{"id":2910,"date":"2026-06-11T09:07:20","date_gmt":"2026-06-11T01:07:20","guid":{"rendered":"https:\/\/jtlcnc.com\/?p=2910"},"modified":"2026-06-11T09:07:21","modified_gmt":"2026-06-11T01:07:21","slug":"how-to-choose-a-suitable-granite-base-cmm","status":"publish","type":"post","link":"https:\/\/jtlcnc.com\/fr\/2026\/06\/11\/how-to-choose-a-suitable-granite-base-cmm\/","title":{"rendered":"How to choose a suitable granite base CMM?"},"content":{"rendered":"

I. First Step: Determine Granite Base Material and Grade (Most Critical)
1) Stone Types (From High to Low)
Indian Black (M10) \/ Imported Black Granite: High density, lowest thermal expansion coefficient, best stability, used for high-precision \/ laboratory-grade CMMs (aerospace, medical, optics).
Jinan Green: Top domestic grade, good rigidity and vibration absorption, first choice for mid-to-high-end bridge machines; relatively expensive.
Zhangqiu Black (Sesame Black): King of cost-performance, most commonly used for ordinary molds, auto parts, and workshop-type CMMs.
Northeast Sesame White: Average stability, only used for low-precision, economical equipment.
\u274c Pitfall Avoidance: Do not buy “dyed granite” or “synthetic marble”; they deform, fade, and lose precision significantly after 1\u20132 years of use.
2) Precision Grade (Flatness)
000 Grade (Ultra-high precision): \u22642\u03bcm\/m, used in laboratories and metrology rooms.
00 Grade (Industrial standard): \u22644\u20135\u03bcm\/m, standard configuration for the vast majority of CMMs.
0 Grade: \u226410\u03bcm\/m, only used for rough measurements and economical machines.
3) Granite Base Requirements
Monolithic Structure (Non-assembled): Base Y-axis guide rail worktable must be from the same block of material, with no assembly stress.
Natural Aging \u2265 2 Years: Internal stress fully released to avoid later deformation.
Surface Grinding Ra\u22640.4\u03bcm: Guide rail and worktable surfaces must be mirror-grade.
II. Select Structure: Moving Bridge vs. Fixed Bridge (Different Granite Applications)
1) Moving Bridge (Most Common, Recommended)
The worktable is a massive granite block, fixed in place; the bridge moves in the Y-direction.
Advantages: High load capacity, stable, good vibration resistance, convenient workpiece loading\/unloading; first choice for molds, auto parts, and 3C products.
Granite: Integrated base worktable Y-axis guide rail, thickness 150\u2013300mm.<\/p>\n\n\n\n

Moving Bridge CMM
2) Fixed Bridge (High Precision)
The bridge is fixed, and the granite worktable moves in the Y-direction.
Advantages: Extremely high rigidity, highest precision (up to 0.5\u03bcm level); aerospace, medical, optics.
Disadvantages: Limited travel, slightly lower load capacity, high price.<\/p>\n\n\n\n

Fixed Bridge CMM
3) Gantry Type (Large Workpieces)
Large monolithic granite base, equipped with cast iron or steel crossbeams; used for automotive body panels and large aerospace components.<\/p>\n\n\n\n

Gantry CMM
III. Reverse Selection Based on “Precision Requirements” (Most Practical)
1) Ultra-high Precision (Within \u00b11\u03bcm)
Scenarios: Aircraft engines, optical lenses, medical implants
Configuration: Fixed bridge Indian Black \/ Jinan Green 000 grade air bearing guide rails constant temperature 20\u00b10.5\u2103.
2) Mid-to-high Precision (\u00b12\u20133\u03bcm)
Scenarios: Precision molds, automotive transmissions, 3C molds
Configuration: Moving bridge Jinan Green \/ Zhangqiu Black 00 grade air bearing guide rails workshop air conditioning.
3) Ordinary Precision (\u00b15\u03bcm)
Scenarios: Machined parts, stamped parts, workshop spot checks
Configuration: Moving bridge Zhangqiu Black 00 grade linear guide rails ordinary environment.
Empirical Formula: CMM precision \u2248 1\/3 to 1\/5 of the workpiece tolerance.<\/p>\n\n\n\n

IV. Travel and Load Capacity: Granite base must be “large and thick enough”
X\/Y\/Z Travel: Based on maximum workpiece size 100\u2013200mm margin; e.g., for a 500\u00d7400\u00d7300 workpiece, select a 700\u00d7600\u00d7500 machine model.
Worktable Load Capacity: Granite base load capacity \u2265 (workpiece fixture total weight) \u00d7 1.5; Common: 500kg, 1000kg, 2000kg.
Base Thickness:
Small machines (below 700): \u2265150mm
Medium machines (around 1000): \u2265200mm
Large machines: \u2265250\u2013300mm
V. Environmental Adaptation: Granite advantages must match the site
High vibration (workshop, with overhead cranes): Must use granite air-bearing guideways independent vibration-proof foundation; shock absorption is 3\u20135 times stronger than cast iron.
Large temperature fluctuations (no constant temperature): Select Jinan Blue \/ Indian Black (thermal expansion coefficient \u2248 6.5\u00d710\u207b\u2076\/\u2103), much more stable than cast iron.
Humid \/ with cutting fluid: Granite does not rust, is acid and alkali resistant, and is easier to maintain than cast iron.
VI. Budget Range Reference (2026 market price, domestic)
Economic type (\u00b15\u03bcm): Moving bridge Zhangqiu Black Grade 00, 150,000\u2013250,000
Mid-to-high end (\u00b12\u20133\u03bcm): Moving bridge Jinan Blue Grade 00 air-bearing, 300,000\u2013500,000
High precision (\u00b11\u03bcm): Fixed bridge Indian Black Grade 000, 600,000\u20131,000,000
VII. Quick Selection Checklist (Directly check off)
\u2705 Granite: Monolithic, natural aging \u2265 2 years, Grade 00 and above
\u2705 Stone material: Precision \u2192 Indian Black \/ Jinan Blue; Standard \u2192 Zhangqiu Black
\u2705 Structure: Mold \/ Auto parts \u2192 Moving bridge; Aerospace \/ Medical \u2192 Fixed bridge
\u2705 Travel: Workpiece size 100\u2013200mm
\u2705 Load capacity: \u2265 (workpiece fixture) \u00d7 1.5
\u2705 Guideways: High precision \u2192 Air-bearing; Standard \u2192 Linear guideways<\/p>\n\n\n\n

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

I. First Step: Determine Granite Base Material and Grade (Most Critical)1) Stone Types (From High to Low)Indian Black (M10) \/ Imported Black Granite: High density, lowest thermal expansion coefficient, best stability, used for high-precision \/ laboratory-grade CMMs (aerospace, medical, optics).Jinan Green: Top domestic grade, good rigidity and vibration absorption, first choice for mid-to-high-end bridge machines;…<\/p>","protected":false},"author":1,"featured_media":2911,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_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-2910","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\/06\/\u5fae\u4fe1\u56fe\u7247_20260610110137_64_137.png",990,936,false],"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":238,"filter":"raw","cat_ID":35,"category_count":238,"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\/2910","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=2910"}],"version-history":[{"count":1,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts\/2910\/revisions"}],"predecessor-version":[{"id":2912,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/posts\/2910\/revisions\/2912"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/media\/2911"}],"wp:attachment":[{"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/media?parent=2910"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/categories?post=2910"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jtlcnc.com\/fr\/wp-json\/wp\/v2\/tags?post=2910"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}