The spindle is the core component of a  lapping machine. Its structural configuration and material properties directly determine the rotational accuracy, rigidity, and thermal stability of the equipment, thereby significantly affecting the flatness, parallelism, and surface roughness of workpieces.

From a structural perspective, different spindles are suitable for various accuracy requirements. Rolling bearing spindles feature a compact structure and good load-bearing capacity, and are mostly used for general-precision surface lapping. However, their contact friction tends to generate heat and vibration, which limits ultra-precision machining. Hydrostatic spindles are supported by a pressurized oil film, offering high rotational accuracy and excellent damping characteristics, which effectively suppress vibration and greatly improve machining stability. Aerostatic spindles operate without contact friction, producing extremely low heat generation and minimal rotational error. They are widely used in high-precision lapping of optical glass and other components, ensuring micron or even submicron-level flatness.

Spindle material serves as the foundation for maintaining long-term accuracy. Medium and low carbon alloy steels, after quenching and tempering, exhibit good comprehensive mechanical properties and can meet the requirements of general lapping machines. Bearing steel features high hardness, excellent wear resistance, and strong dimensional stability, making it suitable for spindles with high requirements for accuracy retention. Ceramic matrix composites have low density and low thermal expansion coefficient, which reduce centrifugal deformation and thermal error during high-speed operation, further enhancing the accuracy stability of the equipment.

In addition, spindle dynamic balance, cooling and lubrication, and assembly technology work together with structure and material. A spindle with a reasonable structure, high-quality material, and precise assembly features small radial runout and stable operation, which effectively reduces machining errors.

In summary, the rational selection of spindle structure and material can effectively control vibration, temperature rise, and deformation, making it the key to improving surface lapping accuracy and ensuring stable machining quality.