Tubular Wire Weld Overlay Technology for Non-Woven Fabric Industry Components
1. Definition and Technical Principles
Tubular wire (also referred to as flux-cored wire or self-shielded tubular electrode) weld overlay is a specialized surface engineering process that deposits a protective or functional metallic layer onto substrate components using a tubular-shaped welding consumable filled with flux material. The process leverages the self-shielding flux within the wire's hollow core to create a stable arc, produce slag coverage over the molten weld pool, and facilitate alloy element transfer to the deposited overlay. This technology is particularly suited for field repair, in-situ component restoration, and overlay application where shielding gas infrastructure may be limited or impractical.
In the context of the non-woven fabric industry, tubular wire weld overlay is applied to critical rotating components—including calender rolls, guide rollers, forming drums, and tension cylinders—that undergo continuous mechanical abrasion, thermal cycling, and chemical exposure from non-woven forming media (polypropylene meltblown compounds, viscose solutions, and polyethylene terephthalate melts). The overlay restores dimensional integrity, enhances surface hardness, and provides corrosion resistance against process chemicals and elevated operating temperatures.
2. Category and Business Positioning
This technology entry falls squarely within the company's TIG/MIG weld overlay technology route, specifically under the MIG/MAG subcategory utilizing tubular (flux-cored) consumables. It represents a knowledge-transfer and qualification-building activity—documented as a technical study and learning experience—aimed at expanding the company's service portfolio into the non-woven fabric manufacturing sector.
The business positioning is threefold:
- Market Expansion: The non-woven fabric industry (particularly medical-grade meltblown fabric, hygiene products, and geotextiles) represents a rapidly growing market segment with significant demand for roll and cylinder restoration services.
- Process Diversification: Tubular wire overlay complements the company's solid-wire TIG/MIG capabilities by offering an alternative process suited for thicker deposits, repair of heavily worn surfaces, and field-service applications.
- Qualification Building: Documenting technical learning experiences supports the company's WPS (Welding Procedure Specification) development pipeline and contributes to personnel certification under relevant national and international welding standards.
3. Technical Purpose and Value
3.1 Primary Technical Objectives
- Dimensional Restoration: Recover worn roll diameters to original specifications, eliminating the need for expensive full-roll replacement and reducing downtime from weeks to hours.
- Surface Hardening: Achieve overlay hardness of 35–55 HRC using appropriate tubular wire grades, extending component service life by 2–5 times compared to unprotected carbon steel substrates.
- Corrosion Protection: Deposit stainless or nickel-based overlays that resist chemical attack from non-woven process additives, antistatic agents, and lubricating oils.
- Thermal Stability: Provide thermal barrier protection for components operating at 80–200°C (meltblown PP/PE forming temperatures).
3.2 Quantifiable Value Metrics
| Value Dimension | Without Overlay | With Tubular Wire Overlay | Improvement Factor |
|---|---|---|---|
| Roll Service Life | 6–12 months | 24–60 months | 2–5× |
| Replacement Cost (per roll) | ¥80,000–¥200,000 | ¥8,000–¥25,000 (overlay only) | 70–90% reduction |
| Downtime for Restoration | 2–4 weeks (procurement + machining) | 1–3 days (overlay + machining) | 85–95% reduction |
| Surface Hardness | 150–200 HB (base steel) | 350–550 HB (overlay) | 2–3× |
4. Key Process and Implementation Points
4.1 Consumable Selection Matrix
| Application Requirement | Tubular Wire Grade | Deposited Hardness | Typical Application |
|---|---|---|---|
| General wear resistance | CHS-41 / AWS A5.20 E71T-8 equivalent | 250–320 HB | Guide rollers, support cylinders |
| High abrasion resistance | CHS-42 / Chromium-cobalt alloy tubular | 400–500 HB | Calender rolls, compression rollers |
| Corrosion + wear | CHS-43 / 309-type stainless tubular | 250–350 HB | Chemical-exposed forming drums |
| High-temperature service | CHS-44 / Ni-based (Stellite-type) tubular | 400–550 HB | Meltblown PP/PE contact surfaces |
| Transition layer | CHS-41 / 309L-type tubular | 200–280 HB | Carbon steel to alloy overlay transition |
4.2 Process Parameters
| Parameter | Typical Range | Notes |
|---|---|---|
| Wire Diameter | 1.2 mm / 1.6 mm | 1.2 mm for thin deposits; 1.6 mm for thick build-up |
| Deposition Rate | 2.5–5.0 kg/h | Higher than solid wire (1.5–3.0 kg/h) |
| Travel Speed | 150–350 mm/min | Depends on desired bead width and overlap |
| Wire Feed Speed | 3.0–6.0 m/min | Correlated with travel speed for consistent deposit |
| Arcing Current | 180–350 A | Higher than solid wire for equivalent bead profile |
| Arc Voltage | 22–30 V | Self-shielded flux provides arc stabilization |
| Interpass Temperature | < 150°C (max) | Critical for preventing excessive grain growth |
| Single Pass Deposit Thickness | 3–5 mm | Multiple passes for thicker build-up |
| Overlap Ratio | 50–60% of bead width | Ensures uniform coverage and no gaps |
4.3 Critical Implementation Steps
- Substrate Assessment: Measure remaining wall thickness, identify wear patterns (uniform vs. localized), determine substrate metallurgy via spark test or portable XRF, and assess existing coatings or heat-affected zones.
