Lost foam casting, invented by an American in 1956 and successfully applied in production, is hailed by the foundry industry as a 21st-century casting technology. Currently, production plants primarily employ two processes: one is dry sand negative pressure lost foam casting, abbreviated as LFC (Lost Foam Casting), suitable for mass production of small to medium-sized castings; the other is a method that embeds foam plastic into molding sand with a binder, making the sand firm, abbreviated as FMC (Full Mould Casting), suitable for the production of large castings, such as machine tool castings, heavy machinery castings, and automotive body mold castings.

When producing cast iron parts using the lost-mold casting process, the solid and liquid phase products from the vaporization and decomposition of foamed plastic accumulate on the casting surface, forming orange-peel-like carbonaceous defects and causing surface wrinkling defects. This is especially true for ductile iron parts, where the carbon content is saturated. Most of the pyrolytic carbon produced by the decomposition of foamed plastic cannot be absorbed by the molten iron, easily forming bright carbon (flaky carbon) inclusions and wrinkling defects, which often appear on the upper surface and upper side of the casting.

The main factors affecting the formation of wrinkles in cast iron parts include: the type of foam plastic, the composition of the casting material, the design of the gating system, the structure of the casting, the pouring temperature, the permeability of the coating layer and the molding sand. XINDA has conducted in-depth research on the impact of coating layer permeability on casting wrinkles and has developed a high-performance coating. To verify whether the coating's performance can meet the actual needs of customers, XINDA conducted pouring experiments in the customer's workshop. The experimental casting materials included FC300 and QT500-7, and the casting weight ranged from 1.2 to 2.4 tons. The results were good, proving that the coating can meet the needs of on-site production.

In the future, Xinda Company will continue its in-depth research on defect control in lost foam casting technology, focusing on the coating requirements of large and ultra-large castings as well as castings with complex structures. The company will further optimize coating formulations and production processes, and develop specialized coating products with higher permeability, stronger high-temperature resistance, and better collapsibility. Simultaneously, it will actively explore the integration of coating technology with intelligent casting production, using digital means to precisely control coating thickness and permeability, thereby achieving a stable improvement in casting quality.