Wet sand casting
Wet sand casting uses recyclable sand and does not require any chemical additives to bind the sand. Instead, it relies only on sand, clay and water, with the water acting as a binder. Clay wet sand molding is the most economical molding method for most metal materials and mass production. Foundries equipped with the latest technology control devices should gradually achieve the best performance repeatedly using wet sand control technology. These control devices include screening and separation of metals, cooling of recycled sand, accurate release of additives when mixing recycled sand, etc.
In wet sand molding, vertical parting and horizontal parting are compared. For foundries that mass produce medium and small, gray iron or ductile iron parts, vertical parting molding is advantageous because of its advantages such as relatively cheap equipment cost, high-speed molding, less personnel required, and small deviation in compactness. However, the vertical parting process is limited in terms of gate scheme and shape, as well as the use of complex cores, filters, chills, sleeves, and pounding cores.
In addition, when casting with alloys with good fluidity, metal penetration and sand sticking are easily caused due to the relatively high static pressure of the metal.
The selection of wet sand molding method requires the following points to be considered:
◆ There must be molding equipment that can mold high-quality castings with uniform hardness.
◆ The template can be quickly replaced.
◆ The loading and unloading of the core and mold are mechanized.
Horizontal parting and vertical parting
The main process starts with the use of a three-dimensional model of the part. Then the mold is made with sand, and the molten metal is poured into the mold to cast the part. The way the mold is made depends on the equipment, as two common processes are horizontal parting and vertical parting.
Horizontal parting sand casting
Horizontal parting sand casting has a lower mold (the bottom of the mold) and an upper mold (the top of the mold). Sand is poured into the lower mold to form a three-dimensional model. The upper mold is also made using a similar independent process. After the sand molds are bonded, the pattern is removed from the upper and lower molds. The upper and lower molds are then locked together. Molten metal is poured into the sand mold through a gating system.
Horizontal-parted sand casting is simply how the upper and lower molds are made and connected. In this process, the upper and lower molds are filled with sand separately, and then the upper mold is placed on top of the lower mold to form the final casting. Horizontal-parted sand casting is ideal for small batch castings. It is economical because the model molds are simple to make. Many industries have benefited from this traditional process, and its common applications include manufacturing transmissions, pumps, and automotive engine blocks.
Vertical-parted sand casting
Vertical-parted sand casting requires the plates to be placed on the sides instead of the top and bottom. One plate is considered a pressure plate and the other is a swing plate because they will both form half of the part model.
The mold plates are placed together and sand is poured in from the top. The pressure plate and swing plate press against each other to compress the sand into half of the desired mold shape. After the sand is bonded together, the swing plate moves away and swings upward to remove the partial mold.
The partial mold moves down the line while the next partial mold is made. The first and second molds are brought together to form a cavity into which the molten metal is poured.
Vertically parted sand casting can be used for mass production. It can produce a variety of applications, including pipe fittings, exhaust manifolds and brake discs.
In the manufacture of non-ferrous alloy castings, vertical parting molding methods have been designed for mass production of various characteristics of such alloy castings and are now being promoted. However, before castings with the required mechanical properties can reach a considerable degree of mass production with this molding method, metal mold casting still has an advantage as a method for mass production of aluminum alloy castings.
Horizontally parted wet sand casting is still one of the favorable molding methods for medium and small batch foundries. Whether it is the upper mold, lower mold method, or the double-sided template method, it is adaptable to the production of complex castings. The mold can be changed within a cycle, and short-term and long-term operations can be effectively produced. However, manual operation needs to be mechanized, and in order to ensure the production of castings with good surface and high dimensional accuracy, the entire set of equipment needs to be modified.