Micro-Milling Process of Metals: A Comparison between Femtosecond Laser and EDM Techniques

Abstract

Nowadays, micro-machining techniques are commonly used in several industrial fields, such as automotive, aerospace and medical. Different technologies are available, and the choice must be made considering many factors, such as the type of machining, the number of lots and the required accuracy specifications in terms of geometrical tolerances and surface finish. Lasers and electric discharge machining (EDM) are widely used to produce micro-components and are similarly unconventional thermal technologies. In general, a laser is particularly appreciated by the industry for the excellent machining speeds and for the possibility to machine essentially any type of materials. EDM, on the other hand, has a poor material removal rate (MRR) but can produce microparts on only electrically conductive workpieces, reaching high geometrical accuracy and realizing steep walls. The most common micro-application for both the technologies is drilling but they can make also milling operations. In this work, a comparison of femto-laser and EDM technologies was made focusing on micro-milling. Two features were selected to make the comparison: micro-channels and micro-pillars. The depth was varied on two levels for both features. As workpiece material, aluminum, stainless steel and titanium alloy were tested. Data regarding the process performance and the geometrical characteristics of the features were analyzed. The results obtained with the two technologies were compared. This work improves the knowledge of the micro-manufacturing processes and can help in the characterization of their capabilities.

Machinability of AA 2024 aluminum alloy by fiber laser engraving process

“…Following the solidification of the liquid metal remaining from the vaporized metal in the interaction area, a thin layer of re‐solidified metal forms on the surface, characterizing the surface and determining the surface roughness [23]. When the laser beam interacts with the metal surface, melting, evaporation, and a cavity with plasma are formed progressively [24]. The molten metal inside the cavity, formed in the interaction area with the pressure effect, is directed towards the outside of the cavity; it completes the solidification process there [21].…”

“…The pulse‐to‐pulse and hatching overlap rates were calculated using Equations 1 and 2 [24–27]. $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {\rm p}{\rm u}{\rm l}{\rm s}{\rm e}-{\rm t}{\rm o}-{\rm p}{\rm u}{\rm l}{\rm s}{\rm e}{\rm \ }{\rm o}{\rm v}{\rm e}{\rm r}{\rm l}{\rm a}{\rm p}{\rm \ }\left({\rm \char37 }\right)=\hfill\cr \left(1-{{{\rm s}{\rm c}{\rm a}{\rm n}{\rm \ }{\rm s}{\rm p}{\rm e}{\rm e}{\rm d}}\over{{\rm b}{\rm e}{\rm a}{\rm m}{\rm \ }{\rm d}{\rm i}{\rm a}{\rm m}{\rm e}{\rm t}{\rm e}{\rm r}. {\rm f}{\rm r}{\rm e}{\rm q}{\rm u}{\rm e}{\rm n}{\rm c}{\rm y}}}\right){\rm x}100\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {\rm H}{\rm a}{\rm t}{\rm c}{\rm h}{\rm i}{\rm n}{\rm g}{\rm \ }{\rm o}{\rm v}{\rm e}{\rm r}{\rm l}{\rm a}{\rm p}{\rm \ ...$$…”

“…The pulse-to-pulse and hatching overlap rates were calculated using Equations 1 and 2 [24][25][26][27].…”

Multi-objective optimization of Nd:Yag laser machining’s conflicting responses while milling micro-channels

“…It was reported that LIPMM resulted in better micro-channels fabrication in terms of aspect ratio and channel depth. Calabrese et al 17 compared the micro-milling process using laser and electrical discharge machining (EDM). Machining of various metals such as aluminum, titanium alloys, and stainless steel was performed.…”