Surface preparation: a trade-off on the amount of material to be removed for valuable repair.
Automated repair using additive manufacturing follows three mains steps that are surface preparation using machining technics, actual repair using additive manufacturing equipment, and surface finishing using machining. Surface preparation is essential for a good quality repair process. In fact, the pre-repair step enables the removal of tiny edges or sharp angles which would make the printing non-consistent. It also allows material deposition on clean surfaces for better structural properties at the interface.
Damaged surface before (a) and after (b) surface preparation computed by Element X
In some cases, machining also permits giving enough clearance around the damaged area for collision-free material deposition.
However, removing too much material would lead to a loss of time, energy, and material during both machining and repair processes. The challenge is then to find an optimized trade-off between removing enough material to build a suitable bed for additive manufacturing while keeping the actual amount of removed material as least as possible.
In the new update of Element X, Elementiam team focused on optimizing this trade-off by taking into account the characteristics of the layer bead used for printing and the geometry of the tools used for machining and additive manufacturing.
Case study: damaged gas turbine blade
In this study, a damaged gas turbine is used to demonstrate the capacity of Element X to compute a surface preparation strategy based on the characteristic of the bead and the geometry of the tools used for repair.
Nominal (a) and damaged (b) versions of a gas turbine blade
Let's consider different tools with different geometries. Element X computes a defect-free pre-repaired surface and the corresponding toolpath, suitable for material deposition and with enough clearance to avoid any collision during the repair process.
Results of the surface preparation process for three sets of parameters with low clearance (a), medium clearance (b) and high clearance (c).
Once the pre-repaired volume has been computed, we just need to get access to the negative volume that will be used for the additive toolpath generation. Element X provides both pre-repaired and negative volumes as STL formats compatible with CAM and CAD software applications.
Machining toolpath (a) and model of the repaired blade with the corresponding pre-repaired and negative volumes (b)
For more information about Element X software and the business scope of Elementiam, please contact us at email@example.com.