Flood and through-tool delivering of cutting fluids have been widely used for the machining operations. The use of a large amount of cutting fluid can impact the environment and increase manufacturing costs, and possibly lead to ground contamination, excess energy consumption, the need for wet chip disposal and potential health and safety issues. Minimum Quantity Lubrication (MQL) machining involves the application of a minute amount of oil-based lubricant to the machining process in an attempt to replace the conventional flood coolant system. This paper presents a classification of MQL methods, discussing their advantages and drawback. Also, the results of measurements of cutting forces and surface roughness when machining one type of aluminum bronze using MQL, are presented. As a medium for cooling and lubricating a system of oil-on-water was used. The results show that the cutting force of less than 16%, and also parameters of surface roughness, compared to machining without the use of coolant and lubricants. Keywords: mql machining, oil-on-water droplet, aluminium bronze, cutting forces, surface roughness.

Damage in a structure is a local perturbation of its physical characteristics, i.e. its stiffness, mass and/or damping. Consequently, damage alters dynamic characteristics of the structure such as natural frequencies, damping value and mode shapes associated with each natural frequency. This is the base of vibration based structural health monitoring techniques. In this paper characteristics of mode shapes are investigated for identifying the location of damage in a beam structure. Cantilevered beam model is investigated numerically by use of finite element method. Slope and curvature of displacement mode shapes differences (between intact and damaged structure) were calculated using a central difference approximation. The results have shown that changes in the mode shape characteristics are good indicator of damage location and severity, and hence can be used to detect damage in a structure.

Machinabilty is a very important feature of materials subjected to machining process and can be analyzed from various aspects. The main question of many machinability studies is, “What are the influencing factors on the machinability?” This work describes experimental investigation on influence of cold flow forming process onto cutting force changes in machining of a 99.5% Al workpiece. the aim of the work is to find if and to what extend the cutting force is changed after plastic deformation in the process of cold flow forming. Full factorial plan has been applied in experimental works on three specimens, one before and two after plastic deformation. Cutting forces were measured by means of a three-component Kistler dynamometer Type 9265B. Regression analysis is performed in Microsoft Excel Data Analysis Package for both specimens. Obtained results have been compared and confirmed the fact that there are significant differences in character of the cutting force changes between undeformed and plastically deformed workpieces.

The surface roughness was the subject of experimental research during cutting steel 30NiMo8 with cermet tool under different cutting conditions. For experimental work the experimental plan was

For time and cost saving reasons, the lowest surface roughness possible is sought in milling operations. High speed milling is recommended in order to minimise the amount of material to be removed in subsequent finishing operations, e.g. grinding, electrical discharge machining or manual polishing. Several roughness parameters are usually employed for the characterization of polished surfaces. In this paper relevant roughness parameters are determined for polishing operations after side milling with cylindrical milling tool or after ball-end milling. It was observed that, in polishing operations after side milling, most relevant parameters are average roughness parameters such as Rk and Ra. On the contrary, in polishing operations after ball-end milling most relevant roughness parameters are those related to peaks, such as Rpk and Mr1.

AIM To investigate the changes in pretransfusion testing during the switch from the agglutination tube test to the gel test. METHODS Clinical significance of positive results has been analyzed in 7667 pretransfusion tests (with 16610 cross-matches) performed by the tube test in 2005-2006, and in 7372 pretransfusion tests (with 17294 cross-matches) performed in 2007-2008 by the gel test. RESULTS In both analyzed periods antibody detection was positive in 1.3% and cross-matching in 0.3% cases. At least one test was positive in 1.4% pretransfusions tested by the tube test and in 1.3% by the gel test, with >75% positive results in women. Analyzing cases with positive cross-matching but negative antibody detection, eight of ten such cases found by the tube test were caused by 'cold antibodies' whereas 'warm non-specific antibodies' caused all three cases found by the gel test. The gel test detected higher proportion of immune antibodies than the tube test (69.8% vs 41.3%, p < 0.001), with a double increase in anti-K and Rh antibodies. The tube test detected 24 cases of clinically non-significant antibodies, as compared with no cases found by the gel test (p < 0,001). 'Non-specific antibodies' more often caused positive cross-matches than antibody detection (42.6% vs. 29.9% by the tube test, 28.9% vs. 18.3% by the gel test). Despite of being close in the detection of irregular antibodies (p=0.062), the difference between the tube and gel test was not significant. 'Non-specific antibodies' were found by both tests more often in women, while clinical departments were of no significance. CONCLUSIONS The gel test has proved to be a more optimal technique of pretransfusion testing. The detection of irregular antibodies is recommended as an obligatory part of pretransfusion testing.

The brushes are used for transmission of electric current from or to rotating surfaces depending on the type of electrical machines. Besides the process of current transmission, what is significant for the brushes is the tribological process, which is the subject of the experiment. The brush was exposed to a planned experiment and a regression and correlation analyses of tribological process of brush wearing relative to the time were undertaken. The interdependency has been tested and determined by regression analysis and by correlation analysis, the connection between the length of wearing Y of the examined brush and observing time X, taken in mode of statistics agglomerates. The wearing of brushes in practice varies relative to the time. The variations may result in extreme wearing of brushes, changes in the current transmission arcing of brushes and the like.

