. Additive metal 3D printing builds complex structures but suffers from rough surfaces and the need to separate support structures.
Hybrid Manufacturing combines both worlds in a single machine. This guide highlights the enormous potential of systems that can print and mill in the same setup.
What is a hybrid machine?
A typical hybrid machine (e.g. from DMG MORI or Mazak) is based on a massive 5-axis CNC machining center. In addition to the milling spindle, a laser print head (usually DED - Directed Energy Deposition) is also integrated, which welds metal powder or wire.
2. How the hybrid process works
The process switches seamlessly between additive construction and subtractive removal:
- Preparation: A base body (often a cheap steel blank) is clamped into the machine.
- Additive construction (DED): The laser welding head applies new material (e.g. high-quality Inconel) to the blank layer by layer.
- Subtractive intermediate processing: Before the component is completely built up and internal surfaces can no longer be reached, the machine automatically switches to a milling head. Internal channels or bearing seats are milled to µm accuracy.
- Further construction: The laser welds the component further and closes the previously milled, perfect cavities.
3. The biggest advantages of hybrid manufacturing
- "Done-in-One": The component does not have to be clamped between a 3D printer and a milling machine. This eliminates zero point errors, reduces idle times (work-in-progress) and saves massive amounts of space in the production hall.
- Multi-material Capability: Since DED blows the material as a powder, different alloys can be mixed during printing. This creates a component with a hard, wear-resistant core and a tough, rust-proof outer skin (gradient materials).
- Accessibility: Due to the 5-axis kinematics of the machining center, support structures can often be completely dispensed with, as the component is simply pivoted into the optimal welding position.
4. Ideal use cases for hybrid machines
The machines are complex and very expensive. They are not worth it for simple parts, but shine in special niches:
- Repair (MRO - Maintenance, Repair and Overhaul): An expensive, massive turbine wheel has a damaged blade tip. The hybrid machine scans the break point, mills out the crack cleanly, welds on exactly new material and mills the blade back to the perfect aerodynamic contour in the same clamping.
- Injection molding tools: A large tool block is prefabricated from inexpensive steel. Only in the top, shaping area does the machine weld copper (for cooling) and high-hard tool steel (for wear resistance) and mill everything directly to the final size.
5. Challenges and limitations
Despite the brilliant theory, there are still technological hurdles:
- CAM programming: Creating machine programs is extremely demanding. The programmer must simultaneously master both the heat input and distortion of welding and the cutting forces of milling (Siemens NX and Mastercam are leaders here).
- Cooling lubricant problem: Milling often requires a lot of cooling lubricant (KSS). However, the laser welding process requires an absolutely clean, grease-free environment. The machines therefore need to clean, blow and dry extremely well before switching between modes.
6. Conclusion: The premier class of production
Hybrid machines do not replace classic PBF powder bed printing for delicate, hollow series components. But when it comes to repairing massive, expensive industrial components or the flexible production of complex individual parts without separate process chains, hybrid production represents the absolute zenith of modern machining.