Toolpaths Programming in an Intelligent Step-NC Manufacturing Context

The current language for CNC programming is G-code which dates from the beginning of the eighties with the norm ISO 6983. With the new technologies, G-code becomes obsolete. It presents drawbacks that create a rupture in the numerical chain at the manufacturing step. A new standard, STEP-NC, aims to overtake these lacks. A STEP-NC file includes all the information for manufacturing, as geometry description of the entities, workplan, machining strategies, tools, etc. For rough pocket milling, the ISO norms propose different kind of classical strategies as bidirectional, parallel or spiral contour, etc. This paper describes a new way of toolpath programming by the repetition of a pattern all along a guide curve. It presents several advantages as building fastness and easiness. The integration of pattern strategies in STEP-NC standard is an other step for the development of these strategies but also for the enrichment of STEP-NC possibilities. A complete STEP-NC numerical chain was built, integrating these pattern strategies. The implementation of this approach of building pattern strategies was made by the development of tools for the complete manufacturing cycle, from the CAD file to the machined part. Several application cases were experimented on machine tool to validate this approach and the efficiency of the developped tools

Iso-level tool path planning for free-form surfaces

The aim of tool path planning is to maximize the efficiency against some given precision criteria. In practice, scallop height should be kept constant to avoid unnecessary cutting, while the tool path should be smooth enough to maintain a high feed rate. However, iso-scallop and smoothness often conflict with each other. Existing methods smooth iso-scallop paths one-by-one, which make the final tool path far from being globally optimal. This paper proposes a new framework for tool path optimization. It views a family of iso-level curves of a scalar function defined over the surface as tool path so that desired tool path can be generated by finding the function that minimizes certain energy functional and different objectives can be considered simultaneously. We use the framework to plan globally optimal tool path with respect to iso-scallop and smoothness. The energy functionals for planning iso-scallop, smoothness, and optimal tool path are respectively derived, and the path topology is studied too. Experimental results are given to show effectiveness of the proposed methods

TOOLPATHS PROGRAMMING IN AN INTELLIGENT STEP-NC MANUFACTURING CONTEXT

International audienceThe current language for CNC programming is G-code which dates from the beginning of the eighties with the norm ISO 6983. With the new technologies, G-code becomes obsolete. It presents drawbacks that create a rupture in the numerical chain at the manufacturing step. A new standard, STEP-NC, aims to overtake these lacks. A STEP-NC file includes all the information for manufacturing, as geometry description of the entities, workplan, machining strategies, tools, etc. For rough pocket milling, the ISO norms propose different kind of classical strategies as bidirectional, parallel or spiral contour, etc. This paper describes a new way of toolpath programming by the repetition of a pattern all along a guide curve. It presents several advantages as building fastness and easiness. The integration of pattern strategies in STEP-NC standard is an other step for the development of these strategies but also for the enrichment of STEP-NC possibilities. A complete STEP-NC numerical chain was built, integrating these pattern strategies. The implementation of this approach of building pattern strategies was made by the development of tools for the complete manufacturing cycle, from the CAD file to the machined part. Several application cases were experimented on machine tool to validate this approach and the efficiency of the developped tools

Integrated process planning for a hybrid manufacturing system

A hybrid manufacturing system integrated CNC machining and laser-aided layered deposition and achieves the benefits of both processes. In this dissertation, an integrated process planning framework which aims to automate the hybrid manufacturing process is investigated. Critical components of the process planning, including 3D spatial decomposition of the CAD model, improvement of the toolpath generation pattern, repairing strategies using a hybrid manufacturing system, etc., are discussed --Abstract, page iv

