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Optics Fabrication Equipment
Kinetic Ceramics Inc. is the world leader in precision photonics machining equipment. Our precision lathe fast axis servo systems have been placed in the field for high volume production manufacturing of challenging shapes in plastics, aluminum, brass and nickel. The solid state piezoelectric actuation is demonstrating its continuous precision and durability advantage in 24 hour a day manufacturing environments. Click here for further information about our Diamond Turning Rotary Module.
Precision Fast Tool Servo Module for
Diamond Turning Lathes
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Square Profile Cut While Spindle Rotates at High Speed |
FTS-400 |
Turnkey Fast Tool
Servo System |
A versatile Fast Tool Servo (FTS-400) has been developed by Kinetic Ceramics Inc. for machining non-rotationally symmetrical components. The cutting tool is driven by a fully temperature compensated and backlash free piezoelectric mechanism allowing surface features to be cut in a part turning at upwards of 6,000 rpm. This fast Z axis lathe accessory is rapidly gaining acceptance.
The servo can be fitted to any lathe including high precision diamond turning machines, forming a supplementary fast 'Z' axis. Typical axis bandwidths for such lathes are less than10Hz, but the FTS provides a bandwidth of up to 1000Hz, allowing the machining of complex shapes on a range of materials at high spindle speeds. Although the technology was developed for direct machining of contact lenses and casting molds, parts that have been successfully machined range from optically clear lens molds to contoured automotive pistons. Better than 12 nm rms. surface finish can be routinely produced and cut depths to 400 microns (.016 inches) are possible.
Extremely fast response coupled with substantial output force and high rigidity were principal requirements for the actuation system. The fast tool servo utilizes state of the art piezoelectric technology, along with a patented mechanical amplification mechanism to achieve these goals. The marriage of mechanical amplifier and piezoelectric actuators has permitted a heretofore laboratory technology to break out into mainstream usage in industry.
Thermal expansion effects in metal structures can be of the same order as the output motion from a piezoelectric actuator, potentially causing tool offset. In the Fast Tool Servo T-lever amplifier, thermal changes cause equal expansion and contraction in both support paths, resulting in no net output displacement.
Feedback control
A double feedback loop is used to linearize the output motion with respect to the control signal over a broad frequency range. A high bandwidth inner loop does most of the work by monitoring the amount of electrical charge stored in each PZ actuator and generating an error signal that is summed with the control signal. The charge loop requires no special stability compensation since it is first order and hence unconditionally stable. A position loop is constructed around the charge loop, with its position sensor mounted on the tool beam.
Diamond Turning Rotary Module
 
System Description
The Kinetic Ceramics RFTS module utilizes a unique piezoelectric shearmotor to produce high frequency angular motion of a lightweight single crystal diamond cutting tool. The shearmotor is mounted in a sealed housing containing a cooling fluid to control the temperature of the high performance piezoelectric driving elements. The housing also contains a temperature sensor to monitor the shearmotor temperature. The tool holder is mounted in a titanium flexure that has very high rigidity in the vertical axis as well as in the tool longitudinal axis. Side to side motion of the cutting tool is unrestricted.
A high power amplifier drives the shearmotor achieving an angular rotation. A drive signal is synthesized for the amplifier with a Windows based virtual instrument providing user control.
Features
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