A base is an important part of 430 vertical milling machine of a machine tool Co., Ltd. It is made of HT300 and weighs 1200kg. The surface quality and casting size are strict. During machining, the two track surfaces are required to be free of any casting defects. Our company uses furan resin sand molding process to produce this casting. It is found that the scrap rate of this casting is high in production. Therefore, we reduce the scrap rate through process improvement and provide customers with satisfactory castings.
The shape of the casting is complex and the overall dimension is (long) × wide × Height) 1612mm × 1165mm × 425mm, which puts forward higher requirements for the modeling process. The appearance of the casting is shown in Figure 1.
The casting adopts wood pattern, furan resin sand modeling, and molten iron is melted in medium frequency induction furnace.
According to the statistics of the waste products of the product in 2020, 130 pieces were produced and 14 pieces were discarded, with a scrap rate of 10.7%. It can be seen that deformation defects account for 50% of the waste products, so deformation defects are the main quality problem of the casting.
In actual production, it is found that for bed castings, due to their complex shape and uneven wall thickness, their own strength should be considered when making casting models to ensure that the quality of castings will not be affected in production; When setting up the gating system, the stress generated in the cooling process should be considered to prevent stress concentration; The chemical composition of gray iron castings should be strictly controlled to ensure that they meet the required performance.