CNC Routers

CNC routers are computer-controlled machines that are capable of cutting complex two-dimensional (2D) and three-dimensional (3D) shapes with router bits that spin at high speeds. CNC routers consist of a mechanical base, linear rails and bearings, stepper motor or servo motor, lead screws or ball screws, power supply, and stepper motor drive or servo motor drive. The mechanical base is the frame that holds all of the router’s components together. Several construction styles are available. C-frame routers have a frame shaped like the letter “C” and include a compound X/Y table and vertical Z-axis column. Gantry-style routers are constructed with a stationary table and a bridge that spans vertical columns. All gantry routers have three moving axes: X, Y, and Z.  Four-axis devices have an additional moving axis. In five-axis configurations, the router head includes rotary and angular axes. Six-axis CNC routers are usually articulated robots with a router head attachment. Articulated robots have arms with three rotary joints.  

Most CNC routers interface to specialized or general-purpose computers that run graphical operating systems such as Microsoft^® Windows^®. Both Microsoft and Windows are registered trademarks of Microsoft Corporation. Computer-aided design (CAD) software is used to read a special file that describes the geometry of the part to be machined. The CAD program outputs a tool path file with information that the controller computer can use to send synchronized, step and direction signals to the stepper motor driver or the servo motor driver. In turn, the motor driver sends signals to the motor, causing it to move in the appropriate direction along a specific axis. The lead screws to which the stepper motor or servo motor is attached move the axes along linear rails that are usually made of aluminum.     

Selecting CNC routers requires an analysis of specifications and features. Devices with 3, 4, 5, or 6 axes are commonly available. For each of these router types, the travel or work area of the X, Y, and Z axes is an important consideration. Maximum speed refers to the maximum traverse rate that CNC routers slide. Spindle power refers to the power rating of the spindle that carries the cutting tool. In terms of features, some CNC routers have machine enclosures to protect operators or contain chips and cutting fluids. Others have multiple spindle heads that allow routers to use several cutting tools to perform different operations with a single machine setup. For example, tool changers allow CNC routers to perform more than one function without requiring an operator to change tooling types. CNC routers with a vacuum system to fixture the parts to be machined are also available.

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