As a critical reference tool in precision measurement areas, granite slabs’ wear resistance directly determines their service life, measurement accuracy, and long-term stability. The following systematically explains the key points of their wear resistance from the perspectives of material properties, wear mechanisms, performance advantages, influencing factors, and maintenance strategies.
1. Material Properties and Wear Resistance Basics
Good Hardness and Dense Structure
Granite slabs are primarily composed of pyroxene, plagioclase, and a small amount of biotite. Through long-term natural aging, they develop a fine-grained structure, achieving a Mohs hardness of 6-7, a Shore hardness exceeding HS70, and a compressive strength of 2290-3750 kg/cm².
This dense microstructure (water absorption <0.25%) ensures strong inter-grain bonding, resulting in surface scratch resistance significantly superior to cast iron (which has a hardness of only HRC 30-40).
Natural Aging and Internal Stress Release
Granite slabs are sourced from high-quality underground rock formations. After millions of years of natural aging, all internal stresses have been released, resulting in fine, dense crystals and a uniform texture. This stability makes it less susceptible to microcracks or deformation due to stress fluctuations during long-term use, thereby maintaining its wear resistance over time.
II. Wear Mechanisms and Performance
Main Wear Forms
Abrasive Wear: Micro-cutting caused by hard particles sliding or rolling on the surface. Granite’s high hardness (equivalent to HRC > 51) makes it 2-3 times more resistant to abrasive particles than cast iron, significantly reducing the depth of surface scratches.
Adhesive Wear: Material transfer occurs between contact surfaces under high pressure. Granite’s non-metallic properties (non-magnetic and non-plastic deformation) prevent metal-to-metal adhesion, resulting in a near-zero wear rate.
Fatigue Wear: Surface peeling caused by cyclic stress. Granite’s high elastic modulus (1.3-1.5×10⁶kg/cm²) and low water absorption (<0.13%) provide excellent fatigue resistance, allowing the surface to maintain a mirror-like gloss even after long-term use.
Typical Performance Data
Tests show that granite slabs experience only 1/5-1/3 the wear of cast iron slabs under the same operating conditions.
The surface roughness Ra value remains stable within the 0.05-0.1μm range over a long period of time, meeting Class 000 precision requirements (flatness tolerance ≤ 1×(1+d/1000)μm, where d is the diagonal length).
III. Core Advantages of Wear Resistance
Low Friction Coefficient and Self-Lubrication
Granite’s smooth surface, with a coefficient of friction of only 0.1-0.15, provides minimal resistance when measuring tools slide across it, reducing wear rates.
Granite’s oil-free nature eliminates secondary wear caused by dust adsorbed by the lubricant, resulting in significantly lower maintenance costs than cast iron slabs (which require regular application of anti-rust oil).
Resistant to Chemical Corrosion and Rust
Excellent performance (no corrosion within a pH range of 0-14), suitable for use in humid and chemical environments.
Rust-resistant properties eliminate surface roughening caused by metal corrosion, resulting in a flatness change rate of <0.005mm/year after long-term use.
IV. Key Factors Affecting Wear Resistance
Ambient Temperature and Humidity
Temperature fluctuations (>±5°C) can cause thermal expansion and contraction, inducing microcracks. The recommended operating environment is a controlled temperature of 20±2°C and a humidity of 40-60%.
High humidity (>70%) accelerates moisture penetration. Although granite has a low water absorption rate, prolonged exposure to humidity can still reduce surface hardness.
Load and Contact Stress
Exceeding the rated load (typically 1/10 of the compressive strength) can cause localized crushing. For example, a certain model of granite slab has a rated load of 500kg/cm². In actual use, transient impact loads exceeding this value should be avoided.
Uneven contact stress distribution accelerates wear. A three-point support or uniformly distributed load design is recommended.
Maintenance and Cleaning
Do not use metal brushes or hard tools when cleaning. Use a dust-free cloth dampened with isopropyl alcohol to avoid scratching the surface.
Regularly check the surface roughness. If the Ra value exceeds 0.2μm, regrind and repair are required.
V. Maintenance and Improvement Strategies for Wear Resistance
Proper Use and Storage
Avoid heavy impacts or drops. Impact energies exceeding 10J may cause grain loss.
Use a support during storage and cover the surface with a dust-proof film to prevent dust from embedding in micropores.
Perform Regular Precision Calibration
Check flatness with an electronic level every six months. If the error exceeds the tolerance range (e.g., the allowable error for a 00-grade plate is ≤2×(1+d/1000)μm), return to the factory for fine-tuning.
Apply protective wax before long-term storage to reduce environmental corrosion.
Repair and Remanufacturing Techniques
Surface wear <0.1mm can be repaired locally with diamond abrasive paste to restore a mirror finish of Ra ≤0.1μm.
Deep wear (>0.3mm) requires return to the factory for re-grinding, but this will reduce the overall thickness of the plate (single grinding distance ≤0.5mm).
The wear resistance of granite slabs stems from the synergy between their natural mineral properties and precision machining. By optimizing the use environment, standardizing the maintenance process and adopting repair technology, it can continue to demonstrate its advantages of good accuracy and long life in the precision measurement area, becoming a benchmark tool in industrial manufacturing.
Post time: Sep-10-2025