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Trends of standardization of seals | General-purpose seal technology | Technologies | NOK CORPORATION

Trends of standardization of seals | General-purpose seal technology | Technologies | NOK CORPORATION

1. Trends in International Standards

The International Organization for Standardization (ISO) has been promoting standardization with the aim of eliminating differences in standards between countries. International standards on seals in general are promoted by the Seal Devices (SC7) committee in Fluid power systems and components (ISO/TC 131) as shown in Table 1.

1.1 O-Rings

Working Group 3 for design criteria for standard O-Ring applications (WG3), which belongs to Sub Committee 7 (SC7), is responsible for drafting and revising standards related to O-rings.
In response to a request from the United States to add dimensions for aerospace applications to ISO 3601/1 O-Ring standards, we have asked the SC7 secretariat to request that the TC20/SC10 committee, which is in charge of aerospace applications, take action.
The United Kingdom submitted a proposal (ISO/CD 15272) for a true millimeter O-ring for ISO/DIS 3601/2 (dimensions of rod and piston grooves) on the grounds that it would be difficult to match the millimeter dimensions, and although it was discussed, there was much opposition from the United States and other major countries. At the 1997 San Antonio meeting, the relationship with ISO 3601/1 was discussed again, but people from major countries thought that a new O-ring standard for millimeter applications was unnecessary and ISO/CD 15272 was discarded. As a result, Sweden stepped down as the organizer and Germany has now taken over the role and manages WG3.
As a result, Sweden stepped down as the organizer and Germany has now taken over the role and manages WG3.
ISO/CD 3601/4 (H series: O-ring standards for fitting) is a special application standard and was removed from the SC7 committee and transferred to the SC4 committee that is in charge of fitting-related standards.
The draft standards of ISO/DIS 3601/5 (backup rings) and ISO/DIS 3601/6 (recommended materials) are currently under discussion and will be standardized in the near future.

1.2 Oil seals

Working Group 4 for rotary shaft lip type seals (WG4), which belongs to Sub Committee 7 (SC7), is responsible for drafting and revising standards related to oil seals.
Although ISO 6194/3 for oil seals has undergone a five-year periodic review, as there is no particular problem, it is expected to be updated without revision.
Regarding ISO 6194/4, however, the United Kingdom proposed a major revision for a five-year periodic review, and the revision proposal is currently under deliberation.
Oil seals incorporating thermoplastic sealing elements are standardized as follows: ISO/DIS 16589/1 (Dimensions and tolerances), ISO/DIS 16589/2 (Vocabulary), ISO/DIS 16589/3 (Storage, handling and installation), ISO/DIS 16589/4 (Performance test procedures), and ISO/DIS 16589/5 (Identification of visual imperfections).

1.3 Packings

Working Group 2 for dimensions for seal housings (WG2), which belongs to Sub Committee 7 (SC7), is responsible for drafting and revising standards related to packings.
At the Paris meeting in December 1998, a proposal to amend ISO 6195 for packings was presented by the British chair, and an additional proposal for the shape of elastomer-energized plastic face wiper rings was submitted by Germany. Market performance led to the acceptance of the German proposal, and it was decided that Germany would redraw and submit the groove dimensions and tolerance tables.
Major ISO Standards for seals are shown in Table 2.

2. Trends in Domestic Standards

The Japan Fluid Power Association (JFPA) is in charge of domestic standards for general seals, and the Japan Auto Parts Industries Association (JAPIA) is in charge of some oil seals on consignment from JFPA.
In recent years, the Ministry of Economy, Trade and Industry (METI) has been trying to coordinate domestic standards with international standards (ISO) as a measure to mitigate trade friction, and therefore promotes compliance of domestic standards (JIS) and group standards with ISO when they are periodically reviewed. In addition, if there is no national standard, work is under way to translate the international standards into JIS. Regarding packing, ISO 10766 (Hydraulic fluid power—Cylinders—Housing dimensions for rectangular-cut bearing rings for pistons and rods) has already been translated and published as JIS B 8663. The following will also be translated and standardized: ISO 5597 (Hydraulic fluid power—Cylinders—Housings for piston and rod seals in reciprocating applications — Dimensions and tolerances) and ISO 6195 (Fluid power systems and components—Cylinders—Housings for rod wiper rings in reciprocating applications — Dimensions and tolerances)
The scope of application of JIS B 2408 will also be revised in the near future in accordance with the review of ISO 6301/3.
Major Japanese Industrial Standards for seals are shown in Table 3.

3. Trends in Group Standards

Group standards are created to supplement the parts where JIS standards do not exist or that are not detailed in JIS standards.
Oil seals and O-rings are regulated by the Society of Automotive Engineers of Japan Inc., and packings are regulated by the Japan Fluid Power Association.
In addition, JOHS and JPAS published by the Japan Fluid Power Association will be unified to JFPS from the new standard.
Major standards established by trade associations for seals are shown in Table 4.

4. Other (International standards)

International standards for seals commonly used in the market are shown in Table 5.

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