Automatic hardness testing facility

Maintaining its policy of continuous investment in technology and facilities, Keighley Laboratories has added a Zwick Roell ZHV-10 automatic micro and macro hardness tester to its Test House resources. Featuring fully automatic Vickers indentation measurement and dedicated hardness testing software, the new equipment will bring about measurable improvements in accuracy, repeatability and productivity, to the benefit of the company’s internal Heat Treatment division and clients of its Technical Services department. Used for the precise measurement of surface hardness and case depth of metallic materials, with test loads between 100g and 10Kg, it will introduce considerable time savings over previously manual routines, freeing up highly skilled operators for other analytical duties.

The new equipment was supplied by Indentec, part of Zwick Roell AG and a worldwide centre of excellence for hardness testing machines, which has a business relationship with Keighley Labs that dates back many years. A UKAS accredited calibration laboratory, Indentec has been additionally contracted to service and recalibrate this and other hardness testing equipment on a long term basis, which will be carried out on site by trained engineers to ISO 6508-2 and ASTM E384 standards.

Such is the sizeable footprint of the new hardness tester, Keighley Labs also took the opportunity to enlarge its existing Test House microscope room, creating a spacious new optical suite. This also houses the advanced zoom stereo metallurgical microscope acquired previously and allows for the installation of further state-of-the-art equipment.

Part of Keighley Labs’ comprehensive mechanical testing and metallography services, the hardness of a material is determined by its resistance to indentation by a hardened ball or diamond indenter, then measuring the size of the permanent impression produced. With loads, pressures and temperatures constantly increasing in modern machinery, metallic parts are subject to increasingly arduous operating conditions and hardness testing is often the best way of establishing that components will survive such stresses, becoming a critical part of the quality control process. Keighley Labs employs this physical testing method as quality assurance for its in-house Heat Treatment division, handling up to a dozen test samples daily, as well as undertaking case depth and surface hardness evaluation of materials and components for external clients.

Vickers testing, using a pyramid-shaped diamond indenter, is suitable for all types of materials and surface treatments and Keighley Labs’ new Zwick Roell ZHV-10 machine is equipped for micro and macro Vickers testing to ISO 6507, although it can be fitted with an alternative Knoop indenter. It features a built-in measuring microscope with four objective lenses, a motorised turret with 1.3 megapixel USB camera, an automatic motorised XY table with 150mm x 50mm travel, for precise positioning of samples, with automatic focus providing an additional motorised Z axis for bringing the test surface into sharp resolution without operator involvement. It also includes a high definition 24” LCD monitor, a microprocessor running Windows XP, flatbed scanner and Indentec ZHµ HD automatic indentation software, with sample scanning facility and a report generator for outputting data to spreadsheet programs, enabling further statistical analysis.

Employing this configuration, Keighley Labs’ technicians can either view and measure test impressions manually, by focusing with the joystick and clicking on indentations with the mouse, or allow the machine itself to intelligently follow predefined patterns, indent the sample, then measure and generate test results, all entirely automatically. They can also set up templates of indentation points, for performing hardness tests on routine samples, and program straight line and transverse patterns for automating case hardness routines and testing welded seams.

Apart from freeing up technicians for other tasks, this ‘click and walk away’ functionality ensures precise sample positioning and imaging, enhanced accuracy, an extremely high level of repeatability and overall increased productivity, reducing standard testing procedures from more than an hour manually, to less than twenty minutes automatically. It also eliminates operator-related errors caused by eye strain, fatigue and inevitable inconsistencies, which can be a common problem in microhardness testing especially.

“The time savings made possible by this automatic hardness tester will enable us to offer faster turnaround times and deliver even more accurate, repeatable and reproducible data,” says Keighley Labs’ Test House Manager, Matthew Mellor. “We chose Indentec because the company has an excellent reputation, with its own service and calibration engineers, and its equipment offers the highest image resolution on the market.”