Digital Vickers Microhardness Tester

What is the Digital Vickers Microhardness Tester?

A digital Vickers microhardness tester presses a diamond pyramid into the surface with loads from grams to kilograms and measures the impression diagonals optically. It resolves individual phases, thin cases and small parts.

Overview

A square-based diamond pyramid with a 136° included angle is pressed into the polished surface for a set dwell time, and the two diagonals of the residual impression are measured with a microscope and converted to a Vickers hardness number. Because the impression scales with load, the same indenter can be used from 10 gf for a coating or a single phase up to 30 kgf for bulk material, and the instrument reports load, diagonal lengths and hardness. Digital models project the impression on screen with automatic edge detection, which reduces reader variation, and they support traverse programming so that hardness profiles across a case or weld are acquired automatically at defined spacings. Traverses are converted to case depth according to the specification limit, and results can be exported with the images for reporting.

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?

• Diamond pyramid indenter with 136° included angle
• Load range from 10 gf to 30 kgf
• On-screen impression measurement with edge detection
• Programmable hardness traverses at set spacing
• Motorized turret with indenter and objectives
• Case depth calculation from traverse data

What are the technical specifications?

A typical digital vickers microhardness tester configuration offers load range of 10 gf to 30 kgf (0.098–294 N), indenter of Diamond pyramid, 136°, magnification of 100× to 500× for measurement, dwell time of 5–15 s settable, hardness range of HV 5 to HV 3000 and traverse spacing of Programmable, 10 µm upward. 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 Digital Vickers Microhardness Tester is used in case depth measurement on carburized or nitrided parts, hardness of coatings and thin layers, phase specific hardness in multiphase alloys and weld and heat-affected zone hardness profiles. 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 Digital Vickers Microhardness Tester?

Select the Vickers tester when features are small or thin and when hardness profiles are needed, and check the low load capability, optics, stage automation and traverse software. Include certified blocks covering low and high load ranges.

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.