- Surface Preparation: Grind worn surfaces to bare metal using 24–36 grit followed by 60–80 grit finishing. Remove all contaminants (oil, rust, old coatings) using degreasing solvent. Ensure surface roughness of Ra 3.2–6.3 μm for optimal weld adhesion.
- Preheat Application: For carbon steel substrates > 25 mm effective thickness, apply preheat of 100–150°C using induction heating or oxy-fuel torch. For stainless or alloy overlays, limit preheat to < 80°C to prevent sensitization.
- Overlay Execution: Apply in a controlled sequence—bottom-to-top for vertical cylinders, spiral pattern for horizontal rolls. Maintain consistent arc length (5–8 mm), avoid crater defects by trailing the torch, and ensure slag is fully removed between passes.
- Post-Weld Heat Treatment: For high-carbon overlay deposits, apply post-weld heat treatment (PWHT) at 550–650°C for 2 hours to relieve residual stresses and reduce cracking susceptibility. For martensitic overlays, austenitize at 800–850°C followed by controlled air cooling.
- Machining to Final Dimensions: After overlay cooling and stress relief, machine the surface to final dimensional tolerances (typically H7 or H8 for roll diameters, Ra 0.4–0.8 μm for surface finish). Allow 3–5 mm machining allowance above final diameter.
4.4 Quality Control During Execution
- Visual Inspection (VT): Every pass—check for undercuts, porosity, slag inclusions, and bead uniformity.
- Dimensional Check: Every 300 mm of roll length—verify deposit thickness is within ±0.5 mm of target.
- Hardness Verification: After machining—spot check at 4 points per meter using portable Vickers hardness tester (HV 5 kgf).
- Adhesion Test: Perform pull-off test per ASTM D4541 or equivalent—minimum adhesion strength of 20 MPa.
5. Applicable Standards and Acceptance Criteria
5.1 Governing Standards
| Standard | Scope of Application |
|---|---|
| GB/T 17493.1 | Flux-cored wire for gas-shielded arc welding—classification and specification |
| GB/T 17493.2 | Flux-cored wire for self-shielded arc welding—classification and specification |
| GB/T 19852 | Welding procedures for weld overlay—general requirements |
| GB/T 26497 | Welding consumables—tubular wire for wear-resistant overlay |
| GB/T 11345 | Ultrasonic testing of welds—technique and acceptance |
| GB/T 3323 | Non-destructive testing—radiographic testing of welds |
| NB/T 47014 | Qualification of welding procedures for pressure vessels |
| ASTM A5.20 | Specification for flux-cored electrodes for gas-shielded arc welding |
| ASTM A5.22 | Specification for self-shielded flux-cored electrodes |
| ASTM A213/A214 | Weld overlay specifications for wear-resistant applications |
| ASME Section IX | Welding, brazing, and fusing qualifications |
| ISO 9589 | Welding—consumables for weld overlaying |
| ISO 14555 | Welding—weld overlaying procedures |
| ISO 5817 | Welding—weld imperfection classification and acceptance |
| ISO 10675 | Welding—welding procedure qualification and validation |
| ISO 17637 | Non-destructive testing—ultrasonic testing of welds |
5.2 Acceptance Criteria for Non-Woven Industry Applications
- Weld Quality: Level B per ISO 5817 (maximum allowable: porosity ≤ 1 mm, undercut ≤ 0.5 mm depth, no slag inclusions > 2 mm).
