Brinell Hardness Tester

What is the Brinell Hardness Tester?

A Brinell hardness tester presses a tungsten carbide ball of 2.5 to 10 mm diameter into the surface with a high load and measures the impression diameter. It averages structure and suits castings and forgings.

Overview

A hardened ball is pressed into the specimen with a load chosen from the standard ratio of load to ball diameter squared, for example 3000 kgf with a 10 mm ball or 187.5 kgf with a 2.5 mm ball, and held for a dwell time of ten to fifteen seconds. The diameter of the impression is measured with a microscope or, on automatic models, with an optical or camera system, and the hardness in HBW is calculated from the load and the impression area. Because the impression is large, the measured value averages grains, inclusions and small inhomogeneities, which is why Brinell remains common for cast iron, castings, forgings, annealed and non-ferrous materials. Automatic models move the specimen through indenting and measuring positions and can perform multiple impressions with statistical reporting. Thickness must be sufficient to support the impression, and the surface should be ground or machined flat.

How does it work?

Hardness expresses resistance to local plastic deformation. In Rockwell testing a diamond cone or hardened ball is pressed in with a preliminary and then a main load, and hardness is read from the additional depth of penetration, which makes the method fast and simple. Brinell testing presses a tungsten carbide ball at a high load and measures the impression diameter optically, giving an average value that suits coarse or inhomogeneous material. Vickers and Knoop testing use a diamond pyramid with loads from grams to kilograms and measure the diagonal lengths of the impression, which allows individual phases, thin cases and small features to be tested. Leeb rebound testing measures the velocity of an impact body before and after striking the surface, giving a portable measurement that is converted to other scales by comparison. The measured value depends on test force, indenter geometry, dwell time, surface finish and support of the specimen, so these are all defined by the standards.

What are the key features?

• Tungsten carbide ball of 2.5, 5 or 10 mm diameter
• Load selection by the standard load to diameter ratio
• Optical or camera based impression measurement
• Automatic indent and measure cycle on some models
• Multiple impression statistics and reporting
• Dwell time adjustable from 10 to 15 s

What are the technical specifications?

A typical brinell hardness tester configuration offers ball diameters of 2.5, 5 and 10 mm, test forces of 187.5, 750, 1000, 3000 kgf, hardness range of HBW 8 to 650, dwell time of 10–15 s settable, magnification for reading of 20× to 60× and minimum specimen thickness of At least 8 times impression depth. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Brinell Hardness Tester is used in cast iron and steel casting hardness control, forging and large part acceptance testing, annealed and non-ferrous material testing and averaged hardness where structure is coarse. Across the wider Hardness Testing class, laboratories also deploy it for hardened and tempered steel acceptance testing, case depth measurement after carburizing or nitriding and casting and forging hardness control.

Which standards and certifications apply?

Relevant standards and methods include ISO 6508, ISO 6506, ISO 6507, ASTM E18, ASTM E10, ASTM E384, ASTM E140 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Verify each tester daily or per shift with a certified reference block whose hardness lies close to the working range, and record the reading, the block identity and the date. Have the machine verified annually for test force, indenter geometry, depth or optical measurement and timing, either in house with traceable devices or by an accredited body. Handle indenters carefully, inspect them for chipping, and replace damaged ones, since a chipped diamond or flattened ball biases every result. Prepare surfaces by grinding or polishing to the roughness stated in the method, support thin specimens rigidly and ensure the surface is perpendicular to the indenter. Report the scale, test force, dwell time and number of readings with every result, and treat scale conversions as estimates rather than equivalent values.

How do I select the right Brinell Hardness Tester?

Select the Brinell tester where a large impression and an averaged result are acceptable, as with castings and forgings, and check load options, ball sizes, impression measurement method and specimen height capacity. Include a certified reference block in the intended HBW range.

How does it compare with other Hardness Testing variants?

Select the scale from the material, the size of the feature and the acceptance criteria in your specification. Rockwell C is standard for hardened steel, Rockwell B for softer metals, Brinell for castings and large forgings where the impression is acceptable, and Vickers or Knoop for thin cases, coatings, welds and individual microstructural constituents. Choose the load range to cover your thinnest feature, remembering that Vickers hardness depends on load at low values. Decide whether you need a manual, digital or fully automatic machine: automatic machines with traverses and motorized stages are used for case-depth series and for high volumes, and they should store test programs so that results are repeatable. Portable rebound testers suit field inspection of large parts but need a conversion relationship established against a bench machine on the same material, and they cannot test thin sections or small parts reliably.