Gabor Laki

57700022800

Publications - 5

Optimizing Parameter Sets for Laser-Textured Piston Rings Using Design of Experiments and Multibody Dynamics Calculations

András Lajos Nagy Gabor Laki Dominika Pintér László Boros

Publication Name: Coatings

Publication Date: 2025-05-01

Volume: 15

Issue: 5

Page Range: Unknown

Description:

Friction and wear reduction in internal combustion engines are crucial for improving efficiency and durability. This study investigates the effect of microtextured surfaces on friction power loss in an engine’s piston ring-cylinder system. A numerical analysis was conducted on piston rings equipped with dimple-shaped microtextures using AVL Excite Piston & Rings, modelling a hard chromium-coated piston ring and a cast iron cylinder. The goal was to determine the optimal surface texture parameters that minimize friction power loss under typical urban driving conditions with SAE 0W-30 oil. A two-step Design of Experiments (DoE) approach was employed, where the first step involved mapping the effects of texture parameters, i.e., dimple depth (A = 0.5, 1, 1.5 µm), dimple distance (B = 120, 160, 240 µm), and dimple diameter (C = 50, 60, 70 µm), to identify influential factors. The second step aimed at locating a parameter configuration with minimal friction power loss. The results demonstrated that the optimized texture parameters can significantly reduce friction power loss. The lowest friction power loss of 8.96 W was achieved with a dimple depth of 2 µm, distance of 80 µm, and diameter of 60 µm, which contributed to an 8.3% improvement over the reference surface. The model built to describe the investigated texturing approach exhibited a strong correlation with an R2 value of 0.93, and the deviation between predicted and measured values was below 1%. Future work will involve tribometer tests to experimentally validate the optimized parameters and confirm the simulation results.

Open Access: Yes

DOI: 10.3390/coatings15050528

A Preliminary Study on Laser Surface Texturing of Passenger Car Engine Piston Rings

András Lajos Nagy Attila Schweighardt Gabor Laki Gergely Kovács

Publication Name: Fme Transactions

Publication Date: 2025-01-01

Volume: 53

Issue: 2

Page Range: 252-259

Description:

Laser surface texturing offers a possible solution for reducing friction between sliding surfaces in engineering applications. Optimized surface topography can also contribute to reduced wear and elevated longevity by modifying the load and speed-dependent friction state in a system. This preliminaryexperimental study investigates the applicability of affordable fibre laser marking systems for microtexturing piston rings, in order to achieve a measurable reduction in friction under subsystem model conditions. A selection of textures are applied to chromium-coated cast iron piston rings. The resulting surface topographies are characterized through confocal microscopy and subjected to friction testing. A correlation analysis is conducted on surface topography parameters to identify key laser process parameters. Findings indicate an improvement in the range of 7–8% in terms of friction coefficient with appropriate texture size.

Open Access: Yes

DOI: 10.5937/fme2502252L

Topography Pre-Treatment of Laser-Textured Surfaces for Friction Simulation in AVL Excite †

András Lajos Nagy Gabor Laki László Boros

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This study presents the challenges arising during the numerical design and simulation of surface-microtextured piston rings. The evaluation of performance is based on the values of asperity and hydrodynamic friction, as well as the lubricant film thickness. The simulation tool AVL Excite Piston & Rings is used to perform the calculations. The aim of this study is to understand how selected surface pre-processing (pre-treatment) steps affect the calculations. Two methods are presented to achieve a realistic surface topography representative of a state after running-in. Pre-treatment is performed through metrological filtering and thresholding of the topography, and Gaussian smoothing of the virtually applied micro-texture array is carried out. The results show the anticipated behavior of decreasing asperity and hydrodynamic friction losses with the concurrent application of both techniques.

Open Access: Yes

DOI: 10.3390/engproc2024079095

Wear behaviour of ceramic particle reinforced atmospheric plasma spray coatings on the cylinder running surface of internal combustion engines

I. Zsoldos Alexander Dudas András Lajos Nagy Gabor Laki Barna Hanula Dirk Bartel

Publication Name: Wear

Publication Date: 2022-08-15

Volume: 502-503

Issue: Unknown

Page Range: Unknown

Description:

Atmospheric plasma spray coatings can provide a solution for corrosion and wear resistant cylinder coating surfaces in hybrid powertrains. This article presents experimental results from a model study of metal matrix composite coating samples of chromium steel with varied ceramic content, in order to characterize the effect of hard particles and porous coating structure on friction and wear. Experiments were conducted on a high-frequency reciprocating rig with coated cast-iron cylinder segments and hard chromium coated piston ring segments. Samples were investigated under continuous and scarce lubrication conditions. A ceramic content of 35 wt% was found to be ideal in terms of friction and wear. Coatings with a higher ceramic content exhibited severe abrasive wear, whereas a ceramic content under 35 wt% allowed for increased adhesion between the ring and cylinder surfaces. A detailed investigation of focused ion beam milled sections of the coated cylinder wall segments revealed a stabilizing effect of the ceramic particles, which reduces the delamination of the coating structure.

Open Access: Yes

DOI: 10.1016/j.wear.2022.204373

A Review on Friction Reduction by Laser Textured Surfaces in Internal Combustion Engines

András Lajos Nagy Jan Rohde-Brandenburger Gabor Laki Barna Hanula

Publication Name: Tribology Online

Publication Date: 2022-01-01

Volume: 17

Issue: 4

Page Range: 318-334

Description:

The internal combustion engine will be required as a bridge-technology in the upcoming decades to achieve a significant reduction in local emissions in the mobility, and logistics sector. Alternative fuel technologies will present new mechanical engineering challenges, including increasing efficiency and reducing mechanical losses. Textured surfaces with appropriate manufacturing parameters can enhance lubrication, and reduce friction in sliding and rolling contacts, e.g., journal bearings, or the piston ring – cylinder subsystem. This paper gives an overview of 80 scientific works related to laser surface technologies, with an emphasis on surface texturing for friction reduction from the viewpoint of engine development. The most common texture types, further directions, and general challenges are highlighted in the summary.

Open Access: Yes

DOI: 10.2474/trol.17.318