Most parts require some sort of surface preparation before laser scanning or white-light scanning can begin. Scanning technology has improved dramatically in recent years such that less preparation is necessary. Even so, if you want to achieve the best positional accuracy from the scan, the surface should be flat (non-reflective), opaque (non-transparent), and white.
The ideal surface to scan is an eggshell. Unfortunately, few eggs require laser scanning.
Therefore, some preparation is usually required to replicate a non-reflective, non-transparent, white surface. If the part can be painted, one of the best prep materials is a flat white spray paint. This adds .0002" - .0004" of thickness to the surface when properly applied. Paint is best used on metal parts such as castings that can be cleaned with a paint remover, or on parts that are disposable.
 A more common prep material is developing powder used for die-penetrant inspections. It adds .0005" - .001" of thickness to the surface and can be washed off with soap and water.
Perhaps your project is too precise to add a layer of paint or powder to the surface. Some parts can be made less reflective by glass bead-blasting. A negligible amount of material is removed from the object, but the surface layer is"disturbed" slightly to reduce reflectivity.
If none of these options are possible, a combination of scanning (for reference) and precision dimensional inspection can be employed.
Proper surface preparation is a critical step in the scanning process. Be sure to discuss it with your service provider before any work begins. |
