The Challenge
A major marine technology client in Aberdeen approached Strategic Innovations Dundee Ltd with a severe production bottleneck. They required low-to-medium volume manufacturing of a high-performance hydraulic actuator manifold block. The component was machined from a solid billet of Duplex Stainless Steel (Grade 2205)—a material notorious for high work-hardening rates, poor thermal conductivity, and extreme tool wear.
The primary engineering challenges were geometric complexity and strict dimensional tolerances. The design featured deep, intersecting internal fluid channels, an asymmetric external profile, and a series of blind keyways. The client’s previous subcontractor relied on traditional 3-axis operations, which required five independent setups. This layout led to cumulative tolerance stack-ups, frequent tool deflection during deep-pocket milling, and an unacceptable reject rate on the internal blind keyways. Furthermore, maintaining a surface roughness of under 0.8 Ra on the sealing faces was proving impossible without costly manual polishing.
The Engineered Solution
Our engineering team in Dundee re-evaluated the manufacturing routing to optimize efficiency and component integrity. We transitioned the component entirely to our advanced 5-axis CNC milling center. By designing a bespoke hydraulic workholding fixture, we condensed five separate operations down to a single setup. This single-source approach completely eliminated the risk of positional errors between intersecting faces, guaranteeing absolute concentricity across the internal fluid ports.
To combat the aggressive work-hardening characteristics of the Duplex stainless steel, we deployed solid-carbide, variable-helix endmills coated with AlTiN. We programmed a trochoidal milling toolpath strategy using a light radial depth of cut (Ae) and maximum axial depth of cut (Ap). This maintained a constant chip load, efficiently evacuated heat into the chips rather than the workpiece, and prevented premature tool failure.
The deep, internal blind keyways presented a distinct challenge where conventional mechanical tooling would deflect or break. To solve this, we routed the parts to our specialized EDM wire erosion department in Scotland. Using precise spark erosion with high-tensile brass wire, we cut the intricate keyway geometries into the pre-hardened Duplex blocks. This process achieved sharp internal corners and micron-level precision without introducing mechanical stress or thermal distortion to the component walls.
Finally, the sealing faces were finished using high-speed contouring cycles on the 5-axis mill. We utilized a dense, overlapping ball-nose toolpath sequence to achieve a flawless, mirror-like surface roughness of 0.4 Ra, completely removing the need for secondary manual finishing.
The Outcome & Operational Impact
By consolidating the manufacturing line at our facility, Strategic Innovations Dundee Ltd delivered outstanding operational improvements for the client. Transitioning to single-setup 5-axis CNC milling achieved a massive 65% reduction in total setup times. By pairing this with high-precision EDM wire erosion, we reduced overall production lead times by 40%, allowing the client to accelerate their assembly schedule.
The surface finish on all critical sealing faces was brought down securely to 0.4 Ra, well exceeding the initial target. Every component was delivered with 100% geometric conformity across the intersecting internal pathways, eliminating the scrap rates seen with the previous manufacturer. This project highlights our position as a leader in precision engineering in Dundee, proving our capacity to solve highly complex, multi-process machining problems for the UK’s demanding subsea and energy sectors.
