Key to the quality of finishing any wood product is the sanding operation. There are six main types of automated sanding, Tim Middleton, product manager at Stiles Machinery, noted in a webcast:

• calibration sanding
• veneer or finish sanding
• sealer sanding
• brush sanding
• orbital sanding
• profile sanding.

Five factors affecting calibration sanding include: type of material to be removed, chip load, feed speed, workpiece width, and the abrasive belt. “The goal of calibration is to make everything flat,” said Middleton. “The flatter we can make it, the more uniform we can make it, the easier it is to apply finish and to sand the finish between coats.”
The goal of veneer/finish sanding is to prepare the surface for stain or finish. This method is used to remove defects in the wood, material handling marks, organic residue and other fibers from the surface of the board. Two types of finish sanding were covered: soft rubber drum and crossbelt.

The advantages of sanding with a crossbelt, said Middleton, include: removal of short fibers, removes tape more efficiently, avoids a “washed-out” appearance, and is more “aggressive” in removing deep scratch marks.

Performed prior to the topcoat, sealer sanding requires a slower belt speed and finer grit sequence. Brush sanding is done for two reasons: “edge breaking” which softens the edges so the sealer can be applied evenly; and fiber removal for improved surface quality. Once the surface has been properly prepped, finishing can occur.

New in Finishing

Among the new technologies in the marketplace today, Pagan noted, are INERT and digital coatings. A patented process, the INERT coating technology applies a “fill” coating that in one pass, can prep and smooth the tops and edges of all types of panels, he said. It can also be used as a topcoat layer over melamine or digital printing, he added. Among the benefits are: VOC free, immediate adhesion and no risk of yellowing.

Pagan also discussed the benefits and opportunities offered with digital printing. Available in single and multi-pass systems, digital printing can be performed on a wide range of substrates, and for a variety of applications. In addition to the ability to take a low-grade substrate and create a high-end digital “veneer” or “textured” surface, digital printing also offers opportunities for batch-one production and fast turnaround, with color consistency throughout the run.

This article was based on the webcast “Sanding & Finishing: Technology’s Next Wave,” presented by Tim Middleton, product manager at Stiles Machinery Inc., and Roy Pagan, technical sales specialist at Cefla Finishing Group.  View the webcast at  WoodworkingNetwork.com/webcasts.