Milling is a process of removing material by using rotary cutters mounted into a machine. CNC (computer numerical control) milling is a computerized version of milling where machine operators program a machine to carry out the milling operations automatically. CNC milling covers a broad spectrum of operations utilized by several industries. We’re going to look at the types of CNC milling machines and their functionality.
Like the drill press mentioned earlier, vertical milling operations have the tooling rotation running vertically (in the direction of gravity). A simple vertical CNC milling machine will have three axes where the tooling moves vertically; the table moves from the front to the back of the machine, as well as from side to side. These machines are common in many machine shops because they are cost-effective, simple to program, but still offer diverse capabilities. This video shows a vertical machining center milling hardened tool steel.
A horizontal CNC milling machine will often have a fourth axis for rotation. In the previous video, you can see the table can rotate to allow the milling head to access other sides of the part. For production (producing many of the same parts) this machine also has a pallet changer. The machine has two working areas. One where the components are being machined and another where an operator can safely work on the next set of components. The advantage is the optimization of cutting time. Without the pallet changer, the machine sits idle while an operator is switching our components or changing machine setups. The video below shows the pallet changer in action.
Multi-Axis CNC Milling Machines
Each additional axis represents an additional type of movement. Going beyond three-axis machines greatly expands the capability of a CNC milling machine. Below is a quick reference to the various types of CNC machines along with some advantages and disadvantages of each. Generally speaking, matching the complexity of the part to the complexity of the machine is a best practice. It doesn’t make sense to produce a low tolerance / simple part in a 5 axis milling machine. That is, unless the increased efficiency of having more axes yields a cost savings advantage.