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This paper is focused on the study of abrasion using a multi-scale roughness analysis of Extreme Amplitude of Peaks to Valleys (EAPV) on stainless steel (316L) surfaces polished with different grit abrasive papers. In order to examine the different abrasive mechanisms at all scales, roughness measurements are carried out. From the log–log plot of the maximum peaks height or maximum valleys depth amplitude...
Tool wear in machining processes strongly depends on the tool–chip interface. The sliding–sticking zones at this interface depend on the evolution of the local conditions of stress, velocity and temperature. Several authors have shown that because of the complexity of the tool–chip contact, the tribological conditions are not fully understood and accurate predictive models have yet to be developed...
It is well known that dimpled surface can improve tribological characteristics. The fundamental aim of the present research is to demonstrate the process of making micro-dimples by ultrasonic nanocrystalline surface modification (UNSM) technology and to evaluate its effects on tribological characteristics. Ball-on-disk test was performed in order to reveal the influence of mechanism and micro-dimples...
In the lubricated upsetting process, it is well known that the coefficient of friction over the contact surface between the tool and the workpiece is distributed nonuniformly and changes with the reduction in height and the position at the interface. In order to increase the reliability of the numerical simulation of cold forging processes, more precise input data of the coefficient of friction at...
This paper demonstrates a new method to extract the friction stress τ from measurements in wire drawing. It is based on simultaneous measurement of drawing force and die temperature; an analytical thermo-mechanical model of the wire drawing operation is used to separate the plastic work W pl from the frictional work. Thanks to the exploitation of the temperature measurement, the necessity...
Environmental protection is an important issue among current manufacturing. Meanwhile, tribology in metal forming is making a great contribution to solve the problems related to both environmental and manufacturing aspects. High performance hard coatings and lubricants are in great demands for solving those problems. Diamond-like-carbon containing silicon, DLC-Si, which is an attractive material to...
Tool damage in sheet metal forming of stainless steel is of high concern for the forming industry. In the present work, ingot cast AISI D2 and advanced powder metallurgy tool steel (PM) cold-work tool steels were evaluated and ranked regarding wear mechanisms and galling resistance. Wear tests were performed using a slider-on-flat-surface (SOFS) tribometer in sliding against austenitic–ferritic (duplex)...
This paper presents the application of an experimental set-up able to simulate similar tribological phenomena as the ones occurring at the tool–chip–workpiece interface in metal cutting. Especially, this system enables to reach contact pressures up to 3GPa and sliding velocities between 0 and 300m/min. In addition to classical measurements of friction coefficients, the system provides information...
The accuracy of forging simulations depends on a lot of parameters. Among them, the tool/workpiece behaviour has a crucial importance. The present paper deals with the processing of experimental data from a versatile friction test device which allows the recording of experimental normal and drag forces on the actual workpiece surface. Tests can be carried out for various sliding velocities, tool and...
The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a more advanced friction model for large-scale forming simulations based on the surface changes on the micro-scale...
Most machining operations require the presence of a cutting fluid in order to ensure their success due to the intensity of thermal and mechanical conditions generated on the cutting tools. In some cases of severe machining, the fluid contributes to lubrication in a physicochemical way thanks to the additives it contains. This study aims to analyze the tribochemical mechanisms of lubrication during...
In the present investigation a series of orthogonal hard turning tests were conducted to study the effects of tool wear and cutting parameters (cutting speed and feed rate), on white and dark layer formation in hardened AISI 52100 bearing steel, using PCBN inserts. Experimental results were presented including quantification of tool wear and microstructure analysis of the machined surfaces. The experimental...
Sliding contact under high pressure between a more or less rough metal surface and a polymer occurs in diverse manufacturing processes. Transfer of the softer material on the harder counterpart is a common phenomenon under such conditions (high pressure) due to high level of polymer wear. The transfer of worn polymer particles on the metal surface generally has a large influence on friction. A model...
In the press forming, dry press forming would be required for environmental problem. In this study, a diamond-like-carbon (DLC) for achieving the dry press forming was applied to the surface of blanks. Then, the effect of the deep-drawability of A5052 aluminum alloy sheet with DLC-coating was investigated due to improve the formability in dry press forming. The deep-drawing experiments were carried...
Tip test is a friction measurement technique for forging process based on upsetting and backward extrusion with a specimen of which the diameter is larger than the punch and smaller than container. Due to the smaller diameter of the specimen, a sharp tip was formed during deformation and a unique linear relationship between the tip distance and maximum load measured was found. In the present paper,...
A new concept of sensor is proposed to measure friction at roll–strip interface during strip rolling. By measuring elastic strains inside the roll, it is possible to evaluate contact stresses at roll–strip interface using an inverse analysis, with the great advantage not to mark the strip with the sensor. Using simulations, this new sensor is designed and its ability to evaluate contact stresses is...
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