Sand casting, as an important casting production method, has been widely used in foundries. According to the external sand mold used in sand casting, it can be divided into three types: clay wet sand mold, clay dry sand mold, and chemical hardening sand mold according to the adhesive used in the molding sand and the method of establishing strength. But no matter which type of sand casting, it cannot do without the participation of casting molds. It can be said that without molds, there is no sand casting. Casting molds have a very important impact on sand casting, which can be roughly divided into three aspects: dimensional accuracy, surface finish, etc. This article will provide a detailed analysis on the casting order website.
1. Dimensional accuracy
Castings are made according to the mold, and the dimensional errors of the mold will be reflected on the casting without exception. Especially for some complex castings, due to the use of multiple molds (outer mold and core box), the cumulative error will seriously affect the dimensional accuracy of the castings. Taking the dimensional accuracy of a certain car cylinder block (4 cylinder) casting as an example, even if each set of tooling can achieve a dimensional accuracy of 99 points, the score at the box may only be 82.5 points. From this, it can be seen how important it is to pursue "zero error" in casting molds.
2. Surface finish
A smooth surface mold not only improves the moldability, thereby reducing mold (core) waste and increasing productivity, but also provides a smooth mold cavity (or sand core), which is conducive to obtaining a smooth casting.
3. Casting defects
Some casting defects may be caused by poor quality of the casting mold, such as the presence of material pouring and unevenness on the surface of the mold, which will lead to poor mold lift, damage to the surface of the mold, and even cause sand holes; Misalignment, extrusion, and sand holes caused by mold installation deviation or wear of positioning pins (sleeves); The arbitrary production or installation of the pouring system may cause the flow of metal slag to deviate from the process design requirements, which may result in defects such as porosity and shrinkage.
In casting production, the process mold equipment is an inseparable system, and good process design depends on the casting mold to reflect it.
Similarly, a poor process design may result in a well processed mold being scrapped due to the inability to produce qualified castings. The reasonable coordination of molds and equipment is equally important. Therefore, when determining the process plan and conducting process design, it is necessary to simultaneously prepare the mold and equipment, that is, to implement concurrent engineering. Because of this, some domestic enterprises not only introduce core making machines but also core boxes, and introduce complex molds (such as car cylinder bodies), which also include process design.
In modern society where innovation is increasingly becoming the main theme of economic development, the product update cycle is shortening day by day, and new products are emerging endlessly. This requires the manufacturing industry to adapt and develop rapidly. As the foundation of the manufacturing industry, the mold industry will inevitably develop accordingly. It can be said that launching high-quality and high-precision molds as soon as possible is one of the primary and key factors in seizing the market.
