Albert Weckenmann, Sebastian Beetz
COMPUTER-BASED INTEGRATED ASSISTANCE FOR COORDINATE MEASUREMENTS

The constant increase of the application areas of coordinate metrology is due to the universality and flexibility of coordinate measurement machines (CMMs). Their varied applications require a high degree of knowledge by the CMM operator. In coordinate metrology, the operator is the main cause for uncertainties. The aim is to achieve small uncertainties, so that reliable and predominantly operator-independent measurement results can be obtained. To reduce these effects, it is necessary to support the CMM operator during his measuring tasks.

Renato R. Machado, Tácito B. Pinto, Itamar Ferreira
INFLUENCE OF THE INDENTER GEOMETRY AND THE MODE CONTROL IN HARDNESS MEASUREMENT BY INSTRUMENTED INDENTATION TEST

Taking into account the technical procedures established on ISO/FDIS 14577-1 standard draft, instrumented indentation tests (IIT) were carried out on macro range, in order to determine hardness and other material parameters, so that, using a universal testing machine adapted with a system developed for this end. Two different indenters and two different modes of control were used. It was observed that despite using different modes of control the values of the parameters analysed were similar considering the same indenter geometry. Concerning to the different indenter geometries the bigger hardness values was observed for HV indenter than HBW indenter. Relating to the mechanical work, the results showed in one hand a similar elastic deformation work for both indenters on the other hand it showed a major plastic deformation work for HV indenter than the HBW indenter.

Samuel Low, James Fink
EFFECTS OF BENDING IN BRASS ROCKWELL B SCALE TEST BLOCKS

As part of a project to produce primary hardness reference blocks for the Rockwell B hardness scale at the National Institute of Standards and Technology (NIST), studies were conducted to observe the stability of the hardness value of the blocks over a period of time and with use. A study of brass test blocks at the 42 HRBW level revealed some interesting instability results when tested using the NIST standardizing machine with it’s large diameter sample support.
After a relatively small number of indentations, each block exhibited an abrupt change in the apparent hardness of the test block. Examination of this phenomena revealed that the abrupt change in hardness was the result of a combination of the bending of the block and the use of the NIST machine’s large diameter flat anvil. This paper discusses the reasons that block bending affects the hardness measurement.

Anton Štibler, Konrad Herrmann
UNCERTAINTY EVALUATION OF THE REFERENCE HARDNESS STANDARD OF SLOVENIA

A commercial hardness testing machine has been provided to represent a reference hardness standard in Slovenia. Various hardness scales which are important for calibration purposes are realized on this machine. The evaluation of measurement uncertainty is one of the most important tasks for establishing this reference standard. Therefore the influence quantities contributing to the uncertainty are determined and the calibration of the machine by direct and indirect method is carried out. Calculations of measurement uncertainties for Brinell, Vickers and Rockwell hardness scales are presented. The hardness scales for Brinell HBW 2,5/187,5; HBW 2,5/62,5; HBW 2,5/31,25, Vickers HV 30 and Rockwell are subject of uncertainty determination in this paper.

Hiroshi Yamamoto, Takashi Yamamoto, Hiroyuki Kawashima, Mikie Shibata
ISO HARDNESS STANDARDS INDENTATION HARDNESS TESTS AND HARDNESS STANDARD BLOCKS

ISO standards for hardness are established from metrological standards for force, length, etc. and daily control requirements via hardness standard blocks. The authors have already stated that the unification of loading speed via ISO standards is important both industrially and economically. In consideration of the international importance of ISO standards for hardness testing, the authors review the current ISO specifications in this report, particularly their definition of loading speed, tolerances for Rockwell reference loads, and other test-block requirements, based on our own experiments. Although it may be necessary to have continuous experimental findings using various hardness testers and test blocks, the following conclusions can be said at present.
(1) As a result of reviewing the basis of defining test force application, it can be generally concluded that LRT would be more appropriate than the indentation velocity as a basis of defining the test force application for indentation hardness tests.
(2) Considering the experiment results and the present situation concerning testing machine and method, the tolerances for the first and second reference loads for Rockwell hardness should be specified independently, and it may be necessary to loosen the tolerance for the second reference load.
(3) In the future, it is hoped that the test load tolerances for overall indentation hardness tests will be reviewed by studying the method of testing the dynamic load being applied during hardness testing, rather than the checking mass of weight or static load.
(4) As regards the ISO requirement for hardness block thickness, it is desirable that that for micro Vickers blocks should be 5 mm or more, and that for non-ferrous HR blocks should be 7 mm or more, based on a through consideration of the characteristics of individual testing methods, test forces, and block materials, as is the case with JIS standards.
(5) It has been confirmed that high-precision hardness blocks play an important role in the experimental verification of various aspects of hardness testing.