Publication: 100cr6 malzemenin sert tornalama işleminde pt cinsinden yüzey pürüzlülüğüne etki eden faktörlerin incelenmesi
Abstract
100cr6 malzemenin sert tornalama işleminde pt cinsinden yüzey pürüzlülüğüne etki eden faktörlerin incelenmesi İnsanlığın makinelerden beklentilerinin her geçen gün artması, malzeme bilimi, bilgisayar destekli tasarım, analiz ve hesaplama kabiliyetleri, hassas ölçüm ve muayene teknolojileri ve imal usullerinde önemli gelişmeleri beraberinde getirmiştir. Günümüzde birçok mühendislik ürünü makine ağır yükler altında, uzay şartlarında, çok düşük ve yüksek sıcaklıklarda, yüksek hızlarda, çok hassas ve mikro boyutlar gibi çok farklı koşullarda insanlığa hizmet etmektedir. İnsanlık olarak sahip olduğumuz makine ve teknoloji üretme gücümüz gurur verici şekilde artmaktadır. Ancak teknolojik ilerlemelerle birlikte kaynak kullanımı ve maliyet faktörleri de giderek önem kazanmaktadır. Ülkelerin, küresel boyuttaki teknoloji yarışında, ürün fiyatındaki rekabet gücü uluslararası ticaretin şeklini belirlemektedir. Zaman zaman ekonomik savaşlara dönüşen bu rekabetin unsurlarından biri de imalat usullerindeki maliyetlerdir. İmalat maliyetleri konusu, talaşlı imalat endüstrisi olarak ele alındığında sert malzemelerin işlenmesinde, taşlama işlemi yerine sert tornalama işlemleri giderek daha fazla tercih edilmektedir. Yapılan akademik çalışmalarda sert malzemelerin işlenmesinde, sert tornalama işleminin, taşlama işleminden daha az beyaz katman oluşumuna sebep olduğu da görülmüştür. İş parçasının alın yüzeyleri, açılı yüzeyleri, delik içi yüzeyleri, radyuslar ve pahlar, eksenel ve radyal geometrik unsurlar tek bir torna tezgahında sert tornalama ile bitirilebilmektedir. Aynı zamanda iş parçasının farklı geometrileri arasındaki eşmerkezlilik, salgı ve konum gibi geometrik toleransların sağlanması da daha mümkün olmaktadır. Rulman çeliklerinin birçok çeşidi olmasına rağmen 100Cr6 çeliği, yüksek sertlik, aşınma direnci ve yorulma mukavemeti özellikleri ile en sık tercih edilenidir. Rulmanlardaki kullanımının dışında özellikle otomotiv ve makine imalatında olmak üzere kritik parçaların imalatında vazgeçilmez niteliktedir. Literatürde sert tornalama işleminin Ra cinsinden yüzey pürüzlülüğüne etkilerinin incelendiği çalışmalar mevcuttur. Ancak endüstride bilhassa sızdırmazlık yüzeylerinde Pt cinsinden yüzey pürüzlülük kriteri ile çok sık karşılaşılmaktadır. Sızdırmazlık beklentisi dış çap ve iç çap yüzeylerinde olsa da genellikle alın yüzeylerinde karşımıza çıkmaktadır. Bu bağlamda yapılan yüksek lisans tez çalışması ile 100Cr6 çeliğin sert tornalama işleminde Pt cinsinden yüzey pürüzlülüğü kriterine etki eden faktörlerin etki düzeylerinin belirlenmesi amaçlanmıştır. Bu amaca yönelik olarak literatür taraması yapılarak sabit kesme koşulları, incelenecek etki faktörleri ve seviyeleri belirlenmiştir. Deneysel çalışmada tam faktöriyel deney dizaynı ile 36 deney dış çap tornalama, 36 deney ise alın tornalama işlemi için gerçekleştirilmiştir. Sert tornalama deneyleri 55 HRC sertlikte 100Cr6 çelikten numuneler üzerinde uygulanmıştır. İncelenen etki faktörleri kater kesme kenar açısı (KAPR), kesici uç köşe radyusu (RE), kesme derinliği (Ap) ve ilerleme yönüdür. Yüzey pürüzlülüğü ölçümleri Ra ve Pt cinsinden yapılmıştır. Optimum faktör seviyelerinin belirlenmesinde Dr. Genichi Taguchi’nin sinyal-gürültü oranı (S/ N) yöntemi kullanılarak “daha küçük-daha iyi” kriteri altında gerçekleştirilmiştir. Faktörlerin etki seviyerinin ise varyans analizi (ANOVA) ile tespit edilmiştir. Elde edilen veriler, sert tornalama işleminde, yüzey kalite kriteri olarak toplam profil yüksekliği (Pt) 2µm’den daha az olan yüzeyler elde edilebileceğini göstermiştir.
