Granite mechanical components are widely used in precision machinery due to their exceptional stability and wear resistance. To ensure performance and longevity, these components must meet a range of technical standards. Below is a summary of key requirements:
1. Handle Design for High-Precision Grades
For grade 000 and grade 00 granite mechanical components, it is generally recommended not to include lifting handles to avoid any interference with precision.
2. Repairable Imperfections on Non-Working Surfaces
Minor chips or dents located on non-functional surfaces may be repaired, provided they do not affect performance.
3. Material Specifications
Granite parts should be manufactured from fine-grained, high-density materials such as gabbro, diabase, or black granite. Acceptable materials should meet the following criteria:
Mica content: ≤ 5%
Elastic modulus: ≥ 0.6 × 10⁴ kg/cm²
Water absorption rate: ≤ 0.25%
Surface hardness: > 70 HS
4. Surface Roughness Requirements
Working surface roughness (Ra): 0.32 – 0.63 μm
Side surface roughness: ≤ 10 μm
5. Flatness Tolerance
The flatness of the working surface must comply with tolerance levels as defined in the relevant standards (refer to Table 1 in specific technical documentation).
6. Perpendicularity Tolerances
The side surfaces must be perpendicular to the working surface according to Grade 12 standards specified in GB/T1184.
Adjacent side surfaces must also comply with the same perpendicularity tolerance level.
7. Surface Wave Deviation
When inspecting the flatness using the diagonal or grid method, the air gap fluctuation on the working surface must remain within the specified limits (see Table 2).
8. Load-Bearing Capacity and Deflection
The central area of the granite component's surface must support concentrated loads within the defined range. The maximum allowable deflection under rated loads is outlined in Table 3 of the standard.
9. Surface Defect Limitations
The working surface must be free from defects that would negatively impact appearance or performance, including:
Sand holes
Air bubbles
Cracks or inclusions
Shrinkage cavities
Scratches, dents, or rust marks
10. Threaded Holes and Grooves
For Grade 0 and Grade 1 components, any threaded holes or grooves present must be recessed and not protrude above the working surface.