Some characteristics of surfaces machined with abrasive waterjet turning

This paper presents an experimental study of abrasive waterjet turning of an extrusion aluminum alloy (AlMg0,7Si). The aim of the paper is to determine differences of two methods from the point of view of machined surface quality and the depth of penetration, i.e., the diameter of the parts after the turning process. During the experiments, the traverse speed of the cutting head and the rotation of the turned parts were changed, other parameters, like pressure of the water, abrasive mass flow rate were kept constant. Diameter and some surface roughness parameters of the test parts were measured after the machining. On the base of experimental results, advantages, and disadvantages of two methods are explained in the paper.

The bed: element of peasant furniture on the territory of the Republic of Moldova, late XIX - middle of XX century

In this article, our attention is focused on the BED as an element of peasant furniture, on the territory of the Republic of Moldova (late nineteenth century - mid-twentieth century). The bed derives in most cases from the bench. As furniture with a special shape, the bed appears in the rural house in the 19th century, first in wealthy families. It is more widespread in the interwar period and after the Second World War. According to the system of joining the parts, the classification of beds can be divided into two categories: beds joined in «feather and gutter»; beds joined with «plug and hollow». The tables present the largest decoration of the bed through various wavy profiles, through variations of planes, turned parts, in rare cases decorated with simple paintings or by imitation veneer. The detailed analysis of the peasant furniture, and of the beds, in particular, starting from the craftsman, who made this furniture, the execution and decoration technique used, tell us about the tendencies of a period, which is worth following closely to better understand the artistic peculiarities of the furniture and traditional art.

Surface Texture after Turning for Various Workpiece Rigidities

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A detailed analysis of 2D surface profiles was carried out by using a large number of parameters that allowed us to distinguish significant differences in the surface microgeometry, which confirmed that determining surface characteristics from one height parameter (Ra—arithmetical mean height) is far from sufficient. The obtained results indicate significantly better roughness and waviness values of the AISI 304 steel surfaces in terms of its size, periodicity, and regularity. Therefore, the turning process of AISI 304 shafts with low rigidity allows one to be able to achieve better quality texture and have a positive effect on the general properties of a workpiece. In all tested samples, surface irregularities decreased along with the distance from the tailstock. The shafts with an L/D ratio of 12 had worse surfaces in the first two sections due to lower rigidity. The results received close to the three-jaw chuck, regardless of the L/D ratio and material type, demonstrated similar waviness and roughness parameters and profiles.

FEA Modelling of the Combined Hard TurningRolling Process Used at Bearing Rings

In general, the production of bearings is a very large series production, which is why in production the technological lines are designed to process a single size of bearings. Changing the production line for different types of bearings is expensive and time consuming, especially where grinding and honing processes are required. An alternative to these abrasive processes is hard turning. The literature indicates that due to highprecision machines, the accuracy of hard-turned parts is comparable to grinding processes. It is also indicated that the integrity of the surface and the topography of the surface together with the residual induced stresses are parameters of interest and that influence the performance of the bearings. So one method of increasing the durability of the bearings is to ensure a low roughness of the elements and high residual induced stresses. Deep rolling is considered as an alternative to honing and rectification processes. Rolling can induce higher surface stresses in the material compared to honing and grinding. The present paper proposes a combined cutting tool made of a hard turning head and a rolling cutting tool for machining bearing rings. A simulation of this combined process is performed with the help of the finite element and thus the internal stress field, the temperature fieldand the topography of the processed surface aredetermined.

In-process and ex-situ measurement techniques for the characterization of surface conditions during cryogenic hard turning of AISI 52100

The surface layer states of a component are of great importance for the application of hard turned parts. Without a multitude of tests and experience, the states cannot be reliably produced due to process-typical disturbance variables such as tool wear and batch inclusions. The aim of this research is to control the surface layer states during cryogenic hard turning of AISI 52100 by feedforward control and the use of a soft sensor. This paper presents the measurement techniques used in this context. On the one hand, the in-process measurement technology and challenges involved are discussed. On the other hand, the challenges in the ex-situ measurement technique for characterizing the surface layer states are shown using micro hardness measurement as an example.

Lines in the Mud: Tank Eco-restoration and Boundary Contestations in Chennai

This article analyses the politics of environmentalism revealed in struggles over the land–water boundary of an urbanising tank in Chennai. In contesting this boundary, property-less settlers on its banks called into question the tank’s ‘nature’ and functions in its urban milieu, and demanded a redrawing of boundaries to reflect the socio-natural transformations that had turned parts of it into land. Simultaneously, propertied residents, in concert with state eco-restoration schemes and court rulings, fought to restore the tank to its ‘original’ dimensions. In foregrounding the liminalities of the urbanising tank, this article suggests the limits of the contemporary property-determined eco-restoration discourse, premised on a return to pristine pasts and original boundaries. It proposes that the stand-off between water body restoration and the defence of working-class housing rights necessitates recognising the tank as an artefact assembled over time by socio-technical and natural processes.

Recent Advances in Turning Processes Using Coated Tools—A Comprehensive Review

Turning continues to be the largest segment of the machining industry, which highlights the continued demand for turned parts and the overall improvement of the process. The turning process has seen quite an evolution, from basic lathes using solid tools, to complex CNC (Computer Numerical Control) multi-process machines, using, for the most part, coated inserts and coated tools. These coatings have proven to be a significant step in the production of high-quality parts and a higher tool life that have captivated the industry. Continuous improvement to turning coated tools has been made, with many researches focusing on the optimization of turning processes that use coated tools. In the present paper, a presentation of various recently published papers on this subject is going to be made, mentioning the various types of coatings that have recently been used in the turning process, the turning of hard to machine materials, such as titanium alloys and Inconel, as well as the interaction of these coatings with the turned surfaces, the wear patterns that these coatings suffer during the turning of materials and relating these wear mechanisms to the coated tool’s life expectancy. Some lubrication conditions present a more sustainable alternative to current methods used in the turning process; the employment of coated tool inserts under these conditions is a current popular research topic, as there is a focus on opting for more eco-friendly machining options.