In precision measurement, the accuracy of your tools depends largely on the quality of the reference surface beneath them. Among all precision reference bases, granite surface plates are widely recognized for their exceptional stability, rigidity, and resistance to wear. But what defines their level of accuracy — and what does “00-grade” flatness tolerance actually mean?
What Is 00-Grade Flatness?
Granite surface plates are manufactured according to strict metrology standards, where each grade represents a different level of flatness accuracy. The 00 grade, often referred to as laboratory-grade or ultra-precision grade, offers the highest level of accuracy available for standard granite plates.
For a 00-grade granite surface plate, the flatness tolerance is typically within 0.005mm per meter. This means that over any one-meter length of the surface, the deviation from perfect flatness will not exceed five microns. Such precision ensures that measurement errors caused by surface irregularities are virtually eliminated — a vital factor in high-end calibration, optical inspection, and coordinate measuring applications.
Why Flatness Matters
Flatness determines how accurately a surface plate can serve as a reference for dimensional inspection and assembly. Even a tiny deviation can lead to significant measurement errors when inspecting precision parts. Therefore, maintaining ultra-flat surfaces is essential for ensuring consistent results in laboratories, aerospace facilities, and manufacturing plants where micrometer-level precision is required.
Material Stability and Environmental Control
The remarkable stability of 00-grade granite plates stems from the natural granite’s low thermal expansion coefficient and excellent rigidity. Unlike metal plates, granite does not warp under temperature changes or magnetic influence. Each plate is carefully lapped and inspected in a temperature-controlled environment (20 ± 1°C) to ensure that flatness remains consistent under working conditions.
Inspection and Calibration
At ZHHIMG®, every 00-grade granite surface plate is verified using high-precision electronic levels, autocollimators, and laser interferometers. These instruments ensure that each plate meets or exceeds the international standards such as DIN 876, GB/T 20428, and ISO 8512. Regular calibration and cleaning are also crucial to preserve long-term flatness accuracy.
Precision You Can Trust
When selecting a granite surface plate for your measurement system, choosing the correct grade directly impacts your measurement reliability. A 00-grade granite surface plate represents the pinnacle of dimensional accuracy — the foundation upon which true precision is built.
Post time: Oct-15-2025