CNC Machine Tool

Accura Technics, LLC announces the successful launch of their MicroTol(TM) product line. The first machine is now in production at a precision optics manufacturer near Rochester, New York. With other applications in bearings, aerospace and automotive industries, the MicroTol(TM) is a versatile CNC machine tool adaptable to turning as well as grinding.

The lead-off machine is tooled for grinding spheres and aspheres in BK7 optical glass. A cross-axis approach is used with the axis of the work spindle horizontal, and the axis of the wheel spindle vertical. The workpiece is routed around the periphery of the grinding wheel by X and Z-axis interpolation to produce either a spherical or an aspherical shape. Spherical shapes can be programmed as a single parameter - radius. Aspherical shapes, such as paraboloids, can be programmed as a point table or with a parametric equation. Tool radius compensation features are used to adjust for wheel diameter.

"Optical components require tight tolerances while maintaining rapid throughput," said Patrick Hurst, president of Accura Technics. "The MicroTol(TM) can generate excellent geometry and surface finish while minimizing the grinding time prior to polishing operations."

The work area consists of a hydraulic chuck supported by Accura(TM)'s proprietary hydrostatic work spindle. Hydrostatic bearings provide added damping and robustness not typically found in work spindle designs. The X and Z-axis slide system is supported by hydrostatic slide bearings and driven by high performance linear motors with glass scale feedback. The 20,000 RPM air bearing wheel spindle is rigidly mounted to the machine base on a micro-adjustable column. The grinding operation is performed with a metal bond diamond wheel.

The MicroTol(TM) has a large, configurable work area that is totally enclosed for coolant containment. Standard X-axis travel is 8" (200 mm). Standard Z-axis travel is 4" (100 mm). Rough and finish wheel spindles on a rotary table can be added for grinding small optics and molds. Expanded capabilities include match grinding and match turning for sub-micron fits. The machine can be fully automated with robot loader and conveyors. Accura Technics is a certified Fanuc Robotics integrator.

Accura Technics' other products include the 1210G vertical axis, multi-surface grinder; and a compact cylindrical OD grinder.