Overview of Cored Wire Feeding Treatment Process
The cored wire feeding treatment for spheroidization (compacted graphite treatment, inoculation) is an advanced casting treatment process. Its core involves wrapping specific composition and particle-sized core materials within a steel strip of specified thickness and width using a wire-winding device, producing a cable-like cored wire coil with appropriate strength and high filling rate. Subsequently, with a dedicated feeding machine, the cored wire is fed into the molten iron in the treatment ladle at a preset speed, thereby achieving spheroidization, compacted graphite treatment, or inoculation of the iron.
Core Material Preparation Methods and Their Characteristics
The core material is the key functional component of the cored wire. Currently, there are three main preparation methods:
The Fusion Method involves smelting, casting, crushing, and sieving the raw materials of the spheroidization formula into granules. Its advantage lies in its uniform composition, with magnesium and silicon existing in the form of a magnesium-silicon master alloy, which has a higher melting point than pure magnesium, leading to more stable absorption during treatment and consistent spheroidization results. Therefore, it is widely used in the production of high-end ductile iron castings. However, due to the high magnesium content, the production process carries significant safety risks requiring special protective measures. Additionally, energy consumption and costs are higher, and the resulting spheroidizing agent has a relatively high magnesium oxide (MgO) content.
The Mechanical Mixing Method uses specialized equipment to physically mix raw materials such as passivated magnesium, rare earth elements, and ferrosilicon according to predetermined particle sizes and proportions. This method eliminates the smelting process, resulting in no burning loss of core material, lower cost, and less magnesium oxide. The drawback is the significant density difference among components, making uniform mixing difficult. This leads to fluctuations in the weight and composition of the core material per unit length of the wire, posing challenges for stable quality control of castings.
The Layered Method employs multi-component layered distribution technology, sequentially filling different core material components into the steel strip in layers before coiling into wire. It shares similar advantages with the mechanical mixing method, such as no fusion process, lower cost, and less magnesium oxide. However, the uniformity of distribution of each component along the length of the cored wire still requires further verification through long-term practice.
Impact of Cored Wire Technical Indicators on Casting Quality
The technical indicators and performance of the cored wire directly affect the final casting quality. The chemical composition of the core material is the fundamental guarantee, where the content of magnesium and rare earth elements needs to be stable with minimal fluctuation. Wuxi Weida Cored Wire Co., Ltd. can customize the ratio according to customer requirements and control deviations.
The particle size of the core material is typically controlled within the range of 0.1 to 2.5 mm, with the proportion outside this range being less than 5%. The core material must be dry, with a moisture content ≤ 0.3%. For spheroidizing wire core material, the magnesium oxide content should not exceed 5.0% of the total magnesium content. Excessive levels can lead to increased slag inclusions, decreased spheroidization grade, and higher costs.
The cored wire's appearance should be free of underfilled wraps, seams, ruptures, leakage, rust, and oil stains, with the core material filled uniformly. This helps reduce slag inclusions and improve the stability and consistency of the treatment effect. The steel strip used must comply with relevant national standards, with a tensile strength of not less than 275 MPa and an elongation of not less than 37%. Product packaging needs to be moisture-proof and rust-proof.
Common Issues in Wire Feeding Process and Countermeasures
In the application of the wire feeding process, the reasonable selection of the feeding method is crucial. Vertical or inclined feeding allows the cored wire to enter vertically near the center of the molten iron, is less sensitive to speed variations, and occupies less space, making it generally recommended. The wire feeding workstation should be as close as possible to the pouring station to shorten molten iron transfer time and prevent spheroidization and inoculation fade.
The dust removal system design must consider its impact on molten iron temperature drop. It is recommended to locate the dust extraction port on the side upper part or top of the feeding room. This helps suppress the magnesium vapor generated by the reaction onto the molten iron surface, which can isolate air, improve magnesium absorption rate, and reduce temperature drop. If the extraction port is on the ladle cover, the air volume, pressure, and speed need to be precisely adjusted according to operating conditions.
