Hardness testing of metallic materials often places high demands on the patience of the user due to the standardised test methods defined within the various ISO and ASTM standards
In particular, the mandatory indentation dwell times are to be strictly observed while the time needed for equipment setup plays a significant role.
The result - a long test time.
Thus, automating such tests is a logical consequence.
Indentec and its parent company Zwick have come up with what they say is an outstanding solution: an automatic system which is fully compliant with international testing standards that is both fast and reliable.
The system comprises two hardness testing devices: a machine for testing according to the Rockwell method and an additional tester for Vickers hardness tests.
Both machines are fully automated and designed for testing a range of components. The specimens are fed into the testers using a six axis industrial robot.
The Vickers system has automatic focus and indentation measurement which eliminates any operator influence normally associated with such tests.
Additional workstations include a barcode reader, which recognises the relevant test to be performed by the label on each specimen and a thickness measuring station with two sensors for determining the specimen thickness.
The system is fully controlled using the Zwick testing software testXpert autoEdition.
Of particular mention is the fact that specimens can be tested in parallel as both hardness testing machines can be operated simultaneously.
If more than one test should be required per specimen, a shifting station will move the specimen the necessary distance.
Thanks to an intelligent test program, the system recognises which of the hardness testers is free and feeds the next specimen accordingly.
Two buffer magazines are provided to harmonise operations, ensuring that the next specimen is ready on time and adjusting discrepancies in times occurring between the Vickers and Rockwell testers.
The result - fast specimen throughput.
Furthermore, the tested specimens are sorted into containers in accordance with specific criteria, eg measured hardness value within/out of tolerance.
The system can conveniently be connected to a higher-level host computer for automatic upload of the relevant test results.
The quality requirements in manufacturing are growing steadily and, with them, the significance of production-geared testing.
In the automobile industry, in particular, dynamic testing is gaining in importance.
Zwick, a testing machine manufacturer based in Ulm, has included a number of servohydraulic testing machines in its offering which are geared especially for these applications. Tailored to the environmental conditions particular to manufacturing and supporting the user through superior ease of operation, these machines enable a variety of stress tests to be performed over numerous cycles.
The key benefit is quality assurance in the running line.
Two examples of Zwick solutions deployed in the industry are presented in the following:.
Testing of rubber-metal bearings.
When rubber-metal bearings are tested in the line in volume production, a variety of characteristic values need to be determined to be able to assure the desired product properties and monitor the production process accordingly.
And it is with this measurement task in mind that Zwick developed a testing system allowing the determination of static and dynamic stiffness as well as the loss angle and loss factor of rubber-metal bearings.
As the testing machines are set up in the production environment, operator safety when inserting and removing the specimens but also during testing is of particular importance.
For this reason, the machine is equipped with a safety light curtain.
Together with an additional two-hand control used to start testing, the safeguard ensures optimal protection for the user.
The measured values are checked against specified tolerances with the results displayed using colored tolerance indicators.
And the testing machine comes with a convenient acoustic signal: a buzzer signals when it is necessary to change specimens or intervene in testing, freeing the operator to perform other activities in the meantime.
Dynamic torsion test bench for clutch tests.
To determine the fatigue rating and the force at break of clutches, Zwick developed a testing concept based on a servohydraulic torsion testing machine tailored to the particular requirements of the customer.
The basic task was to perform tests on the individual components of an automatic clutch.
The test bench was therefore equipped with a multi-functional fixture which the single disks were screwed onto.
As per the customer's wishes, the standard load frame from the servohydraulic product family was not used in this case. Instead a special torsion testing frame was built to accommodate the torsion drive separately at the back of the machine.
The measurement and control electronics as well as all the hydraulic control components are compactly installed in the lower part of the base.
The testing area is sectioned off and equipped with an electric protection door to ensure operator safety.
