The Expanding Role for CNC Machining in Hybrid Manufacturing

It’s a time of tremendous change in manufacturing.  Composite materials like carbon nano-fibers and new polymer resins are replacing metals in some circumstances. Additive manufacturing (or 3D printing) is gaining new capabilities every day, with new materials becoming available and new applications coming to market. Meanwhile, CNC machining continues to expand with new axes of movement, robotic feeding, and AI monitoring and measurement.

Hybrid Manufacturing with Additive Manufacturing

Macfab is increasingly working with additive manufacturers who need levels of precision not available with those processes. They will print a part using whatever materials are required, then we will mill, tap, refine, and provide the necessary surface finishes.  That’s hybrid manufacturing.

Additive manufacturing has some inherent issues. It’s slower than CNC machining -especially on larger parts. And while both technologies run on the same CAD data files, the nature of 3D printing with its layered application produces files that are significantly different from CNC machining files for the same part. Policing the CAD data as the parts move from process to process calls for special software.

Another problem is the shrinkage inherent in printed metal parts once they’re sintered. Then of course the layered printing, while fine, is not artifact-free. CNC machining can address these issues. The fully treated component can be milled to final dimensions with the highest possible accuracy and surface finishes can be refined as needed. Other features such as screw holes can be tapped and features too fine to print can be milled on the part.

Hybrid Manufacturing with Composites

Composite materials have taken over many roles once reserved for metal, especially in the aerospace industry. Composites provide several benefits over metal. In the field of commercial and military aircraft, weight savings is a major consideration.   Resin-based honeycomb panels are a fraction of the weight of even aluminum while providing superior rigidity, sound, and thermal insulation. Composites are used extensively on the new Boeing 787, making up half of the plane’s weight.

Composites, too, rely on CNC machining. Composite panels can be formed to fit a specific application but may require CNC machining to refine edges or cut other features for a proper fit. It’s common for composite-based parts to require CNC machining to clean up joints where two subcomponents are fused together. Adhesive or sonically welded joints can require milling down to maintain design specifications.

Machining composites is often more difficult than metals. Composites often contain glass, carbon, or other abrasive fibers which can quickly dull end mills. They are often harder than metals as well, resulting in higher vibration rates during milling. We have to address those concerns with powerful CNC machines and short tool lengths, as well as adjusting spindle and feed rates.

The combination of these new technologies with CNC machining has served as something of a springboard. It has allowed the new materials and technologies to step past issues which would otherwise have had to be resolved before they could be put to mainstream use.


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