SAND CASTING EQUIPMENT.

Shrinkage and shrinkage so that the effective area of the castings under stress is reduced, and in the hole area is easy to produce stress concentration, so that the mechanical properties of the castings decline. Shrinkage and shrinkage also makes the casting of airtightness, physical properties and chemical properties decline. When the shrinkage and shrinkage is serious, the casting has to be scrapped. Therefore, the production to take the necessary process measures to prevent.

xinyuanzhu group through a number of experiments to prevent castings from shrinkage of the fundamental measures is the use of directional solidification. The so-called directional solidification, even if the casting according to the specified direction from one part to another part of the gradual solidification process. According to the order of directional solidification, the shrinkage of the first solidification part is supplemented by the molten metal of the later solidification part; the shrinkage of the later solidification part is supplemented by the metal liquid of the riser or pouring system, so that the shrinkage of each part of the casting can be supplemented, and the shrinkage is transferred to the excess part of the casting riser or pouring system.

The riser is the cavity in the casting mold stored for molten metal for shrinkage replenishment castings, also refers to the cavity filled with metal. In addition to shrinkage, sometimes also play the role of exhaust, slag collection. After solidification to remove the excess part can be obtained without shrinkage of dense castings.
Measures to achieve directional solidification is in the casting may appear shrinkage of the thick part (hot section) to place the riser, or in the casting away from the part of the pouring cold iron, etc.

Cold iron is to increase the local cooling rate of the casting, the sand, sand core surface or cavity placed in the metal objects. The casting shown in the figure may produce shrinkage holes in most of the thick more than one, if only by the top of the riser, it is difficult to the bottom of the tab to make up for the shrinkage, if the tab of the type wall placed on the two outside cold iron, speed up the cooling rate of the place, so that the thick-walled tab instead of the first solidification, so as to achieve a bottom-up directional solidification.

Directional solidification and layer-by-layer solidification are two different concepts. Directional solidification refers to the order of solidification of each part of the casting; layer by layer solidification refers to the order of solidification on a certain section of the casting. Layer by layer solidification of the alloy surface first solidification, and then gradually thicken to the center of the casting, the center of the casting last solidification. The complementary shrinkage channel of the riser can be kept open for a long time, which is conducive to the realization of the directional solidification of the casting. For pure metal, eutectic composition of the alloy, the process generally uses the principle of directional solidification, to improve the denseness of the casting.

On the contrary, the tendency to paste solidification of the alloy, crystallization of the solid skeleton is better to cover the entire cross-section of the casting, so that the plugging of the riser complementary shrinkage channel, it is difficult to achieve directional solidification.

Xinyuanzhu Group specializes in the production of Ductile iron castings, Pig iron gray iron casting, Steel casting, Brass Casting, Malleable Iron Casting, and undertakes batch casting processing of castings. Welcome guests to cooperate with pictures or samples.