Application and Discussion of Cladding Repair Technology for Roller Presses

Literature Overview

The reference by Zhang Xinsheng, Cao Cheng, Song Liming, and Wang Jianmin (2007), published in Cement Engineering and originating from the Equipment Management Department of Tangshan Jidong Cement Co., Ltd., provides a comprehensive discussion of cladding repair technology as applied to roller press rolls. This multi-author paper reflects a collaborative engineering effort that combines practical experience with systematic technical evaluation. The document covers material selection criteria, process optimization, field implementation challenges, and long-term performance assessment—making it one of the more thorough treatments of roller press roll repair in the Chinese cement industry literature.

Core Technical Framework

The paper establishes a framework for evaluating and implementing cladding repair based on the PDCA (Plan-Do-Check-Act) cycle, ensuring continuous improvement of the repair methodology over successive maintenance intervals. The approach recognizes that roller press roll repair is not a one-time event but a recurring maintenance activity that benefits from systematic data collection and process refinement.

Material Selection Criteria

The selection of cladding materials for roller press applications must balance three competing requirements: wear resistance, impact toughness, and thermal fatigue resistance. The following table summarizes the material evaluation matrix presented:

The paper recommends Cr-Cr₂C₃ hardfacing for high-pressure roller press applications where contact stress is the dominant failure mode, while Co-Cr alloys are preferred for high-temperature applications where thermal cycling is severe. The trade-off between cost and performance is explicitly discussed, with the conclusion that for most cement applications, Cr-Cr₂C₃ provides the best cost-benefit ratio.

Welding Process Optimization

The paper discusses the optimization of welding parameters through systematic experimentation. Key findings include:

• Travel speed: 150–200 mm/min provides optimal balance between penetration and dilution for a 1.2 mm electrode diameter.
• Arc voltage: 22–28 V for SMAW; 28–35 V for SAW with open arc.
• Welding direction: Spiral pattern around the roll circumference to minimize circumferential residual stress.
• Layer sequencing: Bottom-up approach with each layer completely solidified before the next, using interpass temperature control.
• Electrode baking: 350 °C for 2 hours for low-hydrogen electrodes; storage in portable ovens at 100 °C between uses.

Process Sequence for Roll Repair

1. Roll removal and cleaning: Disassemble the roll from the press frame; remove all damaged material to sound substrate using milling or grinding.
2. Surface preparation: Grind to bare metal with 240-grit minimum; degrease with solvent; apply temporary anti-oxidation coating if repair is delayed.
3. Preheating: Uniform preheat to 250–300 °C using induction heating or gas flames; verify with optical pyrometer at multiple points.
4. Transition layer welding: Deposit 2–3 passes of austenitic stainless steel (E309L) to create a thermal expansion buffer.
5. Working layer welding: Deposit 3–5 passes of hardfacing alloy in a spiral pattern; maintain interpass temperature below 250 °C.
6. Post-weld stress relief: Furnace stress relief at 580 °C for 2 hours; controlled cooling rate of 50 °C/h to ambient.
7. Final machining: Grind to specified diameter and profile; verify runout within 0.03 mm/TIR.
8. Quality verification: Hardness test, MT inspection, dimensional verification.

Field Implementation Challenges

The paper candidly discusses several challenges encountered in field implementation:

• Access limitations: Large roller press rolls (diameter 800–1200 mm) are difficult to access for manual welding, requiring specialized fixtures and positioning equipment.
• Ambient conditions: Outdoor repair in cold climates requires additional preheating and controlled cooling; summer conditions require protection from rapid cooling by wind.
• Schedule pressure: Cement plants operate with minimal downtime tolerance, creating pressure to expedite repairs at the expense of quality.
• Skill requirements: Hardfacing welding requires experienced operators; the paper emphasizes the importance of welder qualification and certification.

Quality Control and Performance Assessment

The paper presents performance data from multiple repair cycles at the Tangshan facility:

The improvement in service life over successive cycles demonstrates the effectiveness of the PDCA approach—each cycle incorporated lessons learned from the previous repair, resulting in progressively better outcomes.

Study Insights

This reference stands out for its systematic approach to what is often treated as an ad-hoc repair activity. The application of PDCA methodology to roller press repair transforms it from a reactive maintenance task into a continuously improving engineering process. The multi-author collaboration also reflects the interdisciplinary nature of the challenge, requiring expertise in metallurgy, welding engineering, mechanical design, and production planning. The performance data showing progressive improvement in service life validates the approach and provides quantitative justification for the additional investment in process optimization.