Crawler Crane Structures

Project Overview: Turnkey Delivery of Crane Cores

Openex Large Metal Fabrication Division successfully manufactured and delivered the core structural assemblies for a 650-ton crawler crane to a globally renowned lifting equipment manufacturer. These components—comprising the main rotary table (turntable), the chassis frame, and massive track beams—form the absolute foundational skeleton of the machine, bearing all critical load-transfer and rotational forces.

Acting as the exclusive structural fabricator, Openex provided a true "turnkey" solution: executing everything from raw plate cutting, sequential assembly, robotic welding, heavy CNC boring, extreme-environment anti-corrosion painting, to final packaging.

Extreme Manufacturing Challenges

The 650-ton class requires steel structures capable of surviving catastrophic eccentric loading and massive continuous impact forces in severe field environments.

The Openex Solution: Systematic Fabrication

1. 4-Stage Welding Protocol & Defect Elimination

The project team designed a systematic "Four-Stage Assembly and Welding Protocol" for the frame assemblies to surgically control deformation:

• Stage 1 & 2: Sub-assembly of internal ribbing and main box beam structures.
• Stage 3: Symmetrical welding of secondary stress points, outriggers, and connection ears.
• Stage 4: Final closeout structural welding, immediately followed by vibratory stress relief and post-weld heat treatment.

2. Ultra-Precise CNC Machining Island

Stress-relieved weldments were transferred to our Heavy CNC Machining Island (featuring Waldrich Coburg gantry mills and large floor-boring centers). Utilizing heavy-duty rotary worktables, all critical pinning groups (luffing cylinder mounting, chassis joining interfaces) were machined in a single continuous setup. CMM probe arms continually monitored and compensated for tooling wear on the fly. Result: We successfully locked massive mating hole coaxiality firmly under Φ 0.05 mm—smashing the client’s exacting thresholds.

3. Field-Ready Anti-Corrosion Treatment

Components were abrasive shot-blasted to Sa 2.5 cleanliness, immediately coated with high-film zinc-rich epoxy, and sealed with a heavy UV/weather-resistant polyurethane topcoat designed for harsh offshore/quarry exposures. Outbound shipping included tailored steel framing and active VCI corrosion inhibitor wrap for ocean freight safety.