Heesemann's New Automatic Orbital

Here is a picture of Heesemann's new automatic orbital head from the Ligna show. What follows is a functional description of the process this head uses to remove cross-grain scratches without leaving swirls. (I get somewhat technical and dry.....sorry.) Let me know if you have any questions.

Functional Description of the Principles of the Heesemann OSR-Units


OSR = Orbital Scratch Removal. Drawing 1 shows the basic principle of a simple orbital sander. A pressure beam equipped with abrasive paper is supported by two eccentric bearings on a fixed frame. The eccentric bearings bring the frame into an orbital motion (picture 1). Individual sanding grains on the abrasive paper move on a circular path with the radius of the eccentric bearings. When a workpiece passes the abrasive belt moving in that way, protruding sanding grains will mark individual areas. These sanding lines are similar to the ones shown in picture 2. Even though there are no visible sanding lines only in longitudinal direction, as after wide belt sanding, these sanding marks are clearly visible. They are often called "swirls". Existing orbital sanders try to wipe out these "swirls" by an additional motion overlapping the rotating-swiveling pressure beam. The most common way to achieve a favorable effect is to overlap a second rotary motion. This figure is more complicated; therefore, we show here a motion transverse to the feed direction. This is shown in picture 3. You can see that the swirls on the workpiece surface are overlapping and are somewhat cancelled out. Basically, what the OSR-system has tried to do is to avoid the development of swirls altogether. The sanding paper is pressed down from the inside by a lamella system (photograph 1). It is motor driven back and forth transverse to the feed direction at varying speeds depending upon application. Pictures 4 to 6 schematically describe that constantly new areas of the oscillating abrasive paper are pressed down. This avoids the development of the characteristic marks (swirls) so that they do not have to be wiped out. The result is a high-quality surface without annoying sanding lines. An additional advantage is that a bearing system of high-quality and lasting liability can be used because of the simple orbital motion.