Zhuojin Pipe Fitting Co., LtdManual Arc Overlay Welding Repair of Sugar Cane Mill Roller Shaft Journals
Literature Overview
This paper by Pang Sixiong, Feng Chuanshan, Hu Lifang, Yang Zhongjian, and Liang Shaolu, published in Journal of Guangxi University (Natural Science Edition) (Vol. 22, No. 1, 1997, pp. 91–94), documents the application of manual arc overlay welding for repairing worn and cracked journal bearings on sugar cane mill roller shafts. The research was conducted jointly by Guangxi University (Chemical Engineering Department), Yongning County Pumiao Sugar Mill, and Wuming County Dongjiang Sugar Mill. The study addresses a practical maintenance challenge in the sugar processing industry: the restoration of worn roller shaft journals to serviceable condition through overlay welding.
Core Technical Approach
The authors employed manual shielded metal arc welding (SMAW) to deposit overlay layers on worn and fatigued roller shaft journals. The repair process was validated through extended service testing, with the repaired shafts operating for two complete crushing seasons (processing 4.7 × 10^5 tons of cane) without abnormal failure, and the overlay layer exhibiting a wear rate of only 0.3 mm.
Service Conditions
| Parameter | Value |
|---|---|
| Application | Sugar cane mill roller shaft journal |
| Service duration | 2 crushing seasons |
| Cane processed | 4.7 × 10^5 tons |
| Overlay wear rate | 0.3 mm |
| Failure observed | None |
Process Details and Technical Considerations
Pre-Weld Preparation
The repair process requires careful preparation of the worn surface:
- Surface assessment: Inspection of wear depth, fatigue cracks, and surface condition.
- Machining: Removal of severely worn material and surface damage by machining.
- Crack repair: If fatigue cracks are present, they must be removed by machining or ground out, and the crack root must be checked for complete removal.
- Cleaning: Removal of scale, rust, oil, and moisture from the surface.
- Preheating: Controlled preheating to reduce thermal gradients and prevent cracking.
Welding Procedure
The manual arc overlay welding process involves:
- Consumable selection: Appropriate electrode selection for the base material and service conditions.
- Layer building: Multiple passes to build up the overlay to the required dimension.
- Heat input control: Managing interpass temperature and travel speed to control cooling rates.
- Post-weld treatment: Stress relief and dimensional machining to restore the journal to specification.
Quality Verification
| Inspection Method | Purpose |
|---|---|
| Visual inspection | Surface quality, crack detection |
| Magnetic particle testing | Surface and near-surface crack detection |
| Hardness testing | Verification of overlay properties |
| Dimensional measurement | Confirmation of restored geometry |
| Service monitoring | Long-term performance validation |
Engineering Practice Implications
Application to Similar Repair Scenarios
The methodology documented in this paper is applicable to various heavy-duty shaft repair applications:
- Roller shafts: In sugar mills, mining equipment, and cement plants.
- Journal bearings: In pumps, compressors, and turbines.
- Pinion shafts: In gearboxes and transmissions.
- Crane hooks and lifting components: Where surface wear is the primary failure mode.
Cost-Benefit Analysis
Overlay welding repair offers significant cost advantages over replacement for large-diameter shafts:
| Option | Cost Factor | Downtime | Material Availability |
|---|---|---|---|
| Shaft replacement | High (new forging, machining) | Extended | Limited by supplier |
| Overlay welding repair | Low (consumables, labor) | Short | Available locally |
| Sleeve replacement | Medium (sleeve fabrication) | Moderate | Moderate |
Common Defects and Countermeasures
| Defect | Cause | Countermeasure |
|---|---|---|
| Cracking | High cooling rate, hydrogen embrittlement | Preheating, low-hydrogen electrodes, controlled cooling |
| Porosity | Surface contamination, electrode moisture | Clean surface, dry electrodes, proper storage |
| Excessive dilution | High heat input, excessive penetration | Controlled heat input, appropriate electrode diameter |
| Incomplete fusion | Poor surface preparation, low current | Proper cleaning, adequate current, multiple passes |
| Undercut | Excessive travel speed, improper technique | Controlled travel speed, proper electrode angle |
Study Insights and Reflections
This paper provides a practical, field-validated case study of overlay welding repair technology applied to sugar mill equipment. The extended service testing—two complete crushing seasons with 4.7 × 10^5 tons of cane processed—provides strong evidence of the reliability of the repair methodology.
The wear rate of 0.3 mm over two seasons is remarkably low for a component subjected to the abrasive and corrosive conditions of sugar cane processing. This performance validates the appropriateness of the selected welding consumables and process parameters for the specific service environment.
From an engineering perspective, this study demonstrates the value of overlay welding as a maintenance strategy for heavy-duty components. The ability to restore worn shafts to serviceable condition through welding, rather than replacing them, represents a significant cost saving and reduces equipment downtime.
The collaborative approach between academia (Guangxi University) and industry (sugar mills) is commendable and reflects the practical orientation of the research. The field validation through extended service testing provides the empirical evidence that laboratory testing alone cannot achieve.
This paper also highlights the importance of process documentation and quality verification in repair welding operations. The systematic approach to pre-weld preparation, welding execution, and post-weld verification ensures consistent repair quality and reliable long-term performance.
In conclusion, this study provides a well-documented case study of manual arc overlay welding repair applied to sugar mill roller shaft journals, with strong field validation through extended service testing. The methodology and findings are directly applicable to similar heavy-duty shaft repair applications across various industries, demonstrating the economic and practical advantages of overlay welding repair over component replacement.