Tribological Performance of Laser Patterned Cemented Tungsten Carbide Parts

Fang, Shiqi; Herrmann, Thomas; Rosenkranz, Andreas; Gachot, Carsten; Marro, Fernando García; Mücklich, Frank; Llanes, L.; Bähre, Dirk

doi:10.1016/j.procir.2016.02.228

Cited by 30 publications

(21 citation statements)

References 18 publications

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“…Moreover, SEM-EDS analyses were performed for each set up of laser parameter, in order to assess coating chemical composition after the laser treatment and to evaluate in particular cobalt content. In fact it is reported in literature that selective removal of Co binder can occur when high fluency and high number of loops are used as reported in the laser texturing of cemented tungsten carbide parts [14,15]. A laser probe system Mitaka PF60 was used to acquire the roughness profile: this instrument due to the scan autofocus system offers measurement with high accuracy in the sub-micrometer level.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

confidence: 99%

Nd:YOV4 laser polishing on WC-Co HVOF coating

Giorleo¹,

Ceretti²,

Montesano³

et al. 2017

AIP Conference Proceedings

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“…In a previous study of the authors, laser surface texturing (LST) was implemented to modify and produce specific patterns on the contact surfaces of supporting parts made of cemented carbide. Compared to non-textured surface, lower friction was achieved by these laser-produced line-like structures in the tribological test [10,11]. These innovative surface structures were also applied in a simulation of inner honing processes by the authors, and it was found that guide stones with such innovative surface structures are favorable for obtaining a more stable honing system by lowering the friction [12].…”

Section: Introductionmentioning

confidence: 97%

“…They are widely used on contacting surfaces to improve their frictional performances. Bearings are clear examples of this, where the dimples act as micro-reservoirs that offer supplementary lubricants and local lifting pressure in the tribological system [10,20,21].…”

Section: Introductionmentioning

confidence: 99%

Influence of Laser Pulse Number on the Ablation of Cemented Tungsten Carbides (WC-CoNi) with Different Grain Size

et al. 2018

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Abstract:The ultra-short pulse laser has attracted attention as an advanced tool for functionalizing surface topography, since it has high accuracy and results in little damage. In a previous study, some innovative patterns were introduced on cemented carbide surfaces, such as dimples, which are commonly used as oil reservoirs for bearings. The accuracy is not only related to the inherent features of the laser, but also to the machining processes. Within this context, this study aims to investigate the influence of machining parameters (i.e., pulse number in this study) on the ablation mechanism and resulting surface integrity. Two cemented carbide grades, possessing similar chemical composition but different grain size (small and large), are machined using a femtosond laser set-up with variant pulse number (1-20). The geometrical properties of the produced structure and surface integrity are statistically investigated using different microscopy techniques. It is found that the dimple depth is approximately proportional to the pulse number for both grades, and the coarse grade leads to a higher rate of depth increase. Damage is found in the form of melting and cracking for the binder and the grains, respectively; but this is more pronounced for large-grain grade in terms of the scale and depth. However, these observations are only found at a very superficial position.

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“…More complex patterns, as those associated with surface topography of honing tools, require precise movement control of laser beams. In a recent study, the authors have proven the capability of high precision 5-axis laser micromachining system, combined with a picosecond laser, to move the beams along the x-, y-and z-axis with micrometric precision [21].…”

Section: Introductionmentioning

confidence: 99%

Laser surface texturing of a WC-CoNi cemented carbide grade: Surface topography design for honing application

Fang

Llanes

Bähre

2018

Tribology International

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Abrasive effectiveness of composite-like honing stones is related to the intrinsic surface topography resulting from the cubic boron nitride (CBN) grains protruding out of the metallic matrix. Within this framework, Laser Surface Texturing (LST) is implemented for replicating topographic features of a honing stone in a WC-base cemented carbide grade, commonly employed for making tools. In doing so, regular arrays of hexagonal pyramids (similar to CBN grains) are sculpted by a laser micromachining system. Micrometric precision is attained and surface integrity does not get affected by such surface modification. Finally, potential of laser-patterned cemented carbide tools, as alternative to conventional honing stones, is supported by successful material removal and enhanced surface smoothness of a steel workpiece in the abrasive testing.

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Tribological Performance of Laser Patterned Cemented Tungsten Carbide Parts

Cited by 30 publications

References 18 publications

Nd:YOV4 laser polishing on WC-Co HVOF coating

Nd:YOV4 laser polishing on WC-Co HVOF coating

Influence of Laser Pulse Number on the Ablation of Cemented Tungsten Carbides (WC-CoNi) with Different Grain Size

Laser surface texturing of a WC-CoNi cemented carbide grade: Surface topography design for honing application

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