How to Use Deviation Analysis in Reverse Engineering
Over time, the actual use of a tool or part can outlive its documentation. Or, in production environments, a physical tool can be edited and adjusted to achieve required results. When it comes time to replace this customized part or tool, its print or CAD documentation no longer matches reality. So when a customer needs to accurately document or re-manufacture a legacy item of this kind, reverse engineering (RE) and geometry re-creation are essential.
Designing and Retrofitting
When a part is reverse engineered, designers work within the context of the larger system or device, because the new design must be flawlessly integrated. For example:
In advanced mechanical and aerospace industries, traditional reverse engineering in which only a CAD copy of the old component is developed is less effective than using a 3D model and performing deviation analysis as a final check. 3D re-engineering optimizes the component/sub-system design concerning new materials and the advanced manufacturing technologies often employed in such industries.
As part of an integrated re-engineering plan for the replacement of an aerospace component or sub-system, a 3D scan of the original part is often the first step. This provides a simple neutral model showing the exact surface characteristics around which the engineers must design. Then, using state-of-the-art 3-D modeling techniques, a re-engineered design can be tested in a virtual environment to ensure that it provides the solution required.
Sophisticated technicians can build design files for use in any modern software, and many legacy platforms. We prefer SolidWorks and Creo/Pro-E, and use those regularly for ongoing re-engineering projects with our aerospace clients, so we can speak to the accuracy and ease of re-engineering using those platforms.
Once the re-engineered design is complete, deviation analysis should be used as a final test.
By using Deviation Analysis (DA) as a final proof-of-work when a Reverse Engineering project is completed, the designer can be certain that the re-engineered part will perform as desired.
You may have heard Deviation Analysis being referred to as Comparative Analysis, Computer Aided Inspection (CAI), Computer Aided Verification (CAV), or Color Maps. We prefer the term Deviation Analysis (DA) because it most clearly and precisely describes the goal of the analysis: to detect any deviation between the scan data of a part and its CAD model or the scan data of another of the same part.
In DA, point-cloud data from the scan is overlaid on the CAD model or the other part’s scan data to reveal any deviation between the two. Besides first-article inspection and part-to-part comparison, DA is also used for rapid design verification and tooling validation.
Used in re-engineering, Deviation Analysis employs precise point-by-point comparison to show that the design created matches the newly designed physical part exactly as needed. This extra step enables design technicians to achieve a level of precision in verification that is almost impossible with manual methods.
We use and recommend deviation analysis as a crucial and cost-effective step in assuring the accuracy of any re-engineered model.