Ulvi Şeker

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 Experimental Investigation of the Effects of Different Chip Breaker Forms on the Cutting Forces

The objective of this paper is experimentally investigation of the effects of different chip breaker forms on the cutting forces according to various cutting parameters. AISI 1050 workpiece material, most used material in the manufacturing industry, and SNMG 120408R inserts and PSBNR 2525M12 tool holder have 75° approaching angle according to ISO 3685 are used in the experiments. Seven groups chip breaker form were used in the tests. The chip breaker forms are the coated inserts MA, SA, MS, GH and standard, and the uncoated inserts MS and standard. These inserts are Mitsubishi UC 6010 and UTI20T grade; correspond to ISO P30 and P15 grade, respectively. Machining tests were carried out by using five levels of cutting speeds (150, 200, 250, 300, 350 m/min), three levels of feed rate (0.15, 0.25, 0.35 mm/rev) and two levels of depth of cut (1.6, 2.5 mm). Cutting forces were measured using Kistler dynamometer. The test results show that the highest cutting force values were measured on SA, GH, MA forms, respectively. Complex chip breaker forms cause the increase of the cutting forces. Although the cutting forces on the uncoated inserts were partly small in light cutting conditions, it has increased on the uncoated inserts in heavy cutting conditions compared to coated inserts.

The Mathematical Modeling of the Compressive Stresses on the Cutting Tool in Machining of Inconel 718

In this paper, a mathematical model has been developed for the cutting tool stresses in machining of nickel-based super alloy Inconel 718 used in aircraft and spacecraft industries, nuclear power systems and steam generators etc. necessitating oxidation and corrosion resistance, high temperature and strength. The cutting forces were measured by a series of experimental measurements and stress distributions on the cutting tool were analyzed by means of the finite element method using Ansys software. The mathematical modeling process of the compressive stresses in x, y and z directions was carried out with multiple regression analysis regarding to Ansys stress results depending on the cutting forces and the chip–tool contact area. It is found that model results had good agreement with the Ansys stress results.

Investigation of machinability in Al-MgO composites produced by melt-stirring

Abstract In this study, Al-MgO reinforced metal matrix composites of 5%, 10% and 15% reinforcement-volume ratios were produced by melt-stirring and subjected to machining tests by carbide and coated carbide cutting tools. Machining tests were conducted with 150, 200, 250 and 300 m/min cutting speeds, 0.075, 0.15 and 0.225 mm/rpm feed rates and 1 mm depth of cut. Piezoelectric quartz crystal type dynamometer was used to measure cutting forces. As a result of the tests, it was observed that the increase in cutting speed first led to an increase and then a decrease in main cutting force values (Fc), and the increase in feed rate was accompanied with increased main cutting forces. The most consistent results in terms of Fc values were displayed by 10% MgO reinforced composites. While no abrasion occurred on the surfaces of cutting tools, build up edge formation was observed in the machining tests.

Kauçuk Hava Süspansiyon Körüklerinin Üretim Yöntemi Ve Yorulma Ömrünün Ürün Kalitesi Üzerine Etkisinin Belirlenmesi

Bu calismada, tasitlardaki suspansiyon sistemlerinin bir parcasi olan hava suspansiyon korugunun uretim tipinin urun kalite ozellikleri uzerine etkisi incelenmistir. Uretilen koruklerin ilgili standartlar goz onunde bulundurularak fiziksel ve mekanik ozellikleri belirlenmistir. Uretilen korugun mekanik performanslarinin belirlenmesine yonelik calisma kapsaminda Patlatma Test Makinesi, Tasima-Genisleme ve Omur Test Makinesi kullanilmistir. Imal edilen hava suspansiyon koruklerinin mekanik ozelliklerini incelemek amaciyla patlatma, tasima, genisleme ve omur testleri gerceklestirilmistir. Testler sonrasinda, koruge ait patlatma basinci, tasima yuku degeri, tekrarli yukleme durumunda kuvvet degerlerindeki degisimler belirlenmistir. Ayrica, korugun tasima yuku ve yatay yer degistirme degerleri altinda boyutsal degisimleri tespit edilmistir.

Karbon Fiber Takviyeli Kompozit Malzemelerinin Frezelenmesinde Meydana Gelen Yüzey Pürüzlüğünün Değerlendirilmesi ve Matematiksel Modellenmesi

