Nanosecond laser texturing for high friction applications

AbstractA nanosecond pulsed Nd:YAG fibre laser with wavelength of 1064nm was used to texture several different steels, including grade 304 stainless steel, grade 316 stainless steel, Cr–Mo–Al ‘nitriding’ steel and low alloy carbon steel, in order to generate surfaces with a high static friction coefficient. Such surfaces have applications, for example, in large engines to reduce the tightening forces required for a joint or to secure precision fittings easily. For the generation of high friction textures, a hexagonal arrangement of laser pulses was used with various pulse overlaps and pulse energies. Friction testing of the samples suggests that the pulse energy should be high (around 0.8mJ) and the laser pulse overlap should be higher than 50% in order to achieve a static friction coefficient of more than 0.5. It was also noted that laser processing increases the surface hardness of samples which appears to correlate with the increase in friction. Energy-Dispersive X-ray spectroscopy (EDX) measurements indicate that this hardness is caused by the formation of hard metal-oxides at the material surface

Laser surface texturing for high friction contacts

AbstractA pulsed, nanosecond fibre laser with wavelength of 1064nm was used to texture grade 316 stainless steel and ‘low alloy’ carbon steel in order to generate contacts with high static friction coefficients. High friction contacts have applications in reducing the tightening force required in joints or to easily secure precision fittings, particularly for larger components where standard methods are difficult and expensive. Friction tests performed at normal pressures of 100MPa and 50MPa have shown that very high static friction coefficients greater than 1.25, an increase of 346% over untextured samples at 100MPa, can be easily achieved by single pass laser texturing of both contacting surfaces with the use of low pulse separations. The high static friction coefficients, obtained at 100MPa normal pressure with textures with up to 62.5μm pulse separation (processing speed ∼0.67cm2/s), were found to be associated with a significant amount of plastic deformation caused by the high normal pressures. As a result, higher normal pressures were found to result in higher friction coefficients

Process Optimization for 100 W Nanosecond Pulsed Fiber Laser Engraving of 316L Grade Stainless Steel

High average power (&gt;50 W) nanosecond pulsed fiber lasers are now routinely available owing to the demand for high throughput laser applications. However, in some applications, scale-up in average power has a detrimental effect on process quality due to laser-induced thermal accumulation in the workpiece. To understand the laser–material interactions in this power regime, and how best to optimize process performance and quality, we investigated the influence of laser parameters such as pulse duration, energy dose (i.e., total energy deposited per unit area), and pulse repetition frequency (PRF) on engraving 316L stainless steel. Two different laser beam scanning strategies, namely, sequential method (SM) and interlacing method (IM), were examined. For each set of parameters, the material removal rate (MRR) and average surface roughness (Sa) were measured using an Alicona 3D surface profilometer. A phenomenological model has been used to help identify the best combination of laser parameters for engraving. Specifically, this study has found that (i) the model serves as a quick way to streamline parameters for area engraving (ii) increasing the pulse duration and energy dose at certain PRF results in a high MRR, albeit with an associated increase in Sa, and (iii) the IM offers 84% reduction in surface roughness at a higher MRR compared to SM. Ultimately, high quality at high throughput engraving is demonstrated using optimized process parameters.</jats:p

Laserschneiden von Batteriefolien mit gepulsten Lasersystemen

Die Nachfrage und Innovation bei der Batterieherstellung steigt zunehmend mit dem wachsenden Bedarf an e-Mobilität. Da mechanische Verfahren bei der Produktion von Batteriezellen oft an ihre Grenzen stoßen, kann der Laser als präzises kontaktloses Werkzeug viele Vorteile bieten gegenüber klassischen mechanischen Bearbeitungsverfahren. Die Wahl der passenden Laser-Technologie gestaltet sich jedoch aufgrund der Komplexität der Folienmaterialien und Elektrodenzusammensetzungen als herausfordernd. Während das Schneiden mit kontinuierlichen Lasern oft zu großen Wärmeeinflusszonen führt, insbesondere bei beschichteten Folien, sind gepulste Laser in der Lage, in der Regel eine bessere Qualität beim Schneiden zu erzielen. Der Beitrag gibt einen Überblick über die Herausforderungen des Laser-Schneidens von Batteriefolien und untersucht die Vor- und Nachteile von Nanosekunden- und Pikosekunden-Lasern für eine Vielzahl von verschiedenen Materialien