Abstract
Chatter vibrations arising during machining operations are detrimental for cutting process performance, since they may cause poor surface quality of the machined part and severe damages to machine tool elements. Passive approaches for chatter suppression are based on the integration of special mechanical components with high-damping properties within the machining system. They represent a good solution to this problem thanks to their intrinsic simplicity. Recently, the application of metallic lattice structures inside 3D printed parts obtained from the Selective Laser Melting technology have proven superior damping properties with respect to the same full density material. Here, this idea is further explored by considering the novel configuration where the unmelted powder grains are retained inside the lattice structure by an external shell, acting as a multiplicity of microscopic mechanical dampers. This concept is applied for passive chatter suppression of thin-walled parts that are of particular relevance for industry. Preliminary experimental investigation was first carried out on simple beam-like specimens, and then on thin-walled benchmarks that were identified through modal analysis and tested under real cutting conditions. The main conclusion is that the novel proposed configuration (lattice plus unmelted powder) has higher damping properties with respect to the full density and lattice alternatives. Accordingly, it may be successfully applied for passive chatter suppression in real machining operations.
Highlights
Milling operations of thin-walled geometries, typical of slender parts like compressor and turbine blades, require particular attention
The analysis of literature evidenced that metallic lattice structures—made of AISI 316L and 3D printed by means of the Selective Laser Melting technique—may be a good candidate for attenuating mechanical vibrations of advanced parts
A preliminary experimental study was first carried out on simple specimens, in order to assess the damping properties of the new lattice configuration filled with unmelted powder in comparison to the empty lattice and full density alternatives, for a given static compliance
Summary
Milling operations of thin-walled geometries, typical of slender parts like compressor and turbine blades, require particular attention. Chatter reduction can be achieved by means of part, tool, and machine tool stiffness enhancement, for example by exploiting tailor-made fixtures designed to strengthen weaker parts (e.g., thin-walled) [21,22]. Filling the lattice structure with polymeric materials may further enhance the capability of attenuating mechanical vibrations and reducing acoustic noise in advanced engineering applications, as it was recently illustrated in [26,27,28]. The interaction between lattice structure and powder grains was supposed to be stronger than that obtained by filling the lattice structure with any kind of powder only after the 3D printing process This innovative internal configuration was tested for passive chatter suppression of thin-walled parts. This concept was experimentally studied in two phases: a first preliminary experimental campaign by using simple, beam-like specimens (already studied in [25]) and an advanced experimental campaign on thin-walled parts that were tested by performing both modal analysis and cutting tests
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