Anti-Crushing and Anti-Scratching Measures for Lifting Granite Machine Tool Beds

Granite is highly brittle and has high-precision working surfaces. Direct contact with lifting tools can easily cause dents, edge chipping, and scratches. Core Principle: Lifting tools must never directly contact the processed granite surfaces. Use isolation buffers reasonable force distribution; direct pressure from hard steel components on the stone surface is strictly prohibited.

I. Lifting Tool Selection and Isolation Protection (Most Critical)

1. Prohibit steel wire ropes and steel chains from directly pressing or rubbing against the granite surface
   The sharp edges of steel wire ropes will directly scratch or crack the stone; an isolation layer must be added.

• Priority: Wide lifting slings (flat nylon slings). Choose wide slings rather than narrow ones to increase the contact area and reduce surface pressure; the use of damaged or frayed slings is strictly prohibited.
• Strictly Prohibited: Using thin steel wire ropes to directly cradle the granite body; steel wire ropes must be fitted with rubber corner protectors and rubber sleeves, and can only contact the non-processed sides or the metal lifting ear plates on the base flange.

1. Buffer Isolation Pads
   Place a 5-10mm thick rubber plate / polyurethane soft pad between the sling and the granite contact surface. It must be fully spread out; do not use scrap rubber pieces.

Key Point: For high-precision 00/000 grade Jinan Blue machine beds, slings are not allowed to press on the guide rail surfaces, metrology working surfaces, areas around threaded holes, or reference edges. Slings can only rest on the rough sides or non-processed base areas.

3. Edge Protection to Prevent Chipping
   Fit rubber corner protectors (plastic corner protectors) on the granite edges. The sling must not tighten excessively around the edges to prevent chipping.
4. For machine beds with metal lifting ear plates: Prioritize lifting the metal ears, completely avoiding force on the stone body, which is the optimal solution. If no pre-embedded ears are available, use the lifting screw holes with dedicated lifting bolts; direct binding of the stone body is strictly prohibited.

II. Key Points for Binding and Cradling Methods

1 When cradling, the sling angle should not be too small; the smaller the angle, the greater the local pressure. An angle of 60-90° is recommended to prevent the sling from crushing the granite under high local pressure when tightened.
2 Slings must not cross or twist; twisted slings form sharp edges that can cut the stone.
3 Strictly prohibit slings from crossing over guide rail surfaces or reference planes. If crossing a large surface is unavoidable, a full rubber pad must be laid underneath, and the sling must rest on the pad without touching the stone.
4 Single-point loading is not allowed. Use two-point or four-point lifting to ensure the bed remains level and to avoid tilting and sliding, which causes severe scratching.

III. Lifting, Transporting, and Lowering Operations

1. Pre-lifting Inspection: Confirm that the isolation layers have not shifted or slipped; corner protectors are in place; lifting points are symmetrical. Initially lift the bed 10-20mm off the ground, hold for a few seconds, and observe if the slings or pads slide or shift.
   2 Maintain a low and steady speed throughout the lifting process. Sudden starts, stops, or swinging impacts are prohibited. When the bed swings, do not use steel ropes or chains to drag the stone body; only push the metal parts of the base.
   3 During transport, do not face the granite working surfaces toward the lifting tools or steel frames to prevent scratches from shaking and bumping.
2. Lowering and Positioning
   Pre-lay thick rubber pads at the base support positions. It is strictly prohibited to drop the granite directly onto steel frames or hard cement floors.
   Lower the bed slowly. Do not pull the slings against the stone surface during lowering, as this is the most common cause of surface scratches. Only loosen the lifting tools after the bed is fully landed; do not drag the bed while still attached to the lifting tools.

IV. Prohibited Operations (Must be avoided)

❌ Directly pressing steel wire ropes against any machined surface of the granite
❌ Applying high pressure from narrow slings locally on guide rails or datum surfaces
❌ Tightening slings against sharp edges without using corner protectors
❌ Slings sliding on the stone surface after lifting, causing friction
❌ Hard impact during landing without buffer pads
❌ Directly prying the granite working surface or datum edges with a crowbar

V. Additional Precautions for High-Precision 00/000 Grade Granite Beds

1. Before lifting, cover the working surface with a full sheet of hard rubber board PE protective film for double protection to prevent accidental scratches.
2. Whenever possible, use vertical lifting via lifting holes (pre-embedded threaded sleeves). This is the preferred lifting method for precision granite beds as the slings do not touch any machined surfaces.
3. After lifting is completed, remove the protection and visually and manually inspect all datum surfaces and guide rail surfaces to confirm there are no indentations, scratches, or chipped edges before proceeding with subsequent assembly.