Nov 2 2007
In general, thinking in engineering is carried out conceptually, the concepts being processed in the computer virtually and, in the end, the object or the part is obtained. In the case of inverse engineering, however, the path to be followed is exactly the reverse: the object or the part that physically exists ends up transformed into something virtual. This is exactly what they do in the Product Design Laboratory (PDL) at the Higher School of Engineering in Bilbao.
More than one could be tempted to think that inverse engineering is merely copying. Nothing further from the truth. Inverse engineering can be employed when there are no digital models or, even when they exist, there is a wish to enhance them. A fact to be considered, moreover, is that 80 % of engineering parts are only found in CAD format (one that is only useable with a computer), as they are quite out-dated.
We can also imagine a fire breaking out in a company and all the plans going up in smoke. All the machinery, parts and tools of the company have to be recovered no matter what. In these cases, inverse engineering turns out to be highly useful. How is the process carried out" By scanning the part.
State-of-the-art scanner
At the University of the Basque Country (UPV-EHU) laboratory there is scanner which is the latest thing in advanced technology. It is a mobile scanner, i.e. one that is able to scan any type of part from any angle, given that the scanner is moveable by hand. Moreover, the size of the objects to be scanned is not a problem, as these larger items can be scanned in sections. The scanner only has one limitation: the scanner must respect the overall shape. To this end, certain references are added to the part for digitalisation, in order that a system of references for the object is established. This scanner uses laser technology for the surface digitalisation of the object. While the laser rays move over the surface of the object, the scanner gathers and interprets the co-ordinates of the points on the part. It is capable of reading 18,000 points per second. Thus, in a question of seconds, the complete reading of the surface of objects can be undertaken. The set of points gathered during a scan is visualised on a computer screen.
The scanner uses a software programme for processing the points gathered and completing the set of points. Using this software the precision of the sets of points and certain other characteristics may be modified. Likewise, distortions or unnecessary points that the overall set of original points might have can be eliminated.
To edit the overall set of points obtained, Geomagic software is employed. This programme corrects holes or slight imperfections that the set might have. It also helps to modify or enhance the model: correcting imperfections that the original object might have and even adding certain elements, etc.
A ‘3D’ photocopier
Once the model is completed it is exported in CAD format to a rapid prototype machine. This machine makes plastic prototypes, obtaining the part layer by layer. Two types of material are used for this: one is used solely in the construction of the model, given that this material is subsequently dissolved. But thanks to this material, geometrically complex parts can be built, parts that conventional methods are unable to construct. In the last analysis, the work undertaken is similar to that of a printer: it stores fine layers of plastic on a base instead of placing ink on paper. The base is a previously obtained CAD archive. This will be the archive printed in three dimensions, before obtaining the prototype.
This process can be employed to design a wide range of products in many different fields: a number of surfboards from the surf Pukas company, golf clubs by Makser, and so on. Besides these, the UPV-EHU researchers today have a number of projects for the reconstruction protheses for dental and mandibular pieces. Inverse engineering undoubtedly has multiple applications in fields as diverse as medicine, fine art, archaeology and, of course, engineering.