The Experts below are selected from a list of 2970 Experts worldwide ranked by ideXlab platform
Giulio Barbato - One of the best experts on this subject based on the ideXlab platform.
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how to reach the world wide unified scales for Rockwell Hardness test with conical indenter
2007Co-Authors: Giulio Barbato, S Desogus, K Herrmann, A Germak, Torsten PolzinAbstract:The aim of achieving world-wide unification for Hardness scales using diamond indenter is very important. A co-operative work of some National Metrological Laboratories is necessary, but, before, it shall be defined a common procedure of indentation. This should be performed by means of metrological examinations of influences due to the parameters themselves used for the definition of the scales. Some parameters, that showed to have a very significant influence on measurement results, have been experimentally tested: load dwell times, indentation velocity and indenter geometry. The results show that it is possible to establish a good metrological basis, at least in reference to load dwell times and velocity effects, whereas the measurement of indenter geometry, even with very high accuracy, is not sufficient to guarantee the indenter performances. The preparation of an extended comparison to define world-wide unified scales require, therefore, additional refinements.
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establishing a world wide unified Rockwell Hardness scale with metrological traceability
Metrologia, 1997Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H Ishida, Giulio BarbatoAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard-grade Rockwell diamond indenters characterized by high geometric uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a world-wide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometric measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a world-wide unified HRC scale with an expanded uncertainty of approximately 0,2 HRC and without significant bias with respect to an ideal scale.
Junfeng Song - One of the best experts on this subject based on the ideXlab platform.
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finite element modeling and experimental comparisons of the effects of deformable ball indenters on Rockwell b Hardness tests
Journal of Testing and Evaluation, 2003Co-Authors: Junfeng SongAbstract:Significant differences occur in Rockwell B Hardness (HRB) tests depending on whether the 1.588 mm diameter ball indenter that is used is made of steel or of tungsten carbide (WC). It is important to study and assess the effect of different indenter materials on the HRB tests since the Rockwell Hardness test method standards, published by ASTM International and the International Organization for Standardization, now permit the use of either steel or tungsten carbide ball indenters. In this paper, finite-element analysis (FEA) is used to simulate the HRB indentation process using steel and WC ball indenters on the same test materials under the same testing conditions. The influence of the deformable steel and WC indenters on the HRB tests is analyzed by comparing their FEA results with those of a simulated nondeformable rigid indenter. The contact pressure, stress, strain, and deformations of both the indenters and the tested materials during the loading and unloading period are analyzed. The FEA simulation results show that the HRB difference between steel and WC ball indenters is about 0.4 HRB for 40–78 HRB levels, but increases to 0.56 HRB at the 23 HRB level. The FEA simulation results agree with experimental HRB results.
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simulation and prediction of Hardness performance of Rockwell diamond indenters using finite element analysis
Journal of Testing and Evaluation, 2002Co-Authors: Jack Zhou, Junfeng Song, Roland DewitAbstract:The difficulty in manufacturing Rockwell diamond indenters to the required geometric specifications has resulted in most commercially manufactured indenters to vary in shape from one to another. This difference in shape is thought to be a major contributor to the Rockwell C scale Hardness measurement uncertainty. In this paper, a finite-element analysis (FEA) is used to simulate the Rockwell Hardness measurement process. The influences of the indenter's geometry, including tip radius, cone angle, and form error on Rockwell Hardness tests are analyzed by the FEA model, and further verified by experimental results. A new method is developed to directly input the Rockwell indenters' profiles into the FEA model for Hardness performance prediction. The prediction results show good agreement with NIST experimental results.
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establishing a worldwide unified Rockwell Hardness scale using standard diamond indenters
Measurement, 1998Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H IshidaAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard grade Rockwell diamond indenters characterized by high geometry uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a worldwide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometrical measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a worldwide unified HRC scale with an expanded uncertainty (k=2) of approximately ±0.2 HRC and without significant bias with respect to an ideal scale.
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establishing a world wide unified Rockwell Hardness scale with metrological traceability
Metrologia, 1997Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H Ishida, Giulio BarbatoAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard-grade Rockwell diamond indenters characterized by high geometric uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a world-wide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometric measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a world-wide unified HRC scale with an expanded uncertainty of approximately 0,2 HRC and without significant bias with respect to an ideal scale.
