Máquinas, procesos, personas y datos, las claves para la revolución 4.0

Postprint (published version

Joining metrics enhancement when combining FSW and ball-burnishing in a 2050 aluminium alloy

This report describes the effect of the ball-burnishing process on the mechanical properties of 2050 aluminium alloy that was previously friction stir welded. This process is a fast, environmentally-friendly and cost-effective surface treatment based on the plastic deformation of the surface irregularities. Consequently, residual stress, material hardening and micro-structural alterations are investigated to improve fatigue strength and wear resistance. The results show that the ball-burnishing treatment enhances the surface properties by increasing the material hardness about 37.5% and by decreasing the average surface roughness from 2.23¿µm to 0.06¿µm when a high pressure and a perpendicular burnishing is deployed. Additionally, in-depth compressive residual stresses are generated from -315¿MPa to -700¿MPa depending on the burnishing configuration. Finally, a numerical simulation of the material elastoplastic response is performed to analyze the residual stress continuity in the cross sectional area when using two radial feeds and burnishing pressures. In short, the present study helps to reduce time consumption by selecting the larger radial feed combined with a proper burnishing pressure to ensure the desired quality and compressive residual stress at the surface, which are indices of enhancing the fatigue strength at the nugget zone of the welded area.Postprint (author's final draft

Joining metrics enhancement when combining FSW and ball-burnishing in a 2050 aluminium alloy

This report describes the effect of the ball-burnishing process on the mechanical properties of 2050 aluminium alloy that was previously friction stir welded. This process is a fast, environmentally-friendly and cost-effective surface treatment based on the plastic deformation of the surface irregularities. Consequently, residual stress, material hardening and micro-structural alterations are investigated to improve fatigue strength and wear resistance. The results show that the ball-burnishing treatment enhances the surface properties by increasing the material hardness about 37.5% and by decreasing the average surface roughness from 2.23¿µm to 0.06¿µm when a high pressure and a perpendicular burnishing is deployed. Additionally, in-depth compressive residual stresses are generated from -315¿MPa to -700¿MPa depending on the burnishing configuration. Finally, a numerical simulation of the material elastoplastic response is performed to analyze the residual stress continuity in the cross sectional area when using two radial feeds and burnishing pressures. In short, the present study helps to reduce time consumption by selecting the larger radial feed combined with a proper burnishing pressure to ensure the desired quality and compressive residual stress at the surface, which are indices of enhancing the fatigue strength at the nugget zone of the welded area

The use of hybrid CO2+MQL in machining operations

Nowadays, the environmental concern in machining industry is a fact. Because of that, in this article a new cooling-lubrication system which combines CO2 cryogenic and MQL technologies is presented. The aim of this new cooling-lubrication system is to offer an ecological and economic efficient alternative. Two nozzle adapters are proposed with different CO2 outlets. The developed nozzles are Plug & Play and directly applicable to commercial MQL systems. The behaviors of nozzle adapters were simulated by CFD (Computational Fluid Dynamics) and the optimal nozzle adapter was tested by milling Inconel 718 ®. In these milling tests, the tool life was measured and using different main cooling-lubrication techniques: dry, wet, CO2 stand alone, MQL stand alone and CO2+MQL (proposed alternative)Postprint (published version

Wear and MnS layer adhesion in uncoated cutting tools when dry and wet turning free-cutting steels

Free-cutting steels are developed to produce large quantities of parts with low mechanical behavior, mainly for automotive sector. These alloys contain phosphorous, lead, sulfur, and manganese that help to improve the machinability and surface roughness. However, due to the toxicity of lead, steel mills in recent years have been focusing on non-toxic steels to produce minimum environmental pollution and better machinability. The present work investigates the tool wear during dry and wet turning of free-cutting steels (SAE 1212, SAE 12L14, and SAE 1215) by using uncoated hard metal inserts at three cutting speeds. Additionally, a EDS analysis was performed to determine the presence of Mn and S elements at the rake face of the cutting tool that can induce a higher adhesion of manganese sulfide (MnS). The results show that the SAE 12L14 steel has the best performance in terms of tool life at di erent cutting speeds. This difference is maximum at the lowest cutting speed, which gradually decreases with the increase of the cutting speed. The wear behavior is evaluated in the three steel alloys at each cutting speed and, consequently, the tool wear exhibits a slightly better performance in the dry machining condition for higher cutting speeds (180 and 240 m/min), independent of the steel alloy. Finally, EDS analysis confirms the presence of Mn and S elements at the rake face of the inserts machined in dry condition. Hence, MnS is expected to interpose between the machined surface and cutting tool surface to behave similar to tribofilm by reducing the wear on the cutting edge.Peer Reviewe

The use of hybrid CO2+MQL in machining operations

Nowadays, the environmental concern in machining industry is a fact. Because of that, in this article a new cooling-lubrication system which combines CO2 cryogenic and MQL technologies is presented. The aim of this new cooling-lubrication system is to offer an ecological and economic efficient alternative. Two nozzle adapters are proposed with different CO2 outlets. The developed nozzles are Plug & Play and directly applicable to commercial MQL systems. The behaviors of nozzle adapters were simulated by CFD (Computational Fluid Dynamics) and the optimal nozzle adapter was tested by milling Inconel 718 ®. In these milling tests, the tool life was measured and using different main cooling-lubrication techniques: dry, wet, CO2 stand alone, MQL stand alone and CO2+MQL (proposed alternative