Prefer fine-grained, dense granite such as Jinan Green and Zhangqiu Black; reject raw blocks containing bedding, large mica patches, original dark cracks, or pores; use ultrasonic flaw detection to screen for internal invisible cracks.
Raw blocks must be naturally aged outdoors for \u22653 months to release the original internal stress of the rock layer, avoiding slow cracking in the later stages.
The use of spliced raw blocks to manufacture 00\/000 grade high-precision reference platforms is prohibited.<\/li>\n\n\n\n
Use water-cooled diamond wire saws \/ frame saws for material cutting, with constant temperature water spraying for cooling throughout the process to prevent thermal cracks caused by thermal shock; reserve a 2~3mm finishing allowance on one side, and prohibit deep cutting in a single pass.
CNC milling adopts a symmetrical reciprocating tool path to balance cutting stress on both sides, avoiding single-side stress concentration that pulls and cracks the corners of the stone.
All holes, slots, and corners must have R-shaped fillet transitions (R\u22655mm) to eliminate right-angle stress singularities, which is the core method to prevent corner chipping and radial cracks.
Drilling and tapping use low-speed diamond drill bits with continuous water cooling; dry drilling and impact drilling are prohibited.<\/li>\n\n\n\n
The internal cutting stress of the stone after rough machining is the core cause of later cracking, requiring two stages of aging:
Constant temperature natural aging (standard for high-end ultra-precision platforms)
Lay flat in a dust-free constant temperature workshop at 20\u00b11\u2103 for 2~4 weeks, flipping the stone every 7 days to release stress evenly;
Hot-cold cycle artificial aging (for mass-produced machine tool bases)
Bake at a constant temperature of 80\u2103 for 24h \u2192 deep freeze at -10\u2103 for 4h \u2192 slowly return to 20\u2103 and rest for 72h to thoroughly release residual cutting stress;
After finishing, rest at a constant temperature again for 5~7 days to re-verify accuracy; only if there is no deformation and no new micro-cracks can it proceed to the next process.<\/li>\n\n\n\n
When the internal capillary pores of granite absorb water, thermal expansion and freezing will force open micro-cracks, requiring a two-step sealing process:
Bottom-layer penetration crystallization sealing
Inject silane-modified penetrants under low pressure to seep into the micron-scale pores of the stone, filling the micro-pores with silicate crystals to block moisture penetration and improve the fracture toughness of the matrix;
Surface nano-protective coating
Spray a dense nano-SiO\u2082 coating on the high-precision working surface to form a continuous protective film, isolating oil and water vapor, inhibiting micro-crack expansion, and simultaneously increasing surface hardness.
II. Internal body structural reinforcement technology (improving overall anti-cracking capability from the inside) 1.Lightweight cavity topology optimization (reducing thermal stress and self-weight stress)
Large bases adopt a frame hollow cavity structure, optimizing the cavity layout through finite element simulation to avoid stress concentration areas:
Reduce weight by 30%~50%, reducing self-weight bending tensile stress;
Reduce overall heat capacity, reducing thermal stress during temperature changes;<\/li>\n<\/ol>\n\n\n\n
- \n
- Pre-embedded composite reinforcement (tensile reinforcement) in high-stress areas
Internal reinforcement is applied to the guide rail installation, lifting holes, support points, and eccentric load-bearing areas:
Pre-embedded stainless steel sleeves
All threaded holes and installation holes are integrally pre-embedded with thickened304 stainless steel threaded sleeves to disperse bolt tightening stress and prevent radial cracks around the threaded holes; the outer wall of the steel sleeve is knurled and bonded with epoxy to act as an integral load-bearing unit with the stone, avoiding interface cracking caused by the modulus difference between metal and stone.
Embedded carbon fiber \/ glass fiber reinforcement bars
Ultralong flat plates and cantilever bases are grooved internally to embed carbon fiber bars, which are then cast and cured with epoxy to significantly enhance tensile strength and resist bending tensile cracks; widely in large-scale semiconductor measurement platforms.
Bottom thickened load-bearing ribs
Integrated thickened stone ribs are placed below the support points to disperse concentrated loads and prevent single-point crushing cracking.<\/li>\n\n\n\n - Three-point \/ four-point flexible support structure design (to avoid assembly compression cracking)
Direct tightening of granite surfaces with rigid bolts is strictly prohibited; flexible buffering support system is adopted:
Standard configuration: Spherical self-aligning bearings low-expansion Invar alloy transition spacers elastic rubber buffering layer;
Principle Absorbs assembly stresses and micro-displacements from thermal deformation, controlling local contact stress within the tensile strength of granite (<8MPa);
Support points are located near the of gravity of the base to reduce eccentric bending moments and prevent tensile cracking on one side.<\/li>\n<\/ol>\n\n\n\nIII. Specialized Reinforcement and Anti-Cracking Process for Multi-Block Spliced Bases (Large-Size Split Platforms)
Ultra-large platforms cannot be quarried as a single block, and splicing is a high-risk area for cracking. A dual reinforcement approach of mechanical interlocking chemical composite bonding is adopted:
Mortise and Tenon \/ Dovetail Mechanical Interlocking Structure
Dovetail grooves and concave-convex tenons are machined on the splicing surfaces to significantly increase the contact area and form a mechanical interlock. A simple adhesive layer cannot withstand shear forces, so the mechanical structure blocks the expansion of cracks at the splicing seam.
