How are D-shaped holes machined?

The Special Characteristics and Challenges of D-Type Hole Machining

D-type holes, with a shape between round and square holes, require balancing both curved and straight contours during machining, making it difficult to achieve in a single pass using traditional milling or drilling processes. D-type holes often demand high dimensional tolerances and surface quality, and are prone to shape deviations due to uneven tool wear.

The machining challenge lies in balancing the flatness of straight edges with the smoothness of curved edges.

The toolpath design is complex, requiring machine tools with high rigidity and precision control capabilities.

Multiple tool changes or multi-step processes can easily lead to cumulative errors, affecting the part's fit accuracy.

Analysis of Mainstream Machining Methods

Drilling combined with milling: A reference hole is first drilled using a vertical drilling machine, then the straight plane and curved surfaces are machined using an end mill on a vertical machining center. This method offers high precision but involves more steps.

Multi-functional drilling and milling machine integrated machining: Utilizing a multi-functional drilling and milling machine to complete drilling and milling operations reduces workpiece clamping, improves machining efficiency, and is suitable for small to medium batch production.

Gantry machining center CNC milling: Utilizing the rigidity and large stroke of the gantry machining center, complex contour machining is completed using specialized CNC tools, suitable for large or high-precision D-shaped holes.

CNC lathe tooling: For the internal turning portion of the D-shaped hole, a horizontal lathe is used to initially form the inner hole, combined with milling to achieve the ideal dimensions.

With the development of CNC technology, more and more manufacturing enterprises tend to integrate machining center equipment, enabling multi-functionality, optimizing toolpaths through CAD/CAM programming, reducing manual intervention, and improving accuracy and stability.