Yusuf Kaynak

Marmara University · Department of Mechanical Engineering (Tech)

There has been significant work on establishing relationships between machining performance and the cutting parameters for various work materials. Recent trends in machining research show that major efforts are being made to understand the impact of various cooling/lubrication methods on machining performance and surface integrity characteristics,...

Machinability is a generalized framework that attempts to quantify the response of a workpiece material to mechanical cutting, which has been developed as one of the key factors that drive the final selection of cutting parameters, tools, and coolant applications. Over the years, there are many attempts have been made to develop a standard evaluati...

As with all additive manufacturing processes, selecting appropriate process parameters in the laser powder bed fusion (LPBF) process plays an important role in the surface integrity and mechanical behavior of Inconel 718 components. Hatch distance, laser power, laser scanning speed and layer thickness are the main parameters that can be altered in...

The approved restrictive rules on the containment of Lead element in the chemical composition of the brass alloys which are utilized in drinking water and pumping systems have resulted in developing of new material generations. Neglection or limitation of this element has faced the industry with some serious problems such as lower machinability as...

Considering industrial applications, three main brass alloys including lead-free, low-lead and leaded are being deployed. However, as these materials are used in potable water applications, low-lead and lead-free brass alloy are becoming preferred to leaded ones due to their health effect. On the other hand, Lead is the element increases machinabil...

The Additive Manufacturing (AM) process provides opportunities to fabricate products with complex geometries including conformal cooling channels, etc. While having such an advantage, the low surface quality of the products is a disadvantage of laser powder bed fusion (LPBF). Because of that, a post-process is needed to improve the surface quality....

This study presents machining process and resulting surface integrity properties of brass alloys including leaded (CW617N), low-leaded (CW511L) and lead-free (CW724R). Experimental data on cutting forces and cutting temperatures are presented to assess machining of these alloys. Surface quality, subsurface microhardness and microstructures of machi...

One of the commonly used additive manufacturing methods is extrusion-based 3D printing (e.g., fused filament fabrication or FFF) that is generally required post-processing to make fabricated components ready to be used. This paper considers two major points to assess the surface enhancement of components made of polylactic acid (PLA) material. One...

A Ni-rich Ni50.3Ti29.7Hf20 (at. %) high-temperature shape memory alloy was machined under different cooling conditions, specifically cryogenic cooling and flood cooling, and results were compared with those from dry machining. The effects of cooling on machinability measures such as tool wear, cutting forces and surface quality were evaluated for v...

Laser powder bed fusion process is one of the most widely used Additive Manufacturing techniques for fabricating metal components, however the surface quality of such components still remains a challenge and fails to meet the user expectations. Thus, this study presents a systematic investigation on the effect of post-processing operations includin...

This work presents the effect of burnishing process including burnishing force, burnishing speed and burnishing conditions on surface properties of Inconel 718 alloy fabricated by laser powder based fusion additive manufacturing. As-built, sand blasted and heat-treated specimens are burnished and final surface properties such as surface roughness,...

Parameters used in laser powder bed fusion (LPBF) process are key factors that influence the surface integrity and thus mechanical properties of Inconel 718 components fabricated by additive manufacturing (AM) technique. For this reason, various parameters with different settings through trial and error approach have used by AM community to fabrica...

Machinability, stable productivity, and quality of the components are crucial factors in manufacturing industry. In industrial applications, when cutting parameters and conditions are determined considering experiences gained by engineers which does not resolve the whole problems faced with in case cutting tools and their geometries are involved. T...

The machining of nickel and titanium-based superalloy components is very expensive and involves unusually high lead times compared with other engineering metals such as steels and aluminium. This has led to the development of most suitable additive manufacturing (AM) processes to fabricate these difficult-to-machine metals into near-net shape parts...

Purpose The present study aims to investigate the effect of finish machining and aging processes on the surface integrity of the selective laser melted (SLM) maraging steel samples and compared them with those obtained conventionally. Design/methodology/approach Finish machining and aging were applied on the SLM and wrought maraging samples to inv...