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microform calibrations in surface metrology
International Journal of Machine Tools & Manufacture, 1995Co-Authors: Junfeng Song, F Rudder, Brian R Scace, A. Hartman, Theodore V. Vorburger, J SmithAbstract:Abstract Microform calibrations include the measurement of complex profile forms and position errors of micrometer scale in combination with the measurement of deviations from a specified profile and surface texture of profile segments. Tolerances on the profile form are specified and may correspond geometrically to surface texture parameters. One example of microform calibration is the calibration of Rockwell diamond indenters used for Hardness testing of materials. Previously reported measurement techniques do not meet the stringent microfonn calibration requirements for Rockwell diamond indenters. Inadequate microform calibration of Hardness indenters may be one factor resulting in significant interlaboratory differences in results from Rockwell Hardness tests. By using a stylus instrument, in combination with a series of calibration and check standards and calibration and measurement uncertainty calculation procedures, we have calibrated Rockwell diamond indenters in accordance with the definitions specified in ISO and ASTM standards. Our procedures for conducting microform calibration yield total measurement uncertainties less than ten percent of the tolerance values specified in ISO and ASTM standards. In this paper, the general calibration requirements, calibration and check standards, and calibration and uncertainty procedures that we use in performing microform calibrations are introduced. Some general considerations on stylus radius correction, data fitting, calibration traceability, uncertainty and reproducibility are also discussed.
Torsten Polzin - One of the best experts on this subject based on the ideXlab platform.
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how to reach the world wide unified scales for Rockwell Hardness test with conical indenter
2007Co-Authors: Giulio Barbato, S Desogus, K Herrmann, A Germak, Torsten PolzinAbstract:The aim of achieving world-wide unification for Hardness scales using diamond indenter is very important. A co-operative work of some National Metrological Laboratories is necessary, but, before, it shall be defined a common procedure of indentation. This should be performed by means of metrological examinations of influences due to the parameters themselves used for the definition of the scales. Some parameters, that showed to have a very significant influence on measurement results, have been experimentally tested: load dwell times, indentation velocity and indenter geometry. The results show that it is possible to establish a good metrological basis, at least in reference to load dwell times and velocity effects, whereas the measurement of indenter geometry, even with very high accuracy, is not sufficient to guarantee the indenter performances. The preparation of an extended comparison to define world-wide unified scales require, therefore, additional refinements.
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establishing a worldwide unified Rockwell Hardness scale using standard diamond indenters
Measurement, 1998Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H IshidaAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard grade Rockwell diamond indenters characterized by high geometry uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a worldwide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometrical measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a worldwide unified HRC scale with an expanded uncertainty (k=2) of approximately ±0.2 HRC and without significant bias with respect to an ideal scale.
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establishing a world wide unified Rockwell Hardness scale with metrological traceability
Metrologia, 1997Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H Ishida, Giulio BarbatoAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard-grade Rockwell diamond indenters characterized by high geometric uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a world-wide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometric measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a world-wide unified HRC scale with an expanded uncertainty of approximately 0,2 HRC and without significant bias with respect to an ideal scale.
K Herrmann - One of the best experts on this subject based on the ideXlab platform.
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two approaches for enhancing the accuracy of the Rockwell Hardness test
Measurement Science and Technology, 2009Co-Authors: K Herrmann, Febo MenelaoAbstract:Two approaches have been investigated in our study in order to develop indenter calibration methods with high accuracy. One approach is by establishing a group standard utilizing several indenters, which yields better statistical results than the calibration using only one indenter. The second approach is by correcting the Hardness test values using the indenter's area function determined by a highly accurate stylus profilometer. In the stylus profilometer developed in this study, the indenter is scanned in 3D and is detected by a position stationary stylus probe. The 3D geometry of the indenter is thus derived from the displacements of the indenter which are measured by three homodyne laser interferometers, offering direct measurement traceability. In addition, for achieving a better measurement performance a special radial scan function is designed where the indenter is scanned radially over its apex. A data evaluation method has been established for calculating the indenter's area function from its measured 3D geometry. The correction method of Hardness values based on the indenter's area function is described. In this paper, a group of three Rockwell indenters has been investigated. The mean deviation of HRC values measured by this group of Rockwell indenters has been reduced from 0.11 HRC to 0.06 HRC by using the proposed correction method.
