In scenarios such as precision optical inspection, interferometry, spectral analysis and high-precision coordinate measurement, magnetic interference and metal rusting are two major sources of error that are often underestimated. Spot distortion in optical imaging, jumps in sensor readings and irregular drift of measurement data are frequently not caused by failures of optical lenses or detectors, but hidden disturbances introduced by magnetization or rust of base materials. Although conventional metal guide bases are mature in machining, they inherently carry risks of magnetization and rust. When serving long-term in optical and metrology laboratories, they continuously introduce uncontrollable interference into the whole system. Thanks to the natural advantages of non-metallic substrates, granite air bearing guide bases are perfectly suited for such applications with strict requirements for magnetic field and cleanliness.
The drawbacks of metal bases are continuously amplified in precision optical environments. Materials such as steel and cast iron are easy to be magnetized. Magnetic fields generated by linear motors, electromagnets and cables around the base can be captured by metal substrates and form residual static magnetic fields. Weak magnetic fields can deflect optical paths and disturb signals from electronic sensors and optical encoders, leading to jumps in measured values. Meanwhile, metals still oxidize and rust slowly in humid, constant-temperature laboratories. Tiny metal debris generated by rust may drift into optical paths and air gaps, scratch optical components, contaminate air-floating microholes and break air film uniformity. Even with anti-rust treatments such as painting or electroplating, rust will reoccur once coatings wear off, bringing high maintenance costs and failing to eliminate magnetization risks fundamentally.
As a natural non-metallic microcrystalline rock, granite is non-magnetically conductive. It will not retain remanence and is hardly magnetized by external magnetic fields. When used as an air bearing guide base, the substrate will not create extra magnetic fields to disturb optical paths, photoelectric detectors and precision grating components. For optical motion stages integrated with linear motors, magnetic fields generated during motor operation will not remain on the granite base, fundamentally eliminating optical path shift and measurement jumps induced by magnetic fields. Furthermore, rocks have no physical mechanism for oxidative rusting. Whether in constant-temperature humid metrology laboratories or clean optical workshops, they will not produce rust powder or metal particles, preserving a clean environment inside optical systems and protecting optical lenses, windows and air-floating microholes from contamination damage.
Nevertheless, ordinary granite alone is not sufficient. If the stone contains high levels of impurities including ferromagnetic minerals, weak magnetic response may still exist. At the raw material screening stage, ZHHIMG conducts mineral composition inspection on granite blocks and rejects stones mixed with ferromagnetic minerals such as iron and nickel to ensure non-magnetic substrate performance. Combined with integrated blank forming and long-duration stress relief, the substrate remains stable without impurity particle precipitation under environmental changes. Air-floating microholes and air outlet surfaces are shaped by ultra-precision grinding. The dense and non-porous surface reduces dust adhesion and further maintains the cleanliness of optical platforms.
The non-magnetic and rust-free features bring synergistic benefits when combined with the granite air bearing structure. The air film supports the slide without metal contact friction, producing no metal wear debris. Together with the non-rust and non-magnetic granite substrate, the entire motion system generates almost no contaminants. For equipment with stringent requirements for zero magnetic interference and cleanliness, such as optical interferometry, AOI optical inspection, profile scanning and CMM metrology, it can deliver nanoscale motion accuracy while avoiding long-term performance degradation caused by magnetic disturbance and rust contamination, greatly reducing maintenance frequency of optical systems. 
It should be noted that non-magnetism and rust resistance are only basic requirements. Optical and measuring equipment also demand dimensional stability and excellent vibration damping of the base. ZHHIMG granite air bearing bases combine non-magnetic cleanliness, low creep, low thermal deformation and high damping vibration reduction. In constant-temperature metrology environments, the reference surface stays stable for a long time, and calibration benchmarks of the whole optical system will not be compromised by secondary factors such as magnetization and rust.
When selecting components for precision optical and metrology equipment, engineers focus not merely on flatness and motion accuracy. Magnetic interference, cleanliness and long-term environmental stability have become core evaluation criteria. With natural non-magnetic and rust-free material properties plus ultra-precision air bearing machining technology, granite air bearing guide bases serve as the preferred base solution for precision optical scanning, non-contact measurement and laboratory metrology platforms, ensuring long-term stable and reliable optical imaging and measurement data.
Post time: Oct-09-2026