Casting is one of the earliest metal heat treatment processes mastered by humankind, with a history of approximately 6000 years. China entered its golden age of bronze casting around 1700-1000 BC, achieving a considerably high level of craftsmanship. Casting refers to the process of melting solid metal into a liquid state and pouring it into a mold of a specific shape, allowing it to solidify. Metals cast include copper, iron, aluminum, tin, and lead. Common mold materials include raw sand, clay, water glass, resin, and other auxiliary materials; this is commonly known as sand casting.

Sand casting refers to the casting method of producing castings in sand molds. Steel, iron, and most non-ferrous alloy castings can be obtained using sand casting. Because the molding materials used in sand casting are inexpensive and readily available, and mold making is simple, it is suitable for single-piece production, batch production, and mass production of castings, and has long been a fundamental process in casting production.

The basic raw materials for making sand molds are foundry sand and molding sand binders. The most commonly used foundry sand is silica sand. When the high-temperature performance of silica sand cannot meet the requirements, special sands such as zircon sand, chromite sand, and corundum sand are used. To ensure that the sand molds and cores have sufficient strength and do not deform or break during handling, assembly, and pouring of molten metal, molding sand binders are generally added during casting to bind the loose sand particles together. The most widely used molding sand binder is clay; various drying or semi-drying oils, water-soluble silicates or phosphates, and various synthetic resins can also be used. The external sand molds used in sand casting are classified into three types according to the binder used and the method of strength establishment: clay wet sand molds, clay dry sand molds, and chemically hardened sand molds.

Clay wet sand molds use clay and a suitable amount of water as the main binder for the molding sand. After the sand mold is made, it is directly assembled and poured while still wet. Chemically hardened sand molds use various synthetic resins and water glass as binders, undergoing molecular polymerization under the action of a curing agent to form a three-dimensional structure.

Furran resins refer to a general term for resins produced from furfuryl alcohol and furfural, which contain furan rings. They solidify into insoluble and infusible solids under the action of strong acids. Types include furfuryl alcohol resin, furfural resin, furfuryl ketone resin, and furfuryl ketone-formaldehyde resin.Furran resins are an important synthetic resin used in casting. Using furran resins as a binder in sand casting significantly improves the overall quality of castings. The addition of furran resins offers advantages such as improved dimensional accuracy, smoother surface finish, and clearer external contours.

Furran resins have good industrial value and are currently widely used in the metallurgical casting industry. They can be used for molding, such as in the production of many automotive parts, plumbing and sanitary ware, and tire molds, where furran resin sand molding processes have yielded good economic results.Furan resins possess outstanding corrosion resistance and heat resistance, and their raw materials are widely available, with a simple production process, attracting widespread attention. Furfural is the most basic raw material for manufacturing furan resins, derived from agricultural byproducts such as cottonseed hulls, rice hulls, corn cobs, and corn stalks.

The Influence of Furan Resin Technical Specifications on Castings

The most influential parameters of furan resins on castings are nitrogen content, viscosity, and moisture. Nitrogen content increases the gas evolution of molding sand, especially in steel castings, where nitrogen is more likely to cause defects such as subsurface porosity. Viscosity primarily affects the uniformity of resin mixing with sand, especially in winter when sand temperatures are low; poor fluidity easily leads to uneven sand mixing, causing localized defects in the casting. Excessive moisture causes slow molding sand solidification, poor hardness and penetration, low strength, and a hard outer layer with a soft interior, causing mold collapse. Furthermore, at high temperatures, moisture tends to remain in the molding sand, resulting in low hardness and high gas evolution.

Xinda Company specializes in the production of furan resins, with stable product technical specifications suitable for sand casting, helping enterprises produce qualified castings.