{"id":2393,"date":"2026-04-13T08:49:21","date_gmt":"2026-04-13T00:49:21","guid":{"rendered":"https:\/\/jtlcnc.com\/?p=2393"},"modified":"2026-04-13T08:49:25","modified_gmt":"2026-04-13T00:49:25","slug":"how-are-the-accuracy-grades-of-granite-measuring-tools-classified","status":"publish","type":"post","link":"https:\/\/jtlcnc.com\/es\/2026\/04\/13\/how-are-the-accuracy-grades-of-granite-measuring-tools-classified\/","title":{"rendered":"How are the accuracy grades of granite measuring tools classified?"},"content":{"rendered":"

Classification of Accuracy Grades for Granite (Rock) Measuring Tools, based primarily on National Standard GB\/T 20428-2006 “Rock Slabs” (mainstream grades are Grade 000, 00, 0, and 1; the old standard GB 4987-85 is the same). The core indicator is flatness, with tolerances calculated based on dimensions and diagonal length.<\/p>\n\n\n\n

I. Grades and Core Definitions (National Standard)
Grade 000 (Calibration Grade \/ Metrological Reference)
Highest precision, used in National Metrology Institutes, calibration laboratories, optical\/semiconductor references
Flatness Formula: 1 \u00d7 (1 d\/1000) \u03bcm (d = diagonal mm)
Example: 300\u00d7300mm \u2192 \u22641.5\u03bcm; 1000\u00d71000mm \u2192 \u22642.5\u03bcm
Grade 00 (Precision Inspection Grade)
CMMs, vision systems, precision inspection references
Formula: 2 \u00d7 (1 d\/1000) \u03bcm
Example: 300\u00d7300 \u2192 \u22643\u03bcm; 1000\u00d71000 \u2192 \u22645\u03bcm
Grade 0 (General Inspection Grade)
Workshop precision inspection, tooling and fixture references
Formula: 4 \u00d7 (1 d\/1000) \u03bcm
Example: 1000\u00d71000 \u2192 \u22647\u03bcm
Grade 1 (Ordinary Scribing \/ Rough Inspection)
Mechanical scribing, general assembly inspection
Formula: 8 \u00d7 (1 d\/1000) \u03bcm
Example: 1000\u00d71000 \u2192 \u226414\u03bcm<\/p>\n\n\n\n

II. Quick Reference Table for Common Specifications (\u03bcm, 20\u2103)
Cuadro
Specification (mm) Grade 000 Grade 00 Grade 0 Grade 1
300\u00d7300 1.5 3 6 12
500\u00d7500 2 4 8 16
1000\u00d71000 2.5 5 10 20
1500\u00d71000 3 6 12 24
2000\u00d71500 4 8 16 32<\/p>\n\n\n\n

III. Other Key Precision Indicators
Surface Roughness: Working surface Ra\u22640.02~0.1\u03bcm (Grade 000\/00)
Straightness (Straight Edge): Grade 00 \u22641\u03bcm\/m, Grade 0 \u22642\u03bcm\/m
Perpendicularity (Right Angle): Grade 00 \u22642\u03bcm\/100mm
Parallelism (Parallel Rule): 1\/2~1\/3 of the flatness of the same grade<\/p>\n\n\n\n

IV. Grade Selection Guide
Grade 000: Metrological calibration, semiconductor mask inspection, optical references
Grade 00: CMMs, precision inspection, aerospace
Grade 0: Workshop quality inspection, tooling references, precision assembly
Grade 1: Scribing, rough inspection, general assembly<\/p>\n\n\n\n

V. Comparison with Metal Platforms
Granite: Grade 000\/00 stable, resistant to temperature changes, wear-resistant, rust-proof
Cast Iron \/ Steel: Highest Grade 0~1, easily affected by temperature, vibration, and rust<\/p>\n\n\n\n

\"\"<\/figure>","protected":false},"excerpt":{"rendered":"

Classification of Accuracy Grades for Granite (Rock) Measuring Tools, based primarily on National Standard GB\/T 20428-2006 “Rock Slabs” (mainstream grades are Grade 000, 00, 0, and 1; the old standard GB 4987-85 is the same). The core indicator is flatness, with tolerances calculated based on dimensions and diagonal length. I. Grades and Core Definitions (National…<\/p>","protected":false},"author":1,"featured_media":2396,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_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-2393","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\/04\/\u5fae\u4fe1\u56fe\u7247_20260407144906_14_11.jpg",738,721,false],"author_info":{"display_name":"jinxing6611@gmail.com","author_link":"https:\/\/jtlcnc.com\/es\/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":137,"filter":"raw","cat_ID":35,"category_count":137,"category_description":"","cat_name":"NEWS","category_nicename":"news","category_parent":0}],"tag_info":false,"_links":{"self":[{"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts\/2393","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/comments?post=2393"}],"version-history":[{"count":2,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts\/2393\/revisions"}],"predecessor-version":[{"id":2398,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts\/2393\/revisions\/2398"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/media\/2396"}],"wp:attachment":[{"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/media?parent=2393"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/categories?post=2393"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/tags?post=2393"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}