Choose a CNC lathe for machining cylindrical, conical, or threaded parts. On a lathe, the workpiece is mounted on the spindle, and the tool typically rotates while the workpiece rotates. For machining complex contours, flat surfaces, or special-shaped structures, choose a CNC milling machine. The tool is mounted on the spindle, and the workpiece typically rotates while the tool rotates.
The cutting speed of a CNC milling machine refers to the rotational velocity of the cutter tip. Milling cutters are relatively small, so their rotational speeds are very high, sometimes reaching tens of thousands of rpm. The depth of a milling cutter is a bit tricky to understand, but it can be thought of as the area of penetration into the part, encompassing both the depth and the width of the cutting edge. For example, the feed rate, for a flat surface, is the speed at which the cutter is milling one side of the surface. Based on the three elements of cutting, the material removed is depicted as a small spiral, with the cutter marks forming a cross.
CNC lathes and CNC milling machines operate on different machining principles.
CNC lathes use a rotating workpiece and a fixed tool: The workpiece rotates via the spindle, while the fixed tool performs cutting. They are primarily used for machining rotating parts (such as shafts, disks, and sleeves).
Typical operations include turning external diameters, internal holes, threading, and grooving. Axial motion typically involves two axes: the X (radial) and the Z (axial).
CNC milling machines use a rotating tool and a fixed workpiece: The spindle rotates the milling cutter, while the workpiece is fixed to the worktable. Complex shapes are cut using multi-axis motion. Typical operations include milling planes, contours, slots, drilling, and tapping. Motion axes: At least three (X/Y/Z), with advanced models supporting four or five (e.g., rotary tables).
Tools and Cutting Methods
Lathe tools: Mostly single-point turning tools (such as external cylindrical cutters and thread cutters), which provide a simple cutting path.
Milling machine tools: Multi-edge milling cutters (such as end mills, face mills, and ball-end mills) achieve efficient cutting through the rotation of multiple blades.
Programming Differences
Lathe programming: Common G codes focus on radial (X) and axial (Z) commands (such as G01 for linear turning).
Milling machine programming: Multi-axis linkage (such as G02/G03 for circular interpolation) is required, making programs more complex.
Applicable Workpiece Types
CNC Lathes: Suitable for symmetrical rotating parts (such as screws, bearing seats, and flanges).
CNC Milling Machines: Suitable for non-rotating parts or complex geometries (such as molds, gears, housings, and special-shaped parts).
Combined Machining (Mill-Turn Centers)
Modern high-end machine tools may combine both functions (such as turn-mill centers), offering both turning and milling capabilities, reducing workpiece setup times and improving precision.
Typical Applications
Lathes: Mass-produce shafts, threads, tapers, and more.
Milling Machines: Manufacture molds, precision parts, and aerospace components.
