Anton Stibler, Febo Menelao, Konrad Herrmann
Reference blocks can be used for the verification of hardness testers of rubber in the same way as in the case of hardness measurement of metals. When using hardness reference blocks for verification the so called indirect verification method is applied. This method is not yet part of the standard ISO 18898: Rubber, Verification and Calibration of Hardness Testers, but there is a high chance that this method will be a mandatory part of this standard in near future. This paper deals with some problems when using rubber hardness blocks as a standard for the verification of hardness testers....
He Li, Zhang Feng, Ye Ming, Liu Lianqiu, Wang Beiping
According to the new definition of Rockwell hardness given by the international working group on hardness, the Rockwell hardness primary standard machine has been upgraded. As the new loading system, loading monitor system, PLC control system and laser measuring system have been developed, the function of the new primary standard machine can now meet the requirements of the new definition and its measuring uncertainty can reach the expected values.
Samuel Low, Alessandro Germak, Konrad Herrmann
The measurement of hardness is used extensively by many of the world's manufacturing industries. The conventional hardness tests are the most commonly used methods for acceptance testing and production quality-control of metals and metallic products. For these industries to be successful, it is important that measurements made by suppliers and customers agree within some practical limits. Measurement traceability is a key factor in assuring hardness measurement agreement. This paper discusses the traceability issues related to the measurement of conventional hardness, including calibration,...
Gunwoong Bahng, Nae Hyung Tak
The effect of time-related parameters such as loading velocity, load application time, and gauge reading time on Rockwell hardness measurement was investigated for polymers such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and acrylic plate. It was found that keeping the specific requirements of the test procedure, especially for the time parameter related one, is very important to obtain reliable and repeatable data in polymer hardness measurement. These characteristics of plastic hardness measurement are because of the good elastic properties of polymers and showed...
Takeshi Sawa
The nanoindentation method is one of the recently developed hardness testing methods, and was standardized as ISO14577 in 2002. Recently, papers and reports using the analysis method and parameters defined in ISO14577 have been published. Among those parameters, indentation hardness is used pretty frequently. This is probably because indentation hardness is deemed to be correlated with Vickers hardness, and sometimes indentation hardness is treated as Vickers hardness. Certainly, in the papers cited in ISO14577, it can be confirmed that indentation hardness almost coincides with Vickers...
Tassanai Sanponpute, Nitiwat Sasom, Apichaya Meespalak
Evaluation of measurement uncertainty when correction value in ISO 6508 and ASTM E18 is applied is disputable. Using corrections, discrete and without uncertainty, is a difficulty to provide best measurement capability related to the application using the corrections. In order to study the possibility to complete the corrections to be in term of equations together with uncertainty of the equation, cylindrical shafts at nominal hardness 20 HRC, 40 HRC, and 60 HRC with diameter 6 mm to 38 mm were supplied in this experiment. In addition, this study includes the accuracy of the corrections by...
Malek Naderi, Kasra Sardashti, Ali Sharbatian, Mehdi Iranmanesh
Depth sensing is a novel technique to obtain useful information about mechanical properties of materials. To measure depth of indents, two methods can be employed: in situ depth sensing and residual penetration depth sensing. In this paper, a novel image processing technique is utilized by authors to estimate depth of residual indents, made by a scanning hardness tester. In this quick and simple technique, instead of using depth sensing instruments, microscopic images of scanned areas were analyzed by image analysis software. The profiles of light intensity obtained by the software were...
Takashi Yamamoto, Masayuki Yamamoto , Koichiro Hattori
The Vickers hardness test can cover an extensive range of test loads from several gram-force (gf) to 100 kilogram-force (kgf) with a single hardness scale. It is one of the most reliable strength tests because the simplicity of the testing theory and the indenter shape minimizes variances among hardness values obtained. The most vulnerable aspect of the Vickers method is an error when measuring the diagonal length of an indentation. In particular, an inexperienced operator tends to obtain smaller measurements than the actual length of the indentation. According to research by the authors, it...
Renato Reis Machado, Jorge Trota Filho, Sergio Pinheiro de Oliveira, Islei Domingues da Silva, Bianca da C. O. Muniz
In the light of the ISO 6508 revision, under the ISO TC 164 Technical Committee on Mechanical Testing of Metals, a study on the influence of the extended duration of the preliminary test force was taken, which in some cases a longer time could be required. Several HRC tests were performed with different conditions of time and materials by using the Hardness Standardisation Machine of INMETRO/Brazil.
Tassanai Sanponpute, Apichaya Meesaplak
The effect of environmental vibration on Vickers hardness machine is reported in this paper. Test force 9.807 N (HV1) and 98.07 N (HV10), representing low-force hardness test and normal hardness test, were selected for this experiment. Two machines with different loading mechanism made indentation under influence of single sinusoidal vibration with frequency ranging from 10 Hz to 100 Hz and amplitude ranging from 0.002 m/s² to 0.04 m/s². Indentations were captured by CCD camera and diagonal lengths were measured automatically by software. Response to vibration for each loading mechanism,...