What types of castings are suitable for the production of phenolic resin sand and furan resin sand?

1. Characteristics of Phenolic Resin Sand and Suitable Casting Range for Production

a. General Performance Index of Phenolic Resin Sand: Phenolic resin sand has good heat resistance and can generally be used for a long time below 200 ℃. Some modified phenolic resin sand can maintain its performance at higher temperatures. At high temperatures, phenolic resin produces high levels of residual carbon, which is beneficial for maintaining the structural stability of sand molds and enabling them to withstand the erosion and thermal stress of high-temperature molten metal during the casting process. The breathability of phenolic resin sand is influenced by various factors. When using high-density styling, its breathability is usually controlled between 100-140, which is more suitable. For small castings or situations with extremely high surface quality requirements and relatively low gas emission requirements, the permeability can be around 80-120; For large castings or castings with complex structures and high requirements for gas exhaust, it may be necessary to control the permeability at 120-180 or even higher. Compaction rate can reflect the dryness, wetness, and flowability of the molding sand. Generally speaking, when the ratio of compactness to moisture is between 10-12, it indicates that the dryness and wetness of phenolic resin sand are in a relatively good state. If the ratio is less than 10, the clay content of the molding sand is high and the toughness is poor; If the ratio is greater than 12, the mud content of the molding sand may be low, and the permeability may be high, which can easily cause sand sticking defects in the casting.

b. Phenolic resin sand is suitable for producing various types of castings, mainly including the following: steel castings, alloy steel castings, such as stainless steel impellers, axle box body locomotive parts, petroleum machinery parts, etc. Phenolic resin sand does not contain harmful elements such as nitrogen, sulfur, and phosphorus, which can prevent defects such as porosity and cracks in castings and effectively ensure the quality of alloy steel castings. High manganese steel castings: such as exporting high manganese steel castings, etc. The CO ₂ hardened alkaline phenolic resin sand has excellent process performance. When used in the production of high manganese steel castings, it can make the surface of the castings smooth, with fewer pores, and no cold cracking, hot cracking, or surface carbonization phenomena. Cast iron ductile iron crankshafts: such as large section ductile iron crankshafts for the 6160, 6200, WD615 series diesel engines. Self hardening alkaline phenolic resin sand can solve the problem of local spheroidization in the production of ductile iron crankshafts using self hardening furan resin sand. Nonferrous metal castings and cast aluminum parts: Some complex structured cast aluminum parts can also be produced using phenolic resin sand. In the industry, some enterprises have achieved good technical, economic, and environmental benefits by using ester hardened alkali phenolic resin sand technology to produce aluminum castings on the same production line. In addition, whether it is high-end complex cast steel parts produced in small batches, or cast iron parts, cast aluminum parts, etc. produced in batches, phenolic resin sand can play its advantages and is suitable for casting enterprises of different production scales and types. At the same time, in sand mold 3D printing technology, modified phenolic resin is widely used as a binder for the development of single piece samples of cast steel, cast iron, and non-ferrous metals, as well as the production of casting products with a large variety but small quantity. It has the characteristics of fast response speed, short cycle, and high flexibility.

2. Characteristics of furan resin sand and suitable casting range for production

a. Control range of furan resin sand related index: Heat resistance strength: Generally speaking, ordinary furan resin sand can be used for a long time in an environment of 120 ℃ -140 ℃. Some specially modified furan resins, such as XLZ furan resin, can withstand 180 ℃, and Huibo XLZ600 furan resin adhesive can still maintain high strength in an environment of 230 ℃. There are also furan resins such as sugar alcohol resins, which can withstand temperatures of 400 ℃ -500 ℃, and their carbonized materials can withstand temperatures greater than 2100 ℃. Breathability: When using high-density styling, breathability can refer to 100-140; If it is a regular styling process, the breathability is within the range of 300-500. The breathability of small castings can be between 300-400, while for large castings or castings with complex structures, the breathability may need to be controlled between 400-500 or even higher. Compaction rate: The compaction rate of furan resin sand is usually not strictly controlled within a fixed range, usually around 40% -60%. However, in actual production, adjustments need to be made based on factors such as the characteristics of the raw sand, the amount of resin and curing agent added, and the molding process. In addition, the tensile strength of furan resin sand 8-shaped blocks generally requires that the initial strength (1-hour tensile strength) should be controlled between 0.1MPa-0.4MPa, and the final strength (24-hour tensile strength) should be controlled between 0.6MPa-0.9MPa. The ideal temperature range for sand mixing is 20 ℃ -30 ℃, and the amount of curing agent added is generally 30% -60% of the resin mass.

b. Is furan resin sand suitable for producing various types of castings? Cast iron parts: such as ductile iron parts, gray iron parts, etc. Furan resin sand has good fluidity, can make the surface of castings smooth, high dimensional accuracy, and contains nitrogen, sulfur and other elements. It can meet the process requirements in the production of cast iron parts and has relatively low cost. Steel castings: For some steel castings that require high strength and accuracy, such as gears and shafts of large machinery, furan resin sand can provide good strength and dimensional accuracy while ensuring the formation of castings. However, due to the nitrogen and sulfur content in furan resin sand, defects such as porosity may occur in cast steel parts. It is generally recommended to use nitrogen free or low nitrogen furan resin (with a nitrogen content of less than 1.5%) to produce cast steel parts. Nonferrous metal castings: such as aluminum alloys, copper alloys, and other non-ferrous metal castings. Furan resin sand has good collapsibility and is easy to clean the core, which is beneficial for improving the surface and internal quality of non-ferrous metal castings. Complex structural components: The furan resin sand process can manufacture castings with complex shapes, such as automobile engine cylinder blocks, cylinder heads, and other parts with complex internal cavity structures. It can accurately replicate complex shapes to ensure the dimensional accuracy and surface quality of castings. Precision castings: In precision casting, furan resin sand can be used for shell casting or 3D printing sand molds, suitable for the production of precision instrument components, molds, etc. that require extremely high dimensional accuracy and surface roughness. Furan resin sand is suitable for both small batch production and large-scale assembly line production.