Correlation between machining direction, cutter geometry and step-over distance in 3-axis milling: Application to milling by zones.

Computer-Aided Manufacturing (CAM) occupies an increasingly important role in engineering with all it has to offer in terms of new possibilities and improving designer/manufacturer productivity. The present study addresses machining of free-form surfaces on a 3-axis NC machine tool. There have recently been a large number of studies devoted to planning tool paths on free-form surfaces with various strategies being adopted. These strategies are intended to increase efficiency by reducing the overall length of machining. Often, the choice of the cutter is arbitrary and the work focuses on planning. In order to boost productivity, the present work offers assistance in choosing the cutting tool, the machining direction and cutting by surface zones, adopting a milling strategy by parallel planes. To do so, a comparison is made between milling using a spherical end milling cutter and a torus end milling cutter with the same outer radius. This comparison relates to the radius of curvature of the trace left by the cutter at the point of contact between the tool and the workpiece in relation to the direction of feed motion

From computer-aided to intelligent machining: Recent advances in computer numerical control machining research

The aim of this paper is to provide an introduction and overview of recent advances in the key technologies and the supporting computerized systems, and to indicate the trend of research and development in the area of computational numerical control machining. Three main themes of recent research in CNC machining are simulation, optimization and automation, which form the key aspects of intelligent manufacturing in the digital and knowledge based manufacturing era. As the information and knowledge carrier, feature is the efficacious way to achieve intelligent manufacturing. From the regular shaped feature to freeform surface feature, the feature technology has been used in manufacturing of complex parts, such as aircraft structural parts. The authors’ latest research in intelligent machining is presented through a new concept of multi-perspective dynamic feature (MpDF), for future discussion and communication with readers of this special issue. The MpDF concept has been implemented and tested in real examples from the aerospace industry, and has the potential to make promising impact on the future research in the new paradigm of intelligent machining. The authors of this paper are the guest editors of this special issue on computational numerical control machining. The guest editors have extensive and complementary experiences in both academia and industry, gained in China, USA and UK

A Geometric Approach to Converting CAD Models to CAM Models: an Application on Aeronautical Structure Parts

