Greenstone-Tech, together with six academic and research institutions, recently published a joint paper in the prestigious international journal Computer-Aided Design titled “Challenges in Topology Optimization for Hybrid Additive–Subtractive Manufacturing: A Review.” The study presents the latest research progress in the field of Hybrid Additive–Subtractive Manufacturing (HASM).

What is Hybrid Additive–Subtractive Manufacturing (HASM)?

Hybrid Additive–Subtractive Manufacturing (HASM) is a revolutionary manufacturing technology that combines the advantages of additive manufacturing (3D printing) and subtractive manufacturing (CNC machining). This approach enables the efficient production of complex-shaped components in a single setup.

While HASM excels in producing complex geometries, it still faces challenges in processing simpler mechanical parts, mainly due to relatively higher costs and limited economic efficiency.

Greenstone-Tech’s Research Focus: Topology Optimization in HASM

To address these challenges, Greenstone-Tech and its partners focused on design and process optimization for HASM. Their research concentrated on:

• Mechanical Structure Optimization: Creating designs that are not only lighter but also functionally superior to conventional products.
• Integrated System Approach: Combining product design, software control, additive manufacturing, and subtractive finishing into a seamless workflow.
• Hybrid Processing in One Machine: Additive processes handle near-net shaping, while subtractive processes ensure precision finishing and surface quality.

This integration eliminates errors caused by transferring parts between multiple machines, increases manufacturing precision, improves efficiency, saves workshop space, and reduces overall production costs.

Key Research Breakthroughs

The published paper addresses two core challenges in HASM topology optimization:

1. Residual Stress and Deformation Constraints: Developing methods to optimize topology considering residual stress and deformation.
2. Tool Accessibility in Hybrid Processes: Introducing planning strategies that ensure subtractive machining tools can effectively access complex geometries created by additive manufacturing.

The team proposed innovative methodologies and technical solutions, offering important guidance for future research in HASM optimization.

Greenstone-Tech’s Technological Achievements in HASM

Greenstone-Tech has made multiple breakthroughs in hybrid manufacturing, including the development of proprietary HASM equipment and software systems. These innovations significantly improve the efficiency and accuracy of additive manufacturing and have already been applied at an industrial scale.

Key strengths include:

• Strong product design capability and advanced process development, enabling customization for high-strength steels, superalloys, titanium alloys, and more.
• Pioneering five-axis hybrid manufacturing centers: The first of their kind in China, and among the most advanced globally.

Five-Axis Hybrid Additive–Subtractive Manufacturing Center

The company’s five-axis hybrid machining center is highly integrated, compact, and stable in performance. Key features include:

• Complex Surface Processing: Capable of both 3D printing and milling complex geometries with high precision.
• Dual Powder Feeding System: Supports both single powder and mixed powder delivery, solving challenges in forming and precision for complex parts.
• Superior Mechanical Properties: Produces components with excellent strength and durability.
• High Material Utilization: Significantly reduces waste and lowers production costs, making it suitable for precision industries such as aerospace, automotive, and energy equipment.

Industry Impact and Future Outlook

Greenstone-Tech’s innovations mark a leap forward in hybrid additive–subtractive manufacturing. By combining design optimization, advanced equipment, and industrial application, the company is driving the next generation of intelligent manufacturing.

Looking ahead, HASM will continue to play a transformative role in:

• High-value component repair and remanufacturing
• Lightweight and high-performance part design
• Industrial digitalization and green manufacturing