Advancing Heavy Mining Equipment at a Global Scale
In the global wave of mining equipment transitioning toward larger, high-efficiency models, manufacturing structural core components demands the pinnacle of heavy metal fabrication capabilities.
The Openex Large Metal Fab Division has recently celebrated a major project milestone. Massive ball mill cylinders and key feed/discharge components for Semi-Autogenous (SAG) mills—manufactured for a world-renowned mining equipment OEM—successfully passed strict phase-acceptance tests. Exhibiting exceptional deep-penetration welding, millimeter-precise geometric tolerances, and rigorous project management, this 90-ton fabrication package won high praise during joint on-site inspections.
The Manufacturing Challenge
This project is a benchmark for ultra-heavy steel structure fabrication, fraught with obstacles traversing from initial plate cutting to final machining:
- Extreme Thickness Welding: While the primary cylinder walls measure 83mm thick, the massive flange welding required bonding depths of up to 190mm. Controlling thermal input, interpass temperature, and managing massive internal stress in multi-pass welding without risking cracking or uncorrectable angular deformation was highly critical.
- Monumental Scale vs. Precise Tolerances: Single assemblies weighed over 90 Tons with diameters reaching nearly 8.6 meters (28+ feet). To guarantee decades of low-vibration continuous rotation at the mine site, roundness, concentricity, and flange parallelism required strict, millimeter-level CNC accuracy.
- Complex Value-Chain Syncing: Ten major operational nodes—including heavy rolling, narrowing gap welding, giant VTL machining, stress relief, and anti-corrosion rubber lining—demanded that zero compounding errors were transferred down the fabrication line.
The Openex Solution: Full-Chain Control
Treating this as a cornerstone company project, a dedicated cross-functional task force strictly managed the lifecycle of every Q235B plate.
1. Material Validation & Precise Rolling
Incoming Q235B steel immediately underwent furnace lot verification and Ultrasonic Testing (UT) to check for inner plate laminations. Components were cut using heavy-duty fiber laser/plasma profiles, and curvature was set via our largest heavy plate bending rolls.
2. Dual-Machine Narrow Gap Welding (Zero-Defect)
Conquering the 190mm flange-to-cylinder joint required innovative execution. Openex engineers deployed heavy dual-automated manipulators performing narrow gap synchronous welding internally and externally. By carefully engineering the thermal cycles, residual distortion was mitigated, resulting in 100% NDT/UT pass rates on the first try.
3. Stress Relief & 5-Axis Heavy Machining
Welded megastructures were sent to our oversized thermal furnaces for deep stress relief annealing to establish geometric stability. Our Floor-type Boring mills and massive Vertical Turning Lathes (VTL) completed precise one-time clamping procedures on flange faces and heavy bolt hole configurations, ensuring a seamless interface.
4. Anti-Corrosion & Inner Rubber Lining
Components advanced to grit-blasting booths for high-spec marine-grade paint spray. Finally, specialty teams installed vulcanized, high-wear internal rubber linings designed to protect against violent, high-abrasion ore impacts.
Successful Acceptance Phase & Next Steps
The project passed the initial phase milestone: complete SAG inlet and outlet shell dry-assemblies and tolerance audits verified a perfect alignment, passing the rigorous spec-sheet criteria presented by the international mining OEM. It stands as robust evidence of Openex's absolute reliability as an end-to-end heavy mining structure contractor.
