Desktop CNC Routers: Applications and Specifications
Desktop CNC routers (Computer Numeric Control) are used to precisely mill machined parts from blocks or sheets of stock materials - metal, wood, or plastic. A desktop CNC router has a computer-controlled cutting head that moves on three axes: front to back (x-axis), side to side (y-axis), and up and down (z-axis). The CNC is designed to allow precise and repeatable forming of three-dimensional parts.
Typical applications for desktop CNC routers
Desktop versions are primarily used for rapid prototyping. Engineers can use desktop CNC routers to fabricate parts to test a design prior to committing to a full manufacturing run. An in-house desktop CNC router can greatly reduce the time and cost of making prototype parts, and prevent the high margin costs found with many third-party prototype houses. Once the drawing is complete, this type of machine works to repeatedly cut exact duplicates of a designed part.
Due to the amount of time it takes for the cutting head to trace the entire contour of the desired part, CNC routing is generally not cost effective for large quantity runs when compared to plastic molding, die casting, or other similar mass-production processes. However, a desktop CNC router can be used to make molds when larger prototype runs are required.
Other applications for this type of router include custom engraving, cutting shapes from sheet stock, or carving surface designs into wood or steel.
Most woodworkers understand that they must try out a design first before deciding if it works or not. CNC router tables take out a lot of the guesswork by pre-programming the dimensions into the attached PC. And if something doesn't feel right, you can simply tweak the dimensions.
Here are some of the features you should investigate when comparing different desktop CNC routers:
- IPM - The working speed of a router is measured in inches per minute (IPM) that the cutting head can travel.
- Travel - The maximum distance that the cutting head can move across the part along each axis. Typical travel for a desktop CNC router might range from 12" x 12" x 4" to as much as 24" x 24" x 6".
- Software Compatibility - Make sure the software that comes with the router can accept drawings from the CAD/CAM software that your engineering department currently uses.
- Number of Axes - A four-axis machine will allow the part being cut to be spun in place, permitting cuts into the sides or bottom of the part. Note that routers featuring additional axes are considerably more expensive than standard three-axis routers.
- RPM - The rotational speed of the cutting head should be variable to allow for different applications and expressed in a range (example: 8,000-32,000 RPM), or as the maximum speed (example: 32,000 RPM).
- Horsepower - The power of the rotary motor that spins the cutting head.
- Accuracy (or repeatability) - The dimensional tolerance the desktop CNC router can hold, measured in inches (example: .0006 inches).
- Resolution - Minimum distance between steps of the servo-controlled cutting head. This controls how fine the details or how smooth a surface the cutting head can make. A typical resolution could be .0003125 or finer and can also be expressed as divisions per inch.
- Router Bits (or cutting heads) - Typically sold separately and several bits may be required for different applications.