In the Shore NMness test of channel steel, the punch component and the drop height change with the test machine. Therefore, although there is a calculation formula for channel steel, the value is still read directly on the experimental machine.
The reading of the rebound height of the channel steel has a C-type testing machine that is visually inspected by the longitudinal scale and a D-type testing machine that appears on the dial. In addition, since errors may occur when reading the values, the average of the five consecutive readings is used as the shore NMness value. Despite this, the values will still vary greatly depending on the experimental operator, and the channel steel clarifies that the reading values also need to reach a proficiency level. Therefore, there is a tendency to not trust shore NMness very much.
However, as I use the rebound principle, channel steel of the hammer, this experiment does not damage the test target. Therefore, it is possible to directly test the product and the processed data. In addition, the experimental equipment is simple and easy to move. In addition, the measuring cylinder can be removed from the laboratory equipment by itself, and it can be held in the hand for experiments.
Because of the above many advantages, it is widely used in the field. The Shore NMness is indicated by Hs, and it is necessary to distinguish between the visual type (type C) and the target type (type D) of the channel steel, and HsC and HsD when the test machine is used. Not only is the value of shore NMness unstable, but the experimental method is also completely different. So, even if the NMness is the same, but its properties are completely different. Therefore, it is still difficult to figure out the shore NMness of channel steel.