Micro Vickers Hardness Testers: How They Work & When to Use Them
Micro Vickers hardness indentation on material surface viewed through optical microscopeWhat Is a Micro Vickers Hardness Tester?
A micro Vickers hardness tester is a precision instrument that applies a Vickers diamond pyramid indenter under controlled low loads (typically 1 gf to 1,000 gf) to a material surface and measures the resulting microscopic indentation using an integrated optical microscope and digital imaging system. The hardness value (HV) is calculated automatically from the measured diagonal lengths of the square indentation.
Micro Vickers hardness testers are among the most versatile instruments in the materials testing laboratory, serving applications from metals and ceramics to electronic components and rubber compounds across the metallurgy, semiconductors, precision manufacturing, and materials science industries.
Key Components of a Modern Micro Vickers Hardness Tester
Load Application System
High-quality micro Vickers testers use deadweight loading (traditional) or closed-loop motorized loading (modern) to apply precise indentation loads. Key specifications:
- Load range: Typically 10 gf to 2,000 gf (0.098–19.6 N)
- Load accuracy: ±0.5% of applied load (ISO 6507 requirement)
- Load application speed: Motorized systems apply load at a controlled rate (ASTM E384 specifies 15–70 µm/s indent velocity)
Optical Measurement System
- Magnification range: Typically 100×, 200×, 400×, and 1,000× objectives
- Image capture: CCD or CMOS camera with digital diagonal measurement software
- Measurement accuracy: ±0.1 µm or better for diagonal measurement
- Automatic diagonal measurement: Modern systems use image analysis to automatically detect indentation corners and measure diagonals, eliminating operator measurement variability
Test Stage
- Manual XY stage: For occasional hardness mapping
- Motorized stage: For automated hardness traverses and mapping—essential for production case depth measurement
- Stage travel: Typically 25 mm × 25 mm to 50 mm × 100 mm
Software
Modern micro Vickers systems include software for:
- Automated traverse (case depth) programming
- Statistical analysis of hardness maps
- Pass/fail comparison to specification limits
- Export to LIMS and reporting systems
- Complete ASTM E384, ISO 6507, and ISO 4545 compliance documentation
Fully Automated vs. Semi-Automated Micro Vickers Systems
| Feature | Semi-Automated | Fully Automated |
| Load application | Manual or motorized | Motorized with feedback |
| Stage positioning | Manual XY | CNC motorized XY |
| Diagonal measurement | Manual visual or assisted | Fully automatic image analysis |
| Throughput | 10–20 indents/hour | 100–500+ indents/hour |
| Best for | Occasional use, research | Production case depth, volume testing |
Applications in the Rubber and Polymer Industry
While traditionally associated with metals, micro Vickers hardness testers are also applied to:
- Hard rubber compounds: Shore D elastomers and ebonite that are too hard for Shore A measurement but too soft for standard Vickers macro-hardness
- Polymer blends: Phase-specific hardness of dispersed phases in heterogeneous polymer blends (e.g., HIPS rubber particle vs. PS matrix)
- Filled polymer composites: Hardness of individual filler agglomerates vs. polymer matrix
Why Choose Infinita Lab for Micro Vickers Hardness Testing?
Infinita Lab offers automated micro Vickers hardness testing per ASTM E384 and ISO 6507 with full digital imaging, automated traverse programs, and hardness mapping capabilities. Our accredited laboratory network provides precise, traceable micro-hardness measurements for heat treatment verification, weld qualification, coating characterization, and detailed microstructural analysis.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions (FAQs)
What load should be used for micro Vickers testing of carburized steel case depth? The most common load for carburized case depth measurement is 300 gf (HV 0.3 per ISO 6507 notation), which produces indentations of approximately 40–70 µm diagonal in hardened steel—large enough for accurate measurement while remaining within the case layer for the near-surface indents. Some specifications use 500 gf (HV 0.5) for deeper cases.
How is the automated case depth traverse programmed on a modern micro Vickers system? The operator defines the start point (surface or defined distance from surface), spacing between indents (typically 50–150 µm), number of indents, and test load. The motorized stage positions each indent automatically; the image analysis software measures each diagonal and calculates HV. The software then plots HV vs. depth and automatically calculates the depth at which hardness crosses the specified limit (e.g., 550 HV for effective case depth).
What is the "1/10 rule" in micro Vickers testing for thin coatings? The 1/10 rule states that the indentation depth (approximately d/7 for Vickers) should not exceed 1/10 of the film thickness to avoid substrate influence on the measured hardness. For a 10 µm PVD coating, maximum acceptable indentation depth is 1 µm—requiring an extremely light load (typically 1–5 gf) and a nano-indentation capable instrument rather than a conventional micro Vickers tester.
Can micro Vickers testing be used on curved surfaces? Micro Vickers testing is optimally performed on flat, polished surfaces. For cylindrical specimens (wires, rods), a V-groove fixture or metallographic cross-section is used to present a flat, polished test surface. Direct testing of small-radius curved surfaces introduces focusing errors in diagonal measurement and is generally not recommended for precise hardness values.
What maintenance is required to keep a micro Vickers hardness tester accurate? Key maintenance items include: regular calibration using certified Vickers hardness reference blocks (ASTM E92, ISO 6507-2); cleaning and inspection of the Vickers diamond indenter for damage or contamination (a damaged indenter produces non-square indentations); verification of objective magnification calibration using a stage micrometer; and motorized load system verification against certified deadweights. Annual calibration by an accredited calibration service is recommended for production instruments.
