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Workpiece probing

With CNC-machining centres

Fixed system installation or aggregate for tool changer, which is used in order to trace the workpiece surface and transfer the corresponding values to the control.

This can be necessary when processing with greater precision on the workpiece surface. Most frequent application is the milling of furniture fronts from MDF.

  • Problem: The machine can only define the machine table as the plane of reference. If surface milling is carried out on a workpiece that is not 100% dimensionally accurate (MDF boards exhibit surface tolerances of multiple tenths of mm) then the processing is dimensionally accurate with reference to the machine table, although it is not carried out exactly parallel to the workpiece surface. This can result in visible ledges, which must be removed through extensive rework.
  • If it is possible to trace the workpiece surface then it is always possible to carry out processing precisely parallel to the workpiece surface, even if this exhibits a certain tolerance.

Variants

  • The most simple variant is a tracing device, which is combined with a floating router head. This facilitates the compensation of minor tolerances, without the transfer of data to the control.
  • Advantage: Simple and economical variant
  • Disadvantage: Tracing and compensation of tolerances only possible to a limited degree, workpiece tracing for reading in data not possible
  • A further variant comprises tracing with a separate tracing aggregate and transfer of the data to the control. Using the corrected workpiece data it is thereby possible to implement totally precise surface processing.
  • Advantage: Compensation of any tolerances possible, storing of unknown workpiece data is possible as a basis for the creation of completely new processing programs
  • Disadvantage: Hugely increased processing times with complete tracing
  • The combination of a tracing device and router head exists as a third variant. In this case the tracing device sends data to the control, which correspondingly corrects the router head course in real-time.
  • Advantage: No increase in the processing times, complete workpiece tracing and storing of the data for subsequent processing possible, compensation of any tolerances is at least possible in theory
  • Disadvantage: High costs, technically highly complex and system therefore potentially prone to failures

See also:

Images

Einwechselbares Tastaggregat
HOMAG, 2002
Werkstückbearbeitung mit Tastaggregat
SCM
elektronische Werkstückabtastung
HOMAG, 2002