Investigation of factors affecting pt surface roughness in hard turning of 100cr6 material The ever-increasing expectations of humanity from machines have led to significant developments in materials science, computer-aided design, analysis and calculation capabilities, precision measurement and inspection technologies and manufacturing methods. Today, many engineered machines serve humanity under very different conditions such as heavy loads, space conditions, very low and high temperatures, high speeds, very sensitive and micro dimensions. As humanity, our power to produce machinery and technology is proudly increasing. However, along with technological advances, resource utilization and cost factors are becoming increasingly important. The competitiveness of countries in the global technology race and product price determines the shape of international trade. One of the elements of this competition, which sometimes turns into economic wars, is the costs in manufacturing procedures. When the issue of manufacturing costs is considered as the machining industry, hard turning processes are increasingly preferred instead of grinding processes in the processing of hard materials. Academic studies have also shown that when machining hard materials, hard turning causes less white layer formation than grinding. Academic studies have also shown that hard turning causes less white layer formation than grinding when machining hard materials. Face surfaces, angled surfaces, in-hole surfaces, radii and chamfers, axial and radial geometric elements of the workpiece can be finished by hard turning on a single lathe. It is also more possible to achieve geometric tolerances such as concentricity, runout and position between different geometries of the workpiece. Although there are many types of bearing steels, 100Cr6 steel is the most preferred due to its high hardness, wear resistance and fatigue strength. Apart from its use in bearings, it is indispensable in the manufacture of critical parts, especially in automotive and machinery manufacturing. In the literature, there are studies examining the effects of hard turning process on surface roughness in terms of Ra. However, in the industry, especially on sealing surfaces, surface roughness criterion in terms of Pt is encountered very frequently. Although the sealing expectation is on the outer diameter and inner diameter surfaces, it is generally encountered on the face surfaces. In this context, with the master's thesis study, it is aimed to determine the effect levels of the factors affecting the surface roughness criterion in Pt in the hard turning process of 100Cr6 steel. For this purpose, a literature review was carried out and fixed cutting conditions, effect factors and levels to be examined were determined. In the experimental study, 36 experiments were carried out for OD turning and 36 experiments for face turning with a full factorial experimental design. Hard turning tests were performed on 100Cr6 steel specimens with a hardness of 55 HRC. The influence factors investigated were the catenary cutting edge angle (KAPR), insert corner radius (RE), depth of cut (Ap) and feed direction. Surface roughness measurements were made in Ra and Pt. The optimum factor levels were determined using Dr. Genichi Taguchi's signal-to-noise ratio (S/ N) method under the “smaller-is-better” criterion. The effect levels of the factors were determined by analysis of variance (ANOVA). The data obtained showed that in hard turning, surfaces with a total profile height of less than 2µm can be obtained as a surface quality criterion.
Investigation of factors affecting pt surface roughness in hard turning of 100cr6 material The ever-increasing expectations of humanity from machines have led to significant developments in materials science, computer-aided design, analysis and calculation capabilities, precision measurement and inspection technologies and manufacturing methods. Today, many engineered machines serve humanity under very different conditions such as heavy loads, space conditions, very low and high temperatures, high speeds, very sensitive and micro dimensions. As humanity, our power to produce machinery and technology is proudly increasing. However, along with technological advances, resource utilization and cost factors are becoming increasingly important. The competitiveness of countries in the global technology race and product price determines the shape of international trade. One of the elements of this competition, which sometimes turns into economic wars, is the costs in manufacturing procedures. When the issue of manufacturing costs is considered as the machining industry, hard turning processes are increasingly preferred instead of grinding processes in the processing of hard materials. Academic studies have also shown that when machining hard materials, hard turning causes less white layer formation than grinding. Academic studies have also shown that hard turning causes less white layer formation than grinding when machining hard materials. Face surfaces, angled surfaces, in-hole surfaces, radii and chamfers, axial and radial geometric elements of the workpiece can be finished by hard turning on a single lathe. It is also more possible to achieve geometric tolerances such as concentricity, runout and position between different geometries of the workpiece. Although there are many types of bearing steels, 100Cr6 steel is the most preferred due to its high hardness, wear resistance and fatigue strength. Apart from its use in bearings, it is indispensable in the manufacture of critical parts, especially in automotive and machinery manufacturing. In the literature, there are studies examining the effects of hard turning process on surface roughness in terms of Ra. However, in the industry, especially on sealing surfaces, surface roughness criterion in terms of Pt is encountered very frequently. Although the sealing expectation is on the outer diameter and inner diameter surfaces, it is generally encountered on the face surfaces. In this context, with the master's thesis study, it is aimed to determine the effect levels of the factors affecting the surface roughness criterion in Pt in the hard turning process of 100Cr6 steel. For this purpose, a literature review was carried out and fixed cutting conditions, effect factors and levels to be examined were determined. In the experimental study, 36 experiments were carried out for OD turning and 36 experiments for face turning with a full factorial experimental design. Hard turning tests were performed on 100Cr6 steel specimens with a hardness of 55 HRC. The influence factors investigated were the catenary cutting edge angle (KAPR), insert corner radius (RE), depth of cut (Ap) and feed direction. Surface roughness measurements were made in Ra and Pt. The optimum factor levels were determined using Dr. Genichi Taguchi's signal-to-noise ratio (S/ N) method under the “smaller-is-better” criterion. The effect levels of the factors were determined by analysis of variance (ANOVA). The data obtained showed that in hard turning, surfaces with a total profile height of less than 2µm can be obtained as a surface quality criterion.