The amount of stress required to stretch the rubber specimen to a given elongation percentage (commonly 100%, 200%, or 300%).
Because rubber grips can slip slightly during high-capacity stretching, relying solely on crosshead displacement can introduce errors. JIS K 6251 highly recommends using non-contact (optical or laser) extensometers to track the precise separation of the gauge marks printed on the specimen. 3. Environmental Conditioning
| Feature | JIS K 6251 | ISO 37 | ASTM D412 | |---------|------------|--------|-----------| | | Japan | International | USA | | Test speeds | 500 mm/min (standard) | 500 mm/min (preferred) | 500 mm/min (Die C) | | Specimen types | Dumbbells (3 types) + rings | Dumbbells (3 types) + rings | Die A, B, C, D, rings | | Gauge length | 25 mm (Type 1,2) | 25 mm (Type 2) | 25 mm (Die C) | | Acceptance in Japan | Mandatory | Often accepted if agreed | Rarely accepted | | Technical difference | Slight variations in specimen dimensions | Virtually identical | Wide tolerances on width |
It is the foundational standard used in Japan to test the mechanical strength of rubber materials. Whether manufacturing automotive tires, industrial seals, or rubber hoses, this standard dictates how to prove the material meets quality specifications. jis k 6251 pdf free
JIS K 6251 specifies the methodologies used to determine how rubber reacts under tension. It is heavily based on the international standard ISO 37 , though it features slight modifications localized for Japanese industrial applications.
Standard sizes used for general rubber compounds when ample material is available.
The following reputable platforms provide the most current versions, such as , which recently superseded the 2017 version: JIS K 6251:2023 - Accuris Standards Store The amount of stress required to stretch the
A device (often optical or laser) that tracks the stretching distance between two gauge marks on the sample without physically damaging the rubber. 3. Testing Speed and Environment
JIS K 6251 categorizes test specimens into specific shapes and numbers (e.g., No. 1, No. 2, No. 3, No. 4, No. 5, No. 6, and No. 7 dumbbells).
: The percentage increase in length that occurs before the material fractures. JIS K 6251 specifies the methodologies used to
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: You can buy the full document (typically 30–40 pages) from the Japanese Standards Association (JSA) or authorized retailers like the ANSI Webstore .