Papers by Keyword: Machinability

Abstract: In the first part of this paper inclusion morphology and factors influencing machinability of structural steels are shortly discussed. In the experimental part of this work the effect of calcium addition on the inclusion morphology transformation and the machinability Bindex (according to Volvo standard) for several grades of structural steels are presented.

Abstract: The development of micro-products in industry, like aviation, medical equipment, electronics, etc, has been increasing lately. The need for scaling down of product has been increasing to make the product simpler and complex. Micro-milling has capabilities in producing complex parts. In this study, mapping and comparing the result of the machining process of Inconel 718 and Aluminum Alloy 1100 was employed. In this experiment, Inconel 718 was used as workpiece material and the result of Aluminum Alloy taken from recent studies. Then, A cutting tool with a diameter 1 mm carbide coating TiAlN was used in this experiment. The machining process was performed with three varieties of spindle speed and feed rate with a constant depth of cut. After the machining is done, the mapping of the result surface roughness of Inconel 718 and AA1100 performed. It was found that Inconel 718 has poor machinability compared with AA 1100. Inconel 718 also has a high manufacturing cost compared to AA 1100 because the cutting tool was easy to wear.

Abstract: Based on the hypocycloid theory, a highspeed orthogonal cutting simulation model was established. The cutting parameters (cutting speed, feed rate) and plane forming angle of the workpiece of aeronautical aluminium alloy 7050-T7451 pre-stretched rolled sheet were simulated and validated. The mapping relationship between cutting parameters, anisotropy and cutting performance was analyzed. The results show that the degree of anisotropy and the difficulty of material cutting are proportional to the forming angle, and the anisotropy decreases with the increase of cutting speed and the decrease of feed speed. Finally, the optimal cutting process range of aluminum alloy 7050-T7451 was obtained, which provides data support for highspeed cutting of anisotropic materials.

Abstract: This paper presents a research conducted in order to identify the cutting parameters effect on turning cutting forces and on the resulted machined surface quality for a CoCrWNi alloy. This alloy is a biomaterial used in medical applications for implants manufacturing. The main objective of the research is the development of prediction models for the turning cutting forces and the Ra roughness parameter for dry longitudinal turning with TiAlN PVD coated inserts. In order to achieve this objective, thirteen processing experiments were carried out, during which the cutting forces and roughness parameters were registered. The research results consist of the prediction models for cutting forces and Ra roughness parameter.

Abstract: Ultrasonic-assisted drilling (UAD) is a new process used for producing holes in the hard-to-cut and brittle materials at high accuracy and surface quality. In this paper, statistically designed experiments were conducted to study the machinability of soda glass in UAD. The machinability was measured in terms of the cutting power, surface roughness Ra and Rz and the linear tool wear. Machining conditions include UAD and conventional drilling (CD), abrasive tool concentration, feedrate, and spindle speed. Analysis of variance (ANOVA) defined the significant factors and their interactions, while statistical models were used to predict the process responses used for assessment of machinability indices.

Abstract: Guidelines for production milling, turning and drilling of the standard grades of austempered ductile irons (ADI) have been established. Electron Backscatter Diffraction (EBSD) characterization has clearly shown that severe plastic deformation in the machining-affected-zone, ahead of and beneath the cutting tool, will cause strain-induced martensitic transformation of the austenite in the ausferrite structure that inhibits machinability. This phenomenon is particularly of concern during finish machining where small depths of cut are strongly influenced by surface martensite from prior machining passes.

Abstract: A new method was adopted in this study to machine C/SiC composite. The machinability was studied by processing some shapes in the material in this way. Small deep holes were machined firstly to test whether the copper electrode was suitable enough to be adopted in the Electrical Discharge Machining. Then holes of different diameters were processed by two kinds of electrodes to study the more appropriate electrode material by comparing machining efficiency of two electrodes. Then complicated shapes were machined based on these conditions. Finally, a simulation model was built up to study the influence of the fluid on the electrode and the workpiece in the Fluent 6.3. According to the study, Electrical Discharge Machining Technology is suitable enough to machine the hard and brittle materials like C/SiC composite and the accuracy that the error should not exceed 0.5 mm can also be guaranteed well.

Abstract: A car manufacturer makes crankshafts of materials from various suppliers. The steels from individual batches differed in their grinding behaviour, despite being supplied as a single steel grade. Some deliveries were repeatedly associated with much faster wear of grinding wheels than others. Consequently, the ground surfaces of the crankshafts developed visible patterns and, in some cases, surface cracks. The excessive wear in grinding wheels was suspected to be caused by titanium precipitates. The purpose of this investigation was to identify the phases in which titanium is present in the steels, describe the morphology, sizes and distribution of their particles and compare these aspects for materials from the three suppliers. It was found that titanium was present in the form of carbides or carbonitrides, whose morphology, sizes, distributions and quantities of particles varied greatly between the suppliers. These variations were identified as the cause of the differences in grinding behaviour.

Abstract: The Compacted Graphite Iron (CGI) represents an example of material with remarkable and unexplored properties, especially in terms of resistance and machinability. With better strength and stiffness than several cast irons, as Grey Iron, and better castability, machinability and thermal conductivity than others, as Ductile Irons, this alloy would be, at least theoretically, the perfect material choice for a wide range of practical applications. Nevertheless, discovered more than 50 years ago, it has failed to establish itself in a definitive way. This review intends to highlight benefits and limits in choosing CGI in casting.

Abstract: In this paper, the experimental studies of the finish turning of Ti-6Al-4V titanium alloy with the laser-assisted machining were described. For the tests, a cemented carbide tool was used. The influence of the laser heating on the microstructure of Ti-6Al-4V titanium alloy for kinematics corresponding with the turning process was determined. For a laser scanning rate of 80 m/min and laser power 1200W, the maximum depth of the melted zone was about 50 μm. The beneficial effect of laser assisted machining on components of the cutting force was established. For a cutting speed of 80 m/min, feed rate 0.1 mm/rev, depth of cut 0.25 mm and laser power 1200 W, over 60% reduction of the tangential components of cutting force was observed. The chip-breaking effect for the conventional and the laser-assisted processes was determined. Roughness parameters of the surface after the conventional and laser-assisted turning are compared.