CNC Milling

CNC milling is a particular form of precision machining in which a cutter removes material by moving into the workpiece at an angle. The movement of the cutter is controlled by computer instructions, allowing for extreme precision and repeatability.

Milling is different to CNC turning, another popular CNC service in which a single-point cutting tool is used to cut the workpiece from block or bar materials while it is rotated at speed in a chuck. Unlike milling, CNC turning is generally used to create round or tubular shapes.

CNC milling can be used for the rapid manufacture of either prototypes or end-use parts

Like other machining processes, CNC milling begins with designers creating a digital part using CAD (Computer-aided Design) software. The file is then converted into “G-Code,” which can be recognized by a CNC mill.

CNC mills have a “worktable” and work holding device to keep a block of material — known as the “workpiece” — in place. The worktable may or may not move, depending on the style of the machine.

During the CNC milling process, the rapidly rotating cutting tool makes contact with the workpiece, cutting away material. The tool moves according to the G-Code instructions so that cuts are made in the right places until the part is finished. Some CNC mills use moving worktables to create a greater number of cutting angles.

CNC mills can cut through hard metals. This makes them more versatile than CNC routers, which are similar to 3-axis mills but less capable of penetrating hard materials.

CNC mills are often defined by their number of axes. More axes mean they can move their tool and/or workpiece in a greater number of ways, giving greater cutting flexibility and the ability to make more complex parts in a shorter time.

3-axis: Standard CNC mills have 3 axes, allowing the spindle (and attached cutting tool) to travel along the X, Y and Z axes. If the cutting tool cannot reach an area of the part, the part must be removed and manually rotated.

4-axis: Some CNC mills incorporate an extra degree of movement by rotating on a vertical axis. This enables greater flexibility and the ability to create more complex parts.

5-axis: The most advanced type of widely used CNC mill is the 5-axis mill, which incorporates two extra degrees of movement, often by adding rotation to both the worktable and spindle. Parts usually don’t require multiple setups, since the mill can manipulate them into different positions.

CNC mills are often defined by their number of axes. More axes mean they can move their tool and/or workpiece in a greater number of ways, giving greater cutting flexibility and the ability to make more complex parts in a shorter time.

3-axis: Standard CNC mills have 3 axes, allowing the spindle (and attached cutting tool) to travel along the X, Y and Z axes. If the cutting tool cannot reach an area of the part, the part must be removed and manually rotated.

4-axis: Some CNC mills incorporate an extra degree of movement by rotating on a vertical axis. This enables greater flexibility and the ability to create more complex parts.

5-axis: The most advanced type of widely used CNC mill is the 5-axis mill, which incorporates two extra degrees of movement, often by adding rotation to both the worktable and spindle. Parts usually don’t require multiple setups, since the mill can manipulate them into different positions.