CLADDING TECHNOLOGY SHANXI CO., LTDFully Automatic MIG Surfacing Remanufacturing System Based on Robotic Control
Literature Overview
This 2005 paper published in the Journal of Central South University by Zhu Sheng, Guo Yingchun, and Yang Pei from the National Key Laboratory for Remanufacturing presents a comprehensive robotic system for fully automatic Metal Inert Gas (MIG) surfacing welding. Funded by multiple National Natural Science Foundation projects (50075086, 50235030), the National Basic Research Foundation (413270103), and the Ministry of Education Outstanding Teachers Project (2000476), this research represents a significant contribution to the field of surface engineering and remanufacturing technology.
Core Technical Content
The paper describes a complete robotic welding system designed for the surfacing of wear-resistant and corrosion-resistant overlay layers on industrial components. The system integrates robotic motion control, welding parameter optimization, and real-time process monitoring to achieve consistent overlay quality across complex geometries.
System Architecture
The robotic surfacing system comprises the following key components:
| Component | Specification | Function |
|---|---|---|
| Industrial robot | 6-axis, 200-500 kg payload | Multi-axis motion and positioning |
| MIG welding power supply | 300-800 A, pulse-capable | Arc generation and energy delivery |
| Wire feed system | Constant velocity, 0-30 m/min | Filler metal delivery |
| Torch positioning | 6-axis end-effector | Torch orientation control |
| Real-time monitoring | Arc voltage/current sensors | Process stability feedback |
| Path planning software | CAD/CAM integrated | Weld trajectory generation |
| Cooling system | Water or gas cooling | Torch and component cooling |
Overlay Layer Design and Selection
The research addresses the selection of overlay materials for different service conditions:
- Wear-resistant overlays: Hardfacing alloys containing Cr, Mo, and carbide-forming elements (WC, TiC, Cr₇C₃) for applications in mining, cement, and material handling equipment.
- Corrosion-resistant overlays: Austenitic stainless steels (304, 316, 321) or nickel-based alloys (Inconel 625, Monel 400) for chemical processing and marine environments.
- Heat-resistant overlays: High-temperature alloys with elevated chromium and aluminum content for furnace components and exhaust systems.
The robotic system enables multi-pass surfacing with precise control of layer thickness, typically achieving 1-3 mm per pass and total overlay thicknesses of 5-25 mm depending on the application.
Process Optimization
The authors conducted systematic optimization of welding parameters for each overlay material:
- Current selection: Higher currents (400-600 A) for thick single-pass deposits; lower currents (200-350 A) for multiple thin passes with reduced dilution.
- Travel speed: 100-300 mm/min depending on wire diameter and desired deposition rate.
- Stand-off distance: Maintained at 10-15 mm for stable arc and consistent penetration.
- Travel angle: 5-10° from vertical, forward direction for better wetting and reduced spatter.
- Interpass temperature: Controlled below 200°C for stainless steel overlays; below 150°C for nickel-based overlays to prevent sensitization.
Quality Assurance and Inspection
The paper emphasizes the importance of quality control in robotic surfacing operations:
- Visual inspection: After each pass, the overlay surface is inspected for uniformity, porosity, and undercut.
- Magnetic particle testing (MT): Applied after grinding to detect surface-breaking cracks in ferromagnetic overlays.
- Ultrasonic testing (UT): Used to verify bond strength between the overlay and base metal, particularly for critical applications.
- Hardness testing: Vickers or Rockwell hardness profiles across the overlay depth to verify hardness distribution and dilution zone.
- Corrosion testing: Salt spray testing or immersion testing for corrosion-resistant overlays to verify performance.
Engineering Practice Integration
The robotic surfacing system described in this research has been successfully applied to:
- Mining equipment: Overlaying crusher jaws, conveyor rollers, and bucket teeth with wear-resistant hardfacing alloys.
- Power generation: Surfacing turbine blades and boiler tubes with heat-resistant alloys.
- Chemical processing: Cladding heat exchanger tubes and reactor internals with corrosion-resistant materials.
- Aerospace components: Repairing landing gear components and engine mounts with nickel-based overlays.
The key advantage of robotic surfacing over manual welding is the repeatability and consistency of the process. Once the welding parameters and path are programmed, the system can produce identical overlay layers across multiple components with minimal operator intervention, reducing quality variation and improving production throughput.
Study Insights
This research highlights the transformative potential of robotic automation in surface engineering. The integration of CAD/CAM path planning with real-time process monitoring creates a closed-loop manufacturing system that can adapt to varying component geometries and material conditions. For engineers involved in cladding and overlay work, the robotic approach offers a pathway to scaling up production while maintaining the quality levels required for critical applications.
However, the successful implementation of robotic surfacing requires significant investment in equipment, programming expertise, and quality assurance infrastructure. The initial setup cost is substantially higher than manual welding, but the long-term benefits in terms of labor savings, consistency, and throughput make it economically viable for high-volume production. The challenge lies in the programming of complex geometries, which requires skilled operators and sophisticated software tools.