Effect of Process Parameters on the Surface Microgeometry of a Ti6Al4V Alloy Manufactured by Laser Powder Bed Fusion: 3D vs. 2D Characterization

The influence of the main process parameters, laser power, point distance and time exposure, on the surface microgeometry of Ti6Al4V specimens produced by a pulsed powder bed fusion process was investigated. A 3D characterization was carried out and collected data were elaborated to reconstruct the surface and to determine both the 3D and the 2D material ratio curves along different directions. The 3D material ratio curve gives a slightly lower material ratio of peak zone Mr1 and higher material ratio of valley zone Mr2, reduced peak height Rpk and reduced valley height Rvk than the 2D curves. Roughness is greater in the 3D analysis than in the 2D one, skewness is the same and kurtosis increases from <3 in 2D to >3 in 3D. Roughness and skewness increase on increasing point distance and decreasing time exposure and laser power. Within the investigated ranges (27.3–71.2 J/mm3), an increase in energy density reduces the surface roughness while skewness and kurtosis are not significantly affected. The results indicate that a 3D approach allows better characterization of the surface microgeometry than a 2D one.

Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear

Wear and surface microgeometry aspects of fiber-reinforced hybrid composite dry friction clutch facings are revealed in a novel way: after different, real life automotive tests during their lifetime. This study examines and reveals the tribological response of friction material surfaces to real life application conditions with two different facing diameters and in two directions. Along the increasing activation energy scale, wear values increased according to two different trends, sorting tests into two main groups, namely ‘clutch killer’ and ‘moderate’. Wear results also highlighted the influence of mileage and test conditions, with clutch killer tests also creating considerable wear-more than 0.1 mm-at inner diameters: 1% higher wear was generated by 90% higher mileage; another 1% increment could be caused by insufficient cooling time or test bench-specific conditions. Surface roughness values trends varied accordingly with exceptions revealing effects of facing size, friction diameter and directions and test conditions: small (S) facings produced significantly decreased Rmax roughness, while large (L) and medium (M) size facings had increased roughness values; Rmax results showed the highest deviations among roughness values in radial direction; tests run with trailer and among city conditions resulted in more than 2% thickness loss and a 40–50% roughness decrease.

Discharge Energy as a Key Contributing Factor Determining Microgeometry of Aluminum Samples Created by Electrical Discharge Machining

The aim of this study is first to determine the effect of the discharge energy on the surface microgeometry of aluminum samples created by electrical discharge machining (EDM). Secondly, an additional purpose is to demonstrate the differences between the geometric multiscale methods: length-, area-scale, and curvature. Eleven samples were manufactured using discharge energies ranging from 0.486 mJ to 1389.18 mJ and, subsequently, measured with focus variation microscopy. Standard ISO and multiscale parameters were calculated and used for surface discrimination and regression analysis. The results of linear, logarithmic, and exponential regression analyses revealed a strong correlation (R2 > 0.9) between the geometrical features of the surface topography and the discharge energy. The approach presented in this paper shows that it is possible to shape surface microgeometry by changing the energy of electrical discharges, and these dependencies are visible in various scales of observation. The similarities of the results produced by curvature and length-scale methods were observed, despite the significant differences in the essence of those methods.

Investigation of the microrelief of the soil layer surface and its effect on the strength of soil resistance to tillage

The lack of the operating elements strength calculating methods providing sufficient accuracy of the results is a significant problem in modern agricultural machinery development. The using calculation models do not take into consideration the microrelief of the treated surface, which leads to a significant error in determining both extreme and long-term loads on the working bodies of mechanisms. In this article author analyzes the cultivated soil treated surface microgeometry influence on the forces arising in the tillage tool. The existing design model is considered on the needle harrow example, its disadvantages are indicated and a way to eliminate them is proposed. Experimental data on the soil surface profile microroughnesses size study are presented, regularities of the microroughnesses random distribution are revealed, in particular, the assumption of the normal nature of this distribution is confirmed. The dependences based on the obtained data are proposed for a more accurate acting on the tillage tool loads calculation.

Optimizing the Formation of Hydraulic Cylinder Surfaces, Taking into Account Their Microrelief Topography Analyzed during Different Operations

Causes of the in-service damage to hydrocylinder liners were investigated, and the requirements to their working surfaces were systematized. Roughness parameter Ra was found not to provide a precise estimate of the surface quality because its reduction did not affect surface microgeometry. Additionally, the surface quality was assessed by the Abbott-Firestone curve during the finishing operation. The optimized manufacturing technology for obtaining hydrocylinder liners was offered based on having the required microgeometry and surface quality provided by cutting operations. The quality and service characteristics of internal surfaces of hydrocylinder liners were improved by changing technological operations. In particular, the semi-finish turning was chosen to provide for the surface roughness parameter Ra within 6.3–8.0 μm and the roughness pitch parameter S within 0.4–0.6 mm and homogeneous surface structure. The finishing rolling was replaced by burnishing to form a regular microrelief.

Influence of laser texturing on tribological properties of DLC coatings

The work presents the use of laser texturing of DLC coatings to improve tribological properties. The coatings were applied by the PVD method to the rings made of 4H13 steel. The surface texturing was performed with the TruMICRO 5325c picosecond laser with the radiation wavelength λ = 343 nm. The surface microstructure analysis, surface microgeometry and microhardness measurements and tribological tests were carried out. The problem presented in the paper can be used to extend the knowledge of the areas of application of DLC coatings, especially in sliding friction pairs.

Surface Texture after Turning for Various Workpiece Rigidities

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A detailed analysis of 2D surface profiles was carried out by using a large number of parameters that allowed us to distinguish significant differences in the surface microgeometry, which confirmed that determining surface characteristics from one height parameter (Ra—arithmetical mean height) is far from sufficient. The obtained results indicate significantly better roughness and waviness values of the AISI 304 steel surfaces in terms of its size, periodicity, and regularity. Therefore, the turning process of AISI 304 shafts with low rigidity allows one to be able to achieve better quality texture and have a positive effect on the general properties of a workpiece. In all tested samples, surface irregularities decreased along with the distance from the tailstock. The shafts with an L/D ratio of 12 had worse surfaces in the first two sections due to lower rigidity. The results received close to the three-jaw chuck, regardless of the L/D ratio and material type, demonstrated similar waviness and roughness parameters and profiles.

Microgeometry of the surface of electron beam additive manufacturing products. Selective electron beam melting

The results of the analysis of works related to the formation of surface microgeometry in the process of selective electron-beam melting are presented, and the physical model of this process is refined. The developing additive technology of selective electron-beam alloying and the directions in which its research is carried out, in particular, the analysis of the metallurgical process, the formation of the microstructure of the material, the formation of microstructure defects, are described. The roughness of the surface of products obtained by the SEBM technology, as well as the microgeometry of surfaces and the mechanisms of its formation, depending on various parameters of the process, are considered.

Investigation of the formation of friction surface microgeometry of a wear-resistant coating during friction with a metal counterbody

Were is researched the friction surfaces of wear-resistant coatings with modifying additives Al2O3 and metal counterbody made of ShH15 steel, and also reveals the factors that influence the formation of coating microgeometry of surface during sliding friction. A statistical model has been developed based on the binomial distribution of removed wear particles to describe the frictional interaction during friction of the coating with a metal counterbody.