Re-Engineering Implies Slight changes, Modifications and renovations to total overhaul. This enhances reliability and maintainability or to meet the newly evolving needs of the product users.
Thus, product reengineering may be redefined as the examination, study, capture, and modification of the internal mechanisms or functionality of an existing system or product in order to reconstitute it in a new form and with new features, often to take advantage of newly emerged technologies, but without major change to the inherent functionality and purpose of the system.
This definition indicates that product reengineering is basically structural reengineering with, at most, minor changes in purpose and functionality of the product. This reengineered product could be integrated with other products having rather different functionality than was the case in the initial deployment.
In the following examole, the External Casing was available. The Re-Engineering was to design a Drill Gun for the same casing to avoid Tool Cost using the armature from Angle Grinder and design new Die Cast Part for Front Cover, Jaws for holding the Drill Bit.