Ancienne norme nationale GB 4987-85 (obsol\u00e8te) : clairement divis\u00e9e en quatre cat\u00e9gories : 000, 00, 0 et 1. La cat\u00e9gorie 000 est la plus \u00e9lev\u00e9e. Formule :
Plan\u00e9it\u00e9 de grade 000 : (1 \u00d7 (1 d\/1 000) \u00b5m)
Grade 00 : (2 \u00d7 (1 d\/1 000) \u00b5m)
d = diagonale en mm, \u00e0 20 \u00b0C (Douyin Baike).
Nouvelle version de remplacement GB\/T 20428-2006 \/ 2021 : suppression de la classe 000 ; les classes officielles sont d\u00e9sormais uniquement les suivantes : 00, 0, 1 et 2.
Proc\u00e9dure de v\u00e9rification JJG117-2013 (V\u00e9rification de la plan\u00e9it\u00e9 des plaques de mesure) : cette proc\u00e9dure ne va que jusqu'au grade 00 et ne pr\u00e9voit aucun crit\u00e8re de v\u00e9rification pour le grade 000.
\ud83d\udc49 En d'autres termes : les instituts de m\u00e9trologie tiers ne peuvent pas d\u00e9livrer de certificat de v\u00e9rification de \u201c Grade 000 \u201d ; tout au plus, ils peuvent effectuer une v\u00e9rification jusqu'au Grade 00, et le rapport ne mentionnera que la valeur r\u00e9elle de plan\u00e9it\u00e9 mesur\u00e9e.<\/li>\n\n\n\n
Cela signifie respecter la tol\u00e9rance de plan\u00e9it\u00e9 du grade 000 de l'ancienne norme GB4987-85 (niveau k=1) ;
Largement utilis\u00e9 pour les bases de m\u00e9trologie, les bases de machines \u00e0 mesurer tridimensionnelles (MMT), les semi-conducteurs et les bases optiques ;
Il doit s'agir d'un environnement \u00e0 temp\u00e9rature strictement constante de 20 \u00b1 0,5 \u00b0C, isol\u00e9 des vibrations ; les ateliers classiques ne permettent en aucun cas d'atteindre le niveau de performance 000.<\/li>\n<\/ol>\n\n\n\n
Exemple : une plaque de 1 000 \u00d7 1 000, diagonale \u2248 1 414 mm
Tol\u00e9rance couramment utilis\u00e9e dans l'industrie pour la nuance 000 : \u2248 2,4 \u03bcm
Tol\u00e9rance officielle de la norme nationale pour la classe 00 : \u2248 4,8 \u03bcm<\/p>\n\n\n\n
- \n
- Pi\u00e8ges \u00e0 \u00e9viter lors des proc\u00e9dures de passation de march\u00e9s et de la signature des contrats (Approche pratique)
N'indiquez pas simplement \u201c Grade 000 \u201d, car les organismes de m\u00e9trologie ne reconnaissent pas cette appellation ;
Indiquez la valeur de la tol\u00e9rance de plan\u00e9it\u00e9 ainsi que la formule de calcul correspondante directement dans le contrat ou le cahier des charges, par exemple :
Diagonale d de la surface de travail, plan\u00e9it\u00e9 \u2264 (1 \u00d7 (1 d\/1 000) \u00b5m) (\u00e0 20 \u00b0C) ;
Les certificats d\u00e9livr\u00e9s par des organismes tiers n'indiqueront que la plan\u00e9it\u00e9 r\u00e9ellement mesur\u00e9e en \u03bcm, et non la mention \u201c Grade 000 \u201d ;
De nombreuses petites usines \u00e9tiquettent \u00e0 tort leurs produits \u00ab Grade 000 \u00bb, alors qu'ils n'atteignent en r\u00e9alit\u00e9 que le Grade 00, voire le Grade 0, car il n'existe aucune norme obligatoire en la mati\u00e8re.<\/li>\n\n\n\n - R\u00e9sum\u00e9 succinct
\u2705 Ce terme technique existe bel et bien ; il trouve son origine dans l'ancienne norme nationale GB4987-85, aujourd'hui abrog\u00e9e ;
\u274c Les normes nationales et les proc\u00e9dures de v\u00e9rification nationales en vigueur ne pr\u00e9voient pas de classe de pr\u00e9cision \u201c Grade 000 \u201d d\u00e9finie l\u00e9galement ;
\u2705 Les produits peuvent atteindre les indicateurs de plan\u00e9it\u00e9 correspondant au Grade 000, mais le certificat ne portera pas la mention \u201c Grade 000 \u201d.<\/li>\n<\/ol>\n\n\n\n![\"\"](\"https:\/\/jtlcnc.com\/wp-content\/uploads\/2026\/08\/q-1-1024x544.png\")
<\/figure>","protected":false},"excerpt":{"rendered":"Is there a Grade 000 for granite surface plates? Core ConclusionIn the current national standard GB\/T 20428-2021 “Flatness of Rock Plates”, there is no Grade 000; it only defines: Grades 00, 0, 1, and 2.The old national standard GB 4987-85 did have a Grade 000, which has now been abolished, but the industry, manufacturers, and…<\/p>","protected":false},"author":1,"featured_media":3277,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"categories":[35],"tags":[],"class_list":["post-3276","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"taxonomy_info":{"category":[{"value":35,"label":"NEWS"}]},"featured_image_src_large":["https:\/\/jtlcnc.com\/wp-content\/uploads\/2026\/08\/q-1-1024x544.png",1024,544,true],"author_info":{"display_name":"jinxing6611@gmail.com","author_link":"https:\/\/jtlcnc.com\/fr\/author\/jtlcnc\/"},"comment_info":0,"category_info":[{"term_id":35,"name":"NEWS","slug":"news","term_group":0,"term_taxonomy_id":35,"taxonomy":"category","description":"","parent":0,"count":362,"filter":"raw","cat_ID":35,"category_count":362,"category_description":"","cat_name":"NEWS","category_nicename":"news","category_parent":0}],"tag_info":false,"_links":{"self":[{"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts\/3276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/comments?post=3276"}],"version-history":[{"count":1,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts\/3276\/revisions"}],"predecessor-version":[{"id":3278,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts\/3276\/revisions\/3278"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/media\/3277"}],"wp:attachment":[{"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/media?parent=3276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/categories?post=3276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/tags?post=3276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}