- Dimensional Tolerance: Roll diameter within ±0.02 mm; runout ≤ 0.01 mm TIR; surface roughness Ra ≤ 0.4 μm after machining.
- Hardness Uniformity: Variation across overlay surface ≤ 15% of nominal hardness value.
- Adhesion Strength: Minimum 25 MPa per ASTM D4541 pull-off test.
- UT Scanning: No indications ≥ 2 mm equivalent reflector per GB/T 11345 / ISO 17637.
- Chemical Composition: Overlay chemistry within ±1.0% of specified alloy composition (verified by optical emission spectrometer).
6. Common Risks and Controls
| Risk | Root Cause | Control Measure | Verification Method |
|---|---|---|---|
| Cracking (hot/cold) | Excessive carbon equivalent, rapid cooling, high restraint | Limit CE < 0.6; apply preheat 100–150°C; PWHT 550–650°C; use low-hydrogen consumables | MT/PT inspection per ISO 17638 |
| Poor adhesion / delamination | Inadequate surface prep, contamination, excessive dilution | Grind to bare metal; degrease; control dilution < 30%; use transition layer | Pull-off test per ASTM D4541 |
| Excessive dilution | High heat input, wide bead, insufficient first-pass control | Reduce current by 10–15%; narrow the bead; apply first pass at 70% current | Chemical analysis of first 2 mm overlay |
| Hardness below specification | Excessive dilution, incorrect consumable grade, inadequate cooling rate | Verify consumable certificate; increase overlay thickness; adjust cooling rate | Hardness survey (5 points/m) |
| Porosity | Moisture in flux, contamination, insufficient arc coverage | Store consumables at 150°C for 2 hours; dry before use; maintain arc coverage | VT + RT per GB/T 3323 |
| Dimensional out-of-tolerance | Inconsistent pass thickness, thermal distortion | Control interpass temperature; apply symmetric pass pattern; use backing ring | OD measurement every 100 mm |
7. Application Across the Company's Three Technology Routes
7.1 TIG/MIG Weld Overlay (Primary Route for This Entry)
Tubular wire MIG overlay is the direct technology vehicle for this entry. It offers the highest deposition rate (2.5–5.0 kg/h) among all overlay methods, making it ideal for large-diameter rolls and thick build-up applications. The self-shielding nature of tubular wire eliminates the need for external shielding gas in field conditions, enabling on-site service at customer facilities—a significant value proposition for non-woven manufacturers with limited maintenance infrastructure.
Key advantages for this sector:
- High deposition rate reduces total service time for large rolls (typically 600–1200 mm diameter)
- Self-shielded capability enables field application without gas cylinders or hoses
- Multiple alloy grades available in tubular form provide flexibility in overlay chemistry selection
- Lower consumable cost per kg of deposit compared to solid wire with shielding gas
7.2 Hydraulic Explosive Bonding (Complementary Route)
While tubular wire overlay addresses surface restoration and localized wear protection, hydraulic explosive bonding (HEB) serves as the complementary technology for manufacturing new clad components with integral metallurgical bonding throughout the full cross-section. For the non-woven fabric industry, HEB can produce full-length clad cylinders (e.g., 316L stainless steel on carbon steel) for chemical processing sections where corrosion resistance is required throughout the wall thickness—not merely at the surface.
The relationship between the two technologies is synergistic: HEB produces the base clad component, while tubular wire overlay provides field restoration and localized reinforcement when surface wear occurs during service.
7.3 Explosion Welding (Advanced Route)
Explosion welding (EW) represents the highest-performance bonding route for producing clad plates and pipes with superior interfacial quality. For non-woven industry applications requiring extreme durability—such as high-temperature meltblown PP contact surfaces operating at 200–260°C—explosion-welded clad components provide a permanent, high-integrity base structure. Tubular wire overlay then serves as the maintenance and restoration technology for these EW-produced components during their service lifecycle.
