Collection of terms for miscellaneous rubber products

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Rubber: It stretches greatly after applying a little force. After removing the external force, The nature of recovery (elasticity), a substance that requires a cross-linking reaction. There are natural rubber produced from latex collected from rubber trees, synthetic rubber chemically synthesized from petroleum, etc., and recycled rubber. Rubber that does not need to be cross-linked and can be molded like plastic is called “thermoplastic elastomer”.

O-ring: The so-called O-ring refers to a ring-shaped seal with an O-shaped (circular) cross-section. It is generally installed in a tank and compressed appropriately, and can be used as a seal for various fluids such as oil, water, air, and gas. Depending on the method of use, there are stationary, sports, etc.

Flash: Thin rubber that flows out from the gap of the mold assembly. The size of the flash margin of the O-ring is specified in JIS B2408.

Compression permanent deformation: the permanent deformation rate of rubber after long-term compression load. Care must be taken not to be confused with low-temperature compression permanent deformation.

Elasticity: After removing the load that causes deformation, the material can return to its original shape. The irreversible property is called “plasticity”.

Compression allowance: O-rings are usually compressed for use, so the depth of the installation groove can be set to be slightly smaller than the thickness of the O-ring. The amount of compression is called “compression margin”.

Parting line: The so-called “parting line” refers to the texture of the mold parting line.

Swelling: The oil resistance, chemical resistance, etc. of the selected O-ring are not suitable, and the O-ring becomes soft and swells due to inhalation of liquid.

Curing: Sometimes unreacted vulcanizing agent remains in the rubber, and the vulcanization is continued by heating and the hardness increases. This is called “hardening”. However, when the high temperature continues for a long time or the temperature rises sharply, the rubber will harden sharply and lose its flexibility, and the molecular bonds will break and cracks or even breakage will occur. (Depending on the type of rubber, it sometimes causes the molecular chain to be cut and softened) Ozone cracking: Ozone is a gas with a strong oxidizing power. After being exposed to it, it will promote the severing and cross-linking of the rubber polymer chain. Rubber will deteriorate (low molecular weight will reduce strength, hardening will reduce flexibility). After the deterioration continues to develop, a kind of “cracks” called “cracks” will appear on the surface.

Retaining ring: Used to prevent the O-ring from overflowing when used under high pressure conditions. The installation location should be on the opposite side of the pressurized side. When pressure is applied on both sides, it should be installed on both sides of the O-ring. In addition, it can also prevent O-ring tearing, torsion damage and other accidents at low pressure where overflow is not easy to occur, avoiding damage, and prolonging the life of the O-ring. The materials are leather, nylon, hard rubber, metal, Teflon, etc., but currently, Teflon retaining rings with good fusion properties are mostly used. There are 3 types: circular, oblique cut, and spiral. The ring shape is the best in terms of use effect, but from the perspective of assemblability, most of the oblique shapes and spiral shapes are used.

MSDS: The so-called MSDS refers to the abbreviation of Material Safety Data Sheet, also called “Product Safety Data Sheet”. It refers to the proper use of chemical products for safety, and records the contents of the product. Information about the name of the substance, its hazard and harmfulness information, precautions for use, and environmental impact.

RoHS Directive: Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment EU (European Union) on July 1, 2006. That is, the directive restricting the use of certain hazardous substances in electrical and electronic equipment. Restricted substances include: Pb (lead), Cd (cadmium), Cr6+ (hexavalent chromium), Hg (mercury), PBB (polybrominated biphenyl), PBDE (polybrominated diphenyl ether) and other 6 substances.

Permeability: The property that gas molecules can pass through molecular gaps is called “permeability”. On the contrary, the property that is not easy to penetrate is called “gas barrier”. Rubber is elastic and has a molecular structure. It is not as dense as plastic, so in general, rubber has higher air permeability than plastic. Depending on the material, in the case of inorganic gases (N2, O2, He, etc.), butyl rubber and fluorine rubber are not easily permeable, while silicone rubber is a material that is easily permeable.

Fixation method: Generally, there are 3 kinds of fixation methods: for sports, for cylindrical surface, and for plane.

Torsion phenomenon: O-ring torsion caused by improper installation of O-ring or poor processing of sliding surface, valve opening and closing action, etc. Depending on the situation, it may even be cut off.

PAGE TOP Abrasion resistance: Because rubber is very soft, after rubbing with other materials, it will be shaved off and reduce its volume. This property that is not easy to be shaved off is called “wear resistance”.

Non-adhesive: The O-ring will not stick to the opposite surface even after long-term use. .

Test results table: A table showing the physical properties and specifications of the O-ring material.

Coating: refers to applying a fluororesin coating to the surface of the O-ring. Can improve sliding properties and so on.

PAGE TOP wire diameter: indicates the thickness of the O-ring. In addition, it is also represented by symbols W, π, etc. The inner diameter represents the inner diameter of the O-ring. In addition, it is also represented by a symbol ID or the like.

JASO specifications: Refers to the specifications of the Association of Automobile Technicians. The tolerance of JIS standard wire diameter and inner diameter is very strict.

ISO standard: refers to the standard of the International Organization for Standardization.

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