CLADDING TECHNOLOGY SHANXI CO., LTDCladding Repair of PYZ-2200 Cone Crusher at Chuxiong Mining and Metallurgy
Technical Background and Problem Statement
This 2003 technical paper by Li Shuwen addresses the weld-overlay repair of a PYZ-2200 cone crusher at the processing plant of Chuxiong Mining and Metallurgy Co., Ltd. The PYZ-2200 is a spring-type cone crusher with a nominal crushing chamber diameter of 2200 mm, designed for secondary and tertiary crushing of hard ores in mineral processing circuits. The cone crusher mantle and concave (bowl liner) are the primary wear components, subjected to intense abrasive and impact loading from rock particles in the crushing chamber.
The technical challenge addressed is significant: cone crusher mantles and concaves experience complex multiaxial stress states combined with severe abrasive wear, and their replacement involves considerable downtime, heavy lifting, and material costs. Surface cladding repair offers a viable alternative that can extend component life by 1.5–3 times compared to uncladded steel liners.
Metallurgical Analysis of Cone Crusher Wear Components
Base Material and Service Conditions
| Parameter | Typical Specification |
|---|---|
| Base material of mantle/concave | Q345 / 16Mn low-alloy steel |
| Operating hardness of base | 22–28 HRC |
| Service life without cladding | 800–1500 hours |
| Service life with cladding | 2500–5000 hours |
| Primary wear mechanism | Abrasive (three-body) + impact |
| Typical feed material hardness | Mohs 6–8 (quartz, feldspar, basalt) |
| Feed size range | 0–300 mm |
Cladding Material Selection for Cone Crusher Application
The selection of the overlay material for cone crusher components is governed by the specific wear mechanism. For the PYZ-2200 operating in mineral processing applications, the dominant wear mechanism is abrasive wear with significant impact loading. The following material systems are most commonly specified:
- Cr-Cr₇C₃ cast iron system (D256/D257 electrodes): Provides hardness of 58–65 HRC with excellent resistance to dry abrasive wear. The Cr₇C₃ carbides form a network that effectively resists material removal by sliding abrasion. However, this system has limited toughness and is prone to spalling under heavy impact.
- Ni-Cr-Cr₇C₃ system (D107/D108 electrodes): Offers hardness of 55–62 HRC with significantly better toughness than the Cr-Cr₇C₃ system. The austenitic or martensitic matrix provides good resistance to impact spalling while maintaining excellent abrasive wear resistance. This is often the preferred choice for cone crusher mantles.
- High-speed steel type (D507 electrodes): Provides hardness of 60–66 HRC with good combination of toughness and wear resistance. Suitable for applications where moderate impact loading is present.
- Composite multi-layer systems: A ductile bond layer (e.g., D102, Ni-Cr) followed by 2–3 layers of hardfacing material (e.g., D256, D107) provides optimal combination of bond strength and surface wear resistance.
Welding Process and Quality Control
Recommended Welding Procedure
The cladding of cone crusher mantles and concaves requires careful attention to several process parameters:
- Preheating: The base component must be preheated to 250–350°C to reduce the cooling rate in the HAZ and minimize the risk of cold cracking. For large components, this is typically achieved using induction heating or gas flame heating.
- Welding sequence: A systematic welding sequence is essential to minimize distortion. The mantle is typically divided into 4–6 segments, and welding proceeds in a balanced, symmetric pattern to distribute residual stresses evenly.
- Deposition thickness: The total cladding thickness should be 3–5 mm, with a minimum of 2 mm of effective hardfacing material remaining after post-weld machining. Multi-pass welding is used, with each pass depositing 1.5–2.5 mm of metal.
- Interpass temperature: Maintained at 200–300°C to control the cooling rate and prevent cracking.
- Post-weld treatment: Stress relief annealing at 550–650°C for 2–4 hours is recommended to reduce residual stresses, particularly for heavily clad components.
Non-Destructive Testing Requirements
| NDT Method | Application | Acceptance Criteria |
|---|---|---|
| Magnetic Particle Testing (MT) | Surface and near-surface cracks in cladding layer | No linear indications > 2 mm |
| Ultrasonic Testing (UT) | Bond defects, lack of fusion at base-cladding interface | Per NB/T 47013.3 |
| Hardness testing | Verification of cladding layer hardness | 58–65 HRC for Cr-Cr₇C₃ system |
| Visual inspection | Surface quality, spatter, undercut | No undercut > 0.5 mm |
Engineering Practice and Lessons Learned
The repair of cone crusher components through cladding is not merely a technical exercise but an engineering optimization problem. Several practical considerations emerge from the field experience documented in this work:
- Dilution control: The dilution of the hardfacing alloy by the base steel is a critical parameter. Excessive dilution (above 30–40%) significantly reduces the hardness and wear resistance of the cladding layer. This is managed through careful control of welding parameters, use of a ductile bond layer, and verification of hardness after welding.
- Geometry considerations: The cladding layer must be deposited to conform to the curved geometry of the mantle or concave. This requires skilled welders and sometimes specialized fixtures to maintain consistent weld bead geometry.
- Post-weld machining: The as-welded cladding surface is rough and irregular. Post-weld machining to the required geometry is essential, and this machining removes 1–2 mm of the cladding layer. The design must account for this material removal.
- Repeatability: The cladding repair process must be repeatable across multiple repair cycles. Each successive repair cycle typically requires removal of the previous cladding layer, which can thin the base material. A maximum of 3–4 repair cycles is generally feasible before the component must be replaced.
Comparative Analysis of Repair Strategies
| Strategy | Cost Index | Downtime | Service Life Extension | Complexity |
|---|---|---|---|---|
| Full replacement | 100 | 8–16 hours | 100% (new component) | Low |
| Cladding repair (single layer) | 25–35 | 4–8 hours | 60–80% | Medium |
| Cladding repair (multi-layer) | 35–50 | 6–12 hours | 80–120% | High |
| Cladding + machining | 40–55 | 8–16 hours | 90–130% | High |
Study Insights
The 2003 publication of this work reflects the growing maturity of cladding technology in Chinese mining operations during the early 2000s. The PYZ-2200 cone crusher is a widely used piece of equipment in Chinese mineral processing plants, and the systematic documentation of cladding repair procedures for this specific application provided valuable reference material for maintenance engineers across the industry.
A key insight from this study is the importance of matching the cladding material system not only to the wear mechanism but also to the specific ore characteristics. Different ore types produce different abrasive particles with varying hardness, shape, and angularity, which can significantly affect the wear behavior of the cladding layer. For example, ore containing high quartz content produces sharp, angular abrasive particles that are particularly aggressive against metallic surfaces, while softer ore types produce less damaging wear.
The economic analysis presented in this work is particularly instructive. The total cost of ownership approach—considering not just the repair cost but also the cost of downtime, the cost of lost production, and the environmental impact of component disposal—demonstrates that cladding repair is overwhelmingly the preferred strategy for cone crusher components, with typical return on investment periods of less than 3 months.
This study remains a valuable reference for maintenance engineers working with cone crushers in mineral processing applications, and its fundamental principles continue to guide modern cladding repair practice.