{"id":69770,"date":"2026-05-17T17:28:05","date_gmt":"2026-05-17T17:28:05","guid":{"rendered":"https:\/\/evgroupchina.com\/encyclopedia-of-metal\/en-iso-7091\/"},"modified":"2026-05-19T15:31:06","modified_gmt":"2026-05-19T15:31:06","slug":"en-iso-7091","status":"publish","type":"wiki","link":"https:\/\/evgroupchina.com\/en\/encyclopedia-of-metal\/en-iso-7091\/","title":{"rendered":"EN ISO 7091"},"content":{"rendered":"<h2>Technical aspects and scope of application for EN ISO 7091 washers<\/h2>\n<p>The international standard EN ISO 7091 regulates the geometry and technical requirements for plain washers of the normal series, belonging to product grade C with a hardness of 100 HV. This fastener is designed for use with metric threaded connections having nominal diameters from 1.6 to 64 mm.<\/p>\n<p>The engineering department of EV Group China recommends using washers of this category in the following assemblies:<\/p>\n<ul>\n<li>Hexagon bolts and screws of product grade C with a property class not exceeding 6.8.<\/li>\n<li>Hexagon nuts corresponding to property classes up to and including 6.<\/li>\n<li>Thread-rolled hardened screws.<\/li>\n<\/ul>\n<p>When selecting sizes not covered by the EN ISO 7091 standard, one should be guided by the ISO 887 specifications, which contain an extended nomenclature of normal plain washers.<\/p>\n<p>Important note for design engineers: when working with soft base materials or in the presence of oversized mounting holes in mating parts, EV Group China specialists recommend performing a preliminary calculation of contact stresses to confirm the suitability of 100 HV grade washers. Incorrect selection can lead to surface deformation or loss of preload in the joint.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":[],"wiki_category":[120],"class_list":["post-69770","wiki","type-wiki","status-publish","hentry","wiki_category-iso"],"_links":{"self":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69770","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69770\/revisions"}],"wp:attachment":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/media?parent=69770"}],"wp:term":[{"taxonomy":"wiki_category","embeddable":true,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki_category?post=69770"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}