Technical Advantages of Machining Granite Equipment Bases with Pre-drilled Holes

Granite (such as Jinan Green) equipment bases featuring threaded holes, countersunk holes, through holes, dowel holes, and T-slots are commonly used structures for precision inspection equipment, automation equipment, CMMs, and optical equipment. Compared to ordinary flat plates external adapter plates, the comprehensive advantages are as follows:

1️⃣ Higher Overall Assembly Accuracy

1. Hole positions, dowel holes, and locating datum slots are clamped and machined simultaneously in one setup, ensuring the position, parallelism, and perpendicularity of the holes relative to the working surface. Equipment components are directly secured to the base, eliminating secondary assembly errors caused by adapter plates.
2. Dowel holes achieve positioning and error-proofing, providing high repeatability for component installation. The equipment’s accuracy will not drift after disassembly and reassembly.

Comparison: Adding a steel adapter block to a flat plate introduces cumulative machining and assembly tolerances inherent to the adapter block itself.

2️⃣ Excellent Structural Rigidity and Stability

1. Holes are drilled directly into the granite body, allowing components to sit flush against the black granite reference surface without intermediate layers. This high overall rigidity fully utilizes the inherent damping characteristics of granite to suppress equipment operating vibrations.
2. It avoids the interface gaps caused by adding adapter plates, preventing vibrations from amplifying at the joints. This is ideal for optical equipment, inspection equipment, and high-speed moving mechanisms.

3️⃣ Space-Saving and Simplified Equipment Structure

1. Eliminating extra metal adapter plates and transition spacers reduces the overall volume and makes the equipment structure more compact.
2. The base serves directly as the equipment chassis, with components installed directly onto it. This reduces the number of parts and lowers the overall material cost.

4️⃣ Deformation Resistance and Superior Thermal Stability

1. Granite has an extremely low coefficient of thermal expansion. Holes are formed directly in the body, unlike metal welded or bolted structures, so there is no welding stress or thermal deformation from assembly.
2. When the entire base undergoes temperature changes, the installation holes and working surface undergo synchronized micro-deformations, maintaining stable relative positions. This ensures better accuracy retention under fluctuating temperature conditions.

5️⃣ Wear and Corrosion Resistance with Simple Maintenance

1. Granite is inherently rust-proof and oil-resistant. With protective treatment on the holes, it is immune to workshop cutting fluids and machine oil. It will not rust and expand like cast iron bases, avoiding the deformation of holes caused by rust expansion pulling on threads.
2. The working surface and holes/slots are integrated, making cleaning easy and preventing the accumulation of rust and impurities.

6️⃣ Convenient Assembly and Debugging, Facilitating Later Maintenance

1. Threaded holes, countersunk holes, and dowel holes are pre-set, allowing customers to tighten components directly on-site without the need for field drilling. Secondary drilling on-site is strictly prohibited to prevent impact stress from deforming the granite working surface.
2. The standardized hole array allows for direct reuse of existing holes during later component modifications or upgrades, requiring no changes to the base body.

7️⃣ Reduced Risk of Assembly Errors at the Customer Site

The factory completes all hole and slot machining and verifies hole position accuracy, providing a hole inspection report. Customers receive the finished product for direct installation, controlling accuracy risks at the production stage and avoiding the risk of scrapping parts due to on-site machining.

⚠️ Key Process Precautions (Prerequisites for Advantage Establishment)

1. All holes, slots, and threads must be fully machined before precision grinding; drilling and tapping are strictly prohibited after grinding to prevent stress relief from causing out-of-tolerance flatness on the working surface;
2. An aging/stabilization process must be added after machining to release the cutting stresses caused by drilling and slotting before the final grinding;
3. Threaded holes should be treated with steel wire thread inserts to prevent granite thread stripping and extend the service life of the threads.