复合井盖外部加工方法，最大的优点是可以利用芯子。例如发动机缸体勿论是铸铁还是铸铝都是外部加工方法所无法代替的，如果用外部加工方法加工一个缸体可能需一台汽车的价格。其次是再利用性。

地球的资源已经使用了50%以上，今后再利用加重要性将日益增大。由于循环再利用过程，金属基质被污染是再利用的最大问题。而复合井盖法与塑性加工法比较由于对不纯物的容许量大，今后对复合井盖法将有更高的评价。再次是复合井盖适宜于制造大件制品。比如重达369吨的轧机牌坊，复合井盖以外是难制成的。

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.