Abstract Prediction of chip-breaking in machining is an important task for automated manufacturing. There are chip-breaking limits in machining chip-breaking chart, which determine the chip-breaking range. This thesis presents a study of the effect of 3-D groove insert parameters on chip breaking chart. Based on the chip-breaking criteria, the critical feed rate is formulated through an analysis of up-curl chip formation for 3-D grooves. Also in order to predict chip-breaking limits, for protruded insert grooves in finish machining, analytical models are established. In the analytical models, minimum and maximum depth of cut are identified for using different chip breaking models. As well insert nose radius effects on chip thickness for small depth of cut are studied. In the end, the analytical critical feed rate model is extended to finish machining with 3-D chipbreaking grooves.

Prediction of chip-breaking in machining is an important task for automated manufacturing. There are chip-breaking limits in maching chip-breaking processes, which determine the chip-breaking range. This paper presents a study of chip-breaking limits with grooved cutting tools, and a web-based machining chip-breaking prediction system. Based on the chip-breaking curve, the critical feed rate is modeled through an analysis of up-curl chip formation, and the critical depth of cut is formulated through a discussion of side-curl dominant chip-formation processes. Factors affecting chip-breaking limits are also discussed. In order to predict chip-breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties. A new web-based machining chip-breaking prediction system is introduced with examples of industrial applications.

Poor chip breaking is a normal problem in the field of machining in many manufacturing plants. The researches on chip control has started from the early 1900s, it has developed for more than one hundred years and researchers are still working on it to establish a ‘total’ chip control system. The purpose of this project is chip breaking improvement for reducing downtime and further increasing OEE, because of the problems long chips that cause during a soft turning process. This thesis provides basic theories and existing methods for chip breaking which are helpful to understand chip breaking and to generate solutions for chip breaking optimization. During the project, five concepts are generated and two concepts are tested which are presented in this report. The concept ‘multiple tool paths’, which was verified by tests, could successfully reduce the length of metal chips and improving the performance of chip breaking. / Dålig spånbrytning är ett vanligt problem vid maskinbearbetning i många tillverkningsanläggningar. Forskningen om spånbrytning inleddes under tidigt 1900-tal, den har alltså utvecklats i mer än hundra år och forskare arbetar fortfarande med att skapa ett "totalt" spånbrytningssystem. Syftet med det här projektet är att förbättra spånbrytningen för att minska ledtiden och ytterligare öka OEE vid mjukvarvning på grund av de problem som långa chips orsakar. Denna avhandling behandlar grundläggande teorier och befintliga metoder för spånbrytning som är användbara för att förstå spånbrytning och därmed kunna föreslå lösningar för att optimera spånbrytningen. Under projektet skapades fem koncept, varav två provades. Konceptet "flera verktygsbanor" verifierades genom prov. Det visas att det konceptet med framgång kunde minska längden på metallchip och förbättra spånbrytningens prestanda.

Les aciers inoxydables sont employés dans des secteurs d’activitéspour lesquels les caractéristiques mécaniques et la résistance à lacorrosion sont primordiaux. Les nuances austéno-ferritiques sansmolybdène (lean-duplex), ont une résistance à la corrosion et despropriétés mécaniques supérieures aux aciers inoxydables austénitiques.Cependant, leur usinabilité est inférieure à celle de leur homologueausténitique. Pour améliorer cette propriété des éléments peuvent êtreajoutés dans les nuances, tel que le niobium. L’objectif de cette étude estd’améliorer l’usinabilité des lean-duplex sans dégrader les autrespropriétés. Différentes teneurs en niobium ont été ajoutées dans un1.4362 pour comprendre comment cet élément affecte la microstructure,la résilience, et la résistance à la corrosion par piqûres. Ces résultatsvont permettre de définir une teneur en niobium optimale. Pour finir, desessais d’usinabilité et de résilience ont été effectués sur des couléesindustrielles de 1.4362 avec et sans niobium après divers traitementsthermiques pour comprendre l’influence d’un ajout de niobium sur cesdeux propriétés. / Stainless steels are used in some industries requiring mechanicalproperties and corrosion resistance. Lean duplex have higher corrosionresistance and mechanical properties than the austenitic stainless steels.However, their machinability is below that of the corresponding austeniticstainless steels. To improve it, some elements can be added in thegrade, like niobium. The aim of this study is to increase machinability oflean duplex grades without degrading their other properties. Differentcontents of niobium were tested in a 1.4362 to understand how thiselement affects the microstructure, the toughness and the pittingcorrosion resistance. With these results optimum niobium content isdefined. Turning and toughness experiments were done on industrial1.4362 grades with and without niobium and with different heatstreatments in order to understand how niobium can influence theseproperties.

This document is about the work conducted during four months in the company Poclain Hydraulics. The aim was to improve the productivity of the turning operation on the cams MK04, in a factory environment but with the support of a laboratory. Was also in mind to improve the quality of the part and diminish or eliminate the unbroken chips. In that purpose the trajectories have been analyzed and modified, the cutting conditions studied and adapted, some tool changed, etc. The final result was an improvement of productivity to 140%, an amelioration of the chip breaking and of the part’s quality, leading to significant savings on the process.