Burnishing has been increasingly utilized to improve the surface integrity of manufactured components. The generation of surface and subsurface layers with ultrafine grains, attributed to severe plastic deformation and dynamic recrystallization, leads to improved surface integrity characteristics including surface and subsurface hardness and reduct...

This study focuses on optimizing cutting parameters of NiTiHf high-temperature shape memory alloys using a multi-objective optimization method. The empirical models are used to predict outputs in a turning process of Ni-rich NiTiHf and compared to experimental data. Cutting parameters, such as cutting speed, feed rate, and depth of cut, have found...

This study focuses on the effects of various cutting speeds and cutting conditions including dry, CO2, HPC and flood on the surface integrity characteristics of the machined NiTi alloy. Machining-induced affected layer, microstructure, microhardness and XRD analysis are considered to assess the surface integrity characteristics of NiTi alloy. The f...

Rapid heating, melting, solidification and cooling cycles generates high residual stress in additively manufactured parts, causes to part distortion. Finite Element Method (FEM) is one of the common and practical ways to predict residual stress and distortion taking place during additive manufacturing. Thus, it is possible to determine appropriate...

The performance of machining process is determined by various parameters specially the direction of tool movements during cutting.In this paper, various cutting responses such as machining time (tm), cutting forces (Fr), metal removal rate (MRR), and dimensional accuracy (DA) during the rough pocket milling of the lead-free brass alloys with variou...

The Journal of Additive Manufacturing Technologies is the peer-reviewed journal that reports research work on all aspects of additive manufacturing including additive manufacturing processes, design for additive manufacturing, modelling and simulation of additive manufacturing processes, post-processing in additive manufacturing, and applications o...

This paper attempts to improve the physical and mechanical properties of selective laser sintered polyamide PA2200 components through a vibratory surface finishing process by inducing severe plastic deformation at the outer surface layers. The industrial target of additive manufacturing components is to obtain structures having surface roughness, h...

As industries are increasingly adopting the laser powder bed fusion (LPBF) additive manufacturing (AM) process, it is crucial to understand the process closely and to find ways to improve the final quality of the finished parts. The LPBF process is capable of producing tailored designs, which are lighter in weight and having strength comparable to...

The maraging steel components fabricated using the selective laser melting process exhibit remarkable static strength. However, high pore density and large surface imperfections impede their overall mechanical and chemical performance. Thus, the components are often post‐treated with mechanical‐ and thermal‐based treatments to overcome their inhere...

Additive manufacturing is a rapidly developing field due to the production of complex geometry parts with rapid prototyping with a wide range of applications. In addition to the great advantages, Additive manufacturing produces components with relatively poor surface quality. For this reason, post-processing operations are inevitable to have ready-...

This work explores the machinability and sustainability of newly developed environment-friendly hybrid techniques for Ti-6Al-4 V turning in terms of energy consumption, surface finish, and machining costs. Performances obtained under hybrid turning techniques namely cryogenic-ultrasonic assisted turning and cryogenic-ultrasonic-minimum quantity lub...

This study presents the surface integrity characteristics and wear resistance of maraging steel specimen fabricated by additive manufacturing (AM) direct metal laser sintering (DMLS). After AM process, as-built maraging steels were heat treated by aging 490°C/3h and followed by air cooling. The specimen produced by DMLS were examined considering sc...

The topic of sustainable machining has in recent times emerged as a significant and impactful area of research focus as it directly deals with environmental health and protection, economic growth and prosperity and societal wellbeing with greater human health and safety. More specifically, sustainable machining at product, process and system levels...

Micro-milling is a micro-mechanical cutting method used to obtain complex and three-dimensional micro geometries. Micro-cutting tools are used in the manufacturing of micro-components and the type of workpiece is also important for good surface quality and minimum burr. In this study, micro machinability of Ti6Al4V alloy which is used most frequent...

This experimental study presents the effects of various post-processes including finish machining (FM), drag finish (DF) and vibratory surface finish (VSF) on surface characteristics and wear performance of Inconel 718 specimens fabricated by selective laser melting additive manufacturing. Concentrated characteristics are surface roughness, surface...

