CLADDING TECHNOLOGY SHANXI CO., LTDStudy Note on Wear-Resistant Parts Cladding Manufacturing and Remanufacturing
Literature Overview
The 2008 paper by Liu Zhenying, published in New Century Cement Guide, presents a comprehensive discussion on the manufacturing and remanufacturing of wear-resistant parts through weld overlay cladding. Supported by the National Science and Technology Innovation Fund (Project No. 070092), this research from Beijing Jiake Emerging Technology Co., Ltd. and Tsinghua University Machinery Factory addresses the critical need for durable, cost-effective wear parts in the cement industry.
Core Technical Points
Wear-resistant parts in cement plants—bucket elevator buckets, mill liners, fan blades, chutes, and hoppers—are subjected to severe abrasive wear from cement clinker, raw meal, and fly ash. The average service life of unclad carbon steel components in these applications is typically 3–6 months, resulting in frequent downtime and material waste. Weld overlay cladding with appropriate hardfacing alloys can extend service life by 3–10 times.
Cladding Material Selection for Cement Industry
| Application | Wear Mechanism | Recommended Overlay | Hardness (HRC) | Expected Life |
|---|---|---|---|---|
| Bucket elevator buckets | Abrasive (clinker) | High-Cr-C alloy (Cr 25–30%, C 3–5%) | 55–62 | 18–36 months |
| Mill liners | Impact-abrasive | High-Mn steel (Mn 12–18%) | 25–35 (work-hardening) | 24–48 months |
| Fan blades | Abrasive (fly ash) | Co-Cr alloy or high-Cr alloy | 45–55 | 12–24 months |
| Chutes and hoppers | Sliding abrasion | Medium-Cr alloy (Cr 12–18%) | 45–55 | 12–24 months |
| Pulley surfaces | Impact-abrasive | High-Cr-C or Co-Cr | 50–60 | 18–36 months |
Manufacturing vs. Remanufacturing Approach
The paper distinguishes between greenfield manufacturing (cladding new components) and remanufacturing (cladding worn existing components). Both approaches have distinct advantages:
Manufacturing Cladding:
- Complete control over substrate preparation and weld sequence.
- Ability to design optimal clad-base combinations for specific applications.
- Higher initial cost but longer guaranteed service life.
- Suitable for new equipment procurement or major overhauls.
Remanufacturing Cladding:
- Lower cost due to reuse of existing component body.
- Rapid turnaround time for urgent repairs.
- Limited by the condition of the existing substrate (residual stresses, distortion, corrosion).
- Requires thorough assessment of remaining substrate life.
FMEA Analysis of Cladding Failures
| Failure Mode | Severity | Occurrence | Detection | RPN | Countermeasure |
|---|---|---|---|---|---|
| Overlay spalling | 8 | 4 | 3 | 96 | Improve surface prep, use transition layer |
| Undercut at toe | 6 | 5 | 2 | 60 | Optimize current, use backing bar |
| Cracking in overlay | 7 | 3 | 4 | 84 | Preheat, post-weld stress relief |
| Insufficient thickness | 5 | 4 | 3 | 60 | Multi-pass with thickness monitoring |
| Contamination (S, P) | 6 | 3 | 4 | 72 | Strict consumable storage and handling |
Process Technology and Quality Control
The cladding process for cement industry wear parts typically involves the following steps:
- Surface preparation: Remove existing coating, rust, and scale by grit blasting to Sa 2.5 grade. Repair surface defects (cracks, deep pits) by grinding or plug welding.
- Substrate assessment: Measure hardness, residual stress, and geometry. Determine if the substrate is suitable for cladding or requires replacement.
- Preheating: Heat the component to 200–300°C to prevent cold cracking, especially for high-carbon substrate materials.
- Transition layer (if required): Deposit a nickel-based or 309L layer to bridge the metallurgical gap between the base steel and the hardfacing alloy.
- Overlay deposition: Apply the hardfacing alloy using the selected process (typically FCAW or SAW for thick deposits, GTAW or PTA for thin deposits).
- Post-weld treatment: Stress relief at 500–600°C for high-carbon overlays, or solution treatment for Co-based overlays.
- Inspection: Visual examination, magnetic particle testing (MT) for surface defects, and hardness verification.
Quality control parameters include overlay thickness (typically 3–8 mm for cement applications), hardness uniformity (±5 HRC across the deposit), and absence of surface defects detectable by MT.
Study Insights and Industry Impact
This research represents a significant contribution to the remanufacturing sector in China's cement industry. The systematic approach to cladding material selection, process optimization, and quality control provides a replicable framework for other heavy industry sectors. The economic analysis demonstrates that cladding wear parts can reduce material consumption by 60–80% and downtime by 70–85% compared to conventional replacement. The remanufacturing philosophy aligns with modern sustainability goals by extending component life and reducing raw material consumption. The findings are directly applicable to mining, power generation, and chemical processing industries with similar wear challenges.