"RÉSUMÉ:" La conversion d'un modèle de CAO en un modèle de FAO est la première étape de fabrication intégrée par ordinateur. Les principaux problèmes qui concernent la conversion sont les suivants: définir des volumes de matériau amovible géométriquement, vérifier les accessibilités aux volumes ainsi obtenus, associer les opérations d'usinage avec ces volumes individuellement, sélectionner les outils de coupe, mettre en séquençage les opérations d'usinage et assigner une machine pour exécuter le processus. La détermination des volumes individuels de matériel amovible est le premier problème de la conversion. Dans les dernières décennies, de nombreuses approches ont été développées avec d'énormes efforts, mais aucune étude à ce jour a examiné de manière exhaustive les approches pour générer des volumes de matériau amovible pour traiter des pièces complexes, telles que celles qu’on rencontre dans en aéronautique dans la partie structurelle. Dans la perspective de définir les volumes du matériau amovible, les méthodes existantes se limitent aux fonctions prismatiques. L'objectif principal de cette recherche était de développer des approches systématiques, pour générer automatiquement l'ensemble des volumes de matières amovibles selon les modèles 3D d’une pièce aéronautique structurelle. Il faut alors partir du brut (un morceau de matière première) et usiner toutes les surfaces requises. Grâce à l'outil mathématique disponible des opérations booléennes, il est possible de séparer des géométries volumiques très complexes en volumes plus petits relativement simples. La décomposition du volume delta présente des avantages dans la création des volumes amovibles. Dans cette recherche, les approches de décomposition de volume ont été développées dans le but que chaque volume de matériau puisse être usiné en une seule opération d'usinage. Des arêtes concaves impliquent éventuellement des opérations d'usinage différentes. La détection du bord concave est la première étape de la décomposition de volume intérieur. Dans cette étude, une approche mathématique a été développée afin de vérifier la concavité d'une arête dans la limite d'un modèle solide 3D et une approche de détection des bords concaves est proposée. Générer des faces de séparation est une étape clé pour définir un volume décomposé. Selon la complexité de l'élément de construction, les algorithmes sont conçus pour créer différents types de décompositions de faces correspondant à des formes locales de la pièce à décomposer.----------"ABSTRACT:" Conversion of a CAD model to a CAM model is the initial step of computer integrated manufacturing. Main issues concerning the conversion are as follows: defining volumes of removable material geometrically, verifying accessibilities to so obtained volumes, associating machining operations with these volumes individually, selecting cutting tools, sequencing machining operations, and assign a machine to perform the process. Determination of individual volumes of removable material is the first issue of the conversion. In the past decades many approaches have been developed by enormous efforts but no study up to date has comprehensively discussed approaches to generate volumes of removable material for producing a complex aeronautical structural part. In the perspective of volumetric definition of removable material, existing methods are limited to prismatic features. The main objective of this research was to develop systematic approaches to generating automatically the complete set of volumes of removable material according to the 3D models of both an aeronautical structural part to be produced and the stock (a piece of raw material) to be machined. Due to powerful mathematical tool of Boolean operations available for separating very complex volumetric geometries into relatively simple smaller volumes, delta volume decomposition has advantages in generating removable volumes. In this research volume decomposition approaches were developed for the purpose that every volume of material can be machined in one machining operation. Concave edges imply possible requirement of different machining operations. Detecting concave edge is the premier step of interior volume decomposition. In this study a mathematical approach was developed to verify the concavity of an edge in the boundary of a 3D solid model. Approaches to detecting concave edges were proposed. Generating splitting faces is the key step to define a decomposed volume. According to the complexity of the structural component, algorithms are developed to create different kinds of splitting faces corresponding to local shapes of the part to perform decompositions. Face union is a powerful tool to separate volumes bounded by faces of complex geometries. This research proposed recursive procedures of decomposition. Using the proposed approaches the 3D design model of an aeronautic structural component is converted into volumes of removable material (named sub delta volume and denoted SDV in this research) by means of delta volume decomposition

A knowledge-based approach for the extraction of machining features from solid models

Computer understanding of machining features such as holes and pockets is essential for bridging the communication gap between Computer Aided Design and Computer Aided Manufacture. This thesis describes a prototype machining feature extraction system that is implemented by integrating the VAX-OPS5 rule-based artificial intelligence environment with the PADL-2 solid modeller. Specification of original stock and finished part geometry within the solid modeller is followed by determination of the nominal surface boundary of the corresponding cavity volume model by means of Boolean subtraction and boundary evaluation. The boundary model of the cavity volume is managed by using winged-edge and frame-based data structures. Machining features are extracted using two methods : (1) automatic feature recognition, and (2) machine learning of features for subsequent recognition. [Continues.

A CAD/CAM concept for High Speed Cutting compatible rough machining in die, mould and pattern manufacturing

Die, mould and pattern manufacturing plays a central role in the production of capital and consumer goods. Ever-shorter product life cycles and the expanding diversity of features require continued cuts in production lead times. Recently, these developments in the market, accompanied by a simultaneous demand for improved quality at a lower cost, are becoming clearly noticeable. Along with the streamlining of organizational structures and advanced technological developments, it is above all the introduction of CAD/CAM software that offers great potential for reducing lead times for components with free surfaces. The role of milling in the integrated process chain of die, mould and pattern manufacturing is steadily gaining importance. This is due to the ongoing further development of milling-machine technology, the cutting tools and their coatings, and of the CAD /CAM systems themselves. Generally speaking, the milling process is divided into the operations of roughing and finishing. For rough milling, efficient machining means high stock-removal rates together with close contour approximation and low tool wear. Rough milling is normally carried out layer by layer, i.e. in a 2.SD machining operation with constant depth per cut because the rate of material removal and process reliability are usually highest when this method is used. High-speed cutting (HSC), which has been the subject of extensive university research for far more than ten years, has meanwhile become established as a finishing process in many companies. However, the application of HSC demands the observance of geometric and, above all, technological constraints. A considerable degree of optimization can be achieved when these constraints are applied to rough milling. In the integrated process chain, the CAD/CAM system performs the task of calculating NC programs based on CAD data which meet the requirements posed by rough and finish machining operations. While general interest was focused on the development of CAM strategies for HSC finish machining, advanced development of technology-oriented CAM modules for upstream roughing operations was neglected. The paper at hand deals with the development of a CAM module for rough-machining complex components in die, mould and pattern manufacturing. It provides an insight into the process-technological demands made on HSC operations and their application in rough machining, from which guidelines and requirements on technologically oriented NC functions for CAM software were derived. These encompass both the complete development of an interactive, dialogue-based user guidance function and the algorithmic conversion of the calculation routines. The concept at hand was almost entirely implemented and integrated in the CAD/CAM system developed by Tebis AG, Germany, which was conceived especially for die, mould and pattern manufacturing and is scheduled for introduction to the free market starting in April 2001

