Dalian castings can be made into blanks with complex shapes, especially with complex cavities, such as boxes, cylinder blocks, etc. Wide range of application. Casting can directly utilize low-cost waste parts and chips, and the equipment cost is low. The size and quality of castings are almost unlimited. The shape and size of the casting are very close to the parts, thus reducing the workload of machining and saving a lot of metal materials.
The disadvantages are that there are many production processes, the process is difficult to control, and the casting is easy to produce defects. The castings have poor dimensional uniformity and low dimensional accuracy. Compared with forgings with the same shape and size, the internal quality of infrared carbon sulfur instrument castings is poor and the bearing capacity is less than that of forgings. Poor working environment, high temperature, much dust and high labor intensity.
After finishing the outer contour of the casting, there shall be no casting defects such as air holes. The sand (slag) holes are unevenly distributed small cavities on the casting surface, which are usually irregular, of different depths, and the interior is not bright and clean, without cold mouth. It is mainly because the molten iron is not clean, the slag is mixed during pouring, and the sand is shoveled when the slag filter is lowered.
Small residual sand particles in the mold rush into the mold cavity with molten iron. During mold closing, sand particles fall off due to extrusion between molds or between molds and sand cores. Poor performance of casting sand (e.g. low moisture and low strength) is easy to cause sand washing if water is injected too quickly in the scheme design. The main reason is that the sand in the mold cavity is not clear. Sand particles are intruded from open places such as sprue or riser before pouring. The sand mold is not strong enough and falls off due to external force. 4: The casting is discontinuous or the casting speed is too slow, so the sand particles in the mold cavity can not float to the riser smoothly, but stay in the place with low temperature.
A layer of oxide skin formed on the outer surface of steel castings, commonly known as black skin. It can be removed by sand blasting or machining, and the inconvenient parts can be removed by acid pickling. After this layer of oxide skin is provided, it may fall off and become ugly. It is not easy to take anti-corrosion measures such as paint plating. If it is immersed in the liquid, impurities will appear in the liquid. It should be said that there are not many positive effects.
