Influence of Intensity Distribution and Pulse Duration on Laser Micro Polishing

Nüsser, Christian; Wehrmann, Isabel; Willenborg, Edgar

doi:10.1016/j.phpro.2011.03.057

Cited by 70 publications

(34 citation statements)

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“…Using continuous wave laser radiation the macro laser polishing process creates a continuous remelted surface layer which is between 10-80 μm deep. For micro laser polishing pulsed laser radiation is used, which is a combination of remelting a thin surface layer smaller than 5 μm and vaporization of micro edges [1, [10][11][12][13][14]. In contrast to macro laser Figure 1.…”

Section: Process Fundamentalsmentioning

confidence: 99%

“…Schematische Darstellung des verwendeten optischen Aufbaus [10] polishing, micro laser polishing is a discrete rather than a continuous remelting process. Especially important for micro laser polishing is the intensity distribution of the laser beam within the interaction zone of material and laser radiation [14]. Crucial for the choice whether macro or micro polishing will be used are the initial surface roughness and its spatial wavelength [1].…”

Section: Process Fundamentalsmentioning

confidence: 99%

See 1 more Smart Citation

Design surfaces by laser remelting

Temmler

Willenborg

Wissenbach

2015

Materialwissenschaft Werkst

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Molds and dies are used today in the manufacturing of a wide range of industrial products. They have a broad field of applications from the air and space technology, the automotive sector, to electrical engineering, to household products and consumer goods. The surface of a part or product strongly influences its properties and functions e.g. it's visual appearance. The gloss thereby reflects one of the most important properties of a surface when it comes to evaluate the visual appearance. Therefore, among others, in this paper the influence of laser polishing on the generated specular gloss is investigated for the hot work steel 1.2343 (AISI: H11). On the one hand laser polished surfaces are measured by WLI and investigated by a spectral analysis of surfaces roughness. A spectral analysis is achieved by a discrete convolution of the surface profile with a Gaussian loaded function similar to ISO 11562. On the other hand specular gloss measurements were carried out at 20°, 60° and 85°. For the experiments a fiber‐coupled solid state disc laser (Yb : YAG; Q‐switched) is used (PL,max = 550 W; repetition frequency: fP = 5–20 kHz, pulse duration: tP = 0,7–3,5 µs, pulsed and cw‐operation). In general, scanning velocity and average laser power are two crucial procedural parameters for laser polishing with significant influence on the resulting surface roughness. These procedural parameters are investigated systematically, while other procedural parameters, such as laser beam diameter dL = 250 µm and track offset dy = 25 µm were kept constant. By this a significant reduction of roughness was achieved, especially for the wavelength interval λ < 320 µm. A correlation between specular gloss of surfaces and the measured micro‐roughness is carried out. In order to make a systematic classification laser polished fields are compared to surfaces which were prepared by conventional mechanical manufacturing processes, such as turning, milling, grinding, high end manual polishing etc. Specular gloss shows a good exponential correlation with micro‐ and meso‐roughness were as macro roughness shows no significant influence on the specular gloss. Additionally, a complete process chain for selectively laser polishing of metallic surfaces was developed in order to apply different levels of gloss onto free formed work pieces. Selective laser polishing and the process chain are demonstrated for a free formed tool insert with leather textured surface, where only the indentations of the leather texture were laser polished selectively

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Section: Process Fundamentalsmentioning

confidence: 99%

Section: Process Fundamentalsmentioning

confidence: 99%

Design surfaces by laser remelting

Temmler

Willenborg

Wissenbach

2015

Materialwissenschaft Werkst

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“…Nowadays a different technique available to reduce surface roughness is the laser polishing process. The polishing principle is based on focused radiation of a laser beam that melts a microscopic layer of surface material [5] ( figure 1). This technique is not affected by the surface material mechanical properties, therefore can be successfully applied also to hard HVOF coatings and, with appropriate defined laser spot can also work on small areas or cavities that cannot be reached by mechanical polishing.…”

Section: Introductionmentioning

confidence: 99%

“…Principle of polishing laser radiation in cross section [5] The process parameters optimization aims to obtain a laser beam that only melts the surface peaks of the material; due to capillary pressure the melted material fills the valleys producing a smoother topography with respect to the initial one [6]. In literature recent researches are available on both metallic materials and coating focusing their attention on different type of metals as titanium [7,8] and nickel [9] as well as on coating as Hastelloy C22 [10], ceramic materials [11] and tungsten carbide coating [12,13].…”

Section: Introductionmentioning

confidence: 99%

Nd:YOV4 laser polishing on WC-Co HVOF coating

Giorleo¹,

Ceretti²,

Montesano³

et al. 2017

AIP Conference Proceedings

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Abstract. WC/Co coatings are widely applied to different types of components due to their extraordinary performance properties including high hardness and wear properties. In industrial applications High Velocity Oxy-Fuel (HVOF) technique is extensively used to deposit hard metal coatings. The main advantage of HVOF compared to other thermal spray techniques is the ability to accelerate the melted powder particles of the feedstock material at a relatively high velocity, leading to obtain good adhesion and low porosity level. However, despite the mentioned benefits, the surface finish quality of WC-Co HVOF coatings results to be poor (Ra higher than 5 μm) thus a mechanical polishing process is often needed. The main problem is that the high hardness of coating leads the polishing process expensive in terms of time and tool wear; moreover polishing becomes difficult and not always possible in case of limited accessibility of a part, micro dimensions or undercuts. Nowadays a different technique available to improve surface roughness is the laser polishing process. The polishing principle is based on focused radiation of a laser beam that melts a microscopic layer of surface material. Compared to conventional polishing process (as grinding) it ensures the possibility of avoiding tool wear, less pollution (no abrasive or liquids), no debris, less machining time and coupled with a galvo system it results to be more suitable in case of 3D complex workpieces. In this paper laser polishing process executed with a Nd:YOV4 Laser was investigated: the effect of different process parameters as initial coating morphology, laser scan speed and loop cycles were tested. Results were compared by a statistical approach in terms of average roughness along with a morphological analysis carried out by Scanning Electron Microscope (SEM) investigation coupled with EDS spectra.

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“…The micro dimples can be used in biomedical implants for bone ingrowth and for drug delivery. Lowered surface roughness is for surface polishing of mechanical components [22]. The nano-fibrous structures can be exploited for their optical properties [23], the gecko effect seen in nano hairs [24] or as scaffold for tissue growth [25].…”

Section: Introductionmentioning

confidence: 99%