LIE HomeIssue Contents

LMDCAM, Computer Aided Manufacturing (CAM) Solution for Tool Path Generation for Build-up of Complex Aerospace Components by Laser Metal Deposition (LMD)
J. Flemmer, N. Pirch, A. Gasser, k. Wissenbach, I. Kelbassa and J. Witzel

The success of laser metal deposition (LMD) for repair or fabrication of near-net shaped metals components directly from computer aided design (CAD) solid models without use of time and cost-prohibitive conventional techniques, such as five-axis milling, linear friction welding and electro chemical machining depends on the availability of a close CAD/ computer aided manufacturing (CAM) chain.

Distortion and defects of a worn part implies that the nominal CAD model from the design stage is no longer suitable for the representation of the part geometry. This means that first of all the actual and the target geometry have to be constructed from which the deficit volume is determined. Only with this volume being available the tool paths can be programmed.

The original data format of laser scanned data is a polygonal modelling approach for surface representation. The further step of creating a non-uniform rational B-spline (NURBS) representation of the geometry requires a major commitment in time, both in instruction and in amount of work.

For this reason the Fraunhofer Institute for Laser Technology (ILT) designed a process chain for the laser material deposition (LMD) whose CAM module termed LMDCAM, is based on a polygonal modelling approach for geometry representation. NURBS are only used for the reduction of data noise in the scanned data. The target geometry of worn parts is derived by a best fit with the CAD model from the design stage. LMDCAM supports the generation of all sorts of path pattern within a layer which for example may be derived from a distortion reduction analysis. The functionalities of LMDCAM are exemplified by a repair application and the near-net fabrication of a blade-integrated disk (BLISK) blade direct from the CAD model.

Full Text (IP)