Karbon fiberler ile takviye edilmis kompozitlerin mukavemetlerinin ve rijitliklerinin cam lifleri ile imal edilen kompozitlere oranla cok fazla olmasi, yogunlugunun az olmasi ve yorulma mukavemetlerinin fazla olmasi sebebi ile gunumuzde kullanimlari gittikce artmaktadir. Bununla birlikte bu malzemelerin islenmesi diger malzemelere oranla daha zordur. Bu calismada karbon fiber takviyeli kompozit malzemelerin PCD takimlar islenmesinde meydana gelen yuzey puruzlulugu arastirilmis ve matematiksel bir model gelistirilmistir. Deneylerde calismada kapsaminda tasarimi ve uretimi yapilan uc farkli geometride PCD parmak frezeler kullanilmistir. Deneyler CNC dik isleme merkezinde yapilmistir. Kesme parametreleri olarak 350, 400 ve 450m/dak kesme hiz ve 1270 mm/dak sabit ilerleme miktari secilmistir. Artan kesme hizinin yuzey puruzlulugunu olumlu yonde etkiledigi gorulmustur. Ayrica regresyon analizi sonrasinda elde edilen ANOVA istatistiklerine gore yuzey puruzlulugunde etkili olan parametreler tespit edilmistir.

Delik Delme Operasyonlarında Matkap Geometrisinin, GGG 50 Malzemesi Üzerinde, Delik Kalitesi ve Kesme Performansına Olan Etkisi

Bu calismada, farkli matkap geometrileri ve kesme parametrelerinin delme performansi uzerine etkileri sistematik bir sekilde incelenmistir. Farkli geometrilere sahip dort tip matkap kullanilarak itme kuvveti, moment, yuzey puruzlulugu ve geometrik toleranstan sapma degerleri olculmustur. Deneysel calismalarda ticari olarak temin edilebilen yaygin iki takim geometrisi ile ozgun iki kanal geometrisinin performanslari test edilmistir. Delme operasyonu, 10 mm capinda, iki agizli, helisel, yekpare sementit karbur matkaplar kullanilarak GGG 50 malzemesi uzerinde gerceklestirilmistir. Deney deseni icin matkabin geometrik formu, kesme hizi ve ilerleme miktari olmak uzere dorder seviyeli uc farkli kontrol faktoru ile bir Taguchi Deney Tasarimi olusturulmustur. Deney sonuclarinin degerlendirilmesinde Taguchi S/N analizi ve elde edilen verilerin islendigi grafikler kullanilmistir. Anova analizi yardimiyla da deney parametrelerinin deney sonuclari uzerindeki onemi ve etki oranlari bulunmustur. Deneysel sonuclar degerlendirilerek optimum geometri ve optimum isleme sartlari belirlenmistir. Taguchi Sinyal-Gurultu analizinde “en kucuk en iyidir” yaklasimiyla degerlendirilen sonuclara gore; ilerleme kuvveti, giris-cikis yuzey puruzlulugu, dairesellikten sapma ve diklikten sapma acisindan ozgun olarak gelistirilen 4 numarali takim geometrisi diger geometrilere ustunluk saglarken, ilerlemenin en dusuk oldugu (0,15 mm/dev.) ve kesme hizinin en yuksek oldugu (110-120 m/dak.) kesme parametreleri ise kontrol faktorlerinin optimum seviyeleri olarak belirlenmistir.

Delik Delme İşlemlerinde Kesme Parametrelerinin Kesme Bölgesindeki Sıcaklığa Etkisinin Deneysel İncelenmesi

Drilling is one of the most important machining processes in manufacturing industry. Recently, the work dealing with the problems encountered during drilling and their solution has been increased. Modelling of thermal and mechanical loads developed during drilling has also been increased. In this study, the drillability of AISI 1050 steel widely used in industrial applications will be investigated under various drilling types (hole type) cutting parameters (60, 75, 90 and 108 m/min cutting speed and 0.15, 0.20 and 0.25 mm/rev feed) and cutting tool type (uncoated and TiN/TiAl/TiCN coated solid carbide). Cutting temperatures developed along the drill rake face when drilling with coated and uncoated drill bits will be measured with the help of K type thermocouples inserted in the cooling channels of the drills. When the results of the experiments are evaluated, cutting temperature decreased with increasing feed and coating application significantly reduced cutting temperatures in the cutting zone. Coating application has provided significant benefits in the all parameters.

Evaluation of Surface Integrity during Machining with Different Tool Grades of Sicp/Al-Si Composites Produced by Powder Metallurgy

MMCs components are mostly produced using near net shape manufacturing methods and are subsequently machined to the final dimensions and surface finishes. The MMCs consist of extremely hard reinforcing particles and pose considerable challenges due to the poor machinability and severe wear of the cutting tool. In this study, cutting performance of WC, CBN and PCD cutting tools were investigated with respect to surface roughness during machining of 10 wt % SiCp reinforced Al-Si alloy matrix composites produced by powder metallurgy (PM) method. Average surface roughness (Ra) corresponding to each machining condition was measured. After the machining process the worn insert tips were examined under the scanning electron microscope (SEM). Chip geometry and machined surface photographs have been taken by optical microscopy. The experimental results showed that surface roughness decreased with increasing cutting speed for all of cutting tool materials. The best surface integrity was occurred after the machining with PCD insert at the highest cutting speed employed.