Manufacturing of Crane Hooks

The manufacturing process of crane hooks is intricate, involving several stages such as material selection, fabrication, heat treatment, and inspection. Below is an overview of the key steps and considerations involved in crane hook production:

1. Material Selection: Crane hooks are typically made from high-strength, wear-resistant, and fatigue-resistant alloy structural steel. Common materials include high-quality carbon steel (20-grade) or specialized hook materials like DG20Mn and DG34CrMo.The selected material must offer high mechanical strength and excellent impact toughness to withstand the stress during the start-up and stop phases of the lifting operation.

2. Manufacturing Method: Crane hooks are categorized into two types based on their construction method: forged hooks and laminated hooks.

   • Forged hooks: These are made as a single piece, offering simplicity in manufacturing and ease of use. They are commonly used for lifting weights up to 80 tons.

   • Laminated hooks: Made by riveting together several pieces of cut and shaped steel plates, laminated hooks offer better safety features but are heavier. They are generally used for cranes with larger lifting capacities or in industries such as molten steel handling.

   
   

For forged hooks, the process begins by placing pre-heated steel billets into a forging machine. The hook's initial shape is formed through impact or extrusion. Careful control of temperature, force, and speed is essential during this step to ensure both strength and accuracy in shape.

3. Heat Treatment: To eliminate internal stresses such as cold stress, thermal stress, and welding stresses, crane hooks undergo heat treatment, including tempering. This is a crucial step to ensure the hook maintains its structural integrity and durability during use.

4. Inspection and Marking: Before leaving the factory, crane hooks must undergo thorough inspection and defect detection, particularly for critical applications like railways or ports.The hook's surface must be smooth, free from cracks, folds, sharp edges, burrs, peeling, or overburning.Additionally, a durable mark indicating the hook's opening dimensions should be clearly displayed, as this will serve as a reference for monitoring any changes in the opening size during use.

5. Safety Requirements: The hook must be free of defects that could compromise safety. No welding should be performed on a hook to repair defects.A crane hook should be able to reliably support twice the designated test load without failure.

6. Scrap Standards: A crane hook must be scrapped if it develops cracks, exhibits significant wear or corrosion at critical points, undergoes plastic deformation in the hook handle, or if the opening size increases beyond allowable limits.

   
   

These steps and considerations are based on national standards and industry best practices to ensure that crane hooks meet the necessary quality and safety performance requirements.