What is Reverse Engineering?
"Reverse Engineering is the process of taking a finished product and reconstructing design data in a format from which new parts or molds can be produced."
-The Society of Manufacturing Engineers (SME)
Reverse Engineering (RE) is also defined by the Military Handbook MIL-HDBK-115 (ME) as "…the process of duplicating an item functionally and dimensionally by physically examining and measuring existing parts to develop the technical data (physical and material characteristics) required for competitive procurement."
The most common applications for reverse engineering are:
- Original equipment manufacturer (OEM) unable or unwilling to provide replacement parts
- Prototypes with no models/drawings
- Worn or broken components for which there is no source of supply
- For base model geometry to edit and tailor for improved functionality or new application
In general, our reverse engineering process goes as such:
I. Define Scope of Work
General information is acquired for the customer and then key characteristics are identified.
II. Obtain Dimensional Data
Utilizing our dimensional labís metrology equipment (see
equipment list) and experienced personnel. We obtain all of the relative dimensional data necessary for the creation of an exact CAD replica of the component. If geometry is complex, digitizing or scanning (see
capabilities) may need to be employed.
III. Analyze Data
The dimensional data obtained is recorded, compiled and nominal values are formulated. Fit, function, manufacturing processes, industry standards and customer specifications are factored when setting the CAD model values. To view a PDF version of the sample report, please click here.
IV. Creation of the CAD Model/Drawing
A 3-D model is generated using one of our customer compatible CAD packages. The defined nominal values are used and if digitized or scanned point clouds were necessary, a "best-fit" line, arc or spline is used to generate complex geometry or NURBS surfaces. Additionally "best practices" are utilized when creating models along with the customers' corporate standards when applicable.
Some customers require 2-D drawings of the component. We obtain and use their CAD templates with title block information and any other corporate standards are used where necessary. If a template or title block is not available we use a generic format and follow ANSI Y14 drafting standards and employ best practices in both cases.
V. Ensuring Quality
In addition to checking the dimensional data to the model/drawing, optional verification methods may be employed. Especially on parts containing complex, free flowing surfaces, that are difficult to fully capture on a CMM, and so "best fit" methods are used in the modeling process.
To verify the CAD surfaces the physical part can be partially or fully scanned using our scanning equipment. By comparing the point cloud data with the CAD model, a comparative analysis can be performed generating a report with a color map. The report highlights any deviations and there values from the referenced CAD model to the artifact. If any issues are identified the CAD model can be adjusted and the comparison repeated until even very complex surfaces are modeled accurately.
An alternative approach is:
Point Cloud to NURBS - Reverse Engineering
In addition to using our 3d scanning services and methods to verify difficult surfaces and perform standard dimensional inspection, for some jobs the entire reverse engineering process may be done using scanned 3-D surfaces. Applications include molded or cast objects with slightly less stringent tolerances than most machine parts.
The process here is a little more straightforward than with CMM based reverse engineering. Using our
3d scanning services, the object is scanned with full 3D coverage using our scanning equipment. Separate partial scans are aligned and merged into a single surface made of thousands or millions of triangles in a large mesh. In some cases, parts of the surface are obscured from the scanner and must be filled in manually. Other work is done to enhance features such as sharp edges that may be softened in the scan process. Once the polygon surface is watertight and cleaned up a NURBS surface is generated. NURBS surfaces can be modified in limited fashion by 3-D CAD packages or can be exported directly to IGES or other formats for machining or molding.
QC Inspection is a leader in reverse engineering services and 3d scanning services