Roll Surface Cladding Repair Technology for Roller Presses

Literature Overview and Industry Context

This 2007 paper published in Mining Machinery by Shi Liyan, Zhang Yachun, and Zhang Xingsheng — representing Tangshan Keyuan Environmental Protection Technology Equipment Co., Ltd., CCCC First Harbor Engineering Company, and Tangshan Jidong Cement Co., Ltd. — addresses a specific and economically significant problem in the cement and mining industries: the repair of worn roller surfaces on roller presses. Roller presses are critical equipment in cement clinker grinding and mineral processing, where the rollers experience extreme sliding contact stresses, abrasive wear from feed materials, and thermal cycling. The paper discusses the application of weld overlay cladding as a cost-effective alternative to full roller replacement, drawing on practical industrial experience rather than purely academic research.

Operational Conditions and Wear Mechanisms

Roller press rollers operate under conditions that demand careful metallurgical analysis. The contact pressure between the compression rollers typically ranges from 50 to 200 MPa, with sliding velocities of 1 to 5 m/min depending on the application. The feed materials in cement grinding include limestone, clay, and gypsum, which are highly abrasive. In mineral processing, the materials may include ores with high silica content, creating even more severe abrasive conditions.

Wear Parameter	Typical Value in Cement Roller Press
Contact pressure	50–200 MPa
Sliding velocity	1–5 m/min
Ambient temperature	20–80 °C (ambient)
Surface temperature during operation	100–200 °C
Feed material hardness (Mohs)	5–7 (limestone to silica)
Typical roller surface hardness before wear	HRC 45–55
Typical roller surface hardness after wear	HRC 30–40 (work-hardened or eroded)
Annual wear rate (unclad)	2–5 mm/year

The dominant wear mechanism is abrasive wear, where hard particles in the feed material plow through the roller surface, removing material through micro-plowing and micro-cutting. Secondary mechanisms include adhesive wear from metal-to-metal contact at asperities and fatigue wear from cyclic contact stresses. Understanding these mechanisms is essential for selecting the appropriate cladding alloy and process.

Cladding Material Selection and Process Approach

The paper discusses several cladding material options for roller press repair, each suited to different wear conditions.

Cladding Material	Hardness (HRC)	Key Strengths	Limitations
High-carbon martensitic steel (Cr12MoV)	58–62	Excellent abrasion resistance, good weldability	Susceptible to thermal fatigue cracking
High-chromium white cast iron (Cr20)	60–65	Superior abrasion resistance	Brittle, poor impact resistance
Ni-Cr-C hardfacing alloy	50–58	Good abrasion and impact resistance	Higher cost
Stellite 6 (Co-based)	45–50	Excellent hot hardness, corrosion resistance	Very high cost, lower hardness than martensitic
WC-reinforced Ni-based alloy	55–62	Outstanding abrasion resistance	Requires proper welding procedure

The recommended approach for roller press repair involves several sequential steps. First, the worn surface is ground to remove the damaged and work-hardened layer, ensuring a clean, sound substrate for cladding. The grinding depth typically removes 2 to 5 mm of material. Second, a suitable backing layer may be deposited to improve bond strength and reduce residual stress, particularly when cladding hard materials onto softer substrate. Third, the primary cladding layer is applied using submerged arc welding (SAW), gas metal arc welding (GMAW), or plasma transferred arc (PTA) depending on the geometry and production requirements. Fourth, the cladding surface is machined to the required dimensional tolerance, typically within ±0.1 mm for roller diameter.

The paper specifically advocates for multi-layer cladding strategies where a ductile transition layer is deposited first, followed by the hard cladding layer. This approach mitigates the risk of cracking at the dilution zone, where the base steel composition may contain insufficient alloying elements to support the hard cladding microstructure.

Process Parameters and Quality Control

For submerged arc welding overlay on roller surfaces, the following parameter ranges are recommended:

Parameter	Recommended Range
Welding current	400–700 A
Arc voltage	28–35 V
Travel speed	150–350 mm/min
Wire diameter	1.6–3.2 mm
Flux type	Low-hydrogen, rutile-based
Preheat temperature	150–250 °C (depending on substrate carbon equivalent)
Interpass temperature	200–350 °C
Post-weld heat treatment	550–650 °C for 2–4 hours (stress relief)

Quality control measures include visual inspection of all welds, magnetic particle testing (MT) of the surface and near-surface regions for cracks, ultrasonic testing (UT) of the bond line for lack of fusion, and hardness testing across the cladding cross-section to verify the hardness profile and dilution zone. The paper emphasizes that hardness testing should be performed at multiple depths from the surface to the bond line, as a single surface hardness reading does not capture the full dilution gradient.

Engineering Case Study and Practical Lessons

The paper presents a case study involving the repair of compression rollers at a cement plant where the original rollers had experienced 3 to 4 mm of wear after approximately 12 months of operation. The repair involved grinding the worn surface, applying a two-layer cladding of high-carbon martensitic alloy using submerged arc welding, and machining the surface to specification. The repaired rollers were returned to service and achieved a service life exceeding 24 months before the next repair cycle, representing a significant improvement over the original unclad roller life and a substantial cost saving compared to roller replacement.

Key lessons from this case include the importance of proper surface preparation before cladding, the value of multi-layer cladding for stress relief and dilution control, and the necessity of post-weld stress relief heat treatment to prevent delayed cracking during service. The paper also notes that the cladding repair can be performed in-situ or in a workshop, depending on the roller size and available equipment, with workshop repair generally offering better quality control.

Study Insights and Recommendations

This paper provides valuable practical guidance for engineers responsible for maintenance and repair of heavy industrial equipment. The emphasis on multi-layer cladding strategies, proper heat treatment, and systematic quality control reflects mature engineering practice. For engineers working in related applications — such as cladding of ball mill liners, crushing equipment, and other heavily worn components — the principles described here are directly transferable. The economic argument for cladding repair over component replacement is compelling and should be incorporated into lifecycle cost analyses for any asset-intensive operation. Engineers should also note that the specific alloy selections discussed here may need to be adapted for different service environments, particularly where corrosion resistance is a secondary requirement alongside abrasion resistance.