ON THE EFFECT OF THE SIDE FLOW OF 316L STAINLESS STEEL IN THE FINISH TURNING PROCESS UNDER DRY CONDITIONS

The article presents the results of the research on the plastic flow in the finish turning of 316L (X2CrNiMo17-12-2) stainless steel under dry cutting conditions. The steel was turned at variable cutting speeds and a constant depth of cut. The investigations were based on the Parameter Space Investigation method (PSI) which allowed minimizing the number of test points. It was observed that the phenomenon of slide flow occurred in the range of cutting speeds and feed rates under examination and its intensity depended on the values of these parameters. The phenomenon was more intense in the range of medium and higher cutting speeds and lower feed rates. The side flow results in significant changes between the real and theoretical values of roughness parameter Rz, which range from 40% up to even 330%

An insight into the effect surface morphology, processing, and lubricating conditions on tribological properties of Ti6Al4V and UHMWPE pairs

The effects of surface topography, processing, and environment conditions during tribological contact between Ti6Al4V titanium alloy and UHMWPE friction pairs were systematically evaluated. Hence, in this research the polyethylene samples (blocks) having a constant surface roughness were rubbed against counter-bodies (rollers) made of titanium alloy with different roughness of surfaces. The counter-samples were manufactured using either dry machining and/or minimum quantity lubrication (MQL) conditions. Such cutting conditions are harmless to humans and the environment. Simulated body fluid (SBF) and distilled water was used to simulate the tribological trials. We have noted that the lubricant applied to protect the integrity of machined parts, the rollers, have only minor impact on the tribological features of the friction pairs tested. Further, the samples produced with dry machining demonstrated a slightly lower momentary friction coefficient and temperature. In contrast, the MQL method enable reduced friction surface and significant wear accumulation. Further, it was found that the minimum and maximum values of the Sa texture parameter associated to tribological parameters do not exceed 21% and 4%, when is used dry and MQL methods, respectively. Nevertheless, the distilled water revealed a much better wear resistance when comparing to SBF, and the later one trigger as well as an accentuated wear progress with different patterns. The results of the study are important in the design of new biomedical components produced by finish turning

Cutting tool wear in turning 316L stainless steel in the conditions of minimized lubrication

316L stainless steel has emerged as one of the most used material in design and manufacturing for automotive, aerospace, marine, civil nuclear to produce critical components (valves, seats, pipes etc.). Despite, their huge application, during the machining of 316L stainless steel numerous challenges arise in terms of tool wear that are very detrimental for the surface of machined part. To obtain an extended life of tool used for machining commonly 316L stainless steel two different methods of cooling based on minimum lubrication condition, namely Minimum Quantity Lubrication (MQL) method and Minimum Quantity Cooling Lubrication (MQCL) with the addition of extreme pressure and anti-wear (EP/AW) method, respectively were settled. The use of the MQL method resulted in a reduction of the cutting tool wear by approximately 9% compared to the MQCL + EP / AW method and by approximately 21% compared to dry machining. Further, the highest values of wear indices were achieved during dry machining and the lowest ones in the method of minimized lubrication which validate the minimum lubrication as beneficial for reducing the wear progress

On the analysis of chip shaping after finishing turning of Ti6Al4V titanium alloy under dry, wet and MQL conditions

The shape and type of chip give general information about the cutting process. This paper presents the results of testing the shape and type of chips of Ti6Al4V titanium alloy after it finishes turning. The process was carried out under dry, wet and MQL (Minimum Quantity Lubrication) conditions at variable cutting speeds and feed rates and a constant depth of cutting. For planning the tests, the PSI (Parameter Space Investigation) method was used, which allows the experiment to be carried out while minimizing the number of experience points. It was found that the cutting speed and feed affect the type and shape of the chip, and clear differences were observed between dry and wet cooling conditions, and MQL conditions. During turning, the intensity of the cutting speed and feed influence on the chip compression ratio was changed. It was similar for dry and wet cooling conditions but smaller for MQL conditions. The purpose of this research is to analyze the chip shaping when Ti6Al4V titanium alloy finishes turning under dry, wet and MQL cooling conditions

Sliding Layer Formation during Tribological Contact between Expanded Graphite and Stainless Steel—A Pilot Study

The sliding layer created during operation of the expanded graphite–steel combination has had a huge impact on the effectiveness of the friction process, and thus on the sustainable development of society. Knowledge of the factors determining the properties of the sliding layer will make it possible to reduce friction resistance in the future through the proper design and selection of sliding pairs for given applications. This paper studies the effect of the moisture content of expanded graphite on the formation of a sliding layer on a stainless steel surface. The tests were carried out in static contact for 30 s and dynamic contact for 15 and 30 min, for loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. To determine the changes in surface geometry due to material transfer, the Ra roughness value of the surface of stainless steel samples was measured. In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, the results of the surface roughness of stainless steel samples working with dry and moist graphite rings were compiled. The obtained results show that the presence of water in the stainless steel-expanded graphite friction node affects the formation of a sliding layer. The resulting layer reduces the surface roughness of the cooperating materials and prevents their accelerated wear. After 5 min of work with the water-soaked graphite counter-sample, depending on the applied friction conditions, a reduction in the surface roughness of the stainless steel sample was achieved in the range of 11–18% compared to the initial value. After 30 min of operation, the surface roughness decreased by 3 to 25%. Pilot studies have shown that operating conditions influence the formation of a sliding layer in the stainless steel-expanded graphite tribological contact. This confirms the validity of conducting further research in this area

Evaluation of the Surface Topography of Ti6Al4V Alloy after the Finish Turning Process under Ecological Conditions

