The Brinell Indentation Method & HBW Formula
The Brinell test measures a metal's deformation resistance by driving a hardened tungsten carbide ball into the workpiece under heavy force, specifically the standard 3,000 kgf test force applied by the Qualitest Motorized Brinell Hardness Tester QHB-3000E electric test head. Optional force settings of 1,000 kgf, 750 kgf, and 500 kgf as well as a 5 mm ball indenter are available for lighter alloy testing.
Holding the test force steady for 10 to 15 seconds on steel (or up to 30 seconds on non-ferrous metals) leaves a clean spherical crater across a testing range of 95 to 653 HBW.
HBW = 2P / [π D (D - √(D² - d²))]
Where:
- P = Applied force in kilograms-force (kgf)
- D = Diameter of the carbide ball indenter (10 mm or 5 mm)
- d = Mean diameter of the permanent indentation impression (mm)
To maintain test comparability across different force levels and ball sizes, international standards require sticking to defined load factors (P/D² = 30 for steel and iron, 10 for copper alloys).
Closed-Loop Motorized Force Application vs. Manual Testers
Legacy manual dead-weight machines rely on hand-pumping or open levers, which suffer from pressure drops and operator-induced force spikes. Slamming a manual lever down too fast drives the indenter deeper than intended, producing artificially low hardness readings.
The QHB-3000E replaces manual levers with a patented, motorized electric-hydraulic head. Activated by a single button and powered by a rechargeable lithium battery pack delivering around 450 tests per charge, the system applies and holds the load automatically. Real-time sensors adjust force continuously, giving this mobile unit (featuring a 350 mm height x 100 mm depth throat capacity at 13.7 kg net weight) benchtop force precision.
| Testing Aspect | Legacy Manual Dead-Weight / Portable Testers | Qualitest QHB-3000E Motorized System |
|---|
| Force Application | Manual hydraulic hand-pumping subject to pressure drops | Single-button automated loading with real-time status indicator light |
| Power Drive | Manual operator physical effort | Built-in lithium battery pack (approx. 450 test cycles per charge) |
| Force Accuracy | Open to operator speed variations and mechanical wear | Motorized closed-loop control meeting full benchtop standards |
| Impression Reading | Handheld optical scale reading with manual conversion tables | Included 20X Reading Microscope or QualiScope™ II Plus CCD scanning |
| Capacity & Portability | Bulky desktop frames or low-accuracy rebound pens | Generous 350 mm height x 100 mm depth opening at 13.7 kg net weight |
Optical Diameter Measurement & System Integration
The QHB-3000E calculates HBW numbers directly from the permanent indentation diameter using two optical measurement setups:
- Included 20X Reading Microscope: Position the handheld optical microscope over the crater rim, measure two perpendicular diameters (d1 and d2), and average them.
- QualiScope™ II Plus CCD System: Upgrade to an automated camera setup mounted over the impression. High-precision image processing detects circular impression borders automatically, displaying hardness readings directly on screen to eliminate operator visual fatigue.
Standard Compliance and Operational Parameters (ASTM E10 & ISO 6506-2)
To maintain strict compliance with ASTM E10 and ISO 6506-2 on raw forgings, castings, or heavy steel plate:
- Surface Preparation: Grind and clean test specimen surfaces so impression perimeters show crisp contrast under optical lenses.
- Anvil Selection: Use the included Flat anvil, V-type anvil, or Dome type anvil to seat flat plates, round bars, or curved components securely.
- Friction & Ball Maintenance: Keep the installed 10 mm carbide ball (and included spare ball) clean, preventing surface friction from inflating hardness values.
