I. Material and Appearance Requirements 1. Material Selection (Core Indicators) Table Indicator Technical Requirements Test Standard Typical Application Scenarios Material Fine grain, dense and uniform; preferred materials: Jinan Green / Mount Tai Green / Zhangqiu Black; recycled or dyed materials prohibited Petrographic analysis (GB/T 9966.3) High-precision benchmarks, machine tool beds Bulk Density ≥2.6 g/cm³ GB/T 9966.3 (Archimedes method) Ensures rigidity and stability Compressive Strength ≥80 MPa (Precision grade ≥245 MPa) GB/T 9966.3 Heavy-load bases, gantry components Water Absorption Rate ≤1.0% (Precision grade ≤0.25%) GB/T 9966.3 Moisture and deformation resistance Linear Expansion Coefficient (2～5)×10⁻⁶/℃ (Lower is better) GB/T 9966.3 Constant temperature / variable temperature environments Hardness Shore Hardness HS≥70; Mohs Hardness 6～7 Shore hardness tester Wear resistance, scratch resistance Internal Stress ≥3 months natural aging, residual stress ≤0.02 μm/m Vibration aging test Long-term dimensional stability 2. Appearance and Defects Working Surface: No cracks, pits, loose structure, or scratches; natural stripes/color spots allowed (if they do not affect precision). Non-working Surface: Small area repairs allowed; no large-scale looseness or cracks. Dimensional Deviation: Tolerance for length, width, and thickness ≤±0.5 mm (large components ≤±1.0 mm). Radioactivity: Complies with GB 6566 (natural stone); no special restrictions for civil use/laboratories. II. Precision and Geometric Tolerances (Core) 1. Precision Grades and Flatness According to GB/T 20428-2006, precision components commonly use Grade 000, 00, and 0. The flatness tolerance formula is as follows: Table Grade Flatness Tolerance (μm) Tolerance for 1000×1000 mm Applicable Scenarios Grade 000 1×(1 d/1000) ≤7 μm Metrological benchmarks, semiconductor equipment Grade 00 2×(1 d/1000) ≤10 μm Precision machine tools, CMMs Grade 0 4×(1 d/1000) ≤14 μm Precision inspection, tooling fixtures 2. Geometric Tolerances Parallelism / Perpendicularity: ≤0.005 mm/m (Precision grade ≤0.002 mm/m). Straightness: ≤0.003 mm/m (for guides). Surface Roughness: Working surface Ra≤0.32～0.63 μm; side surface Ra≤10 μm. Hole/Groove Position: Positional tolerance ≤±0.02 mm; no protrusion after steel bushing insertion. 3. Inspection Conditions Temperature: 20±2℃ (Precision grade 20±0.5℃). Measuring Tools: Level, autocollimator, laser interferometer, feeler gauge (accuracy ≥0.001 mm). III. Structural and Machining Process Requirements 1. Structural Design Integrated Design Preferred: Gantry/bases should be integrally formed where possible to reduce splicing (splicing step ≤0.003 mm). Grooving/Drilling: T-slots, threaded holes, and steel bushings must match design; edges chamfered R≥0.5 mm to avoid stress concentration. Weight Reduction Design: Topology-optimized structure, reducing weight by 20%～40% without sacrificing rigidity. 2. Machining Process Blank Preparation: Diamond wire saw / water jet cutting; control cut surface roughness Ra≤3.2 μm. Rough Machining: Rough grinding to shape, leaving 0.5～1.0 mm allowance for finish grinding. Finish Machining: CNC precision grinding in a constant temperature workshop (20±0.5℃); grinding wheel grit ≥2000. Lapping: Manual lapping to design precision; surface Ra≤0.2 μm. Protection: Working surface treated for anti-contamination and pore sealing; non-working surface coated with protective agent.
IV. Performance and Reliability Requirements
- Mechanical Properties
Vibration Resistance: Dampingratio ≥ 0.05 (40% higher than cast iron), amplitude ≤ 0.02 mm/s.
Wear Resistance: Wear ≤ 0.3 μm aft maintenance cycle ≥ 2 years.
Impact Toughness: Only local grain detachment upon impact, no plastic deformation. - Environmental Adaptability
Acid and Alkali Re: No obvious corrosion after immersion in 5% HCl/NaOH for 24 hours.
Rust and Magnetism Resistance: Non-rusting, non-magnetic, good insulationerformance.
Thermal Stability: Dimensional change ≤ (2-5)×10⁻⁶/℃ for every 1℃ temperature change.
V. Acceptance and Inspectio Standards
- Acceptance Items
Таблица
Item Inspection Method Qualification Standard
Material Properties Third-party testing (GB/T 9966 seriomplies with Part 1 of this standard
Flatness Laser interferometer / Autocollimator Within tolerance of corresponding grade
Form and Position Tolerance Coordinate Measung Machine (CMM) ≤ 0.005 mm/m
Surface Roughness Roughness meter Ra ≤ 0.63 μm
Dimension Deviation Caliper / Micrometer ≤ ±0.5 mm
Appearance Visual inspection Magnifying glass (≥10x) No defects affecting precision
ry Documents
Material certificate, test report (including GB/T 9966 series).
Processing drawings, precision inspection records.
Installation and maintenance manual, warranty certificate (precisionwarranty ≥ 1 year).
VI. List of Key Standards
GB/T 20428-2006: Rock Slabs (Core metrology standrd).
JB/T 7974-2013: Technical Conditions for Granite Precision Components (Mechanical industry standard).
GB/T 9966 series: Test methods for natural sto (Physical / Chemical property testing).
GB 6566: Limit of radionuclides in building materials (Safety standard).
JG 117-2013: Verification regulation for slabs (Metrological calibration).
VII. Selection and Application Suggestions
Select grade according to scenario:
Metrology benchmark / Semiconductore 000, water absorption rate ≤ 0.13%.
Precision machine tools / CMM: Grade 00, flatness ≤ 10 mm.
General inspection / Tooling: Grade 0, meets usage requirements.
Supplier Capability: Prioritize manufacturers with ore source control, constant temperature processing, and full-process inspection, oviding CNAS certified reports.
Installation and Maintenance:
Installation: Level adjustment to ≤ 0.005 mm/m, avoid direct sunlight / vibration sources.
Maintenance: Regular cleaning (neual cleaner), avoid strong acid corrosion, calibrate precision once a year.
