ISO 6507-2:2018 pdf download – Metallic materials -Vickershardness test— Part 2: verification and calibration of testing machines
ISO 6507-2:2018 pdf download – Metallic materials -Vickershardness test— Part 2: verification and calibration of testing machines.
5.5 VerIfication of the testing cycle
The testing cycle shall be timed with equipment having a maximum expanded uncertainty of 1 s. The timing values obtained shall fall within the limits set for the testing cycle in Iso 6507-1.
5.6 Uncertainty of calIbratIon/verIfIcatIon
Uncertainty of the calibration/verification results shall be determined. An example is given in AnnexA.
6 Indirect verification
6.1.1 Indirect verification shall be conducted in accordance with the schedule given in Clause 7.
6.1.2 Indirect verification involves verification of the overall performance of the testing machine by means of reference blocks calibrated in accordance with ISO 6507-3.
6.1.3 Indirect verification should be carried out at a temperature of (23 ± 5) C. If the verification is made outside this temperature range, this shall be reported In the verification report.
6.1.4 The instruments used for verification and calibration shall be traceable to national standards.
6.2 Test force and hardness levels
The testing machine shall be verified by testing reference blocks that have been calibrated In accordance with ISO 6507-3. The blocks shall have been calibrated using the same test forces that the machine will use for future testing. When verifying more than one test force, at least two reference blocks shall be selected from the hardness ranges specified below for each test force that the machine will be verified. The set of blocks needed for verifying the machine for all the test forces shall be chosen so that at least one reference block From each hardness range is used for the verifications. When verifying testing mac-hines using only one test force, three reference blocks shall be used, one from each of the three hardness ranges specified below. The hardness ranges should be chosen, when possible, to replicate the hardness levels most commonly tested when using the specific test forces.
— c25O HV
— 400 HV to 600 HV
Measurement uncertainty analysis is a useful tool to help determine sources of error and to understand differences between measured values. This annex gives guidance on uncertainty estimation but the values derived are For information only, unless specifically instructed otherwise by the customer. The criteria specified in this document for the performance of the testing machine have been developed and refined over a significant period of time. When determining a specific tolerance that the machine needs to meet, the uncertainty associated with the use of measuring equipment and/or reference standards has been Incorporated within this tolerance and It would therefore be inappropriate to make any further allowance for this uncertainty by, for example, reducing the tolerance by the measurement uncertainty. This applies to all measurements made when performing a direct or indirect verification of the machine, in each case, It is simply the measured value resulting from the use of the specified measuring equipment and/or reference standards that is used to assess whether or not the machine complies with this document. However, there may be special circumstances where reducing the tolerance by the measurement uncertainty is appropriate. This should only be done by agreement of the parties involved.
The metrological chain necessary to define and disseminate hardness scales is discussed in ISO 6507.1.