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how to reach the world wide unified scales for Rockwell Hardness test with conical indenter
2007Co-Authors: Giulio Barbato, S Desogus, K Herrmann, A Germak, Torsten PolzinAbstract:The aim of achieving world-wide unification for Hardness scales using diamond indenter is very important. A co-operative work of some National Metrological Laboratories is necessary, but, before, it shall be defined a common procedure of indentation. This should be performed by means of metrological examinations of influences due to the parameters themselves used for the definition of the scales. Some parameters, that showed to have a very significant influence on measurement results, have been experimentally tested: load dwell times, indentation velocity and indenter geometry. The results show that it is possible to establish a good metrological basis, at least in reference to load dwell times and velocity effects, whereas the measurement of indenter geometry, even with very high accuracy, is not sufficient to guarantee the indenter performances. The preparation of an extended comparison to define world-wide unified scales require, therefore, additional refinements.
David J Pitchure - One of the best experts on this subject based on the ideXlab platform.
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the effect of suggested changes to the Rockwell Hardness test method
IMEKO World Congress, 2000Co-Authors: David J Pitchure, C D FlaniganAbstract:In the latest revision of the ISO Rockwell Hardness test standard (ISO/FDIS 6508(E), 1999), the introductory paragraphs introduce changes to the test practice; one new to this revision, and one suggested as a possibility for the next revision. The change to the new revision is the addition of allowing the use of hardmetal or tungsten-carb ide balls for all Rockwell scales that use ball indenters. The change suggested for the next revision is to redefine the standard test forces presently based on rounded kilogram-force values, to converted and rounded Newton values. Since the development of the test method over 80 years ago, an incalculable amount of Rockwell Hardness measurements have been made following essentially the same procedures. This paper discusses how these new changes
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the effect of suggested changes to the Rockwell Hardness test method
IMEKO World Congress, 2000Co-Authors: David J Pitchure, C D FlaniganAbstract:In the latest revision of the ISO Rockwell Hardness test standard (ISO/FDIS 6508(E), 1999), the introductory paragraphs introduce changes to the test practice; one new to this revision, and one suggested as a possibility for the next revision. The change to the new revision is the addition of allowing the use of hardmetal or tungsten-carb ide balls for all Rockwell scales that use ball indenters. The change suggested for the next revision is to redefine the standard test forces presently based on rounded kilogram-force values, to converted and rounded Newton values. Since the development of the test method over 80 years ago, an incalculable amount of Rockwell Hardness measurements have been made following essentially the same procedures. This paper discusses how these new changes
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establishing a worldwide unified Rockwell Hardness scale using standard diamond indenters
Measurement, 1998Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H IshidaAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard grade Rockwell diamond indenters characterized by high geometry uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a worldwide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometrical measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a worldwide unified HRC scale with an expanded uncertainty (k=2) of approximately ±0.2 HRC and without significant bias with respect to an ideal scale.
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establishing a world wide unified Rockwell Hardness scale with metrological traceability
Metrologia, 1997Co-Authors: Junfeng Song, Torsten Polzin, David J Pitchure, S Desogus, A Germak, H. Yang, H Ishida, Giulio BarbatoAbstract:Recently developed microform measurement techniques have reduced the measurement uncertainties in the geometry of Rockwell diamond indenters. It is now possible to establish standard-grade Rockwell diamond indenters characterized by high geometric uniformity, high Hardness performance uniformity, interchangeability and reproducibility. By using the standard indenters under different national standard machines and a standardized testing cycle, a world-wide unified Rockwell Hardness scale could be established with metrological traceability, stability and reproducibility. Geometric measurements and Hardness tests in five laboratories have shown that tightly controlled indenter geometry can significantly improve the consistency of Rockwell C Hardness (HRC) measurements. These results support the feasibility of establishing a world-wide unified HRC scale with an expanded uncertainty of approximately 0,2 HRC and without significant bias with respect to an ideal scale.