This paper describes findings in the surface topography of Ti6Al4V alloy after finish turning process under dry and MQL (minimum quantity lubrication) machining. The research was fulfilled in the range of variable feeds per revolution of 0.005-0.25 mm/rev and cutting speeds of 40-100 m/min using the depth of cut of 0.25 mm that fits finish processing conditions. The test plan was developed on the way to use the Parameter Space Investigation (PSI) method. The topography features were measured by a Sensofar S Neox optical profilometer using the Imaging Confocal Microscopy technique. Ra parameters and surface roughness profiles as well as 2D images and contour maps were analyzed. Under the studied machining conditions, lower Ra roughness parameters are obtained in the feed rate of 0.005-0.1 mm/rev and cutting speeds of 40-60 m/min. In comparison with dry machining, up to 17% reduction in Ra parameter values was obtained using the MQL method and vc = 70 m/min and f = 0.127 mm/rev as well as vc = 47.5 m/min and f = 0.22 mm/rev. Depending on the machining conditions, peaks and pits as well as feed marks typical for the turning process are observed on the machined surfaces

Cutting Forces and Chip Shaping When Finish Turning of 17-4 PH Stainless Steel under Dry, Wet, and MQL Machining Conditions

This paper analyses three components of total cutting force and chip shape changes when finish turning 17-4 PH (precipitation hardening) stainless steel. A Finite Element Method (FEM) simulation of cutting forces was also performed using the Johnson–Cook constitutive model. The results were compared with those obtained from experimental studies. Variable feeds of 0.05–0.4 mm/rev and depth of cut of 0.2–1.2 mm with a cutting speed of 220 m/min were used. The studies were carried out under dry and wet cooling conditions and with the use of minimum quantity lubrication (MQL). This research was realized based on the Parameter Space Investigation (PSI) method. Statistical analysis of the obtained results was carried out using Statistica-13 software. It was found that the cutting force Fc and feed force Ff depend on the depth of cut and feed, and the passive force Fp depends mainly on the feed. Compared to dry cutting conditions, a reduction of 43% and 39% of the cutting force Fc was achieved for wet machining and MQL machining, respectively. Regardless of the cooling conditions, a favorable chip shape was registered for ap = 1–1.1 mm and f = 0.25–0.3 mm/rev. Compared to the experimental studies, the FEM simulation showed differences of ~13% for the cutting force Fc and of ~36% for the feed force Ff

Effects of Hard Oxides Reinforcing of Iron-Based MMCs on the Surface Topography Features after Finish Turning

Effects of Hard Oxides Reinforcing of Iron-Based MMCs on the Surface Topography Features after Finish Turnin

Corrosion Resistance and Surface Bioactivity of Ti6Al4V Alloy after Finish Turning under Ecological Cutting Conditions

The influence of cooling conditions and surface topography after finish turning of Ti6Al4V titanium alloy on corrosion resistance and surface bioactivity was analyzed. The samples were machined under dry and minimum quantity lubrication (MQL) conditions to obtain different surface roughness. The surface topographies of the processed samples were assessed and measured using an optical profilometer. The produced samples were subjected to electrochemical impedance spectroscopy (EIS) and corrosion potential tests (Ecorr) in the presence of simulated body fluid (SBF). The surface bioactivity of the samples was assessed on the basis of images from scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis. The inspection of the surfaces of samples after turning under dry and MQL conditions revealed unevenly distributed precipitation of hydroxyapatite compounds (Ca/P) with a molar ratio in the range of 1.73–1.97. Regardless of the cutting conditions and surface roughness, the highest values of Ecorr ~0 mV were recorded on day 7 of immersion in the SBF solution. The impedance characteristics showed that, compared to the MQL conditions, surfaces machined under dry conditions were characterized by greater resistance and the presence of a passive layer on the processed surface. The main novelty of the paper is the study of the effect of ecological machining conditions, namely, dry and MQL cutting on the corrosion resistance and surface bioactivity of Ti6Al4V titanium alloy after finish turning. The obtained research results have practical significance. They can be used by engineers during the development of technological processes for medical devices made of Ti6Al4V alloy to obtain favorable functional properties of these devices

Analysis of Power Grid Parameters Depending on the Variable Concentration and Size of Copper Nanoparticles and Aerosol Formation Parameters in the Minimum Quantity Lubrication Method During Turning of Ti6Al4V Titanium Alloy

Titanium alloys belong to the group of difficult-to-cut materials, machining of which leads to a number of challenges including large thermal loads on the cutting inserts and difficulties in obtaining a high quality machined surface. Great cutting forces, in turn, result in increased energy consumption. Therefore, it becomes important to attempt to reduce the amount of power consumed during machining, which can be achieved, among other things, by reducing the value of the coefficient of friction in the cutting zone. This paper presents a study on the influence of the size as well as the Cu nanoparticle concentration added to cutting fluid in MQL method on the power grid parameters while turning of Ti6Al4V titanium alloy. In this research, nanoparticles of 22 nm and 65 nm at concentrations of 0.5 wt% and 0.75 wt% were used. Turning process was carried out with constant cutting parameters and variable aerosol formation parameters, i.e. mass flow rate of nanofluid and volumetric flow rate of air. Based on the study, the use of 22 nm nanoparticles at 0.5 wt% concentration is recommended to achieve the smallest monitored values of the power grid parameters. The statistical analysis revealed that, out of the aerosol formation parameters considered, both the air flow rate and nanofluid flow rate do not significantly affect the values of the analysed power network parameters. However, the most significant factor is the variable nanoparticle size