OKK HP300S

The OKK VP-600 is a mid-range precision VMC with a 600 mm X-travel envelope focused on structural rigidity and mid-range accuracy for die and mold work. The HP300S is a high-speed specialist machine in the 300 mm travel class, optimized specifically for the highest spindle speeds (30K–40K RPM), finest surface finish quality, and thermal accuracy stability for small-part precision work. The VP-600 is the more versatile production machine; the HP300S is the right choice when the application specifically requires 30,000+ RPM, maximum surface finish quality, or very small part precision that exceeds the VP-600's capability.

Yes. Graphite electrode machining for sinker EDM is one of the HP300S's primary application areas. Graphite at 30,000–40,000 RPM with HSK tooling and appropriate carbide or diamond-coated tooling produces electrode surfaces with Ra values in the 0.2–0.4 µm range directly from the machine, reducing or eliminating the grinding and polishing steps required when electrodes are machined on lower-speed equipment. Key requirements for graphite machining include dust collection (graphite dust is electrically conductive and abrasive), MQL or dry machining rather than flood coolant (graphite degrades with water), and appropriate spindle seals to prevent graphite ingress into spindle bearings.

For the HP300S's primary applications in die and mold, the most commonly used CAM systems are Hypermill (Open Mind), PowerMill (Autodesk), Mastercam, and NX CAM. All support the high-speed machining toolpath strategies (3D offset, scallop height-controlled parallel finishing, pencil tracing) required for complex mold cavity machining. The key CAM requirement for the HP300S is a system that can maintain consistent chip load through variable-curvature surfaces — systems with adaptive feed rate control through tight corners and cusp areas protect the small-diameter tooling and maintain surface finish quality. Fanuc post-processors for 31i-B5 are widely available from all major CAM vendors.

OKK installs temperature sensors at multiple points in the spindle housing, spindle motor, and machine structure. A thermal growth model — calibrated empirically for the specific machine's thermal behavior — uses real-time sensor readings to calculate the expected Z-axis displacement caused by spindle motor heat and structural temperature changes. The control continuously adjusts the Z-axis zero offset to counteract this calculated displacement, maintaining the spindle tip's Z position within specification regardless of spindle running time, speed, and load history. This is different from a simple warm-up program: compensation is active throughout the shift, not just at machine start.

The HP300S ATC is designed for the small-diameter, short-reach tooling appropriate for precision high-speed machining. Maximum tool diameter is typically 80 mm (adjacent pockets occupied) or 120 mm (adjacent pockets empty). Maximum tool length is 250 mm. Maximum tool weight is 3 kg. These limits reflect the machine's application focus on small-to-medium precision parts where tool sizes are primarily in the 0.5–20 mm diameter range. Large face mills and high-diameter roughing tools are not the intended application; if occasional larger-diameter roughing is required, a separate roughing machine is the standard approach in shops using the HP300S as a dedicated precision finisher.