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1

Theoretical determination of voltage arise in machining of gray cast irons

Yardimeden A., Inan A., Aksoy M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

79-82

EN

Purpose: Machining conditions should be well determined in order to increase production speed and minimize machining cost. However, it is difficult to produce all information for optimum machining conditions. Therefore it is generally accepted provide the most influential factors for determination of optimum machining conditions. The optimum machining conditions would provide longer tool life and better surface finish quality. Design/methodology/approach: Taylor mentioned a relative between cutting speed and tool life and developed model from consecutive experimental studies completed under invariable machining conditions. Recently the factorial regression analysis has been extensively applied for providing optimum machining conditions for expected tool life and surface roughness. In the present study, voltage differences between workpiece and cutting tool were also taken into consideration for theoretical determination of machining conditions. The results of experimental study carried out for machining of gray cast irons (at different chemical compositions) were modeled by using regression analysis method. Findings: The influence of cutting speed, feed rate, diameter and depth of cut on the voltage difference were investigated. Consequently theoretical values obtained from the equation were similar to the experimental values. Practical implications: The results of experimental study carried out for machining of gray cast irons (at different chemical compositions) were modeled by using regression analysis method. Originality/value: In the present study, a mathematical model was improved using regression analysis method of potential differences between workpiece and cutting tool and, machining on the lathe which is made different chemical compositions of gray cast iron.

2

Stress analysis of shrink-fitted pin-pin hole connections via Finite Element Method

Ozben T., Yardimeden A., Cakir O.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 1

45-48

EN

Purpose: FEA analyses are frequently faced with modeling situations where field surface and changing contact cannot be assumed ignored. Design/methodology/approach: The effect of stress in machine elements due to friction between working machine parts has to be considered for analyzing the machine component with ANSYS software package. The interaction between the hole surface and pin was modeled with contact elements. In this study, examination of stress in pin-pin hole connections was carried out by using ANSYS program. Findings: The connection in pin-pin hole plates occurs between surface of pin hole in plate and side surfaces of pin. Stresses in contact surface of selected machine elements were investigated. Three different materials such as steel, aluminium and structure steel were analyzed under three different rates of cylindrical plate radius r and length of hexagonal pin 2h (r/h = 2.5, 5 and 7.5). Stress analysis was carried out in x, y and z axises. Research limitations/implications: Among the stress forms, in general, the maximum stress for all the three types of materials examined here was found to be occurring as the von Mises stress. Originality/value: The comparison of the maximum normal stress, maximum shear stress and von Misses stress were determined.

3

Selection of cutting fluids in machining processes

Cakir O., Yardimeden A., Ozben T., Kilickap E.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 2

99-102

EN

Purpose: During machining operation, friction between workpiece-cutting tool and cutting tool-chip interfaces result high temperature on cutting tool. The effect of this generated heat affects shorter tool life, higher surface roughness and lowers the dimensional sensitiveness of work material. This result is more important when machining of difficult-to-cut materials, due to occurrence of higher heat. Design/methodology/approach: Different methods have been reported to protect cutting tool from the generated heat during machining operations. The selection of coated cutting tools are an expensive alternative and generally it is a suitable approach for machining some materials such as titanium alloys, heat resistance alloys etc. Another alternative is to apply cutting fluids in machining operation. They are used to provide lubrication and cooling effects between cutting tool and workpiece and cutting tool and chip during machining operation. Hence the influence of generated heat on cutting tool would be prevented. Findings: As a result, important benefits would be achieved such longer tool life, easy chip flow and higher machining quality in the machining processes. The selection of cutting fluids should be carefully carried out to obtain optimum result in machining processes. Various factors are affecting the selection of cutting fluid type in machining operation such as type of workpiece materials, cutting tool material and the method of machining processes. Research limitations/implications: In this study, the selection of cutting fluids for machining processes was examined. The effects of workpiece material, cutting tool and machining process type were determined in detail. Originality/value: In this study, the studies about cutting fluid application in machining processes have been evaluated. The selection criteria of cutting fluids have been examined. Suitable cutting fluids for various material machining processes have been determined according to cutting tool materials.

