Tubular Welding Wire Overlay Process in Non-Woven Fabric Industry

Literature Overview and Background

This 1998 publication by Pang Ming and Fu Wenlong addresses the application of tubular (tubular wire) welding wire overlay in the non-woven fabric industry, specifically targeting industrial textiles. The authors represent Shanghai Textile Machinery Research Institute and Shanghai Dayang Welding Technology Engineering Company, reflecting a collaborative effort between academic research and industrial engineering practice. During the late 1990s, the non-woven fabric industry in China was rapidly expanding, and the demand for high-performance forming tools and rollers with wear-resistant surfaces became increasingly critical. The tubular wire overlay process emerged as a practical solution to extend the service life of critical components in this sector.

Core Technical Content and Process Principles

The tubular welding wire overlay process involves feeding a hollow tubular wire filled with flux or metal powder through a welding torch, where the wire serves simultaneously as both the consumable electrode and the shielding medium. This configuration offers several advantages over conventional solid wire overlay welding, including reduced gas consumption, improved deposition efficiency, and enhanced process stability.

Process Parameters and Technical Characteristics

Parameter	Typical Range	Function
Welding current	200-350 A	Controls melting rate and penetration
Travel speed	300-600 mm/min	Determines deposition rate and bead geometry
Shielding gas flow	10-20 L/min	Protects molten pool from atmospheric contamination
Wire diameter	1.2-1.6 mm	Balances deposition rate and process stability
Overlay thickness	2-5 mm per pass	Controls final surface properties
Interpass temperature	<150 °C	Prevents thermal cracking and ensures metallurgical bonding

The tubular wire configuration provides inherent gas shielding from the flux contained within the wire, which significantly reduces the sensitivity of the process to ambient wind and improves outdoor or semi-outdoor applicability. The self-shielding characteristic makes this process particularly attractive for industrial environments where complete gas shielding setup is impractical.

Application in Non-Woven Fabric Industry

In the non-woven fabric industry, critical components such as forming rollers, pressing rolls, and laying head rollers are subjected to severe abrasive wear from continuous contact with fibrous materials. The overlay process applied to these components typically uses wear-resistant alloys containing chromium, molybdenum, and carbide-forming elements to achieve surface hardness exceeding 40 HRC. The metallurgical bond between the overlay layer and the base carbon steel substrate must withstand cyclic thermal loading during the fabric forming process, where temperatures can reach 150-250 °C.

Engineering Practice and Defect Analysis

Common Defects and Countermeasures

Defect Type	Root Cause	Countermeasure
Poor bond strength	Insufficient base metal preheating	Preheat to 150-200 °C
Porosity	Flux moisture absorption	Store wire in dry conditions; use dry box
Cracking	High carbon equivalent of base material	Select appropriate filler; control interpass temperature
Uneven surface finish	Unstable travel speed	Use automated wire feeder with constant speed control
Delamination	Incompatible thermal expansion coefficients	Use transition layer with intermediate expansion coefficient

The study emphasizes the importance of base metal surface preparation, including thorough cleaning of mill scale and oxidation to ensure proper metallurgical bonding. The authors recommend using a grinding process to create a clean, slightly roughened surface prior to overlay application, which promotes mechanical interlocking and improves bond strength.

Quality Control Considerations

Quality assurance for tubular wire overlay in industrial textile applications requires a systematic approach encompassing visual inspection, magnetic particle testing of the overlay surface, and hardness profiling through the overlay thickness. The bond strength between overlay and substrate should be verified using a microhardness traverse test, ensuring no abrupt transition that could indicate incomplete melting or poor metallurgical bonding.

Study Insights and Implications

This literature represents an early but valuable exploration of adapting welding overlay technology to the textile machinery sector. The authors demonstrate that tubular wire overlay offers a cost-effective alternative to full replacement of worn rollers, reducing downtime and material costs significantly. The self-shielding characteristic of tubular wires is particularly advantageous in textile factory environments where gas supply infrastructure may be limited.

From a modern perspective, the process parameters described remain relevant, though contemporary equipment with digital control systems would enable tighter process window control. The fundamental metallurgical principles governing bond strength, dilution control, and residual stress management continue to apply. Engineers working on similar applications today should note that the tubular wire overlay process, while somewhat superseded by plasma transferred arc (PTA) and laser cladding in high-end applications, remains a viable and economical solution for medium-production environments where capital investment for advanced equipment is constrained.

The key takeaway for practicing engineers is that process selection should be driven by a balanced assessment of required surface properties, production volume, available equipment, and total cost of ownership, rather than defaulting to the most advanced technology available.