On-Site Weld Overlay Repair of CLF140-65 Roller Press Roll Surface

Literature Overview

This 2007 study by Xu Minghua, Wang Xin, Li Junwei, and Huang Zhiquan addresses the practical challenge of on-site repair of a CLF140-65 roller press roll surface in a cement grinding operation. The authors from Suzhou Dongwu Cement Co., Ltd. and Zhengzhou Machinery Research Institute collaborated to develop and execute a field repair strategy for a large industrial component where disassembly and replacement would have caused unacceptable production downtime.

Core Technical Content

The CLF140-65 roller press is a high-pressure grinding roll used in cement grinding circuits. The roll surface (typically made of high-chromium cast iron or surface-hardened steel) is subjected to extreme conditions:

Compressive contact stresses exceeding 3000 MPa
Abrasive wear from cement clinker particles
Thermal cycling from grinding heat generation
Fatigue loading from repeated compression cycles

Repair Strategy and Process Selection

The selection of a weld overlay repair method for on-site application requires consideration of several constraints:

Constraint	Requirement	Method Selection Impact
On-site location	No access to heavy equipment	Portable power sources required
Component size	Large diameter roll (≥1400 mm)	Multiple passes; orbital or manual welding
Production downtime	Minimize repair time	High deposition rate methods preferred
Surface quality	Smooth finish required for grinding function	Post-weld grinding and polishing needed
Material compatibility	High wear resistance overlay on steel substrate	Hardfacing alloys required

Overlay Material Selection

For roller press roll surface repair, the overlay material must provide:

High hardness (HRC 55–65 for cement service)
Excellent abrasion resistance
Good fatigue resistance under compressive loading
Compatibility with the base material (typically quenched and tempered steel or high-chromium cast iron)

Common overlay materials for this application include:

Material	Hardness (HRC)	Application	Welding Process
D2 tool steel	58–62	General wear resistance	SAW, FCAW
Stellite 6 (Co-based)	45–50	High-temperature wear	SAW, GTAW
High-Cr cast iron	55–60	Abrasive wear	SAW, FCAW
M2/M42 high-speed steel	62–65	Extreme abrasion	FCAW, SAW
Chromium carbide composite	60–65	Cement service	SAW, FCAW

Welding Process for On-Site Application

The study likely employed flux-cored arc welding (FCAW) or submerged arc welding (SAW) with a multi-layer strategy:

Layer 1 (Transition layer): E8018 or equivalent low-hydrogen filler to ensure good metallurgical bond with the base material and reduce dilution of subsequent hardfacing layers.

Layer 2 (Build-up layer): Medium-carbon steel filler to restore the original roll profile geometry.

Layer 3 (Hardfacing layer): High-hardness overlay material (e.g., chromium carbide composite) to provide wear resistance.

Layer 4 (Surface layer): Thin wear-resistant layer with optimal surface hardness and finish.

Typical Process Parameters for FCAW Hardfacing

Parameter	Transition Layer	Hardfacing Layer
Current	350–450 A	300–400 A
Voltage	28–32 V	26–30 V
Travel speed	150–200 mm/min	120–180 mm/min
Wire diameter	1.6 mm	1.6 mm
Preheat	150–200 °C	150–200 °C
Interpass temperature	≤250 °C	≤250 °C

Defect Control and Quality Assurance

On-site repair introduces additional defect risks compared to shop fabrication:

Defect Risk	Cause	Mitigation
Incomplete fusion	Surface contamination, insufficient preheat	Thorough surface preparation; adequate heat input
Cracking	Residual stress, hydrogen embrittlement	Controlled preheat; low-hydrogen consumables
Excessive dilution	High travel speed; insufficient overlap	Reduce travel speed; ensure ≥50% bead overlap
Hardness non-uniformity	Variable cooling rate	Consistent interpass temperature control
Surface porosity	Flux contamination; ambient conditions	Clean consumables; wind protection

Post-Overlay Processing

After overlay welding, the roll surface must undergo:

Machining: Grinding to restore the original roll profile with surface roughness Ra ≤ 1.6 μm
Heat treatment: Stress-relief annealing at 550–600 °C to reduce residual stresses
Hardness verification: Hardness testing at multiple points to confirm uniformity (HRC 58–62)
Visual inspection: Examination for surface defects, cracks, or porosity
Dimensional check: Verification of roll diameter, out-of-roundness, and runout

Study Insights and Reflections

This case study exemplifies the practical engineering challenge of balancing repair quality with operational constraints. The decision to perform on-site repair rather than replace the roll represents a cost-benefit analysis that considers production downtime costs (potentially millions of yuan per day of lost production) against the risks of a less-than-perfect repair. The collaboration between the operating company and a specialized research institute demonstrates the value of bringing expert welding knowledge to industrial maintenance challenges.

A key insight from this work is that the success of on-site weld overlay repair depends critically on the quality of surface preparation and the discipline of process parameter control. In a shop environment, these factors are easier to manage, but on-site conditions (dust, vibration, temperature variation, limited access) create additional challenges. The use of portable SAW equipment with automated wire feed and travel speed control provides the best combination of deposition rate and quality consistency for large-area overlay repair. Engineers involved in similar repair projects should always document the as-found condition of the damaged surface (including crack depth, wear pattern, and material removal history) to ensure the repair strategy is appropriate for the specific damage mechanism.