Low-Shrinkage Epoxy Structural Adhesive Bonding
Traditional cement mortar is eliminated in favor of a mineral-filled epoxy adhesive with a thermal expansion coefficient matching that of granite. It features a curing shrinkage rate <0.02% and a bonding strength \u22653MPa, transferring loads and inhibiting the cracking of the splicing seam. The adhesive layer thickness is controlled at 0.1~0.2mm to prevent debonding caused by temperature differences in thick adhesive layers.
Backside Pre-embedded Tensioning Steel Pin Reinforcement
Stainless steel pins are horizontally pre-embedded at the back of the splicing seam and sealed with epoxy injection. These pins pull the two stone blocks together laterally, offsetting the tensile stress at the splicing seam caused by the bending of the plate surface.
IV. External Composite Constraint Reinforcement System (Anti-Cracking for Full Machine Service)<\/p>\n\n\n\n- \n
- Steel Full-Enclosure Constraint Frame
A steel outer frame is assembled around the four sides of the large machine tool base, flexibly tightened with low-expansion bolts:
It limits the free thermal expansion of the granite, preventing tensile cracks caused by unconstrained deformation;
The steel frame absorbs vibration and impact, dispersing local impact stress to prevent corner chipping;
Non-metallic buffer pads are placed between the steel and the stone to avoid the rigid compression of the stone surface by the metal.<\/li>\n\n\n\n - Bottom Composite Counterweight Reinforcement
The bottom of the lightweight hollow base is integrated with a thickened granite counterweight seat, or cast iron counterweights are added:
This lowers the center of gravity of the entire machine, reducing the alternating bending stress caused by dynamic machining and equipment movement, and preventing the continuous expansion of long-term fatigue micro-cracks.
V. Micro-crack Repair and Reinforcement Process (Reinforcement After Fine Cracks Appear in Finished Products)
Crack Cleaning and Widening Treatment
The moisture inside the crack is dried with hot air, loose debris is removed, and shallow cracks are widened to 0.3~0.5mm to ensure full penetration of the adhesive liquid;
Mineral-Filled Epoxy Grouting Reinforcement
A high-toughness, low-shrinkage stone powder epoxy adhesive is selected to match the hardness and thermal expansion coefficient of the granite. It is injected in layers, with short glass fibers pre-embedded in wide cracks for reinforcement. Color-matched stone powder is added for color adjustment, allowing the repaired area to be ground and polished to restore surface flatness;
Deep Through-Crack Metal Pin Reinforcement
For through-cracks with a depth >5mm, stainless steel reinforcement pins are diagonally implanted and completely encased in epoxy. This forms a “bridging structure” that blocks crack extension and prevents subsequent fracture under load.<\/li>\n<\/ol>\n\n\n\nVI. Anti-cracking protection design for service environment matching
Constant temperature and humidity working conditions
Precision instrument workshop control: 20\u00b11\u2103, temperature change rate \u22640.5\u2103\/h, eliminating periodic thermal stress caused by drastic temperature differences; environmental humidity 40%~60%, reducing pore water absorption and freeze-thaw cracking.
Vibration isolation and buffer protection
Air springs \/ damping vibration isolation pads installed under the base to isolate continuous ground vibrations, avoiding fatigue micro-cracks induced by alternating stresses;
Lifting and transportation protection
Soft foam fully wrapping the working surface, multi-point flexible support with a solid wood frame, prohibiting single-point lifting and direct contact of steel wire ropes with stone edges, eliminating transport impact cracking.
VII. Summary of anti-cracking shortcomings of SiC base compared to granite
Even with a full set of reinforcement processes, granite still has inherent defects:
Tensile strength is far lower than SiC ceramics, making it prone to micro-cracks under heavy load and high-speed scanning conditions;
Thermal conductivity is only 3~5W\/(m\u30fbK), generating huge thermal stress from local heating, making it unusable in water-cooling conditions;
Extremely heavy self-weight limits the design of lightweight reinforced structures, making it unable to replace the SiC integrated water-cooled base in aerospace and EUV lithography machine scenarios.<\/p>\n\n\n\n![\"\"](\"https:\/\/jtlcnc.com\/wp-content\/uploads\/2026\/04\/\u5fae\u4fe1\u56fe\u7247_20260425172344_2_45-1024x722.png\")
<\/figure>","protected":false},"excerpt":{"rendered":"Anti-cracking process and structural reinforcement technology for granite precision platform basesThe tensile strength of granite is extremely low (only 8~14MPa), making it highly susceptible to micro-cracks and through-cracks caused by residual mining stress, machining cutting stress, thermal stress from temperature changes, concentrated loads, and hard assembly compression. The complete technology is divided into six major…<\/p>","protected":false},"author":1,"featured_media":2822,"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-3045","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\/05\/\u5fae\u4fe1\u56fe\u7247_20260525151849_7_11.png",626,800,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":310,"filter":"raw","cat_ID":35,"category_count":310,"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\/3045","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=3045"}],"version-history":[{"count":1,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts\/3045\/revisions"}],"predecessor-version":[{"id":3046,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/posts\/3045\/revisions\/3046"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/media\/2822"}],"wp:attachment":[{"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/media?parent=3045"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/categories?post=3045"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jtlcnc.com\/es\/wp-json\/wp\/v2\/tags?post=3045"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Steel Full-Enclosure Constraint Frame