Manufacturing and Calibration of Precision CNC Routers Using a Laser Tracker System

Abstract

Computer Numerical Control (CNC) Multi Axis Routers are typically found in the aerospace, woodworking, plastics, and composites industries. Unlike heavy duty, precision machining centers costing millions of dollars with accuracies within a few thousands on an inch over the machines volume, CNC Routers are an affordable alternative. Traditionally, they are employed for lightweight, lower accuracy applications of wood and plastics. Today, the growing use of composites especially in the aerospace industry creates the need for much higher-accuracy CNC Routers. In an effort to open new markets while meeting the high performance and accuracy requirements for their customers, C.R. Onsrud Inc., implemented a program using three-dimensional metrology to help control the manufacture and calibration of 50 standard models of 3-Axis, 4-Axis, and 5-Axis CNC Routers, CNC Mills, and CNC Machining Centers. Throughout machine construction, laser trackers are used to ensure the overall alignment, quality and testing. For customers requiring high accuracy machines, C.R. Onsrud employs a special volumetric calibration procedure using a laser tracker and a motorized spindle targeting system. This volumetric calibration procedure can improve the accuracy of the machine by a factor of four over the machines basic mechanical capability. This volumetric calibration process can be accomplished in one – two shifts, thereby significantly reducing machine downtime.