How Is the Surface Finish of WAAM Titanium Parts Improved After Printing?

Initial Rough Machining for Stock Removal

The surface finish improvement process begins with substantial rough machining to remove the characteristic waviness and layer markings of as-deposited WAAM titanium. Using specialized CNC machining techniques, typically 3-8mm of material is removed from all critical surfaces. This step eliminates the gross surface irregularities and provides a uniform baseline for subsequent finishing operations. Given titanium's poor thermal conductivity and tendency to work-harden, this machining employs optimized cutting parameters, high-pressure coolant systems, and specialized tool geometries to maintain surface integrity while achieving efficient material removal.

Precision Finish Machining and Contouring

Following rough machining, precision finish machining achieves the final dimensional tolerances and significantly improves surface roughness. Multi-axis CNC systems perform contour following operations that create smooth, continuous surfaces with tight tolerances. For complex internal features or deep cavities, deep hole drilling and boring operations ensure precise dimensional control. The finishing passes use refined cutting parameters—lower depths of cut, higher speeds, and specialized tool paths—to achieve surface roughness values of Ra 0.8-1.6μm, suitable for most structural applications in the aerospace industry.

Abrasive and Vibratory Finishing Techniques

For components requiring superior surface quality, abrasive flow machining (AFM) is particularly effective for WAAM titanium parts. This process forces a viscous, abrasive-laden media across surfaces, uniformly deburring and polishing complex geometries, internal passages, and hard-to-reach areas. Vibratory finishing with ceramic media provides general surface smoothing and edge radiusing, while shot peening introduces compressive stresses that enhance fatigue resistance. For medical implants or fluid system components, electropolishing creates a smooth, mirror-like finish while simultaneously passivating the surface to improve corrosion resistance.

Thermal Treatment and Final Validation

All surface improvement processes are performed after critical thermal treatments, including Hot Isostatic Pressing (HIP) and stress relief annealing, to ensure dimensional stability. Final surface quality is validated through comprehensive material testing and analysis, including surface roughness measurements, visual inspections, and non-destructive testing, to verify that the enhanced surface finish meets the stringent requirements for titanium components in critical applications.