What is a sub-assembly in engineering design?

A sub-assembly in engineering design refers to a group of two or more parts that are assembled together as a functional unit before being integrated into a larger assembly or system. This process can streamline the overall assembly by allowing engineers to focus on smaller groups of components, ensuring that each sub-assembly meets specific design and performance criteria. Once the sub-assembly is complete, it can be combined with other sub-assemblies or parts to form the final product.

The choice highlighting that parts are assembled and then combined with others accurately reflects this concept. It shows the process of building complexity step-by-step, which is a common practice in engineering to improve efficiency and quality control. Sub-assemblies are crucial in large manufacturing processes where different teams may work on different components simultaneously before they are brought together in the final assembly stage.