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Standardization of O-Ring Sizes

When the O-Ring concept was originally developed, there was no standardization of sizes. Product designers and manufacturers would design O-ring seals specifically for their applications and machinery, meaning O-Ring suppliers would only produce specific sizes they had customers for. Very few sizes, if any, were used by more than one customer and this lack of standardization discouraged O-Ring manufacturers from producing in the most economical quantities.

The United States government recognized the commercial need for standardized O-Ring sizes and developed the aerospace size standard chart (AS568). The AS568 size chart identifies standard sizing by inside diameter and cross-sectional thickness, with reference dimensions for outside diameter. Other standard size charts include British Standard (BS), European standard, and Japanese standard.


               Advantages & Disadvantages of Standardization
  Advantages  Disadvantages
  • Fewer parts to manage in inventory and manufacturing

  • Reduced training costs and time

  • More routine purchasing, handling, inspection procedures

  • Orders fillable more quickly from inventory

  • Opportunities for long production runs and automation

  • Need for fewer parts justifies expenditures on perfecting designs and improving quality control procedures
  • Designs may be limited High cost of design changes increases resistance to improvements

  • Decreased variety results in less consumer appeal


View O-Ring Size Chart

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