This study presents the results of an experimental investigation on the effect of drilling process on surface integrity characteristics of lead-free brass alloy. Experimental data on dimensional accuracy and the surface quality of the holes, subsurface characteristics including microhardness and microstructure is presented and analyzed to evaluate...

One of the challenges is to produce holes with expected dimensional accuracy in metal additive manufacturing. Although post-processing is usually carried out for the additively manufactured components but improving the quality of the holes produced through additive manufacturing seems to be required. Otherwise, it is difficult to obtain expected qu...

Phase transformation and shape memory response of NiTi alloys are sensitive to the variation of temperature and stress. Thus, the phase transformation of NiTi alloys becomes more complex during machining process. This study presents findings from a major study involving modelling of machining-induced phase transformation of NiTi alloys performed by...

A metal component fabricated by additive manufacturing (AM) is generally required to be heat treated to enhance microstructural and mechanical aspects. This present study aims to contribute to the literature in understanding the effect of heat treatment and various heat treatment temperatures on as-built components fabricated by AM. In this study,...

μ was typing mistake in Eq. 1. The correct symbol in Eq. 1 should be π.

The present study focuses on the effects of cutting speed, feed rate and cutting tool material on the machining performance of carbon graphite material. Polycrystalline Diamond (PCD) cutting tools are used in machining experiments and its performance is compared with the tungsten carbide (WC) and Cubic Boron Nitride (CBN) tools. Machining performan...

Additive Manufacturing (AM) has been recognized as a promising manufacturing technology for the industries including aerospace and biomedical; however, the surface finish requirement for the components used in such industries imposes a severe constraint. Thus, finishing process for any manufacturing operation including additive manufacturing needs...

This present study focuses on the surface integrity characteristics of the machined NiTiHf high temperature shape memory alloys. The NiTiHf specimens were machined under dry, minimum quantity lubrication (MQL) and cryogenic cooling at two different cutting speeds. Experimental data on microhardness, latent heat and phase transformation temperature...

Additive manufacturing (AM) has been becoming more widespread and its usage area has been increasing in different industries. However, the mechanical and microstructural properties of the metal parts printed by additive manufacturing required further investigation. In this study, various heat treatment temperature were applied to Inconel 718 produc...

Martensitic stainless steels are widely used in a wide range of industrial applications where the mechanical properties such as durability, wear-resistance, and fatigue behavior should be high. In many applications, such as bearings or gears, they are exposed to tribological conditions causing wear. One of the reasons for this tribological wear is...

The reinforcements of nanoparticles have an important role in improving the machinability of nanocomposite materials. Except for the known nanoparticles such as carbon nanotube, graphene, nanoclay, etc., the effect of boron nitride reinforcement on the machinability of composite materials are a recent research topic. In this study, boron nitride na...

Extreme tool wear and resulting short tool life is one of the main issues in cutting process of near beta Ti alloys. This study provides an extensive experimental results and new findings that helps to understand the progressive tool wear and the corresponding measures in high speed machining of Ti-5553 alloy under various coolant and lubrication (...

New-generation aerospace alloys gain more interest due to their advanced properties. Ti-5553 alloy can be categorised as new-generation aerospace alloys, but it is also difficult-to-machine material. For this reason, machining performance and the role of cutting parameters on machining of this particular alloy needs to be well investigated. This st...

Machining of Ni-rich Ni50.3Ti29.7Hf20 (at.%) high temperature shape memory alloys was evaluated under flood cooling conditions. Effects of various cutting speeds (between 20 and 120 m/min), depth of cuts (between 0.4 and 1mm), and the associated cutting forces on the work-piece surface quality and tool wear of this alloy are presented. Experimental...

https://manufacturingscience.asmedigitalcollection.asme.org/article.aspx?articleid=2724224 Titanium alloy Ti-5Al-5V-3Cr-0.5Fe (Ti-5553) is a new generation of near-beta titanium alloy that is commonly used in the aerospace industry. Machining is one of the manufacturing methods to produce parts that are made of this near-beta alloy. This study pre...

