Pico- and Femtosecond Laser Micromachining for Surface Texturing

Abstract

The pico-and femtosecond laser micromachining has grown up as a reliable tool for precise manufacturing and electronic industries to make fine drilling and machining into hard metals and ceramics as well as soft plastic and to form various nano-and microtextures for improvement of surface functions and properties in products. The ultrashort-pulse laser machining systems were developed to describe the fine microdrilling and microtexturing behavior for various materials. Accuracy in circularity and drilled depth were evaluated to discuss the effect of substrate materials on the laser microdrilling. Accuracy in unit geometry and alignment was also discussed for applications. A carbon base mold substrate was micromachined to transcribe its microtextures to transparent plastics and oxide glasses. Three practical examples were introduced to demonstrate the effectiveness of nano-/ microtexturing on the improvement of microjoinability, the reduction in friction and wear of mechanical parts and tools, and the surface property control. The fastrate laser machinability, the spatial resolution in laser microtexturing as well as the laser micromanufacturing capacity were discussed to aim at the future innovations in manufacturing toward the sustainable society.

Simultaneous Nano-Texturing onto a CVD-Diamond Coated Piercing Punch with Femtosecond Laser Trimming

“…Under optimized trimming conditions, the nanotextures were formed through the nano-channels up to the punch head with sufficient depth. These channels eject the debris particles of work materials from the piecing process not only when using dry but also when using wet types of lubrication [13]. As demonstrated in [24], where the adhesion of debris fragments onto the cutting surfaces was significantly ameliorated by the presence of microtextures, the piercing punch life was greatly prolonged by this emission of debris fragments from the work materials.…”

“…The single-shot power was estimated to be 0.25 GW. High-powered irradiation of 200 fs was used to drive the well-defined ablation into the targeted materials [13].…”

“…The laser machining track overlapped the working range 20 times by rotating the work. As pointed out in [13][14][15], the LIPSS-ripple period is controllable by the laser fluence, pulse width, and so forth for femtosecond laser nanotexturing. In fact, LIPSS using high and low spatial frequencies with very different periods can be produced via the same laser setup depending on the process conditions.…”

“…Let us consider the directivity of the unidirectional nanotextures in Figure 5c. As discussed in [13,16,17], the nanotextured ripples in the lateral direction are induced by femtosecond laser scanning in the longitudinal direction on a relatively smooth surface with a low roughness. In the present trimming process of the diamond coating on the cylindrical punch, the scattering laser was skewed by the local curvature on the trimmed diamond surface so that every nanotextured ripple was formed in the axial direction with a skewed angle.…”

“…When using this femtosecond laser irradiation, a nanotexture was formed on the irradiated surface by LIPSS (Laser Induced Periodic Surface Structuring) [12]. Since this first discovery on LIPSS, many studies have reported its theoretical and experimental factors, as well as its application to the modification of surfaces and optical properties and its tribological performance [13]. This nanotexturing has the possibility to work simultaneously with the laser trimming of diamond-coated punches.…”