U-shaped Precision Granite Gantry (Integrated Granite U-shaped Gantry)

I. Structural Definition

The U-shaped granite gantry is an integrally molded U-shaped closed stone frame, overall ground and processed from a bottom platform base two vertical granite columns on the left and right a top granite crossbeam. It features no metal splicing and an overall single-datum structure; the internal hollow area serves as the space for workpiece placement, Z-axis movement, and optical path passage, which is the same U-shaped optical gantry structure as the ALIO equipment in your picture.

II. Core Materials (Two Main Types)

1. Jinan Blue Granite (Domestic 000 Grade)
   Density 2.98t/m³, Shore hardness HS75, thermal expansion coefficient 0.6×10⁻⁶/℃, high cost-performance ratio, used for general inspection equipment;
2. Indian Black Granite (High-end Optical/Semiconductor)
   Denser grains, impurity-free, stronger damping and vibration reduction performance, dedicated to dust-free nano-grade equipment.
   Unified physical properties: no internal stress, rust-proof, non-magnetic, insulating, resistant to acid and alkali corrosion, no creep deformation after ten years of long-term use.

III. Unique Advantages of the U-shaped Structure (Compared to Split Gantries and Steel Gantries)

1. Extremely Strong Precision Consistency (Core Advantage)

The entire gantry is integrally processed from a single piece of stone. The base, columns, and crossbeam are ground on the same datum plane, and flatness, perpendicularity, and parallelism are formed in one go, eliminating assembly errors caused by metal bolt splicing; the three-axis orthogonality can reach 000 grade, and the overall geometric error is reduced by more than 70% compared to assembled metal gantries.

2. Ultra-high Vibration Damping, Suppressing High-speed Motion Resonance

The crystal damping ratio of natural stone is 6 times that of cast iron. The U-shaped closed-loop frame forms a stable cavity, and the vibrations generated by the high-speed start and stop of the slide and lens are quickly absorbed. Laser imaging and wafer inspection are jitter-free, and the repeat positioning is stable at the nano-level.

3. Extremely Low Thermal Drift, Precision Does Not Drift in Temperature-varying Environments

The thermal expansion coefficient of the entire frame is unified. When the temperature fluctuates, the base, columns, and crossbeam undergo synchronous micro-deformation, avoiding thermal expansion misalignment between steel/aluminum crossbeams and stone bases; under a workshop temperature difference of ±5℃, the optical path offset can be controlled within 0.1μm.

4. U-shaped Hollow Open Working Space

Unobstructed from the front, convenient for workpiece loading and unloading, lens module disassembly and assembly, and light source arrangement, suitable for visual inspection, wafer alignment, and laser processing; the overall rigidity of the closed U-frame far exceeds that of the C-shaped single-sided column, and the downward deformation of the crossbeam under heavy load is extremely small.

5. Maintenance-free Cleanroom Compatibility

The stone has no coating, does not oxidize, and does not shed debris, making it suitable for Class 100/1000 cleanrooms. Acid and alkali cleaning will not corrode the datum plane.

IV. Standard Precision Grades (Industry Universal)

000 Grade (Preferred for Semiconductor/Optical Laser)

• Base flatness: ≤2μm/1000mm
• Column perpendicularity, crossbeam parallelism: ≤0.8μm/m
• Three-axis orthogonality: ≤1″ arcsecond
• Installation threaded hole positioning tolerance: ±0.02mm (pre-embedded stainless steel anti-stripping sleeves)

00 Grade (Universal for 2D, AOI, Precision Dispensing)

Flatness ≤4μm/m, perpendicularity ≤1.5μm/m, suitable for micron-level dimension inspection equipment.

V. Customizable Processing Technology

1. Guide Rail Integrated Processing: Integrated slotting of columns and beams, direct embedding of air-bearing guide rails/ball linear guide rails, eliminating secondary assembly errors;
2. Threaded Holes/Countersunk Holes/Pin Holes: Pre-embedded stainless steel sleeves at all positions to prevent stone chipping and thread stripping;
3. Weight-Reducing Honeycomb Slots: Honeycomb milling on the back of large gantry structures for weight reduction, reducing weight by 40% and increasing rigidity by 35%;
4. Nano-Polishing and Sealing: Surface sealing treatment to prevent dust and liquid penetration;
5. Matching Components: Bottom can be equipped with granite vibration-damping brackets and air-bearing vibration-damping foot pads.

VI. Main Application Scenarios

1. Semiconductor Equipment: Wafer inspection machines, die bonders, chip laser dicing, photolithography alignment platforms (standard configuration for ALIO high-precision positioning equipment);
2. Optical Measurement: Fully automatic 3D vision inspectors, laser interferometers, high-magnification microscopic imaging stages;
3. Precision Inspection: Large gantry CMMs, long-stroke 2D vision measuring machines, glass cover AOI inspection;
4. Laser Processing: Femtosecond laser micromachining, PCB laser drilling, optical component polishing machine tools;
5. Scientific Research Laboratories: Spectroscopic testing platforms, nano-displacement experimental stages.

VII. Key Selection Differentiation Points

1. Nano-level optical paths, dust-free semiconductor → Indian Black 000-grade integrated U-shaped gantry air-bearing integrated guide rails;
2. Mass vision inspection, industrial automation equipment → Jinan Green 00-grade, embedded ball guide rails;
3. Large-sized heavy-load workpieces → Thickened beams/honeycomb weight-reducing structures, thickened load-bearing base at the bottom;
4. Low-temperature, temperature-fluctuating workshops: Prioritize overall granite full U-shaped structures, prohibit steel/aluminum beams paired with stone bases.