The aim of this article is to present some results of investigations on machined surface quality produced by high-speed cutting technologies and conventional turning. Machined surface quality demands significantly affect cost of production and increase the price of a product. Hence, obtaining a good quality of surface while lowering production costs has been metalworkers' preoccupation since beginning their jobs. One possible approach for solving that problem is introducing high-speed machining facilities into production. High-speed machining allows higher productivity, excellent surface finish and good dimensional accuracy in the manufacturing process. Therefore these technologies have considerable advantages over traditional machining technologies. In this article some high-speed machining tests on different materials with different hardness, different machinability index, and by using different experimental approaches have been illustrated. Hard turning and high-speed turn milling, in particular, have been analyzed from the aspect of applicability of these technologies on conventional machines, since these machines still can be found in many manufacturing facilities. Results obtained through these experiments confirmed advantages of high-speed technologies over conventional machining. It has been shown that common production machines, e.g., a universal lathe, in combination with new cutting tools, might be use effectively in some high-speed applications also.

This article contains results of experimental research activities of white layer formation (WLF) and its characteristics during a process of turning hardened steels (THS), which have been carried out in laboratories of DD Cimos TMD Ai Gradačac. WLF. Characteristics during the THS process were analyzed from the aspects of influence caused by machining parameters as well as tool flank wear width. Experimental tests of tool wear have been performed. The tool used in experimental tool wear was ceramic cutting insert CNGA 120408T, catalogue mark IN22 Al2O3-TiCN. In accordance with achieved results, value of tool flank wear 220 µm has been set as the criterion of wear. In accordance with defined wear criterion, determination of level and type of influence that machining parameters have on WLF and its characteristics were carried out in accordance with planned experimental methodology. Experiments have shown that cutting speed and tool flank wear width (for all other machining conditions unchanged) can be used for control of WLF and its characteristics. Structural changes in surface layer of the working piece, during the cutting process of hardened material, except for the WLF are also presented through a transition zone, e.g., dark layer, which has lower hardness than the initial material. Hard WL can take over a protection role for a machined surface from abrasive actions, while softened zone (dark layer) can take over a function of WL solder with the initial material. Analysis of achieved results points to a possibility of controlling the WLF and its characteristics, and therefore a possibility of using WL in a positive context. The basis for the above mentioned is the effect of additional plastic deformation of WL (APDWL), which occurs only under certain machining conditions. The effect seen, if follows WLF, results in decrease of machined surface roughness compared to its expected value. Accordingly there is a possibility for identification of WL on a machined surface by measuring the roughness parameters without previous metallographic preparation of samples.

High speed machining became a common machining solution for various machining applications. This fact is caused by many advantages that HSM can offer to manufacturers – good surface quality, shorter production cycles etc... Yet, the main problem producers faces here is increasing costs generated by high cutting tool price used in this application. This problem is common denominator most of the today high speed machining investigation. The paper shows an example of solving the problem by analyzing chip shape generated in this process in order to determine minimal cutting speed to be used in high speed area. In that sense it has been introduced new factor authors called “measure of segmentation”, Ms, used to make clear distinction between conventional and high speed regions. Therefore, this cutting speed or cutting regime can contribute in increasing cutting tool life and improving economic benefits of HSM processes.

Purpose: The purpose of work is to show an example of 3D modeling and optimization combined with the design and production of prototype and experimental testing of a very important composing part of the mechanism for compensating the aeration in automobile hand brake. The basic notions about purpose, function, buyer’s demands, specifics of the hand brake assemble construction are given. The proposal of concept for the development of the assembly, conceived by the buyer, is given as well. Design/methodology/approach: Very important task of the mechanism for compensating the aeration in automobile hand brake is to assure its function safety and a permanent grip angle of the hand brake. A new construction is made, which will satisfy the above mentioned demands, then the 3D technique is used to choose an optimal model, and, based on it, prototypes were produced and experimentally tested in real conditions. Findings: A new design of the elements of hand brake is developed. Research limitations/implications: The proposed methodology is repeatable for other similar mechanisms. Practical implications: Based on the research, new design of the mechanism of automobile hand brake is developed, by which the advancement of final product is enabled. Originality/value: : The demands of construction and mechanism functional safety are entirely satisfied.

This paper describes the use of rapid prototyping technology for the production of lower limb prostheses and a model of modern technology transfer to Bosnia and Herzegovina - BiH. This country was identified as one of 24 States Parties with significant numbers of mine survivors, and with “the greatest responsibility to act, but also the greatest needs and expectations for assistance” in providing adequate assistance for the care, rehabilitation and reintegration of survivors.

Abstract With the advent of recent advances in machine tools design (main spindle, feed drives, etc.), high-speed milling has become a cost-effective manufacturing process to produce products with high surface quality, low variations in the machined surface characteristics, and excellent dimensional accuracy. In taking into account the most obvious advantages of high-speed machining over conventional machining, a key issue is to identify the effective range of cutting speed that corresponds to high-speed machining producing improved machining performance. The simple reason for this is the fact that machining performance improves when entering the high-speed region but, large increase in cutting speed is not cost-effective due to rapidly increasing tool-wear rates and high power consumption. In order to address this issue requiring a trade-off, an attempt has been made in this paper by formulating an approximate procedure which is based on the analysis of chip-formation mechanisms and a chip-shape analysis, together with the use of metallographic methods. This procedure includes fundamental understanding of the well-known phenomena of white layer formation during the high-speed machining of hardened steels. Essentially, the white layer generated on a machined surface represents a surface defect. Therefore, it is necessary to determine the factors influencing its generation and its prevalent characteristics. There is lack of knowledge in this area, which tends to present the influence of the white layer on the surface integrity and performance of the machined part as a function of machining conditions. This article provides a basis for the determination of the optimal range of cutting speeds and feed rates in high-speed milling of hardened steels ensuring minimized influence of the white layer on the workpiece quality and machined surface integrity.