復合井蓋外部加工方法，最大的優點是可以利用芯子。例如發動機缸體勿論是鑄鐵還是鑄鋁都是外部加工方法所無法代替的，如果用外部加工方法加工一個缸體可能需一臺汽車的價格。其次是再利用性。

地球的資源已經使用了50%以上，今后再利用加重要性將日益增大。由于循環再利用過程，金屬基質被污染是再利用的最大問題。而復合井蓋法與塑性加工法比較由于對不純物的容許量大，今后對復合井蓋法將有更高的評價。再次是復合井蓋適宜于制造大件制品。比如重達369噸的軋機牌坊，復合井蓋以外是難制成的。

Composite covers external processing methods, the biggest advantage is that you can take advantage of the core. Such as the engine block is cast iron or cast aluminum or not all external processing methods can not be replaced, if the processing of a cylinder with an external processing methods may require a car's price. Followed by the re-utilization.

The earth's resources has spent more than 50%, plus the importance of recycling in the future will be increasing. Since the recycling process, the metal substrate is contaminated is the biggest problem of recycling. The complex covers law and plastic processing method comparison due to the large amount of impurities allowed in the future for composite covers law will have a higher rating. Once again, suitable for the manufacture of composite covers large products. For example, weighs 369 tons of mill arch, outside composite covers are made difficult.