I. Minimal internal stress, permanent non-deformation
Natural granite undergoes natural geological aging over hundreds of millions of years, completely releasing internal stress. Compared to cast iron, cast aluminum, and welded steel structures:
It does not exhibit aging creep or long-term stress rebound;
The geometric accuracy of the CMM table, crossbeam, and column remains stable for decades;
The machine maintains verticality, parallelism, and straightness over the long term, ensuring measurement repeatability and stability.
II. Extremely low coefficient of thermal expansion, resistant to temperature variation errors
The linear expansion coefficient of granite is much lower than that of steel and cast iron:
Dimensional deformation is negligible under minor environmental temperature fluctuations and workshop day-night temperature differences;
CMMs perform micron-level precision measurement where temperature change is the largest source of error; granite significantly suppresses measurement deviations caused by thermal deformation;
It maintains high precision without strict temperature control, making it suitable for ordinary precision workshops.
III. High rigidity strong vibration damping, resistant to vibration interference
The material is dense with high hardness and overall rigidity; loads do not cause sinking or micro-deformation;
The natural crystalline structure possesses excellent vibration damping and absorption properties, far superior to cast iron;
It isolates micro-vibrations from workshop cranes, machine tools, and foot traffic, preventing mis-triggering of the CMM probe and trajectory deviation, thereby improving measurement precision and stability.
IV. High hardness and wear resistance, lasting working surface precision
Mohs hardness of 6-7, wear-resistant, resistant to scratches and wear:
The measurement platform withstands long-term placement of fixtures and workpieces without developing indentations or scratches;
The precision ground reference surface maintains ultra-high flatness for a long time, requiring minimal maintenance and eliminating the need for frequent rework.
V. Rust-proof, corrosion-resistant, and good insulation
It is not afraid of humidity, cutting fluids, or mild acid/alkaline fumes; it never rusts, unlike cast iron which is prone to rusting, peeling, and precision degradation;
Natural stone is insulating and non-conductive, making it suitable for CMM electrical systems with photoelectric, grating, and precision sensors, avoiding interference from static electricity and leakage current.
VI. Uniform material, easy for ultra-precision grinding
Granite has a uniform and dense structure with no sand holes or pores:
It can be ground to a mirror-like ultra-high flatness, meeting CMM requirements for micron and sub-micron benchmarks;
It is suitable for integral machine beds, gantry crossbeams, and guide rail bases, featuring one-piece molding without assembly errors.
VII. Good dimensional stability, suitable for large integral components
It can be made into ultra-large integral bases and gantry columns with strong integrity and no splicing seams; the machine’s geometric structure forms a rigid closed loop, making it more stable than assembled steel structures and suitable for large gantry-type CMMs.
