Rade AA Granite Square

High Precision Granite Square

The Ultimate Reference for Absolute Perpendicularity

Instrument Definition:The Pinnacle of Angular Metrology

A High Precision Granite Square represents the apex of geometric reference technology—a master-grade instrument engineered to establish,verify,and maintain perfect 90-degree relationships with uncertainty measured in fractions of an arc-second.Unlike standard inspection squares,these instruments are manufactured as certified metrological artifacts for national standards laboratories,primary calibration facilities,and industries where angular accuracy directly impacts product performance,safety,and regulatory compliance.

Material Selection&Scientific Foundation

Ultra-Premium Granite Selection

Quarry Source:Exclusive blocks from geologically stable formations with documented century-long dimensional stability

Density Requirements:Minimum 3.00 g/cm³,typically 3.02-3.08 g/cm³for optimal vibration damping

Crystalline Structure:Ultra-fine grain(<0.5mm crystal size)with isotropic properties verified through ultrasonic tomography

Thermal Characteristics:Certified thermal expansion coefficient 5.0-5.5×10⁻⁶/°C with documented isotropy

Material Certification Protocol

Spectroscopic Analysis:Verifying mineral composition and homogeneity

Ultrasonic Mapping:Identifying internal flaws or discontinuities at micron scale

Thermal Cycling Test:30-cycle test between 15°C-25°C to verify dimensional stability

Long-Term Creep Study:90-day monitoring under load to confirm absence of plastic deformation

Manufacturing Excellence&Process Control

Multi-Stage Manufacturing Protocol

Phase 1:Rough Shaping&Stress Relief

Low-Stress Cutting:Diamond wire cutting with controlled feed rates to minimize subsurface damage

Extended Stabilization:180-day minimum natural aging in temperature-controlled environment

Cryogenic Treatment:Optional deep freeze cycling for stress relief of critical applications

Phase 2:Precision Machining

Vibration-Isolated CNC:Machining centers mounted on active air isolation systems

Diamond Tooling:Single-crystal diamond tools for sub-micron surface finishes

Temperature-Controlled Environment:Manufacturing at 20°C±0.5°C with gradient control

In-Process Metrology:Laser interferometer verification between machining operations

Phase 3:Ultra-Precision Finishing

Quantum Lapping:Proprietary process achieving surface flatness≤0.025µm/100mm

Sub-Nanometer Finish:Final polishing to 0.02-0.05µm Ra(1-2µinch)using colloidal silica

Edge Perfection:Micro-beveling with radius control to 0.01mm±0.002mm

Cleanroom Assembly:Class 100 environment for final assembly and inspection

Accuracy Classification System

Grade HP1(Ultimate Reference)

Angular Accuracy:90°±0.25 arc-seconds(±1.25µrad)

Blade Straightness:0.05µm per 100mm(0.000002"per 4")

Face Flatness:0.03µm per 100mm(0.0000012"per 4")

Surface Finish:0.02-0.04µm Ra(0.8-1.6µinch)

Measurement Uncertainty:≤0.1 arc-seconds(k=2)

Applications:National measurement institutes,primary angle standards

Grade HP2(Primary Standard)

Angular Accuracy:90°±0.5 arc-seconds(±2.5µrad)

Blade Straightness:0.10µm per 100mm(0.000004"per 4")

Face Flatness:0.06µm per 100mm(0.0000024"per 4")

Surface Finish:0.04-0.08µm Ra(1.6-3.2µinch)

Measurement Uncertainty:≤0.2 arc-seconds(k=2)

Applications:Accredited calibration laboratories,semiconductor metrology

Grade HP3(High-Precision Master)

Angular Accuracy:90°±1.0 arc-seconds(±5µrad)

Blade Straightness:0.20µm per 100mm(0.000008"per 4")

Face Flatness:0.12µm per 100mm(0.0000048"per 4")

Surface Finish:0.08-0.16µm Ra(3.2-6.3µinch)

Measurement Uncertainty:≤0.4 arc-seconds(k=2)

Applications:Aerospace calibration labs,precision optics manufacturers

Metrological Certification&Documentation

Complete Certification Package

Primary Calibration Certificate:NIST/PTB traceable with full uncertainty budget

3D Geometric Error Map:Volumetric characterization using laser tracker or ultra-precision CMM

Interferometric Analysis:Phase-shifting interferometer data for all critical surfaces

Material Property Report:Density,thermal expansion,and structural integrity documentation

Environmental Performance Data:Dimensional stability across temperature/humidity ranges

Long-Term Stability Prediction:Based on material science analysis

Calibration Methodology

Primary Angle Standard Comparison:Measurement against reference polygons or angle dividers

Autocollimator Measurement:Using electronic autocollimators with 0.01 arc-second resolution

Laser Angle Interferometry:Direct measurement of angular deviation via heterodyne interferometry

Reversal Techniques:Multiple measurement positions to eliminate systematic errors