Journal: Additive Manufacturing, Elsevier (https://www.sciencedirect.com/science/article/pii/S2214860418307383) Abstract Metal additive manufacturing is an emerging method to fabricate components used in the aerospace and biomedical industries. However, one of the significant challenges in this approach is the surface quality of the fabricated co...

Shape memory alloys (SMA) are widely used in the biomedical field due to their unique properties. Among these alloys, NiTi alloys are the most widely used. Machining process is one of the techniques to form these materials. If the NiTi alloys are mechanically forced to be cut, the crystal lattice structure can change and thus phase transformation c...

Ti-5553 alloy is considered as a next generation aerospace alloy, however, it is also considered as difficult-to-machine material due to its thermal and mechanical properties. As limited research work presented in literature on machining process of this alloy, more research is needed to determine appropriate machining strategies for this alloy. Thu...

ZET Eklemeli imalat, geleneksel imalat yöntemleriyle üretimi mümkün olmayan parçaların üretiminde kolaylık sağlayan bir yöntem olarak görülmektedir. Ancak eklemeli imalatla üretilen parçaların yüzey kalitesinin beklenen seviyede olmaması önemli bir problem olarak karşımıza çıkmaktadır. Bu çalışmada, Inconel 625 toz malzemesi kullanılarak, toz yatak...

ÖZET Uzay, otomotiv ve biyomedikal alanlarında kullanılan Şekil Hafızalı NiTi Alaşımın talaşlı imalatı sırasında karşılaşılan en büyük sorunlardan biri kesici takımda meydana gelen aşınmalar ve bunun sonucu oluşan kötü yüzey kalitesidir. Özellikle biyomedikal alanında tercih edilen NiTi alaşımın yüzey kalitesi önem arz etmektedir. Bu çalışmada, kes...

Selective laser melting (SLM) is one of the most commonly used additive manufacturing (AM) techniques to manufacture metal components; however, during building process partially melted powders and/or pores on the outer surface of metallic parts results in very high surface roughness and eventually poor surface quality of components manufactured by...

Among additive manufacturing (AM) techniques, Selective Laser Melting (SLM) is widely used to fabricate metal components, including biocompatible bone implants made of 316L stainless steel. However, an issue with the components manufactured using this technique is the surface quality, which is generally beyond the acceptable range. Thus, hybrid man...

This experimental study focuses on various cooling strategies and lubrication-assisted cooling strategies to improve machining performance in the turning process of AISI 4140 steel. Liquid nitrogen (LN2) and carbon dioxide (CO2) were used as cryogenic coolants, and their performances were compared with respect to progression of tool wear. Minimum q...

This study presents investigation of chip formation process of Ti-5553 alloy that is a next generation near beta titanium alloy and has potential to be replaced with currently commonly used Ti-6Al-4V due to its superior properties such as high corrosion and fatigue resistance. Experimental part of this study includes orthogonal cutting process of T...

In this experimental study, cryogenic machining process of 316L stainless steel has been investigated. Liquid nitrogen as cryogenic cooling was utilized and it was delivered the cutting region from three different directions. These directions are flank face, rake face, and both flank and rake face. In these experimental study, tool wear, cutting te...

It is a well-known fact that Titanium alloys are commonly used materials in various industries, in particular aerospace and biomedical applications. Among titanium alloys, Ti-5553 is a new generation high temperature near beta alloy. As it has superior properties such as high tensile strength and fatigue life, it has a potential to be used in aeros...

Havacılık ve savunma sanayilerinde kullanılan birçok parçanın üretiminde talaşlı imalat yöntemi yaygın olarak kullanılmaktadır. Bu yöntem kullanılarak gerçekleştirilen imalat süreçlerinde meydana gelen termal ve mekanik etkiler imal edilen malzemelerde mikroyapısal dönüşümlere sebep olabilmekte olup bu durum nihai ürünün yorulma ömrü, korozyon dire...

