The Janka hardness test measures the robustness of wood samples to damage and wear. It measures the force required to implant a 11.28 millimeter (0.444 inch) diameter steel ball in the middle into a wood sample. This method leaves a hemispherical curve with an area 200Ã, mm 2 . The common use of Janka's hardness rank is to determine whether a species is suitable for use as a floor.
Wood hardness varies with the direction of wood grain. Tests on the surface of the board, perpendicular to the grain, are said to be "side violence". Testing the surface of the stump piece is called the "final hardness" test. Side violence can be subdivided into "radial violence" and "tangential violence", although the differences are small and often overlooked.
The results are expressed in various ways, which can cause confusion, especially when the actual units used are often not installed. Overall, the resulting size is always one of the strengths. In the United States, the measurement is in pound-force (lbf). In Sweden it is in kilogram-style (kgf), and in Australia, either in newton (N) or kilonewtons (kN). This confusion is greatest when results are treated as units, for example "660 Janka".
The results of the Janka hardness test tabulated below are performed in accordance with ASTM DÃ, 1037-12 test method. The wood supplies tested range from 1 "to 2" thick. Janka's average tabulated rate of violence. There is a standard deviation associated with each species, but these values ​​are not given. It is important to note that no testing is done on the actual floor. Other factors affect the way floor work: core types for engineered floors such as pine, HDF, poplar, oak, birch; direction and thickness of the grains; floor or worn top surface, etc. This chart is not regarded as absolute; is intended to help people understand which forests are more difficult than others.
Video Janka hardness test
Typical Janka hardness value
Maps Janka hardness test
References
External links
- Janka Hardness Scale For Wood - Side Hardness Chart of Some Woods
- USDA - Wood Handbook - Wood as an Engineering Material
- USDA - Janka Hardness Using Non-Standard Specimens
Source of the article : Wikipedia
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