Papers by Keyword: Chip Formation

Abstract: A great deal of effort and research has been dedicated to recycled aluminum alloys, mainly to recycling processes and to the mechanical properties of recomposed parts; however, very limited work has been oriented towards the machinability of recycled aluminum materials. Recycled and recomposed aluminum parts sometimes need machining to obtain the final usable part shape and for assembly purposes. The acceptability of using recycled materials in design and engineering applications depends not only on their mechanical properties, but also on their machinability. This paper investigates the machinability of recycled aluminum alloys based on surface finish, cutting forces and chip formation. Two recycled foundry aluminum alloys were used: one from aluminum can covers and another from aluminum chips produced during machining. The machining operations investigated included turning and drilling under dry and wet conditions. The two tested recycled aluminum alloys showed different machinability behaviors and different part quality characteristics, suggesting that it would be desirable to consider separating aluminum wastes and chips considered for recycling by origin or type prior to melting and recasting.

Abstract: Titanium alloys are commonly used for many aerospace and medical applications because of their properties like high strength to weight ratio, corrosion resistance and heat treatment capabilities. But, due to the factors like low thermal conductivity and chemical reactivity with the cutting tool, it poses a challenge for the machining operations. In this study, a 3D Finite Element Model of the milling process of Ti-6Al-4V, titanium alloy has been developed using Deform 3D FE software. Milling was done experimentally under different speeds and feed rates using a Tungsten carbide end mill cutter. The cutting forces obtained from FEM study were compared and validated with the experimental results. The machinability of the Titanium alloy was investigated using cutting forces and chip microstructure.

Abstract: High-speed cutting (HSC) or high-speed machining (HSM) is an issue that the scientists deals with in long-term. To demonstrate the explicitness, that a full HSC machining process is considered, it is necessary to monitor the series of factors. In particular, the process of chip formation, cutting forces, cutting temperature, vibration, tool life and surface finish quality in relation to the method of machining, machined material and its properties. The article deals with the detailed analysis and evaluation of the chip formation in order to determine the hard area, transition area and veritable HSC machining. The evaluation process is based on the proposed experimental model, which is confronted with the measurement results.

Abstract: The chip formation mechanism during precision cutting of metallic glass (Zr₅₅Cu₃₀Ni₅Al₁₀ at%) was investigated around the glass transition temperature (673 K). Orthogonal cutting of metallic glass are conducted on a fly-cutting machine at various cutting speeds. The new surface of the chips was slightly shiny while the free surface exhibited lamellar slip structure. The cutting temperature was a proportional to the cutting ratio and chip shear angle. The surface integrity worsened with an increased flow of cutting chip due to an increase in the cutting speed. An increase in the cutting temperature caused the chips formation to change from flow type chips to discontinuous chips. When the cutting speed exceeded 300 m/min, the shear angle increased while the shear pitch of the chips decreased. It appears that when the cutting temperature exceeded the glass transition temperature, the strength of the metallic glass decreased and the ductility mode changed due to viscous flow.

Abstract: Residual stresses in fused silica induced by two machining methods, diamond blade saw cutting and GC grinding wheel grinding, are studied in this study. Photoelastic method would be applied as measuring tool analyzing the gradient of residual stresses caused by different machining condition. This sentence is strange with analyzing the chips of grinding and observation of surface defects, it is assumed that the stresses gradient differs probably cause by the different material removal mechanism.

Abstract: A modern meshless method known as Smooth Particle Hydrodynamics (SPH) was involved in achieving numerical simulation of chip formatting during the orthogonal cutting of AA6060-T6 alloy with the aim of finding a convenient method for investigating the chip formation and reducing the costs of experimental research by involving numerical simulation in order to get information about the parameters describing the process. Based on a few experimental orthogonal cutting results the procedure to achieve a proper numerical simulation of the chip formation process is presented. The procedure and the results may be applied when simulation data and prognosis data about machining AA6060-T6 data are needed.

Abstract: Cutting fluid is a well-known as one of an important element in machining process. However, the consumption of mineral oils as cutting fluid has been raising concern due to worldwide interest in environmental and health matters. The application of vegetable-oil based lubricant is seen can overcome the problem but requires a research study about the machinability. This research paper represents the machinability of using several possible vegetable oils as cutting fluid in term of chip formation and tool wear during drilling operation on stainless steel, AISI 316. In particular, the performance of the vegetable oils; palm, sesame, olive and coconut oils were compared under minimum quantity lubrication (MQL) technique. The result reported that the coconut oil indicates the best machinability in term of highest and uniform chip thickness and least wear on the drill bit under same condition with others. These performances are followed by palm, olive and sesame oil. In additional, the viscosity measurement indicates that coconut oil has the lowest value which can possesses better fluidity and faster cooling capacity than other oils. Overall, coconut oil is recommended as viable alternative lubricants during drilling of stainless steel.

Abstract: Titanium Alloys are unique due to their high strength-weight ratio,good fracture and corrosion resistance characteristics.They form a significant metal portion of the aircraft structural and engine components. However, their low thermal conductivity and high reactivity with cutting tools during machining, makes them difficult-to-machine materials. In this work, an investigationof the thrust force, torque and chip morphology in drilling of Ti6Al4V, titanium alloy using tungsten carbide tipped drill has been carried out at varying cutting speeds of 19.4, 27.14, 43.41 and 67.82m/min at a constant feed rate of 0.15mm/rev.The machinability, work hardening and thermal softening effects of titanium alloy, during drilling, has been analysed through the effects of the machining process on the thrust force, torque and chip microstructure.

Abstract: The paper considers the intensity degree of a plastic shear deformation e_i when cutting, the results of experimental studies that determine a travel trajectory of a cutting material layer through a plastic deformation zone in a chipping area and comparative analysis of deformation conditions of a sample material machined by various tool rake angles (γ=0o and γ=15o).

Abstract: Chip formation is a dynamic process that is often nonlinear in nature. A chip may not form when the depth of cut is less than a minimum chip thickness. It is aimed to investigate influence of depth of cut on contact phenomenon in micromachining. This paper presents a series of simulation works by finite element method on depth of cut effect on micromachining. A model is developed with consideration of the Johnson-Cook material and Arbitrary Lagrangian–Eulerian (ALE) method. In this work investigate the effect of depth of cut on the contact phenomenon during micromachining AISI D2. The results of the analysis are showed in aspects of interrelationship between material separation and frictional shear contact, distribution of stick-slide regions and contact stress on the work piece and cutting tool. It is found that the sticking and sliding was occurred on three zones as primary, secondary and tertiary shear zone. The contact phenomena can be showed around the tool edge radius where material flows around it and piles in front of the cutting tool through material separation. The investigation of contact phenomena inclusive under three criteria such as a/r < 1, a/r > 1 and a/r = 1 on positive rake angle.