Case Study: Hybrid PCD Combination Drill for WCBS Valve Body Machining
Aoshiji developed a hybrid PCD-and-carbide combination drill for high-volume machining of a 6061 aluminum WCBS brake-by-wire valve body. The custom tool integrates two machining stages into one tool to reduce tool changes, save tool-magazine capacity and control chip evacuation across a large diameter difference.
The precision stage uses PCD cutting edges to achieve the required Ra 1.6 surface finish on the 120° bottom face, while the higher-stock-removal stage uses carbide with application-specific cutting geometry for chip breaking and cost control.
At 5,000 rpm and 0.26 mm/rev, the final production tool achieved a stable tool life of 8,000 components compared with approximately 2,000–4,000 components for the previous tool—an improvement of 2–4× under the reported production conditions.
WCBS Valve Body Case Results at a Glance
| Item | Production Data |
|---|---|
| Workpiece | WCBS brake-by-wire valve body |
| Material | 6061 aluminum alloy |
| Machine | Horizontal machining center |
| Coolant | Internal coolant, emulsion |
| Tool Concept | Hybrid PCD + carbide combination drill |
| Machining Diameters | Ø11 mm + Ø23.81 mm |
| Surface Requirement | Ra 1.6 on the 120° bottom face |
| Speed | 5,000 rpm |
| Feed | 0.26 mm/rev |
| Previous Tool Life | 2,000–4,000 pcs |
| Customer Target | ≥4,000 pcs |
| Aoshiji Tool Life | 8,000 pcs |
| Result | 2–4× longer tool life |
01 WCBS Valve Body Machining Application
The workpiece is a 6061 aluminum valve body used in a WCBS (Wire-Controlled Brake System) for automotive brake-by-wire applications. The component contains multiple precision hydraulic features that must be machined efficiently while maintaining dimensional accuracy, surface finish and stable chip evacuation in high-volume production.
In this application, limited tool-magazine capacity and cycle-time requirements made it necessary to combine two machining positions into a single custom tool rather than use separate tools for each operation.
Aoshiji also supports custom cutting tools for automotive manufacturing where cycle time, tool life and process stability are critical.
02 Customer Machining Requirements
| Requirement | Customer Application |
|---|---|
| Workpiece | WCBS valve body |
| Material | 6061 aluminum alloy |
| Machine Tool | Horizontal machining center |
| Coolant | Internal coolant, emulsion |
| Machining Features | Ø11 mm + Ø23.81 mm |
| Bottom Geometry | 120° bottom face |
| Surface Finish | Ra 1.6 |
| Tool-Life Baseline | 2,000–4,000 pcs |
| Customer Tool-Life Target | ≥4,000 pcs |
| Production Requirement | Combine two machining positions in one tool |
03 Machining Challenges
Tool Magazine Capacity and Cycle Time
Two machining positions had to be integrated into one tool because of limited tool-magazine capacity and strict cycle-time requirements. The large diameter difference between the two stages increased the difficulty of maintaining tool-body rigidity and stable cutting performance.
Ra 1.6 Surface Finish on the 120° Bottom Face
The precision stage had to generate a 120° bottom face with an Ra 1.6 surface-finish requirement directly with the combination drill, placing high demands on cutting-edge stability and finished-surface quality.
Large Stock Removal and Chip Entanglement
The larger-diameter stage required substantial material removal. The large radial stock caused long continuous chips and severe chip-entanglement risk, making chipbreaker geometry and chip evacuation critical to stable production.
Tool-Life Stability
The previous tool delivered approximately 2,000–4,000 components with significant life variation. The customer required a more stable process and a substantially longer usable tool life while maintaining machining accuracy and production cost control.
04 Hybrid PCD + Carbide Combination Drill Design
One Tool for Two Machining Stages
The two required hole features were integrated into one combination tool, reducing tool-change demand and saving tool-magazine capacity while maintaining one controlled tool setup. This project follows the same engineering principle used in our multi-stage PCD combination tools for stepped and multi-feature hole machining.
Stepped Core Design for Rigidity and Chip Space
A stepped core-thickness design was engineered around the large diameter difference between the two cutting stages. The body structure had to provide sufficient rigidity while preserving the chip space required for reliable evacuation.
PCD Precision Stage for Surface Finish
PCD cutting edges were applied to the precision stage responsible for the 120° bottom face. The wear resistance and edge stability of PCD were used to maintain the required Ra 1.6 finish in high-volume machining of 6061 aluminum. Similar drawing-specific solutions are developed across our custom PCD cutting tools range for precision machining of aluminum and other non-ferrous materials.
Carbide Stage for High Stock Removal and Cost Control
The higher-stock-removal stage used carbide rather than PCD where the tolerance and surface-finish requirements were less demanding. Application-specific radial rake and clearance geometry were used to improve chip breaking, reduce chip entanglement and control total tool cost.
The steel tool body, brazed cutting elements and final precision-ground geometry were produced through Aoshiji’s controlled PCD tool manufacturing process.
| Tool Brand | Diameter | Speed | Feed | Tool Life |
|---|---|---|---|---|
| Original Brand Tool | ∅11 / ∅23.81 | 5000 r/min | 0.26 mm/rev | 2,000–4,000 pcs (unstable, large fluctuation) |
| Aoshiji® Custom Tool | ∅11 / ∅23.81 | 5000 r/min | 0.26 mm/rev | 8,000 pcs (Stable & consistent) |
| Conclusion | Tool life improved by 2–4× with stable and consistent performance | |||
Under the reported production conditions, the Aoshiji tool achieved a stable service life of 8,000 components, representing approximately 2–4× longer tool life than the previous tool while maintaining the required machining quality.
06 Why the Hybrid Tool Design Worked
The successful result came from assigning different cutting materials and geometries to the functions where they provided the greatest value rather than using one cutting material for the entire tool.
PCD was applied to the precision stage that required Ra 1.6 surface quality in 6061 aluminum, while carbide was used at the higher-stock-removal stage to control tool cost and allow chipbreaker geometry to be optimized for the heavier cut.
The stepped steel-body design provided the structural support required across the large diameter change, while integrating both stages into one tool reduced tool changes and tool-magazine demand. The resulting design addressed surface finish, chip control, tool life and production efficiency as one machining system rather than as separate tool problems.
07 Conclusion
This WCBS valve-body project demonstrates how a drawing-specific hybrid PCD combination drill can solve several production constraints at the same time. By combining a PCD precision stage, a carbide high-stock-removal stage and a stepped tool-body design, the final tool integrated two machining positions while maintaining surface quality and improving chip control.
At 5,000 rpm and 0.26 mm/rev, the production tool achieved a stable tool life of 8,000 components compared with approximately 2,000–4,000 components for the previous tool, representing a reported 2–4× improvement under the customer’s production conditions.
Aoshiji develops custom PCD cutting tools from component drawings, machining conditions, tolerance requirements and production targets for automotive and other high-volume precision-machining applications.
