Mining cutting picks are indispensable tools in high-intensity operations such as coal mining, rock excavation, and tunnel construction. They operate in extremely harsh environments and are subject to long-term impact loads and abrasive wear. This damage directly affects equipment operating efficiency and operational safety.
Traditional repair methods such as electric welding or spraying are low in cost, but they have disadvantages such as poor repair accuracy, easy peeling of the cladding layer, large heat-affected zones, and short service life. PTA welding technology has become an important solution for cutting pick repair and wear resistance due to its metallurgical bonding, excellent wear resistance, and good cost control advantages.
Common problems with mining cutting picks
Mining cutting picks are commonly used in equipment such as roadheaders, coal cutters, and shield machines. During operation, they frequently come into contact with hard rock, coal seams, and other high-hardness materials, and are subjected to high-frequency impact and severe abrasive wear. Common problems include:
- Dull and chipped cutting pick heads
- Cracks or fatigue damage in the tooth body
- Wear at the tooth seat connection
- Surface corrosion and pitting
- Short service life and frequent maintenance
These issues not only increase maintenance costs but also lead to frequent equipment downtime and reduced production capacity, becoming a bottleneck hindering the efficient operation of mining equipment.
Technical principles of PTA welding
Plasma Transferred Arc welding (PTA) is a high-energy beam surface metallurgical strengthening technology. It uses a high-temperature plasma arc to melt selected metal alloy powders and deposit them on the surface of the workpiece, forming a strong metallurgical bond with the substrate. This technology can be used to strengthen cutting picks, tooth surfaces, and other parts, thereby significantly improving their wear resistance and service life.
Advantages of PTA welding technology:
- High-temperature local heating with a small heat-affected zone
- Dense, uniform, and high-hardness cladding layer
- Metallurgical bond with the substrate, not easy to fall off
- A variety of wear-resistant alloy powders can be customized
Compared with traditional methods such as hardfacing and spraying, PTA welding has higher adhesion strength and wear resistance, and is suitable for surface strengthening of large quantities of high-strength mining tools.
Advantages of PTA welding for mining cutting picks
- Significantly improves the wear resistance of cutting picks
The hardness of the cladding layer can usually reach HRC60 or above, which is significantly higher than that of ordinary hardfacing layers, effectively delaying blade wear and making it suitable for extreme conditions such as hard rock mining.
- Reduces the frequency of cutting pick replacement
PTA welding can increase the service life of cutting picks by 3-5 times, reducing maintenance frequency, increasing equipment operating time, and reducing total operating costs.
- Improves reliability and safety
The metallurgical bonded reinforcement layer has stronger adhesion and is not prone to flaking or cracking, ensuring operational safety and equipment stability.
- Highly controllable and adaptable to complex structures
PTA welding is suitable for cutting picks with complex shapes and tooth bodies, and the cladding thickness and position can be controlled to meet the requirements of fine repair and reinforcement.
- Repair and reinforcement
Not only is it suitable for repairing old cutting picks, but it can also be used to reinforce the surface of new cutting picks, extending their service life and improving product performance.
PTA welding repair process for cutting picks
1. Cleaning and pretreatment of cutting pick surface
Remove surface oil, oxide layer, and impurities to ensure that the substrate is clean, which is conducive to the metallurgical bonding of the cladding layer and the substrate.
2. Alloy powder selection and ratio
Select the cladding material according to the usage environment and requirements of the cutting pick. Commonly used materials are:
- Iron-based alloys: general-purpose cutting pick reinforcement
- Nickel-based alloys: corrosion resistance and high temperature resistance
- Cobalt-based alloys: extreme wear and high temperature impact conditions
- Addition of hard particles such as WC (tungsten carbide), Cr, and Nb to improve hardness and erosion resistance
3. PTA welding operation
Use CNC PTA welding equipment to clad the tooth body or cutting head according to the predetermined trajectory and parameters. Control the cladding thickness, width, and depth to ensure a uniform and crack-free reinforced layer.
4. Post-processing and heat treatment
Includes grinding and shaping, stress-relief annealing, etc., to restore tooth profile accuracy, eliminate internal stress, and enhance operational stability.
5. Inspection and acceptance
Includes hardness testing, metallographic analysis, microstructural observation, etc., to ensure the cladding layer meets quality standards.
Frequently Asked Questions (FAQ)
Q1: How long is the service life of cutting picks after welding?
The service life depends on the working conditions and the type of alloy powder. Generally, it is 3 to 5 times longer than that of ordinary cutting picks, and some high-strength welding can last more than 6 times longer.
Q2: Which is better, PTA welding or laser welding?
Laser welding has higher precision and less heat impact, but it is more expensive. PTA welding is suitable for mass production and medium precision requirements, and has a superior cost-performance ratio.
Q3: Is the welding layer prone to cracking or peeling?
No. Due to the metallurgical bonding and dense cladding layer, it is not prone to peeling under normal operation. Reasonable post-treatment can further reduce the risk of cracking.
Q4: Is it suitable for all cutting picks?
Cutting picks with intact structures and no serious fractures can basically be clad. For severely deformed or fractured teeth, it is recommended to replace them with new ones.
Plasma welding not only significantly improves the wear resistance, impact resistance, and service life of cutting picks, but also has good process adaptability and economy, making it suitable for many high-wear applications such as coal mines, tunnels, water conservancy, and subways. For mining companies seeking equipment stability and lower maintenance costs, plasma welding is currently the most cost-effective and sustainable solution for surface strengthening of cutting picks.
Interested in PTA welding mining cutting picks equipment? Please contact us. Shanghai Duomu Industrial Co., Ltd. is not only a welding equipment manufacturer, but also provides customized wear-resistant and corrosion-resistant solutions for the entire industry!
Post time: Aug-08-2025