Ibrahim Ciftci

Design and construction of a dynamometer for measurement of cutting forces during machining with linear motion

Abstract Considerable studies concerning cutting force measurement and its analysis in the past have been tackled by many researchers and organisations. As a result, many dynamometers were developed. Work to date has shown that most of these dynamometers are for turning and milling. In this study, a dynamometer has been designed and constructed using bending beam type load cells for shaping. Cutting force measurement tests on St 44 steel workpiece material during shaping have been performed. The obtained results were compared to the theoretically calculated ones, and a good agreement between the experimentally obtained and theoretically calculated results were seen. Therefore, the ‘1,1 coefficient’ used in the theoretical calculation of cutting forces during shaping was experimentally verified. This system is considered to be of vital significance as it enables the researchers to investigate the effect of rolling direction on the machinability of materials.

The effect of alloying elements on surface roughness and cutting forces during machining of ductile iron

Due to its enhanced strength, ductility and toughness, ductile iron has poor machining properties when compared to flake graphite cast iron. However, when a steel part is replaced with ductile iron, better machinability is considered to be the most important gain. This study presents the results of machining tests of ductile irons (DIs) alloyed with Ni and Cu at various amounts to determine the effect of their microstructures and mechanical properties on cutting forces and surface roughness. Six different groups of ductile iron specimens alloyed with various amounts of Ni and Cu were subjected to machining tests and their machinability were investigated based on cutting forces and surface roughness criteria. The results show that alloying ductile iron with Ni and Cu at various amounts affected cutting forces developed during turning and surface finish of the machined components significantly, in terms of both criteria, the best results obtained were for the specimen alloyed with 0.7% Ni and 0.7% Cu.

The tribological properties of A356-SiCp metal-matrix composites fabricated by thixomoulding technique

Abstract In this study, A356-SiCp metal-matrix composites were produced through thixomoulding process, and these composites were subjected to wear tests. The composites containing various volume fractions of SiCp particles (5%, 10%, 15% and 20%) as the reinforcement were produced at two different temperatures of 590°C and 600°C. The influences of processing temperatures and reinforcement ratio on the properties and wear behaviour of the composites were investigated. Prior to the wear tests, microstructural properties and hardness of the composites were determined. For the wear tests, a pin-on-disc-type wear apparatus was employed to carry out the wear tests. The wear tests were carried out at 2.0 m/s sliding speed under 15 N load and for four different sliding distances. A scanning electron microscope (SEM) was used to examine the wear mechanisms on the worn surfaces of the composites. The results indicated that sphericity rate and hardness of the composites produced at 590°C were higher than those of the composites produced at 600°C. In addition, the composites produced at 590°C exhibited lower weight loss and friction coefficient.

An investigation into the wear behaviour of TiB2 particle reinforced aluminium composites produced by mechanical alloying

Abstract In this study, wear behaviour of TiB2 particle reinforced aluminium (Al) composites produced by the mechanical alloying method was investigated. TiB2 ceramic particles of four different volume fractions were mechanically alloyed with Al and A356 alloy matrix materials. The mechanically alloyed particles were cold presses and then sintered at 550°C. After the sintering process, the composites were characterised through hardness measurements, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Wear tests were also carried out on a pin-on-disc type wear apparatus under 10, 25 and 50 N loads. Wear loss of the composites were found to decrease with increasing hardness which increased with increasing TiB2 particle volume fraction. However, increasing the applied load and sliding distance increased the wear loss. Wear surface examinations showed that various wear mechanisms were effective in wear of the composites.

The Effect of Aging and Sliding Speed on Wear Behaviour of Cu-Cr-Zr Alloy

Abstract In this study, the sliding wear behaviour of non-aged and aged Cu-Cr-Zr alloy specimens were investigated. The specimens were aged for 2 h at the temperatures of 450 °C and 475 °C. Prior to the wear tests, microstructural examinations and hardness measurements were performed on all Cu-Cr-Zr alloy specimens. The wear tests were performed on a pin-on disk type wear apparatus at the sliding speeds of 0.5 ms−1, 1.0 ms−1 and 1.5 ms−1 as well as under 40 N applied load. After the wear tests, the worn surfaces of all samples were analyzed by SEM and energy dispersive X-ray spectroscopy (EDS). The experimental results indicated that aging heat treatment led to increase in the hardness values of Cu-Cr-Zr alloys and the highest wear loss was observed for non-aged specimens. With increasing sliding speed, the wear loss increased to a maximum value beyond which it decreased.

Mg2Si partikül takviyeli magnezyum alaşımlarının tornalanmasında yüzey pürüzlülüğünün optimizasyonu

Bu calismada, Mg2Si takviyeli Mg alasimi malzeme, geleneksel dokum yontemiyle ergiyik halde Mg matrise %10 oraninda ilave edilen Al-12Si ana alasimi icindeki Si ile Mg reaksiyona girerek Mg2Si takviyesini olusturarak metal kaliba dokulerek uretilmistir. Silindirik sekilde uretilen malzemeler uzerinde tornalama yontemiyle isleme deneyleri yapilmistir. Kesme parametrelerinin yuzey puruzlulugu uzerindeki etkileri arastirilarak optimum isleme sartlarinin belirlenmesi amaclanmistir. Bu amacla dort farkli kesme hizi (250, 350, 450 ve 550 m/dak), iki farkli ilerleme degeri (0,1 ve 0,2 mm/dev) ve iki farkli kesici takim uc yaricapi (0,4 mm ve 0,8 mm) kullanilarak Taguchi’nin L8 dikey dizini ile deney tasarimi yapilmistir. Isleme deneyleri kuru kesme sartlarinda CNC torna tezgâhinda gerceklestirilmistir. Kesme parametrelerinin yuzey puruzlulugu uzerine etkisini belirlemek amaciyla varyans analizi (ANOVA) yapilmistir. Elde edilen analiz sonuclarina gore yuzey puruzlulugu uzerinde % 57,6 katki orani ile en etkin parametrenin ilerleme hizi oldugu tespit edilmistir.