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This paper investigates the interaction between cutting tool edge radius and material separation due to ductile fracture based on Atkins' model of machining. Atkins' machining model considers the energy needed for material separation in addition to energies required for shearing at the primary shear zone and friction at the secondary shear zone. However, the effect of cutting tool edge radius, which becomes significant at microcutting conditions, was omitted. In this study, the effect of cutting tool edge radius is included in the model and its influence on material separation is investigated. A modification to the solution methodology of Atkins' machining model is proposed and it is shown that the shear yield stress and the fracture toughness of the work material can be calculated as a function of uncut chip thickness. © 2009 Elsevier Ltd. All rights reserved.

Cutting process design includes the construction of cutting plan and finding of optimal trajectory for cutting tool moving. The first problem is known as cutting-and-packing one. The most significant results are received for the problem of rectangular cutting-and-packing. The problem of finding the optimal cutting tool moving trajectory is formalized as problem of constructing the Eulerian cover with ordered enclosing. In the given research the composition of both problems to common system of cutting process design is considered. © 2009 IFAC. Honeywell

cited By 31; International audience; The vacuum cathodic arc deposition (CAD) process is now widely used on an industrial scale to prepare protective hard coatings on cutting tools, metal molds, etc.... It has been recognized that high ionization levels of cathodic arc discharges and high ion energy can provide advantages such as enhanced adhesion required for mechanical applications involving high loads. CAD allows deposition of a wide range of hard compounds as nitrides or carbonitrides. However, CAD is also often associated macrodroplet generation that degrades the surface roughness of coatings. The recent trend is to develop advanced nanostructured hard coatings in order to enhance properties as hardness, toughness, and oxidation resistance. This paper recalls the basic aspects of both CAD technology and nanostructured thin films synthesis. Deposition and characterization of both nanocomposite and nanolayered hard coatings are described. Mechanical behaviors of nitrides can be significantly enhanced by nanolayering. The first example deals with the development of hard nanolayered nitrides coatings for cutting tools protection. It is clearly shown in this example that TiN/AlTiN coatings perform better than CrN/AlTiN and TiN/CrN for the same periods and the best performance is reached for the thinnest periods. It is also shown, in a second example, how silicon addition in CrN can lead to enhancement of oxidation resistance associated with the nanocomposite structure. Thus, relationships are established between deposition conditions, nanostructure and mechanical behaviors or oxidation resistance of the coatings. This short review recalls that CAD remains a powerful and industrial technology for nanostructured hard coatings deposition. © 2011 Elsevier B.V.

Bu çalışmada, Ç1050 ve Ç4140 çeliklerinin kaplamasız ve kaplamalı seramik kesici takımlarla işlenmesinde, kesme parametreleri ile iş parçası ve takım sertliklerinin, takım ömrü ve takım aşınması üzerindeki etkileri araştırılmıştır. Taguchi Tekniği kullanılarak en yüksek takım ömrü değerlerini veren optimum kontrol faktörleri belirlenmiştir. Tahminsel takım ömrü denklemleri çıkartılmıştır. Ayrıca, aşınmış uçların SEM görüntüleri incelenerek takım aşınma tipleri belirlenmiştir. Deneysel sonuçlar, sırasıyla iş parçası sertliği, kesme hızı, kesme hızı-ilerleme miktarı etkileşimi, kesme hızı-iş parçası sertliği etkileşimi, talaş derinliği-kesici takım sertliği etkileşimi, ilerleme miktarı-iş parçası sertliği etkileşimi ve ilerleme miktarının takım ömrü üzerinde en etkili faktörler olduğunu göstermiştir. Faktör etkileşimlerinin yer aldığı ikinci dereceden tahminsel denklem daha güvenilir sonuçlar vermiştir. Ç1050 ve Ç4140 çeliklerinin seramik takımlarla işlenmesinde çentik, yan kenar ve krater aşınması gözlenmiştir. In this study, the effects of cutting parameters and the effects of workpiece hardness and tool hardness on tool life and tool wear have been investigated in machining of AISI1050 and AISI4140 steels by uncoated and coated ceramic cutting tools. Optimum cutting conditions for maximum tool life were determined using the Taguchi technique. Predictive tool life equations were derived. In addition, types of tool wear were observed by shown worn surfaces with a scanning electron microscope (SEM). The results indicated that the workpiece hardness, cutting speed, cutting speed-feed rate interaction, cutting speed-workpiece hardness interaction, dept of cut-cutting tool hardness interaction, feed rate-workpiece hardness interaction and feed rate were found out to be the most effective factors among control factors on tool life. It is observed that the second order predictive equation provided more reliable results. In machining AISI1050 and AISI4140 steels, notch wear, flank wear and crater wear observed on ceramic tools. Gazi Üniversitesi TEF-07/2003-38

Double enveloping worm gearing is expected to have contact over larger number of teeth and higher load carrying capacity compared to single enveloping worm gearing. In this paper, contact in this gearing is analysed by geometrical simulation of worm gear tooth generation using intersection profiles of different axial sections of worm representing the hob tooth profile with transverse plane of worm gear. The analysis reveals that in the engaging zone a straight line contact always exists in the median plane and intermittent contact exists at the extreme end sections of worm. This has lead to the idea of using two fly cutters positioned at the location identical to the extreme end sections of worm to generate full worm gear tooth thereby eliminating the need for hobs of complex geometry. For a given worm, a mating worm gear is machined in a gear hobbing machine using fly tool in two settings and nature of contact with the worm is checked by a blue test. � 2009 Elsevier Ltd. All rights reserved.