Materials Science Forum Vol. 526

Abstract: In an increasing competitive market where offer exceeds demand, developing customer value is nowadays a key driver of industrial activities. Reducing costs, increasing quality, deliver on time and the introduction of the right product quickly are unavoidable elements to succeed. A higher product variety for mass production and short lead-time are main features of mass customization. Flexibility arises as a productive and competitive factor to face it, of particular interest in assembly systems, which allow the postponement of final variety, integrating all former tasks of the supply chain. In this scenario, flexibility helps to face uncertainty in decision-making, while the increase of system complexity requires extra control and management efforts. Both flexibility and complexity are briefly reviewed. Next, it is introduced a joint analysis of flexibility and complexity useful for decision-making. Both are linked to the uncertainty of the possible states of the system and a quantitative approach of general application is presented. Finally, based on a model simulation, a first case application illustrates product variety increase in an assembly system and some decisionmaking trade-offs.

Abstract: Frequently, to validate FEM simulations of the cutting process it is compared the predicted results with the experimental cutting forces. In addition, other parameters are measured and it is possible to predict the chip geometry in some particular conditions. This paper presents a new development of the photogrammetry and its applications in the study of the chip geometry. In the orthogonal milling case, it is possible to obtain a 3D model of the deformed chip employing photogrammetry digitization techniques.

Abstract: Many investigations have been developed related to precision machining with features in the millimetre scale. In this paper different cutting force models for micromilling are analyzed and compared. A new model based on specific cutting force that also considers run-out errors has been developed. The estimated cutting forces obtained with this model had good agreement with the experimental data. Also, the proposed model allows to be implemented within the machine control for the on-line optimization of the micromilling process.

Abstract: The equal channel angular drawing (ECAD) process is an innovative method to obtain materials with high plastic strain in a continuous way. This deformation is higher than the deformation achieved by a conventional wire drawing process, for the same reduction of the cross section, so if an adequate thermal treatment is employed later, it could be possible to obtain an initial material with high value that could be useful in conventional manufacturing processes. This process consists in drawing a material through a die where two circular channels intersect at an angle between 90º and 135º. In this work a study using finite element of the plastic strain and the stresses that appear for one aluminium alloy AA-1370 has been carried out. Two ECAD passes have been made, where for the second pass the billet has been rotated 180º along the longitudinal axis. Finally, a calibrated pass has been carried out in order to obtain the billet with homogeneous dimensions in all the cross section. All the simulations have been calculated at room temperature and by using good conditions of lubrication. In order to perform the FEM simulations, a three dimensional geometry has been used. To analyze by FEM the second ECAD pass and the calibration pass, the deformations and stresses achieved in the previous passes have been taken into consideration. This has been done with the aim of achieving higher accuracy. Moreover, a comparative analysis with experimental results has been carried out.

Abstract: The main objectives of this work are the study of the obtained surface roughness on steels, using face cutting edge inserts milling tools in finishing face milling operations with microlubrication (MQL), and comparison of the results obtained with the widely-used radius inserts. This experimental study analyzes the roughness and surface appearance obtained with both sort of inserts. The interest about this study is to determine the steel types and the optimal cutting conditions for milling with this face cutting edge inserts. Another result analysed is the utility of the MQL implementation compared to the dry system.

Abstract: Light alloys are increasingly applied in different industrial sectors, mainly aerospace. Because of this, it is needed to analyze their behavior in the different processing procedures and, specially, machining. On the other hand, up to a few years, cutting fluids were successfully employed in these processes since their coolant and lubricant properties. Notwithstanding, environmental necessities have promoted researches focused on the development of cleaner processes avoiding cutting fluids, in particular, dry machining. However, this process can change tool geometry and affect to the material giving rise to changes in the design specifications. In this work, geometrical deviations, particularly straightness deviations, in the dry turning of UNS A92024 (Al-Cu) alloy are studied as a function of feed and cutting speed through a parametric model.

Abstract: In this paper, a 3D dynamic model for the prediction of the stability lobes of high speed milling is presented, considering the combined flexibility of both tool and workpiece. The main aim is to avoid chatter vibrations on the finish milling of aeronautical parts, which include thin walls and thin floors. In this way the use of complex fixtures is eliminated. Hence, an accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor.

Abstract: For effective rough milling, an optimized criterion is required to select the feedrate. In this study, a method to obtain the most appropriate reference cutting force for rough milling was developed. The reference cutting force was determined by considering the transverse rupture strength of the tool material and the area of the rupture surface. A finite element method analysis was performed to accurately calculate the area of the rupture surface. Using the analyzed results, the effect of various cutting parameters on the chipping phenomenon was determined. The calculation method for the reference cutting force considered the area of the rupture surface, the effect of the rake angle, and the axial depth of cut. The experimental results clearly show that the reference cutting force obtained from the proposed method met the desired constraints.

Abstract: The objective of this study is to compare the machinability of a sintered steel sample with that of a nodular graphite iron sample. We have developed a method that not only allows us to study the machinability, but also enables us to determine the optimum cutting conditions to suit criteria for maximum production or maximum quality. The method is based on a drilling test using constant axial force at the tip of the drill.