Can spindle motors be used for both milling and turning operations?
For cutting steel, a spindle motor with high power and torque is necessary. Typically, spindle motors with power ratings of 5-10 horsepower and high torque capabilities are best suited for cutting steel in CNC machines.
Spindle motors are the heart of milling machines and lathes. They rotate the cutting tool and shape the material by removing chips. While both milling and turning require spindle motors, the two machining methods have different requirements for the spindle.
Different power and speed requirements
Milling operations typically require more powerful spindle motors than turning operations. Milling cuts horizontally through the workpiece, removing a large volume of material per revolution. Turning cuts the workpiece longitudinally, removing a smaller volume of material.
Turning spindles also typically rotate at a higher constant surface speed than milling spindles. The higher the speed, the better the surface finish when turning.
Spindles must be adapted to different tools
Milling spindles are designed to hold milling cutters protruding from the side of the spindle. Turning spindles hold turning tools along the spindle centerline. Some spindles have a large taper (e.g., CAT or BT) and can accommodate a variety of toolholders for different machining operations. However, the maximum speed of the spindle still needs to match the speed requirements of the particular machining operation.
Although milling and turning have different requirements for spindles, there are also multifunctional spindles that can be used for both milling and turning, especially for smaller parts. Compact row tool lathe spindles can accommodate multiple tools on the centerline, including turning tools and light milling heads. Machining centers using high-torque milling spindles can also mount thin turning tools to perform combined milling and turning operations.
In summary, while most spindle motors are designed for milling or turning, a number of versatile options and strategies allow the use of single spindle motors for both types of machining operations, especially on smaller parts. Milling and turning can be performed with single spindle motors by properly selecting spindle speeds, tools, and fixtures based on the material and features being cut. However, for high-volume production, it is recommended that single purpose milling and turning spindles be used to obtain the best results.