What are the structural features of high-precision machine tools?

Nov 29,2021

To achieve highly precise cutting motions, motion control in high-precision machine tool machining typically relies on advanced functional components.

In the areas of guideways and bearings, high-precision machining machines commonly employ hydrostatic lead screws and hydrostatic guideways, as these components are essential for achieving precise, smooth positioning, trajectory control, and even tiny-distance movements—key requirements for highly accurate machining processes. Additionally, the electric spindles used in ultra-precise machining centers can also incorporate either hydrodynamic or hydrostatic bearing designs, enabling simultaneous support and cooling functions while enhancing the spindle's stiffness and damping characteristics.

In terms of position control, since precise measurement is essential for achieving high-precision machining, ensuring that the machine tool’s motion meets the required accuracy level demands electronic scales with measurement precision 1 to 2 orders of magnitude higher. Currently, high-precision machining centers typically employ glass gratings with resolutions as fine as 0.05 to 0.1 μm. Moreover, the machining accuracy, surface finish, and tool life of a machine tool are directly proportional to its rigidity; thus, high-precision machines place particular emphasis on the design and material selection of the machine bed.

The machine bed is made of ductile cast iron and, after optimization through finite element analysis, achieves a static stiffness of 120 N/μm—three times higher than that of typical CNC machines. Additionally, its high-frequency dynamic stiffness is 2 to 3 times greater than conventional machine tools. Furthermore, the JIG series machines feature a three-point support design for the bed, with peripheral systems such as the tool magazine, electrical cabinet, and pallet exchange unit physically separated from the bed itself. This innovative approach not only simplifies machine installation but also enhances overall stability and significantly reduces bed vibrations.

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