What is the method to solve the shrinkage defects of castings?

(1) In the thick and hot spots formed by the machine tool casting structure, rapid solidification is implemented, artificially causing the basic balance of the temperature field throughout the machine tool casting. Use internal and external cold iron, and locally use zircon sand, chromite sand or special coatings with large heat storage.

(2) Reasonable process design. Inner runners are located at the opposite wall of the machine tool castings, which are numerous and scattered for several hours. The molten metal that enters the thick wall early is solidified first, and the thin wall solidifies later, so that all parts of the molten metal are basically solidified in equilibrium. For machine tool castings with uniform wall thickness, multiple internal runners and air vents are used. There are many inner runners, scattered and evenly distributed, so that the overall heat is balanced. The vent holes are thin and many, that is, the exhaust is smooth and heat dissipation.

(3) Change the position of the inner runner

(4) The use of modeling materials with large heat storage is important for the production of anti-wear products with lost foam! Chromite sand can replace other sand species with low heat storage such as quartz sand, and it will achieve good results.

(5) Low-temperature fast burning, open pouring system. Make the molten metal fill the mold quickly, smoothly and evenly. This depends on individual conditions.

(6) Nodular iron machine tool has high mold strength, surface hardness ≧90, and sand box rigidity, which is beneficial to eliminate shrinkage porosity.

(7) When the riser is needed, move the hot riser for the first time and leave the hot festival. If the riser is placed on the hot section, the size of the riser will be increased, resulting in "heating on the heat". If it is not done properly, not only the shrinkage porosity is difficult to remove, but also concentrated shrinkage cavities will be produced, which reduces the process yield.

(8) Tilt placement and alloying of molds benefit. Eliminating shrinkage defects of machine tool castings is a complicated process of understanding and implementation. Based on the basic principle of "heat balance", scientific analysis should be done on ju body castings, a reasonable process plan should be formulated, suitable modeling materials, tooling and correct operation and standardization should be selected. Then any shrinkage defects of machine tool castings can be solved.