4

Impacts of the structure and processing conditions on the voltage arise in machining of gray cast irons

Yardimeden A., Inan A., Aksoy M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 2

81-84

EN

Purpose: Machining is one of the most widely used manufacturing processes. The machining of gray cast iron is important because of wide application of these materials in various industries. The machinability studies have been carried out for these materials and it was reported that the amount of graphite in cast irons was one of the influential factor in tool wear during machining. This study is aimed to provide new approach to examine tool life by considering voltage arise during machining of gray cast irons. Design/methodology/approach: The experimental study carried out to measure voltage values during various machining conditions such as cutting speeds, feed rates and depth of cut. Chemical compositions of the four different gray cast irons were machined and the experimental results were compared to the machining of brass and steel. The selected machining conditions were 0.16, 0.32 and 0.48 mm feed rates, 0.5, 1 and 1.5 mm depths of cut and 125, 250 and 355 rpm spindle speeds, respectively. Findings: It was observed that the voltage difference was detected during the machining of cast iron specimens. This was due to increase of graphite particles within total intersections. This would lead to conclusion that high graphite particles would increase voltage and this would provide information about tool wear. Research limitations/implications: Because of being cheap, the usage of cast iron with lamella graphite particles in specific electric circuits to be used in industrial applications need to be further investigated. Also whether or not the cost iron with lamella graphite particles can be used as voltage storage under intensive stress needs to be investigated. Originality/value: Impacts of the structure and processing conditions on the voltage arise in machining of gray cast irons.

5

Chemical machining

Çakir O., Yardimeden A., Özben T.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 8

499-502

EN

Purpose: Nontraditional machining processes are widely used to manufacture geometrically complex and precision parts for aerospace, electronics and automotive industries. There are different geometrically designed parts, such as deep internal cavities, miniaturized microelectronics and fine quality components may only be produced by nontraditional machining processes. This paper is aiming to give details of chemical machining process, industrial applications, applied chemical etchants and machined materials. Advantages and disadvantages of the chemical machining are mentioned. Design/methodology/approach: In this study, chemical machining process was described its importance as nontraditional machining process. The steps of process were discussed in detail. The tolerances of machined parts were examined. Findings: Paper describes the chemical machining process, industrial applications, applied chemical etchants and machined materials. Practical implications: The machining operation should be carried out carefully to produce a desired geometry. Environmental laws have important effects when chemical machining is used. Originality/value: The importance of nontraditional machining processes is very high.

6

Biomechanical comparison of the wedge supported plates at PTO

Yardimeden A., Kelestemur M. H., Esenkaya I.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 8

495-498

EN

Purpose: Proximal tibial osteotomy (PTO) is a widely used surgical procedure for the treatment in medial compartment osteoarthritis of the knee with mal-alignment, particularly in young and active patients. Several types of plates are developed recently at the medial opening wedge osteotomy technique. The main aim of this study is to make stress analysis and compare the stability of a commonly used anatomic "T" plate and 3 different wedge supported plates and their combinations which are designed by one of the author of this article. Design/methodology/approach: In this biomechanical study, calf tibial models were used in order to compare the stability of the plates under axial compression loading. 2 and 4 holes rectangular shape wedge supported plates, 4 holes reversed "L" shape wedge supported plates or combination of these and 6 holes anatomic "T" plates were used for the models. The compression behaviour of the model was tested by using a universal mechanical testing machine. And, a numerical method, ANSYS finite element code, was used for the stress analysis of the plates. Findings: The specimen fixed with the combination of 4 holes reversed "L" shapes and 2 holes rectangular shape plates and 6 holes anatomic "T" plates showed significantly better stability than those of others. The numerical and experimental results were well agreed. Practical implications: When Ti alloy plate is compared with stainless steel plate it is observed that the stress values do not change under applied loads and it does not show an advantage in term of stress. However, literature indicates that it has higher fatigue life and better electro-chemical properties. Originality/value: Biomechanical comparison of the wedge supported plates at proximal tibial osteotomy.