Capability Profile of Hard Cutting and Grinding Processes

A comprehensive characterization of 3D surface topography induced by hard turning versus grinding

In face milling processes, the surface quality of the machined part depends on many factors, including feed, cutting tool geometry and tool errors. In this work, a numerical model for predicting the surface profile and surface roughness as a function of these factors is presented, incorporating a random values generation algorithm that makes it possible to determine the variation in surface roughness from the values that can be adopted by tool errors. This work is focused on round insert cutting tools and the influence of tool errors such as radial and axial runouts. The results that correspond to a number of teeth equal to 4, insert diameter of 12 mm, depth of cut of 0.5 mm, cutting speed of 120 m/min and feed of 0.4–1.4 mm/rev are analysed. Milling experiments are made to verify the validity of the model and the discrepancies between the experimental and theoretical surface profiles are assumed to be a consequence of different factors such as the variation in undeformed chip thickness along the surface profile.

Influence of radial and axial runouts on surface roughness in face milling with round insert cutting tools

Successful casting of three groups of austenitic ductile irons was achieved covering a carbon equivalent (CE) range from 3.51% to 5.04%. The three groups implied the change of C, Si or Ni contents to control the CE%. In case of using Ni element to vary CE%, austenitic ductile iron could be obtained starting from 13.5% up to 34.7% Ni. Generally, the microstructure consisted of graphite nodules embedded in austenitic matrix. Nodule characteristics were affected by the variation of CE%. Nodularity was almost 100% for all tested specimens. Slight decrease in hardness and tensile strength (σu) was observed with increasing the CE%. 0.2% proof stress (σ0.2) showed almost a constant value with increasing CE%. Tensile elongation was mainly increased with increasing CE% with different degrees owing to the alloying element (C, Si or Ni).

C, Si and Ni as alloying elements to vary carbon equivalent of austenitic ductile cast iron: Microstructure and mechanical properties

In the study, 4% cobalt and nickel elements were added to ductile iron (DI) to investigate the effects of the alloying elements on both its microstructure and its mechanical properties. The results show that 4% cobalt alloyed ductile iron (4% Co-DI) not only increases the nodule count and ferrite content in the microstructure, but also improves the mechanical properties such as yield strength, tensile strength, impact toughness and fracture toughness ( K IC ) as compared to unalloyed DI. In contrast, with 4% nickel addition, there is a decreased nodule count and increased pearlite content in the matrix. However, this material (4% Ni-DI) has the highest hardness and strength but the lowest ductility and toughness among all the ductile irons. In the case of microstructure, all kinds of iron have a sufficient nodularity up to 90% and the sequence of the nodule count is 4% Co-DI (150 nodules/mm 2 ) > DI (106 nodules/mm 2 ) > 4% Ni-DI (85 nodules/mm 2 ). Moreover, it appears that cobalt plays an important role in stabilizing the ferrite phase, whereas 4% nickel accelerates the formation of pearlite in ductile iron.

Microstructure and mechanical properties of 4% cobalt and nickel alloyed ductile irons

Evaluation of machinability of austempered ductile irons in terms of cutting forces and surface quality

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

In this study, wear behavior of B4C particle reinforced Al matrix composites produced by powder metallurgy technique has been investigated under dry sliding conditions. Characterization of composites were determined by microscopic examinations, hardness measurements and abrasive wear tests. Abrasive wear tests were conducted with 180 and 400 Mesh Al2O3 paper under 10 N and 20 N load 0,2 m s-1 sliding speed. Hardness increased by addition of B4C particles. While 20 % B4C particles reinforced composites have shown the highest hardness values, 10 % B4C particles reinforced composites have shown ultimate wear resistance.

INVESTIGATION OF ABRASIVE WEAR BEHAVIOURS IN B4C /Al COMPOSİTES DEPENDING ON REINFORCEMENT VOLUME FRACTION

Bu calismada, toz metalurjisi yontemi ile uretilen Al matrisli B4C parcacik takviyeli kompozitlerin kuru kayma kosullarindaki asinma davranislari incelenmistir. Kompozitlerin karekterizasyonu mikroyapi incelemeleri, sertlik olcumleri ve abrasif asinma deneyleri ile yapilmistir. Abrasif asinma testleri, 180 ve 400 Mesh Al2O3 zimpara kullanilarak 10 N ve 20 N yuk altinda 0,2 m s-1 kayma hizinda gerceklestirilmistir. Sertlik B4C parcacik ilavesi ile birlikte artmistir. % 20 B4C parcacik takviyeli kompozit en yuksek sertlik gosterirken, % 10 B4C parcacik takviyeli kompozit en yuksek asinma direnci gostermistir.

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B4C /Al KOMPOZİTLERİN TAKVİYE HACİM ORANINA BAĞLI OLARAK ABRASİF AŞINMA DAVRANIŞLARININ İNCELENMESİ

Bu calismada Kuresel Grafitli Dokme Demirlerin (KGDD) mikro yapi ve mekanik ozellikleri uzerine mekanik titresimin etkileri incelenmistir. Dokumler geleneksel yas kum kalipta yapilmistir. Bu calismada, ferritik KGDD (GGG 40) malzeme kullanilmistir. Calisma sonuclari, titresim uygulamasiyla KGDD malzemesinin mikro yapisi ve mekanik ozelliklerinde degisimlerin meydana geldigini gostermistir. Sonuclara bakildiginda, tane ve grafit kure boyutlarindaki kuculmeye bagli olarak KGDD’in mekanik ozellikleri gelismistir.

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Hasan Hasirci

Papers

Evaluation of machinability of austempered ductile irons in terms of cutting forces and surface quality

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

INVESTIGATION OF ABRASIVE WEAR BEHAVIOURS IN B4C /Al COMPOSİTES DEPENDING ON REINFORCEMENT VOLUME FRACTION

B4C /Al KOMPOZİTLERİN TAKVİYE HACİM ORANINA BAĞLI OLARAK ABRASİF AŞINMA DAVRANIŞLARININ İNCELENMESİ

Mekanik Titreşimin Küresel Grafitli Dökme Demirlerin Mikroyapı ve Mekanik Özelliklerine Etkileri