Reverse engineering is the opposite of forward engineering.
It takes an existing product, and creates a CAD model, for modification or reproduction to the design aspect of the product.
Reverse engineering is usually undertaken in order to redesign the system for better maintainability or to produce a copy of a system without access to the design from which it was originally produced.
Reverse engineering can be viewed as the process of analyzing a system to:
Identify the system's components and their interrelationships
Create representations of the system in another form or a higher level of abstraction
Create the physical representation of that system
Reverse engineering enables the duplication of an existing part by capturing the component's physical dimensions, features, and material properties.
Before attempting reverse engineering, a well-planned life-cycle analysis and cost/benefit analysis should be conducted to justify the reverse engineering projects.
Reverse engineering is typically cost effective only if the items to be reverse engineered reflect a high investment or will be reproduced in large quantities.
Reverse engineering of a part may be attempted even if it is not cost effective, if the part is absolutely required and is mission-critical to a system
Reverse engineering of mechanical parts involves acquiring three-dimensional position data in the point cloud using laser scanners or computed tomography (CT). Representing geometry of the part in terms of surface points is the first step in creating parametric surface patches. A good polymesh is created from the point cloud using reverse engineering software. The cleaned-up polymesh, NURBS (Non-uniform rational B-spline) curves, or NURBS surfaces are exported to CAD packages for further refinement, analysis, and generation of cutter tool paths for CAM. Finally, the CAM produces the physical part.