Plastic Hardness Measurement Analyzer
ISO/TS 19278 has been published.
Plastics — Instrumented micro-indentation test for hardness measurement of plastic materials
As the performance of plastics improves, their range of application expands. Plastics used in parts that require durability, such as windows frame of automobiles and cases of cell phones, must not be easily damaged, plastics used in parts of mechanisms such as gears must not easily deform, and plastics used in parts that absorb impact such as bumpers must have just the right amount of flexibility. For evaluation of such parts, it is effective to determine hardness. The hardness of plastics is used not only for evaluation of resistance to deformation or resistance to damage of a material when the material is deformed by foreign matter or when it is subjected to damage, but also for quality control of blend polymer mix, checking the quality stability of molded products, etc. Existing test methods have a number of issues, listed below, which the standard solves. As a result, quality control departments can measure more diverse sample shapes, and the utilization of hardness testing for material selection and performance screening in R&D departments will likely increase.
The standard ISO/TS 19278 adopts a micro-indentation method, so measurement can be carried out with a smaller indentation and test force than for either the Rockwell hardness method or the ball indentation method. Therefore, test samples smaller than those used with conventional test methods can be measured without scale (under the same conditions). With the standard, the measurement conditions are set in advance taking into consideration the effect of the characteristic material properties of plastic, such as the possibility of measurement errors occurring due to plastic surface detection, and the effect of relaxation properties, so high reproducibility is achieved.
Problems of conventional hardness methods and merits of testing methods with ISO/TS 19278
|Conventional hardness method
(Rockwell hardness method)
|ISO/TS 19278 micro-indentation method||With ISO/TS 19278...|
|Indenter||It is necessary to change the diameter of a steel ball indenter in accordance with the hardness of the test sample.||Original Berkovich indenter only. No change
|Test force||The initial test force is 98.07 N, and the maximum test force is large, ranging from 588.4 N to 980.7 N. It is necessary to change the maximum test force in accordance with the hardness of the test sample.||Maximum test force is small, 500 mN.|
|Impression depth||300 to1600µm||From several μm to several 10s of μm|
the same conditions
|The scale must be selected in accordance with the hardness of the test sample so that HR is in the range of 50 to 115.||Scaleless measurement can be performed.|
the test sample
|If the thickness of the test specimen is less than 6 mm, it is necessary to stack test samples. This affects the data.||Test samples with thickness less than 6 mm can be measured as they are|
Note: FRP is not covered by ISO/TS 19278.
Convenient Points Regarding the DUH Series
- Because the conditions are the same it is not necessary to change the test conditions.
- Measurement complying with the standard can be carried out on thinner and smaller test samples.
- Test samples can be fixed by restraining from above with a fixing vice, without the use of adhesive.
- Tests can be simply carried out by selecting the special test mode with software.
- Impression depth can be measured up to 100 μm, so a wide range of hardness can be