By comparing the energy consumption per unit casting of traditional pattern modeling and compound forming method (before optimization), it is found that the compound forming method can reduce the energy consumption by about 3.86% under the production conditions of A1B1 and A1B1, and about 1.16% under the production conditions of A1B1 and A1B1. The reduction of energy consumption at this time is mainly due to the reduction of molten iron smelting energy consumption per unit casting caused by different production conditions and casting process parameters. Compared with the optimized composite forming method, the total energy consumption is reduced by 5.26% and 5.90% respectively, specifically 2.2572e + 07j and 2.3593e + 08j. At this time, part of the energy consumption reduction is to reduce the machining allowance of the casting and reduce the hot metal smelting energy consumption per unit casting. The other part is to shorten the mold forming time and reduce the energy consumption of casting auxiliary equipment. In addition, it can be seen from the figure that under the two production conditions, the energy consumption of sand mold NC milling is increased to a certain extent compared with the traditional pattern modeling, because the energy consumption of wood mold manufacturing equipment is shared equally by multiple castings, and there is additional energy consumption of milling machine and sand discharge equipment compared with the traditional pattern modeling. Sand mold 3D printing reduces the number of casting auxiliary equipment due to the simplification of casting process, that is, the energy consumption carrier is reduced, and the energy consumption is the lowest under the joint action of low hot metal smelting energy consumption.

In terms of energy efficiency ratio, it can be seen from Figure 1 that the ranking according to casting methods basically shows an upward trend. Among them, the energy efficiency ratio of sand mold 3D printing is the highest, which is the result of the lowest energy consumption in the casting process and nearly 90% production efficiency. Secondly, the production efficiency of the optimized composite forming method under A1B1 production conditions reaches 93.21%, and the production time per unit casting is shortened to 10.123h, which further reduces the worker time in the casting process compared with the traditional pattern modeling. Compared with the traditional shape, its energy efficiency ratio has been significantly improved under the two production conditions, which are 189% and 166.07% respectively. In addition, although the energy efficiency ratio of sand mold 3D printing is higher than that of composite forming method, the unit casting time of composite forming method is about 8.149h less than that of composite forming method in single piece and small batch casting production, which has obvious production advantages.

In conclusion, compared with the traditional pattern molding, the composite mold process optimization design scheme described in this paper can effectively reduce energy consumption in casting production, and has an energy efficiency ratio close to that of sand mold 3D printing. At the same time, the unit casting production time in mass casting production reaches the level of traditional pattern molding (based on the completion of pattern manufacturing), It has full applicability in mass casting production.