Note: The 2017 version has been superseded as of December 12, 2023, by the 2023 version.
Cut the rubber into the specified dumbbell shape using a die cutter.
The point during extension where deformation changes from elastic (reversible) to plastic (permanent). Why Professionals Search for the JIS K 6251 PDF
The standard has undergone several revisions to maintain technical relevance: Latest Version: JIS K 6251:2023
Ensure the die blades are perfectly sharp. Any micro-nicks or rough edges along the specimen side walls will cause premature failure, artificially lowering your tensile strength results. Equipment and Environmental Requirements jis k 6251 pdf
Commonly referred to as the "modulus" (e.g., 100% or 300% modulus), which measures the force required to stretch the rubber to a specific length.
It defines standard methods to measure how rubber materials behave under tension until they reach their breaking point. Key Measured Properties
: Many countries have their own standards bodies that may either adopt JIS standards or provide access to them. For example, in the United States, you might check the American Society for Testing and Materials (ASTM) or the American National Standards Institute (ANSI).
This draft is designed to help you understand the scope, methodology, and key changes in the standard (specifically focusing on the current edition, ). Note: The 2017 version has been superseded as
| Feature | JIS K 6251 (Japan) | ISO 37 (Intl) | ASTM D412 (USA) | | :--- | :--- | :--- | :--- | | | Dumbbell Type 1, 2, 3 | Dumbbell Type 1, 2, 3 | Dumbbell Type C, D, etc. | | Test Speed | 500 mm/min (Standard) | 500 mm/min | 500 mm/min (Common) | | Die Dimensions | Harmonized with ISO | Standard | Slightly different die profiles | | Calculation | Force / Original Cross-Section | Force / Original Cross-Section | Force / Original Cross-Section |
The maximum stress the rubber can withstand before breaking. Elongation at Break: The percentage increase in length at the moment of rupture. Tensile Stress (Modulus):
Measuring elongation by crosshead travel is inaccurate because rubber slips slightly in the grips. JIS K 6251 requires tracking the drawn on the narrow section of the dumbbell. This tracking must be done using:
The American standard for rubber tension. While similar in objective, ASTM D412 uses different dumbbell designations (e.g., Die C) compared to JIS dumbbell numbering. Accessing the JIS K 6251 PDF Why Professionals Search for the JIS K 6251
The standard mandates that specimens be free of surface defects (bubbles, nicks) which can cause premature failure. The thickness must be measured precisely, typically between 2.0mm and 3.0mm for standard dumbbells.
The standard applies to both (thermoset rubbers) and thermoplastic rubbers (elastomers). Its primary purpose is to determine the tensile stress-strain properties, which are critical indicators of a material's durability and elasticity.
The point at which the rubber begins to deform plastically rather than elastically (applicable to specific thermoplastic rubbers). Test Specimen Types and Preparation
The maximum tensile stress recorded executed up to the point of rupture.
Because JIS K 6251 is a copyrighted document published by the Japanese Standards Association (JSA), a "PDF" is usually purchased rather than free. You can find the document in the following places: