Installation, Commissioning, and Maintenance Key Points for Granite Machine Tool Guides (Granite Guides)
Applicable to: Jinan Qing Granite Guides, Integrated Granite Bed Guides, Air Bearing / Hydrostatic / Linear Guide Installation Bases; Granite has high brittleness and unique thermal characteristics, and its installation and maintenance logic differs significantly from cast iron guides.
I. Pre-installation Precautions
- Site Environment Requirements
Temperature Control
Granite has a low coefficient of linear expansion, but local temperature differences are strictly prohibited. The guides must not be exposed to direct sunlight or direct air conditioning vents; uneven ground temperature will cause the guides to arch and twist.
Recommended environment: Constant temperature ±0.5~±1℃, temperature gradient <0.3℃/m.
Foundation and Vibration
Vibration-damping foundations / vibration-damping pads must be used; although granite has good damping, external low-frequency vibrations will still affect precision;
Keep away from vibration sources such as stamping machines, milling machines, and air compressors;
The foundation must fully settle; foundations of new workshops must be left to rest for at least 30 days before installation.
Чистота
The installation area must be dust-proof; metal sand particles and cement dust falling on the ground surface of the guide can easily press out permanent pits. - On-site Resting of Workpieces (Crucial)
Granite components undergo constant-temperature grinding before leaving the factory and cannot be installed immediately upon arrival at the site:
Large guides / beds: Rest in a constant-temperature workshop for 48–72 hours to allow the stone temperature and ambient temperature to fully equilibrate;
It is forbidden to adjust the level immediately after transporting from a low-temperature outdoor environment into a constant-temperature room; the temperature difference will cause temporary deformation, and the precision will drift again after leveling once the temperature equilibrates. - Lifting Protection
Directly binding granite edges with steel wire ropes is strictly prohibited; soft slings and rubber corner protectors must be used;
Single-point lifting, violent impacts, and rolling are prohibited; stone is prone to invisible internal micro-cracks under impact, which will lead to gradual deformation and chipping later;
Lift the precision-machined guide surface facing upwards to avoid friction and scratching the ground surface.
II. Core Specifications for Installation and Leveling - Support Layout Principles (Top Priority)
Granite has good rigidity but poor bending resistance; unreasonable support will easily cause stress deformation.
✅ Standard Method: Three-point main support auxiliary support (unloading support)
The three-point support determines the reference plane; do not hard-press all supports simultaneously;
Auxiliary supports only bear the self-weight; do not force them tight, as excessive jacking force will cause the guide to twist forcibly;
❌ Error: Tightening all multi-point shims with full force to force “leveling” creates internal stress, causing precision drift after temperature changes. - Leveling Operation
Use precision levels and laser interferometers for monitoring; leveling torque should be uniform, gradual, and involve multiple cycles;
Re-measure every 30 minutes during the leveling process to release minor stresses in the stone;
After leveling is complete, do not over-tighten the nuts to prevent local compression from causing indentations and deformation;
Guide Splicing Structure (Segmented Splicing of Long Guides)
The splicing surface must be clean and free of impurities; metal debris must not be trapped;
Control the splicing gap and calibrate for equal height; tighten bolts uniformly in a diagonal pattern to avoid single-side compression causing the guide surface to bulge;
After splicing is complete, rest in a constant-temperature environment for 24 hours and re-measure the straightness. - Assembly of Guide Pairs (Three Structures)
1) Granite working surface directly as an air bearing / hydrostatic guide (no steel guide, ultra-precision equipment)
The ground surface must not be bumped; no direct contact with any hard tools;
Thoroughly blow out the air chambers before air supply to prevent solid particles from entering the air film gap;
Sealant and thread adhesive must not contaminate the guide working surface.
2) Granite base external steel linear
III. Operational Taboos
Prohibit hard objects from striking the guide rail working surface.
Dropping wrenches, workpieces, or tools will cause irreparable dents and chipped edges; once the grinding precision of the granite surface is damaged, it can only be re-ground at the factory and cannot be repaired on-site.
Avoid prolonged exposure to localized heat sources.
Close-range local heating by welding torches, heat guns, or high-power light sources causes local thermal expansion, leading to permanent micro-deformation of the guide rail.
Load Specifications
Concentrated single-point pressure exceeding the design load is not allowed; excessive local compressive stress will generate internal micro-cracks.
Cleaning Medium Distinction
Air-float granite guide rail surface: Prohibit large-scale water rinsing! Moisture penetrating the stone’s micropores will cause internal stains over time; water vapor will also affect the air-float bearings;
For minor stains, use a lint-free cloth anhydrous ethanol / isopropyl alcohol for light wiping.
IV. Daily Maintenance Details
- Cleaning and Maintenance
Daily: Use a lint-free brush to sweep away floating dust first, then wipe with a lint-free cloth;
Oil stains: Wipe with anhydrous ethanol; prohibit strong alkaline or strong acid cleaners (which corrode the microcrystalline structure of the stone surface, reducing gloss and making it prone to contamination);
Strictly prohibit scraping the guide rail surface with steel wire brushes, sandpaper, or blades. - Regular Inspection Cycle
Daily: Visually check the guide rail working surface for bumps, scratches, or dust accumulation; for air-float models, inspect the air supply filtration system (once the filter fails, dust entering the air film will directly scratch the guide rail);
Monthly: Re-check the equipment level and whether the support shims are loose;
Quarterly: Use a laser interferometer to re-measure the guide rail straightness and positioning accuracy; compare with original factory data to monitor long-term deformation trends. - Lubrication System (By Structure)
Air-float granite guide rail: No lubrication required! Focus on ensuring the air source is dry and clean, with three-stage filtration (dust, water, and oil removal); oil in compressed air will penetrate the stone pores and be difficult to clean;
Hydrostatic guide rail: Regularly change the hydraulic oil and use precision filtration to prevent impurities from entering the friction pair;
Steel linear guide rails installed on granite bases: Regularly apply grease according to steel guide rail specifications, taking care not to contaminate the granite reference surface. - Moisture Protection
Granite is a microporous material; in long-term high-humidity environments:
Control environmental humidity at 40%–65%;
For long-term downtime, the guide rail surface can be covered with a dust cover; it is not recommended to apply large amounts of machine oil for sealing (oil penetrating deep into the stone is difficult to remove).
V. Common Faults and Taboos (Pitfall Summary)
❌ Forcing leveling with shims and multiple-point support → Stress deformation, accuracy deviation with temperature changes
❌ Direct installation upon arrival without constant-temperature stabilization → Short-term accuracy compliance, drift after a few hours
❌ Hard object impact on the grinding surface → Permanent defects, unrepairable on-site
❌ Cleaning with strong acids/alkalis and excessive flushing → Surface micropores damaged, prone to dust accumulation
❌ Directly lifting by the edge of the prism with steel wire ropes → Chipped corners, invisible internal cracks
❌ No precision filtration of the air source (for air-float guides) → Long scratches pulled out on the guide surface
❌ Random drilling and tapping on the granite body → Prone to cracking, new threads must use embedded steel thread inserts
VI. Requirements for Long-term Storage
Clean dust and oil from the guide rails;
Cover with a dust cover;
Avoid drastic ambient temperature fluctuations;
Do not remove the support shims, do not loosen all supports, maintain the original load-bearing state;
Do not stack heavy objects directly on the guide rail surface.
