Marble surface plates, including precision marble plates, are widely recognized for their stable accuracy and ease of maintenance. Their exceptional performance under heavy loads is due to several inherent material and structural properties:
Dense and Durable Material: Marble has a tightly packed crystal structure and a smooth, wear-resistant surface with low roughness, providing a highly stable measurement base.
Naturally Aged and Stress-Free: Over millions of years, natural marble undergoes aging, eliminating internal stresses and ensuring material stability without deformation.
Chemical and Magnetic Resistance: Marble is resistant to acids, alkalis, corrosion, and magnetism, making it ideal for precision environments.
Minimal Thermal Expansion: With a low coefficient of linear expansion, marble maintains high accuracy even under temperature fluctuations.
Impact Behavior: Surface impacts or scratches create only shallow indentations without causing burrs or raised areas, so measurement precision remains unaffected.
Key Limitations
While marble plates are highly precise, they are sensitive to excessive impact and prolonged exposure to high humidity, which can lead to minor deformation. The material has a low water absorption rate (≈1%), so careful handling is necessary during transportation and use.
Industrial and Laboratory Applications
Marble surface plates are ideal reference tools for the inspection of instruments, precision tools, and mechanical components. Compared to cast iron plates, marble's unique properties provide superior stability and precision, especially in high-accuracy measurements.
Material Composition and Physical Properties
Marble plates are primarily composed of pyroxene, feldspar, minor olivine, biotite, and trace magnetite. Their natural black luster, uniform and dense structure, and high hardness allow them to maintain accuracy even under heavy loads.
Performance Standards (GB4987-85):
Grade 000: 1×(1 + d/1000) μm
Grade 00: 2×(1 + d/1000) μm
Grade 0: 4×(1 + d/1000) μm
Grade 1: 8×(1 + d/1000) μm
(d = diagonal length in mm; standard measurement temperature 20±2°C)
Physical Characteristics:
Density: 2970–3070 kg/m³
Compressive Strength: 245–254 N/mm²
Coefficient of Thermal Expansion: 4.61×10⁻⁶/°C
Water Absorption: <0.13%
Shore Hardness: Hs 70+
Advantages
Marble surface plates offer excellent wear resistance, high stability, superior precision, and corrosion resistance. They are the preferred choice for industrial and laboratory measurement tasks.
Purchase Considerations
When selecting a marble surface plate, buyers should prioritize quality, material, and precision over price alone. Some manufacturers may reduce costs by compromising design and production standards, which can negatively affect accuracy. Always ensure the chosen marble plate meets required standards to avoid potential quality issues.