What are the key parameters to consider when selecting a marble platform?

When selecting a marble(granite)measurement platform,to ensure it meets the requirements for high precision and long-term stability,the following key parameters and characteristics should be prioritized:

I.Core Material Properties

Stone Type and Origin

Prioritize natural granite with high stability and a low coefficient of thermal expansion,such as"Jinan Black"or"Taishan Black"from Shandong,China.These stones have high density(typically≥2.8 g/cm³),uniform mineral grain structure,and minimal long-term deformation.

Hardness and Wear Resistance

The Mohs hardness should be≥6.5(granite rich in quartz is preferred),ensuring the surface is resistant to scratches and extending its service life.

Chemical Stability

The stone must be resistant to acids,alkalis,rust-proof,and non-magnetic to prevent corrosion in humid or chemical environments.

II.Accuracy Grade and Machining Quality

Flatness Tolerance

Select the appropriate grade according to usage requirements,such as the Chinese national standard grades(e.g.,000 grade,00 grade,0 grade).For example:

000 grade:Highest precision,suitable for metrology labs or ultra-precision inspection,with flatness up to±1.5µm(for a 300×300 mm platform).

00 grade:Commonly used for CMM bases,with accuracy at the micron level.

Surface Roughness

The surface roughness(Ra value)of a high-quality platform should be≤0.2µm,ensuring stable workpiece placement and reducing wear.

Machining Process

Whether CNC precision grinding is combined with manual polishing.

Whether edges are chamfered to prevent chipping.

III.Structural Design and Physical Performance

Platform Thickness and Rib Reinforcement Design

Thickness should correspond to the platform size(e.g.,a 1000×1500 mm platform typically has a thickness≥200 mm).Internal网状(rib reinforcement)design is essential to enhance rigidity and reduce deformation under its own weight.

Load Capacity

Clarify static load(uniformly distributed load)and dynamic load(local pressure)parameters to avoid overloading during use,which could lead to micro-cracks or deformation.

Temperature Adaptability

The coefficient of thermal expansion should be≤5.0×10⁻⁶/°C to ensure dimensional stability in temperature-controlled environments(e.g.,20±1°C).

IV.Certification and Inspection Documentation

Third-Party Inspection Report

It is essential to obtain a flatness inspection report issued by an authoritative institution(e.g.,a provincial metrology institute),including grid measurement data and temperature correction values.

Material Certification

Ensure the stone composition and density comply with natural granite standards,avoiding the use of artificial stone or inferior marble.

Certificate of Conformity and Accuracy Grade Label

The platform body should be engraved with the accuracy grade,serial number,and manufacturing date.