Simultaneously measures roughness and contour

June 20, 2008
The new HOMMEL nanoscan in just one pass with a single probe can measure roughness and contour of practically any shape. The new instrument can measure surfaces with a stroke of 24mm with a resolution of 0.68 nanometers (nm) over the entire measuring range. Capable of complex measuring tasks, nanoscan features an innovative integrated software/hardware concept that enables users to capture micro- and macro-structures of parts with very narrow tolerances in short cycle times.The nanoscan is ideal for producers of high-precision parts and assemblies where contour and roughness features are critical, such as fuel injection, transmission parts, pumps, and valves for automotive, aerospace and medical applications. “The user can transform measuring task quickly and easily into a measuring program and evaluate all the common roughness and contour characteristics with sophisticated yet user-friendly software,” said Andy Blind, VP Standard Products at Hommel-Etamic America Corp. “Nanoscan uniquely offers resolutions which are sufficient for roughness measurements and can be used at the same time for wide measuring ranges which are required for contour measurement.” he continued. “The workpiece surface is transferred to a laser interferometer through a tactile stylus tip. The technology used here is a modern digital distance measurement in which high-precision dimensional bodies are scanned by an interferometer using laser light. Due to the constantly high resolution of the interferometer of 0.6 nm, structures of the workpiece surface can be recorded ranging from the submicrometer range to 24 or 48 mm (depending on the probe arm length). These properties allow this measuring system to be used flexibly wherever the roughness and contour of a workpiece surface are to be measured in one go.” Measurement tasks can be set up and performed on the operator panel while CNC-controlled axes allow fully automatic measurement runs in short cycles with guaranteed reproducible measuring results. The measuring accuracy of the nanoscan is based on a mechanical precision-designed and built column and traverse unit. The horizontal and vertical axes are equipped with high resolution, digital scales providing a resolution of 10 nanometers. A minimal guidance error of 0,3 microns over the traverse of 200 mm in the horizontal axis supports the measuring head travel. Column (vertical) travel is 550 mm with repetitive positioning accuracy of less than 10 microns.The precision of the nanoscan’s laser interferometer-based measuring head contributes to a high linearity of the measuring system which is so accurate that there is no need for complex internal compensation routines. With a low residual noise level in the range of 10-20 nm, the instruments are suitable for measuring roughness on optical components. Probing force is electronically controlled and can be set for each measurement individually to protect against surface damage and collisions. The ergonomic design of the measuring stations feature separation of the evaluation units from the generously dimensioned granite plate on active dampers. In addition, a magnetic coupling of the probe arms on the traverse unit simplifies handling, operation and safety. It speeds up change-over of probe arms and at the same time provides a collision protection. The various different available probe arms are equipped with a transponder, i.e. RFID data medium, which enables instant automatic identification of the specific probe arm by the system, includes the probe calibration date.