Search

Laser surface texturing (LST) and coating deposition are implemented on cemented carbide (WC-CoNi) tools to extent their application in abrasive-like machining processes. The topographic features of a conventional cubic boron nitride based honing stone are achieved by LST, whereas wear resistance is enhanced by deposition of a ceramic layer. Three tool types are considered here: uncoated and coated LST WC-CoNi tools, besides a honing stone used as reference. They are tested under abrasive-like cutting conditions using an in-house workbench and a workpiece made of 20MnCr5 steel. Wear resistance and mechanisms as well as surface integrity of the tools after cutting tests are evaluated. It is found that LST cemented carbide tools achieve similar material removal effectiveness to the honing stone. Furthermore, coated LST tool exhibits a better cutting capacity, in terms of machined workpieces with smoother surfaces and enhanced wear resistance. However, the cutting process using cemented carbide tools is not as stable as the one developed employing the honing stone. The different response is related to the tribological conditions of the cutting edges of the laser-shaped pyramids. Damage within constitutive microstructural phases is clearly reduced for the coated condition, although it is still directly related to geometrical complexity of the pyramids. [ABSTRACT FROM AUTHOR]

Laser surface texturing has become popular in recent years, as its application in various fields may result in relevant benefits in different fields, such as tribological performance enhancement of contact surfaces. As frontline engineering materials, cemented carbides are widely used in the mining and manufacturing industries. In the case of cutting tools, surface texturing of working surfaces of cemented carbides emerges then as an interesting option. In this work, line-like structures are produced on the surface of a chosen cemented carbide grade by the method of direct laser interference patterning (DLIP), using nanosecond and femtosecond laser pulses, respectively. Specific laser setups are individually configured to obtain topographic features on the scale of a micrometer. It is aimed to assess the production precision using such configuration and compare the possible ablation effects induced by the two typical laser setups. Topographic features of the produced patterns are characterized using confocal laser scanning microscopy. Morphological features and surface integrity are examined by scanning electron microscopy combined with focused ion beam (FIB) milling. It is found that satisfactory geometrical precision is achieved both nano- and femtosecond lasers. It also complies with theoretical estimations. Surfaces formed by the femtosecond laser are cleaner and show smoother patterns, exhibiting lower melting or microcrack formation. [ABSTRACT FROM AUTHOR]

Cemented carbides are outstanding engineering materials widely used in quite demanding material removal applications. In this study, laser surface texturing is implemented for enhancing, at the surface level, the intrinsic bulk-like tribological performance of these materials. In this regard, hexagonal pyramids patterned on the cutting surface of a tungsten cemented carbide grade (WC-CoNi) have been successfully introduced by means of laser surface texturing. It simulates the surface topography of conventional honing stones for abrasive application. The laser-produced structure has been tested under abrasive machining conditions with full lubrication. Wear of the structure has been characterized and compared, before and after the abrasive machining test, in terms of changes in geometry aspect and surface integrity. It is found that surface roughness of the machined workpiece was improved by the laser-produced structure. Wear characterization shows that laser treatment did not induce any significant damage to the cemented carbide. During the abrasive machining test, the structure exhibited a high wear resistance. Damage features were only discerned at the contacting surface, whereas geometrical shape of pyramids remained unchanged. [ABSTRACT FROM AUTHOR]

Honing is often implemented as surface finish process by improving geometrical and form precision of workpieces. Guiding stones, usually made of hard materials with requirement of excellent tribological properties, play a key role as a supporting part in the honing tool. In this paper, cemented carbides are intended for guiding application as substitute of diamond or CBN composites. Innovative surface textures, namely crossing-line patterns and dimple arrays, are fabricated by means of short pulse laser on a cemented tungsten carbide (hardmetal) grade. Implementation of these processing conditions yields satisfactory geometrical accuracy. The cemented carbide stones patterned by laser together with a traditional diamond guiding stone were tested on a lubricated pin-on-disc tribometer. Both cross-line patterns or dimple arrays are found to improve frictional conditions compared to the traditional guiding stone, but the former are more favorable to build up a stable sliding scenario with minimized friction than the latter. Pattern density has a more significant impact on friction, diminishing in the case of dimple arrays. • Reproduction of honed surface topography on cemented carbide grade • Satisfactory surface integrity and geometrical precision obtained by nanosecond laser. • Crossing-line patterns achieved better frictional conditions than dimple arrays. • Pattern density has a significant impact on frictional performance. [ABSTRACT FROM AUTHOR]