To prevent wire breakage faults, attention should be paid to: confirming the coiling/feeding method (currently mainly internal-pull type) before threading; checking the cored wire for cracks, powder leakage, uneven weight per meter, or empty sections; ensuring the welded joint between two wire coils is strong; placing the wire coil as close as possible to the feeder to reduce feeding angle and resistance; possibly adding guide devices; and designing auxiliary components at the feeder inlet to eliminate spiral bending of the wire.

To address wire blockage issues, it is essential to ensure the feeder outlet guide tube and the lower guide tube are aligned and the distance is minimized; improve the verticality of the cored wire entering the treatment ladle to avoid touching the ladle wall; a positioning mechanism can be set at the bottom of the treatment ladle; adjust the feeding speed based on residual magnesium levels to prevent touching the bottom; and regularly clean accumulated slag inside the guide tubes and ladle cover.
Measures to reduce temperature drop during treatment include: adding insulation materials and ensuring sufficient ladle wall thickness during ladle lining construction; promptly applying exothermic covering agent after tapping and covering for insulation; fully preheating or 'heating' the treatment ladle before use; avoiding the use of roller conveyors for long-distance molten iron transfer, and not locating the dust suction port on the ladle cover in such cases.
Ladle cover design must consider durability. It is recommended to use steel plates with a thickness of not less than 10 mm and refractory material with a thickness of not less than 100 mm. The inner cavity dimensions of the cover should match the treatment ladle, with a recommended inner cavity height of not less than 400 mm. The inner wall should be coated with graphite paint before use, and daily cleaning and maintenance should be strengthened.
To ensure stable residual magnesium content, reliable feeding machines should be selected and the speed calibrated regularly; fine-tune the feeding length based on the analysis results of each batch of raw material composition; strictly control process parameters such as preheating temperature, tapping temperature, treatment temperature, and pouring time; and determine a reasonable feeding speed.
The aspect ratio (height of molten iron to ladle inner diameter) inside the treatment ladle is ideally between 1.1 and 1.2. If too high, the feeding speed must be increased, potentially causing violent reaction and increased magnesium burning loss; if too low, the feeding speed is slow, and the reaction concentrates on the upper-middle part of the molten iron, also reducing magnesium absorption rate.
In workshops employing multiple processes, it is advisable to store returns separately. For example, returns generated from the wire feeding process have a greater shrinkage tendency and possess heredity, so they should be managed separately and their influence assessed.
For the production of large castings, in addition to the common issues mentioned above, the following measures can be taken: using multiple cored wires simultaneously based on the amount of molten iron; strengthening rapid online metallographic and composition testing after treatment to allow for remedial wire feeding if necessary; in core material composition design, besides magnesium, strategically adjust rare earth content and consider adding elements like calcium, barium, or antimony to address issues arising from large wall thickness and long solidification time; simultaneously enhance inoculation treatment, such as using methods like stream inoculation, inoculant blocks in pouring cups, or in-mold inoculation.
Introduction to Wuxi Weida Cored Wire Co., Ltd. Products
Wuxi Weida Cored Wire Co., Ltd. is committed to the research, development, and production of high-quality spheroidizing, inoculating, and compacted graphite treatment cored wires. The company's products feature uniformly stable chemical composition of the core material, precise particle size control, high wire compactness, and minimal weight error per meter, ensuring consistency and reliability of the treatment effect. Its products facilitate intelligent wire feeding operation and enable effective control of smoke and dust, significantly improving the production environment. They can meet the stringent quality requirements for cored wires in high-end castings.
The company utilizes advanced fully automated cored wire production lines, offering a variety of specifications and grades of series products. Core material composition can also be customized according to customer requirements. Furthermore, Wuxi Weida Cored Wire Co., Ltd. can supply matching wire feeding workstations, providing a complete solution for spheroidization, inoculation, and compacted graphite treatment of various castings.