A new geometric-and-physics model of milling and an effective approach to medial axis transforms of free-form pockets for high performance machining

Mechanical part quality and productivity depend on many parameters in CNC milling processes, such as workpiece material, cutters, tool paths, feed rate, and spindle speed, etc. To pursue high performance machining, the cutting parameter optimization is in high demand in industry, though it is quite challenge. This innovative research successfully addresses some essential problems in optimizing the cutting parameters by developing a new geometric-and-physics integrated model of milling and proposing an effective approach to the medial axis transforms of free-form pockets. In this research, an original geometric model of 21/2- and 3-axis CNC milling is developed and integrated with a well-established mechanistic model. A main research contribution is that this integrated model can predict complex milling processes in higher fidelity with instantaneous material remove rates, cutting forces and spindle powers, compared to prior machining models. In the geometric model, an in-process workpiece model is introduced by using a group of discrete Z-layers and applying the B-Rep scheme to represent the workpiece shape on each layer, in order to accurately represent instantaneous cutter-and-workpiece engagement in 2Yz- and 3-axis milling. Hence, the un-deformed chip geometry can be found even for complex part milling, which is then fed to the mechanistic model to predict instantaneous cutting forces. By using this integrated model, cutting parameters can be optimized for profiling, pocketing, and surface milling to ensure steady cut and the maximum material removal rates. This model has been verified by experiments, and will be implemented into a software tool for Bombardier Aerospace. Another important research in this work is to propose aggressive roughing of free-form pockets for ultimately high cutting efficiency. For this purpose, an accurate, efficient approach to the medial axis transforms of free-form pockets and an optimal approach to multiple cutters selection and their path generation are proposed. The main contributions of this research include (1) a new mathematical model of medial axis point, (2) an innovative global optimization solver, the hybrid global optimization method, (3) an optimization model of selecting multiple cutters for the maximum material removal rate. This research can substantially promote aggressive roughing in the machining industry to increase cutting efficiency of free-form pockets. The technique has been validated using considerable number of cutting tests and can be directly implemented into commercial CAD/CAM softwar

Proceedings of the 4th International Conference on Innovations in Automation and Mechatronics Engineering (ICIAME2018)

The Mechatronics Department (Accredited by National Board of Accreditation, New Delhi, India) of the G H Patel College of Engineering and Technology, Gujarat, India arranged the 4th International Conference on Innovations in Automation and Mechatronics Engineering 2018, (ICIAME 2018) on 2-3 February 2018. The papers presented during the conference were based on Automation, Optimization, Computer Aided Design and Manufacturing, Nanotechnology, Solar Energy etc and are featured in this book

Special Issue of the Manufacturing Engineering Society (MES)

This book derives from the Special Issue of the Manufacturing Engineering Society (MES) that was launched as a Special Issue of the journal Materials. The 48 contributions, published in this book, explore the evolution of traditional manufacturing models toward the new requirements of the Manufacturing Industry 4.0 and present cutting-edge advances in the field of Manufacturing Engineering focusing on additive manufacturing and 3D printing, advances and innovations in manufacturing processes, sustainable and green manufacturing, manufacturing systems (machines, equipment and tooling), metrology and quality in manufacturing, Industry 4.0, product lifecycle management (PLM) technologies, and production planning and risks