CLADDING TECHNOLOGY SHANXI CO., LTDRobot-Based Cladding Additive Manufacturing Process and Method Research
Literature Overview
This study, published in Manufacturing Automation in 2013, was conducted by researchers from Nanjing University of Aeronautics and Astronautics, Capital Aerospace Machinery Company, and Tianjin University. The work investigates the application of robotic systems in weld overlay cladding as an additive manufacturing technique, representing an early and significant contribution to the field of automated cladding processes. The research addresses the critical need for precision, repeatability, and productivity in complex geometrical overlay applications that are difficult to achieve through manual welding operations.
Core Technical Content and Process Architecture
The study examines a robotic cladding system architecture that integrates multi-axis robotic motion control with advanced welding power sources. The key technical objective is to achieve layer-by-layer deposition with controlled dilution, uniform microstructure, and geometric accuracy suitable for aerospace-grade components. The process parameters investigated include welding current, travel speed, arc voltage, layer thickness, and interpass temperature control.
| Process Parameter | Typical Range | Engineering Significance |
|---|---|---|
| Welding Current (SAW) | 400–700 A | Controls heat input and dilution rate |
| Travel Speed | 200–500 mm/min | Determines deposition rate and layer geometry |
| Arc Voltage | 25–35 V | Influences bead width and penetration |
| Layer Thickness | 1.5–3.0 mm | Affects residual stress and dilution |
| Interpass Temperature | 150–250 °C | Controls microstructure evolution |
| Shielding Gas Flow | 15–25 L/min | Prevents oxidation and contamination |
The robotic system employs a multi-pass strategy where each subsequent layer is deposited over the previous one with precise overlap ratios. The study highlights that overlap ratios between 30% and 50% provide optimal bonding without excessive dilution. The positioning accuracy of the robotic system is maintained within ±0.1 mm, which is critical for achieving consistent cladding quality across large surface areas.
Microstructural Evolution and Bond Quality
A critical finding of this research is the systematic control of microstructure through process parameter optimization. The authors demonstrate that by maintaining interpass temperatures below 250 °C and controlling the cooling rate, columnar grain growth can be minimized in favor of finer equiaxed grains. This is particularly important when cladding nickel-based alloys or austenitic stainless steels onto carbon steel substrates, where dilution control directly impacts the corrosion and mechanical performance of the overlay.
The bond strength between the cladding layer and the base material is evaluated through macrographitic examination and mechanical testing. The study confirms that proper groove preparation, including a slight undercut or bevel, combined with appropriate first-pass parameters, ensures metallurgical bonding without cracking or delamination. The dilution ratio is maintained between 10% and 20% for most applications, with lower values preferred for high-performance alloy overlays.
Integration with Engineering Practice
From an engineering practice perspective, this research is highly relevant to modern automated cladding operations in pressure vessel fabrication and aerospace component repair. The robotic approach enables the following advantages over manual welding: consistent bead geometry, reduced operator fatigue and variability, improved productivity through continuous operation, and the ability to clad complex geometries that would be impractical manually.
In the context of bimetal pressure vessel fabrication, robotic cladding is particularly valuable for large-diameter vessels where manual welding would require extensive tacking, frequent repositioning, and would exhibit significant variation in overlay quality. The system described in this study can be adapted for cylindrical cladding applications by integrating a turntable or linear axis to accommodate circumferential welding patterns.
The FMEA analysis of the robotic cladding process reveals several critical failure modes: electrode misalignment leading to incomplete overlap, wire feed irregularities causing porosity, and thermal distortion of thin-walled components. Countermeasures include in-process monitoring of wire stick-out, real-time arc characteristic feedback, and thermal simulation-based pre-compensation of robot path planning.
Study Insights and Engineering Implications
This 2013 publication represents a foundational work in robotic cladding that anticipated the broader adoption of additive manufacturing in the welding community. The systematic approach to process parameter optimization, combined with the emphasis on microstructural control through thermal management, provides a methodology that remains directly applicable to contemporary robotic cladding systems. Engineers working on bimetal pressure vessel fabrication should note that the principles of overlap ratio control, interpass temperature management, and dilution minimization established in this study are universal across cladding process types, whether SAW, GMAW, or PTA.
The integration of robotic motion control with welding process monitoring represents a paradigm shift from reactive quality control to proactive process assurance. For organizations transitioning from manual to automated cladding operations, this study provides both the technical framework and the process philosophy necessary for successful implementation. The emphasis on reproducibility and quantifiable process parameters aligns with modern quality management systems required by ASME and NB standards for pressure equipment fabrication.