Guide to wide belt sanders | 5

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Finest or lacquer sanding

When sanding already painted workpieces, the following challenges must be taken into account:

  • Sanding belt and feedrate must be coordinated.
  • The varnish must not be sanded through.
  • Fibres swollen and set up by the ingress of water should be sheared off cleanly.
  • Grain break-outs and clogged sanding belt pores create streaks on the painted surface.

Varnishes tend to smear if the sanding belt speed is too high. The following machine characteristics are derived from these challenges:

  • The continuously variable control of sanding belt and feedrate allows the sanding process to be adapted to different lacquer systems.
  • A plunge controlled sanding pad prevents the lacquer from sanding through at the edges. A segmented, electronically controlled sanding pad does the same on the surface.
  • Cross sanding unit at the end of the machine allow for finest surfaces, but are not absolutely necessary for lower demands of the surface.
  • Diagonal sanding units, chevron belt unit (superfinish-aggregates) and brush sanding units blur sanding belt flaws.

Gernerally, as long as the wood structure and not the gloss is in the foreground, cross sanding units can be dispensed with. Those who occasionally process gloss varnishes are well advised to use the diagonal sanding unit. If the processed wood has a strong tendency to swell, if the workpiece is veneered or if it is lacquered MDF boards, a cross sanding unit is required. The cross sanding unit is indispensable for sanding high-gloss surfaces. As several cross sanding processes with different grain sizes are necessary before polishing, the processing time can be reduced considerably by placing one or two additional cross sanding units at the end of the machine.