This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-Ray diffraction (XRD) analysis and Differential scanning calorimeter (DSC) techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens we...

316L stainless steel has wide range of applications in various industries including biomedical, and aerospace. This study presents experimental results of machining process of 316L stainless steel. Wide range of cutting speeds were used to measure the effectiveness of high pressure coolant (HPC) and flood cooling at particularly higher cutting spee...

This study provides an experimental result of machining process of 316L stainless steel. The aim of this study is to determine the effect of high-pressure coolant (HPC) for increasing tool life in machining process of 316L stainless steel. Turning experiments were conducted at constant cutting parameters under various conditions including high-pres...

This paper presents a series of experimental investigations of the effects of various machining conditions [dry, flooded, minimum quantity lubrication (MQL), and cryogenic] and cutting parameters (cutting speed and feed rate) on thrust force, torque, tool wear, burr formation, and surface roughness in micro-drilling of Ti–6Al–4V alloy. A set of unc...

Materials with ultrafine-grained (UFG) structure become the prioritised selections for specific applications where high strength, hardness, wear/corrosion resistance, etc. are sought. Machining materials with UFG structure requires further research as their mechanical and material properties are different from the ones with regular coarse grains. I...

As one of the chipless machining processes, burnishing has been performed on manufactured components as the final operation to improve the surface integrity, including reduced surface roughness and increased surface and subsurface hardness. Refined surface layers with ultra-fine grains or nano-grains could be generated during the burnishing process...

There has been a substantial growth in using carbon fiber-reinforced plastic (CFRP) composite materials in aerospace and automotive industries due to their superior properties. This experimental study presents results from a comprehensive and systematic study investigating the effects of cryogenic cooling on drilling performance and surface integri...

NiTi shape memory alloys have gained increased interest in various industries, including biomedical and aerospace applications due to their unique properties such as shape memory effect and superelasticity. Martensitic phase transformation in NiTi significantly affects the surface integrity characteristics. This phase transformation needs to be bet...

This paper presents an analysis of experimental results on cutting forces, chip-tool contact length, chip breakability, and machining-induced layer of AISI 1045 steel from cryogenic cooling and comparison with the results from dry machining processes. The experimental study illustrated that cryogenic cooling helps to improve machining performance o...

Poor machinability from conventional machining processes is a major shortcoming that limits the manufacture of NiTi components. To better understand the effect of phase state on the machining performance of NiTi, cutting temperature, tool-wear behavior, cutting force components, tool-chip contact length, chip thickness, and machined surface quality...

Surface and subsurface characteristics of structural components, depending on the functions and their usage in service, can the critical aspect from service life viewpoint. Generated surface and subsurface characteristics of manufactured components affect wear, corrosion and fatigue resistance, and consequently determine safe-life of components tha...

The effects of cutting speed in cryogenic and dry machining on the surface integrity characteristics (the affected layer, microhardness, transformation response, transformation temperature, and latent heat for transformation) of NiTi shape memory alloys are investigated. It has been found that the cutting speed has remarkable effects on the surface...

This study investigates the effects of fabrication (vacuum arc remelting (VAR) melted vs. vacuum induction melting combined with VAR (VIM + VAR)), processing (hot rolled + fully annealed vs. cold worked + superelastic anneal) and machining conditions (dry, cryogenic, and minimum quantity lubrication (MQL)) of NiTi alloys on their progressive tool-w...

NiTi shape memory alloys are widely used in biomedical and aerospace industries. While the basic thermo-mechanical and shape memory properties have been determined in detail, the effect of final manufacturing processes on microstructural and shape memory properties of NiTi have not been as rigorously investigated. Machining techniques, especially t...

This experimental work reports the results of a study addressing tool wear, surface topography, and x-ray diffraction analysis for the finish cutting process of room-temperature austenitic NiTi alloy. Turning operation of NiTi alloy was conducted under dry, minimum quantity lubrication (MQL) and cryogenic cooling conditions at various cutting speed...