Differences and Applications of Belt-Driven and Built-In Spindles

The spindle is the heart of a CNC mill-turn machine, playing a crucial role in cutting, torque, horsepower, and speed. There are different types of lathe spindles, each suited for specific conditions. The appropriate spindle is chosen based on the cutting situation.

Belt-Driven Spindle:

The spindle itself is connected to a pulley and driven by a toothed or flat belt. The advantages include low cost, suitability for heavy cutting, easy maintenance, and inexpensive belt replacement. The disadvantages are limited high-speed capability, lower precision, higher vibration frequency, and rougher surface finish on the workpiece during turning.

Built-In Spindle:

The spindle does not require a pulley, as the motor's rotor and stator are integrated with the spindle housing. It features compact size, high precision, high speed, and low vibration. This type is suitable for workpieces requiring high precision and fine surface finish. Additionally, the built-in spindle offers quicker acceleration and deceleration compared to belt-driven spindles, significantly reducing machining time. However, it is costly, generates high temperatures that require oil or water cooling, and in case of a crash, the entire spindle might need to be replaced.