Granite surface plates are essential tools in precision measurement and equipment assembly. To ensure long-term accuracy and stability during use, strict standards must be followed throughout the installation process. This article outlines the key requirements and best practices for assembling and installing granite surface plates.
1. Basic Requirements
Visual Inspection
The working surface must be free from major defects that could affect performance, such as pores, cracks, inclusions, scratches, dents, or rust.
Minor chipping on non-working areas is acceptable if it doesn't interfere with functionality and can be properly repaired.
Material Selection
The granite used should be of fine grain and high density-typically diabase, gabbro, or high-quality granite (e.g., Jinan Black Granite).
Key material properties include:
Mica content < 5%
Elastic modulus > 0.6 × 10⁴ kg/cm²
Water absorption < 0.25%
Surface hardness > 70 HS
These properties ensure the granite's long-term dimensional stability and resistance to environmental changes.
2. Precision Standards
Surface Roughness
Working surface roughness (Ra): 0.32 to 0.63 μm
Side surfaces: up to 10 μm
Maintaining low roughness is crucial for high-precision measurement tasks.
Perpendicularity Tolerance
The verticality between the working surface and side faces should meet national or international tolerance standards (e.g., GB/T 1184 Grade 12 or equivalent), ensuring overall geometric accuracy.
Deflection Control
For Grade 000 and 00 granite plates, it is recommended not to install lifting handles to avoid deformation.
If handles are required, their position must be carefully selected to prevent any impact on flatness.
3. Installation & Mounting Requirements
Foundation Preparation
Ensure the base is flat, stable, and free of vibrations or shock.
It should be precision-ground and meet specific flatness and smoothness standards.
Leveling & Adjustment
The surface plate must be installed horizontally and adjusted using precision leveling pads or screws.
Measurement tools such as spirit levels or dial indicators should be used during adjustment to verify flatness and alignment.
Fixing Method
Choose a mounting method based on the environment and use case:
Bolt mounting
Adhesive bonding
Embedded support systems
During fixation, ensure no gaps or looseness between the plate and foundation to maintain its stability and accuracy.
Surface Protection
Use soft pads or covers during installation to protect the working surface.
Avoid direct contact with sharp or hard tools to prevent scratches or damage.
4. Inspection and Acceptance
Precision Testing
After installation, conduct comprehensive testing for flatness, perpendicularity, and parallelism using certified precision instruments.
Follow national or industry standards for test procedures and tolerances.
Appearance Check
Inspect for cracks, dents, scratches, and ensure all markings (model, serial number, precision grade) are clearly visible and accurate.
Documentation
Create a complete inspection report that includes:
Product model & specifications
Precision grade
Test results
Date of inspection
Inspector's name and signature
Conclusion
Proper installation of a granite surface plate involves careful planning and adherence to strict technical standards-from material selection and foundation preparation to final inspection. By following these detailed guidelines, users can ensure optimal accuracy, stability, and longevity of their granite measuring equipment, meeting the demands of modern precision engineering and metrology.