Accredited Step Calibration Services
In coordinate metrology and precision machining, the “step” is the fundamental unit of distance verification. At DRS Technologies, we provide expert step calibration services to ensure your reference masters—including step gages, check masters, and thin-film step height standards—maintain their sub-micron accuracy. Our laboratory utilizes high-stability comparators and laser interferometry to provide the precise data required for CMM performance audits.
Why Incremental Accuracy is Critical for CMM Verification
Step gages are used to identify linear errors and “pitch” inconsistencies in coordinate measuring machines and CNC tools. Because these masters are used to calibrate other equipment, their own measurement uncertainty must be exceptionally low. Over time, thermal fluctuations and physical handling can lead to microscopic changes in step faces. Regular calibration by DRS Technologies ensures your masters remain compliant with ISO 10360-2 and ASME B89 standards.
Our Technical Step Calibration Process
Our metrology experts employ a rigorous comparison protocol to verify every increment of your gauge:
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Surface Topography and Parallelism Audit: We inspect each step face for flatness and parallelism relative to the base, ensuring that the measurement point does not shift due to surface irregularities.
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Linear Distance Verification: Using high-accuracy bridge-type CMMs or laser measurement systems, we measure the distance from the “zero” face to every subsequent step in the series.
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Step Height Analysis: For micro-metrology, we verify vertical step heights using contact profilometry or interference microscopy to ensure accuracy at the nanometer or micron level.
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Coefficient of Thermal Expansion (CTE) Consideration: We perform all calibrations in a strictly controlled $20^\circ\text{C}$ ($68^\circ\text{F}$) environment and apply thermal compensation to account for the specific material of your gage (e.g., steel, ceramic, or zirconia).
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Certification and NIST Traceability: Every service concludes with a comprehensive certificate featuring “As-Found” and “As-Left” data for every step, along with documented NIST traceability and an expanded uncertainty statement.
Specialized Support for Step Measurement Standards
We provide professional calibration for a wide array of step-based artifacts:
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Step Gages (Check Masters): Used for verifying CMM volumetric accuracy and linear travel.
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Step Height Standards: Precision artifacts for calibrating profilometers and AFM systems.
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Feeler Gages and Thickness Steps: Verification of incremental gaps and shim thicknesses.
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VMM Calibration Plates: Optical step standards used to verify magnification and Z-axis depth in video systems.
Frequently Asked Questions
What is the difference between a Step Gage and a Gage Block set?
While a gage block set consists of individual pieces, a Step Gage consists of multiple measurement faces fixed on a single bar. This eliminates the “wringing error” accumulated when stacking blocks and provides a faster, more stable way to check long-distance linear accuracy in a single setup.
How often should a CMM Step Gage be calibrated?
Due to their role as primary reference standards, a twelve-month calibration interval is standard. If the gage is frequently transported between facilities or used on the shop floor for machine tool setup, a six-month interval may be necessary to monitor for mechanical wear.
How do you handle different materials like Ceramic vs. Steel?
Material choice affects thermal stability. Ceramic steps are highly resistant to wear and thermal expansion, while steel is more common but sensitive to temperature. During calibration, we utilize the specific material’s CTE to ensure the data is accurate to the standard reference temperature of $20^\circ\text{C}$.