Lost foam casting has become a pivotal technique in modern foundry operations due to its exceptional flexibility and precision. Yet, beneath the seemingly straightforward act of pouring lies profound technological expertise and extensive accumulated experience. From the precise selection of process configurations to the rigorous control of production details, each stage conceals intricate knowledge. Drawing upon practical experience, this article systematically dissects the core process elements and operational techniques of lost foam casting, providing industry practitioners with a practical reference.

Within the production workshops of lost foam casting, all eyes are often fixed upon the intricate foam models, precision sand boxes, or the torrent of molten metal surging at high temperatures. Yet, there exists a seemingly unassuming material that acts as an “invisible guardian”, permeating the entire process and determining the quality, cost, and efficiency of every casting – the lost foam coating.

As a typical thick-walled, large-scale, regular-shaped casting, engine flywheels must simultaneously meet multiple technical requirements during lost foam casting, including material density, dimensional accuracy, and dynamic balancing performance. The production process is influenced by numerous factors such as the quality of the white model formation, coating properties, gating system design, and dry sand filling, making it highly susceptible to various casting defects. This article systematically addresses key issues based on practical production experience and industry technological advancements, proposing practical solutions.

High manganese steel is widely used in the manufacture of wear-resistant castings in mining, metallurgy, construction machinery and other fields due to its excellent wear resistance, impact resistance and toughness. However, in the traditional casting process of high manganese steel castings, problems such as dimensional deviation, rough surface and internal defects often occur, which are difficult to meet the production requirements of high-quality castings. As a near-net-shape technology, the lost foam casting (LFC) process can effectively overcome the above defects and significantly improve the dimensional accuracy and surface quality of castings. It can adapt to the needs of different complex structures and production scales, providing a reliable technical approach for the high-quality manufacturing of high manganese steel castings.

The lost foam casting process is a highly efficient method for producing complex metal parts with excellent surface finish and dimensional accuracy. To establish a successful lost foam production line, careful consideration must be given to the layout and selection of equipment. This article outlines the steps involved in designing a lost foam production line, using the example of a transmission housing with an annual output of 5000 tons.

This paper systematically elaborates on the complete process scheme for manufacturing CNC machine tool bases using the lost foam casting method. As the core load-bearing component of CNC machine tools, the base must possess high shock absorption, pressure resistance, dimensional stability, and corrosion resistance. Gray cast iron HT300 is selected as the casting material (its mechanical properties are superior to the commonly used HT150 and HT250, making it more suitable for the load requirements of the base).

In the lost foam casting process, cold shut (also known as misrun) manifests as incompletely fused seams on the castings, with the joining edges appearing smooth and interlocked. When the seam surface exhibits obvious signs of misrun and the severity of the defect increases, it develops into an overlap. Incomplete pouring is characterized by partially unfilled sections of the casting, resulting in missing material, with the unfilled areas ending in a rounded shape (see Figure 13: Incomplete Pouring).

Sand adherence is a common defect in the lost foam casting process, specifically manifested as difficult-to-clean molding sand adhering to part or all of the surface of the casting. This defect not only affects the appearance quality of the casting but may also hinder subsequent processing procedures and even weaken the mechanical properties of the casting to a certain extent.

In the lost foam casting process, if the gases produced by the decomposition of the model cannot be discharged in time, they may enter the casting and form gas holes. The following explains the causes of gas holes and the corresponding preventive measures from two aspects: