Blog

Additive and Subtractive Composite Processes: Overcoming the Forming Bottleneck of Titanium Special-Shaped Parts

Titanium special-shaped parts such as aircraft engine blisks and spacecraft honeycomb hulls, due to their thin walls, deep cavities, and freeform surfaces, were once considered "machining forbidden zones." Traditional subtractive machining resulted in material utilization rates of less than 30%, and dimensional drift exceeding 0.05mm was common. However, the maturity of additive and subtractive composite processes is changing this situation.

The combination of laser deposition manufacturing (LDM) and five-axis milling has become a core solution. In the machining of TC17 titanium alloy blisks, LDM technology is first used to deposit the blank layer by layer at a rate of 300g/h, increasing material utilization to 95%. Five-axis RTCP precision compensation technology is then used for precision milling, achieving a blade surface profile error within 3μm. This approach reduces welds by 80% and shortens the machining cycle from 28 days to 7 days. For complex internal cavities with depth-to-diameter ratios exceeding 10:1, internally cooled tools and a high-pressure mist cooling system provide dual protection. An 8MPa high-pressure airflow carries cutting fluid directly to the cutting zone. Combined with electrochemical machining technology, this precisely forms air film holes with a diameter of 0.3mm±0.01mm, resolving the chip evacuation challenges associated with traditional processes. Using this technology in the topological optimization of a drone's fuselage frame, the system achieved a 45% weight reduction while maintaining a static strength of 1.5 times the design load.

Full-process digital control further ensures precision. The integration of 3D scanning modeling (with an accuracy of 0.005mm), finite element simulation, and online laser measurement results in a machining error prediction rate exceeding 95%. In the manufacture of deep-sea submersible pressure hulls, Ti5553 titanium alloy components produced using a composite process successfully withstood 100MPa hydrostatic pressure, achieving a 20% performance improvement over traditional forgings.