Common Casting Defects and Their Impact on Mining Equipment Performance
The casting process plays a fundamental role in the production of industrial castings. Especially in heavy industries such as mining equipment, a large number of sensitive and heavy parts, from shells and liners to pump impellers and rock crusher parts, are made by casting. These parts must withstand harsh working conditions, shock loads and severe wear. Accordingly, the quality of castings (the absence of defects in castings) is of particular importance; because any structural defect can lead to reduced performance, increased wear, sudden failure and even hazardous safety conditions.
In fact, a large part of the parts used in the transportation and heavy equipment industries – including mines – are made of castings. Therefore, identifying and eliminating common casting defects is an essential step to ensure the stable and safe operation of mining equipment. In the following article from Sepahan Foolad Atashgah, we intend to examine common casting defects and their impact on the performance of mining equipment. Stay with us.
The most common casting defects
Shrinkage Cavities:
During cooling and solidification of the metal, a reduction in volume occurs, which if there is no proper feeding path for the melt, creates empty cavities in the part. These cavities weaken the integral structure of the part and reduce the mechanical properties.
Common Casting Defects, Gas Porosity:
During cooling, the molten metal releases dissolved gases (for example, hydrogen), and these gases form bubbles within the metal. These gas porosity appear in the form of micropores or large pores and reduce the strength of the part. High pouring temperature and excessive mold humidity are factors that exacerbate this defect.
Hot Tearing and Segregation:
Hot tearing occurs when excessive shrinkage during solidification places the part at its weakest point (minimum strength) and causes irregular linear fracture. Also, segregation (chemical composition heterogeneity) in bulk parts can lead to the concentration of impurities or alloying elements in specific areas, which makes the mechanical properties variable and weak in some places.
Inclusions:
Cast parts may contain non-metallic particles such as slag, mold sand, or surface oxides. These “inclusions” appear as lumps or dispersed particles in the alloy and create barriers in the metal, reducing the toughness and ductility of the part.
Scabbing/Mold Surface Defects:
In sand casting, sometimes a thin layer of mold sand remains on the surface of the part or the top layer of sand separates (sanding). This defect causes an uneven, flaky surface of the part, which interferes with the final performance and increases the possibility of uneven wear.
Dimensional Defects and Deformation:
Errors in mold construction or irregular stresses during cooling may cause the dimensions of the final part to not match the design specifications. Curvature or distortion and dimensional deformation (warping) in the part are also defects that negatively affect proper assembly and equipment operation.
Common Casting Defects, Impact of Casting Defects on Mining Equipment
Ball Mill:
Ball mill castings (such as inner shells and liners) are subjected to severe impact and wear. The presence of shrinkage or gas pockets in these parts causes stress concentration and increases the likelihood of fracture and cracking. These defects also lead to faster liner wear and reduced service life, which can lead to unexpected production line shutdowns.
Chutes and chutes (junctions and ducts):
These parts are used to transport and guide minerals. Cracks or inhomogeneities in the walls of the chutes lead to sudden dropping of parts and load loss, which in addition to safety problems, can lead to failure of the material conveying system. The presence of inclusions on the inner surface of the chutes also causes severe wear and blockage of the path.
Liners and equipment body shells:
These parts are usually exposed to heavy static and dynamic loads. Internal voids or the presence of trapped gases may cause liners to break down over time or cracks to penetrate from below the surface, leading to the loss of protective layers and damage to the casing. In addition to reducing efficiency, such a situation poses a safety risk to operators.
Pump blades and crusher casings and wear parts:
In water transfer pumps and crusher casings, dimensional accuracy and integral structure are critical. The presence of non-metallic particles (slag) in the pump blades can disrupt pump performance by causing severe wear or dynamic imbalance. In crusher casings and mining wear parts, internal cracks or voids lead to sudden failure during operation, which increases the cost of repairs and premature replacement of the part. In general, any casting defect will somehow affect the durability, efficiency and safety of mining equipment.
Solutions to prevent casting defects
Proper design of the casting process:
Installing a suitable sprue system and providing gas outlet channels (vents) ensures a uniform flow of the melt and releases gas bubbles. The use of a chiller and a directional solidification guide in sensitive sections prevents the formation of a shrinkage cavity.
Control of raw materials and mold conditions:
Choosing mold sand with an appropriate refractory factor, precise control of the moisture content of the sand and mold coating, and its preheating prevent the accumulation of gases and the formation of gas bubbles. The use of degassers and compliance with all metallurgical requirements (correct alloying) are also effective in reducing the presence of impurities.
Inspection and Quality Control:
After pouring and cooling, technicians must examine the castings using non-destructive testing (NDT) methods such as X-ray radiography, ultrasonic, and dye penetrant methods to identify any internal or surface defects. Mechanical tests (hardness, tensile strength, and impact) in the quality control laboratory will also ensure that the parts comply with the technical specifications.
Selection of appropriate materials and coatings:
According to the application of the part in the mining environment, the appropriate alloy type and chemical composition are selected to provide the necessary cold workability and corrosion-wear resistance. The use of resistant coatings and appropriate heat treatment also helps to increase the integrity of the casting structure.
Expertise and capabilities of Sepahan Foolad Atashgah
History and infrastructure:
Sepahan Foolad Atashgah Casting Industries Company has more than 30 years of experience in casting steel and cast iron parts and, relying on research and development, uses the most advanced laboratory equipment and production lines.
Production Capacity:
The company has 7 melting furnaces with a simultaneous capacity of 20,000 kilograms of molten metal, located in an area of 25,000 square meters. Sepahan Foolad Atashgah’s total annual production capacity in the field of industrial castings is estimated at about 25,000 tons.
Mining Industry Coverage:
Focusing on the mining, steel, cement and copper industries, Sepahan Foolad Atashgah produces parts such as liner shells, shafts, blades and other casting items with high quality. The company’s cooperation with large domestic and foreign factories is proof of the quality of its products and compliance with global standards.
Quality Control and Standards:
This industrial unit has an integrated quality management system and each manufactured part undergoes precise tests before delivery. Quality assurance based on international standards and the use of expert personnel and equipped laboratories guarantees the reduction of defects and the provision of uniform and reliable parts.
Conclusion
Using the services of reputable and specialized companies in the field of casting, such as Sepahan Foolad Atashgah, guarantees the production of defect-free and high-quality parts. Professional suppliers with sufficient experience, advanced technical knowledge and strong laboratory facilities minimize the possibility of casting defects.
Using defect-free casting parts significantly reduces maintenance costs, reduces unwanted production line stops and increases the life of mining equipment. High-quality, healthy parts improve operating efficiency and increase operational productivity.
Sepahan Foolad Atashgah Company is ready to provide superior quality industrial casting services to the country’s mining industries by combining 30 years of expertise and high production capacity. To order quality casting parts and benefit from the capabilities of this complex, you can contact the sales department and Commercial Manager of this company.