7.4 Integrated Technology Matrix
| Application Need | Technology Route | Typical Component | Performance Target |
|---|---|---|---|
| New clad roll manufacture | Explosion Welding | Meltblown forming drum | Full-wall corrosion resistance, 10+ year life |
| Cost-effective clad production | Hydraulic Explosive Bonding | Chemical-resistant guide cylinder | Full-wall protection, 5–8 year life |
| Roll surface restoration | Tubular Wire MIG Overlay | Worn calender roll | Hardness 400–500 HB, 2–3 year service life |
| Field repair / emergency | Tubular Wire MIG Overlay | On-site damaged component | Rapid restoration (4–8 hours), 1–2 year life |
| Transition layer for dissimilar materials | TIG Overlay (solid wire) | 309L transition on carbon steel | Prevents cracking in subsequent overlay passes |
8. Contribution to Qualification Building, Product Delivery, and Customer Value
8.1 Qualification Building
- WPS Development: This technical study directly feeds into the development of Welding Procedure Specifications for tubular wire overlay on carbon steel and stainless steel substrates, which must be qualified per NB/T 47014 and ASME Section IX.
- WPQ (Welder Performance Qualification): Documented process knowledge supports the training and certification of welding personnel capable of executing tubular wire overlay to specified quality levels.
- Process Validation: Systematic documentation of parameters, consumable selection, and acceptance criteria establishes a validated process database that accelerates future WPS approvals for new customer applications.
8.2 Product Delivery Enhancement
- Shortened Lead Times: Field-applicable tubular wire overlay eliminates the need to ship heavy rolls to the workshop, reducing delivery timelines by 50–70%.
- Cost Optimization: Overlay restoration costs 70–90% less than full component replacement, enabling competitive pricing while maintaining quality standards.
- Service Flexibility: Self-shielded consumables enable service in remote or hazardous locations without requiring gas infrastructure, expanding the geographic reach of service offerings.
8.3 Customer Value Delivery
- Reduced Downtime: Non-woven fabric production lines operate 24/7; rapid in-situ overlay restoration minimizes production losses that can exceed ¥50,000–¥100,000 per hour of downtime for large-scale meltblown facilities.
- Extended Asset Life: Properly executed overlay extends roll service life by 2–5×, deferring capital expenditure on new equipment.
- Performance Consistency: Uniform overlay hardness and thickness ensure consistent fabric quality—critical for medical-grade non-woven products where thickness uniformity and strength properties must meet regulatory specifications (e.g., FDA 21 CFR, EU MDR).
- Technical Partnership: Documented technical expertise positions the company as a qualified technical partner rather than merely a repair service provider, enabling long-term maintenance contracts and preventive service programs.
9. Recommendations for Implementation
- Establish a dedicated WPS library for tubular wire overlay covering minimum three consumable grades (wear-resistant, stainless, Ni-based) on two substrate types (carbon steel, stainless steel).
- Develop a field-service toolkit including portable power supply, wire feeder, grinding equipment, hardness tester, and consumable storage system for on-site deployment.
- Create a qualification matrix mapping consumable grades to non-woven industry applications, with documented test results (hardness, adhesion, chemical composition) for each combination.
- Implement a customer feedback loop tracking overlay performance in service—recording service life, failure modes, and performance metrics to continuously improve consumable selection and process parameters.
- Pursue industry-specific certifications such as NADCAP (for aerospace-adjacent non-woven applications) or ISO 9001 process-specific annexes to demonstrate compliance capability to non-woven manufacturers with stringent quality requirements.
10. Conclusion
Tubular wire weld overlay technology represents a high-value, technically differentiated capability that directly addresses the maintenance and restoration needs of the rapidly growing non-woven fabric industry. By mastering this process—documented through systematic technical study, validated through WPS qualification, and deployed through field-service capability—Cladding Technology Shanxi Co., Ltd. can position itself as an indispensable technical partner to non-woven manufacturers seeking to minimize downtime, extend asset life, and maintain product quality consistency. The integration of tubular wire overlay with the company's hydraulic explosive bonding and explosion welding capabilities creates a complete technology ecosystem spanning new component manufacture through field restoration—a comprehensive value proposition that few competitors can match.