Development of working procedures of a 5 Axis CNC milling machine

Dissertação de mestrado em Mechanical EngineeringThe work developed and presented on this dissertation tends to the installation and configurations of a 5-axis CNC machine with the creation of working procedures intended to build a stable workflow that can be employed by any individual expected to use the machine. Being a large field within mechanical engineering as well as being involved in a large selection of different industrial sectors, the concept of 5-axis machining will be explored to develop knowledge in terms of CAM programming and manipulation/optimization of toolpaths. The importance/functioning of the transmission of information both from post-processor to the controller and from the controller to the actual machine is also a critical point in this work as they are directly related to the quality of the parts produced. To accomplish this, the theoretical knowledge foundations regarding CNC machining work were researched, studied, and explained. Furthermore, the machine model in question (HY-6040 5-axis CNC Router) was meticulously analysed regarding to the machines structure, post-processor, and controller. Upon assembling all this information, and through the production of some test parts, a permanent manufacture workflow for different machining approaches was established and described.O trabalho desenvolvido e apresentado nesta dissertação tende à instalação e configuração de uma máquina CNC de 5-eixos, com a criação de procedimentos de trabalho destinados a criar um fluxo de trabalho estável que possa ser empregue por qualquer individuo que pretenda utilizar a máquina. Sendo um grande campo dentro da engenharia mecânica e estando também envolvido numa grande seleção de diferentes setores industriais, o conceito de maquinagem em 5-eixos será explorado com a finalidade de desenvolver conhecimentos a nível de programação CAM e manipulação/otimização de trajetórias de corte. A importância/funcionamento da transmissão de informação quer do pôs-processador para o controlador, quer do controlador para a máquina constituem também um ponto critico neste trabalho já que estão diretamente relacionados com a qualidade das peças produzidas. Para a realização de tal, foram pesquisados, estudados e explicados os fundamentos do conhecimento teórico relativamente ao trabalho de maquinagem CNC. Para além disso, o modelo da máquina em questão (HY-6040 5-axis CNC Router) foi meticulosamente analisado quanto à estrutura da máquina, pós-processador e controlador. Após reunir toda esta informação, e través da produção de peças teste, foi estabelecido um fluxo de trabalho de manufatura (CAD/CAM/Maquinagem) para diferentes abordagens de maquinagem

Toolpath algorithm for free form irregular contoured walls / surfaces with internal deflecting connections.

This paper presents a toolpath generation method to efficiently machine free form irregular contoured walls / surfaces (FIWS) containing internal deflecting connections (IDC’s). The toolpath generation method is based on a series of identifications and calculations, where initially a ‘Main Computable Zone (MCZ)’ in the Machinable Areas (Ma’s) of FIWS is identified based on the Tool track dimensions (Td). Then the MCZ’s are divided into Split Computable Zones (SCZ’s) and Split Computable Zones for Internal Connections (SCZI’s) which are subsequently sub divided as ‘Categorized Computable Zones’ (CCZ) with simple-medium-high complexity. The identification of CCZ’s is based on the 10 different types of FIWS representations developed for this study. From the CCZ’s categorization of complexity, they are further split into smaller ‘Machinable Zones (MZ’s)’ using a 4-step algorithm. In the algorithm, the first step calculates a common plane (CP) to cut the steep areas in the CCZ’s where the tool cannot have full access for machining. Once the CP is identified, the second step is to extend it by moving them along the CCZ’s and calculate the necessary ‘Machinable Zones (MZ’s)’ in the next stage. This is done by finding the intersection of CP with the FIWS through a point to point / line plane intersection concept. After this step, the MZ’s are re-iterated by including the open and closed surface criteria and is analyzed for the IDC’s to be combined in the fourth stage. This is achieved by adding up the IDC’s with the existing MZ’s computed by the algorithm. At every stage, the algorithm considers tool collision avoidance and tool rubbing in the CCZ’s and MZ’s . This is by an automatic computation based on the height to fixture clearance for safer neck length which avoids collision and rubbings in the final toolpaths. Finally, a combined tool path is generated for all the MZ’s and has been verified / tested for a sample part and impeller containing similar shapes using UG NX / STEP –NC software

Analysis of Different Tool Path Strategies for Free Form Machining with Computer Aided Surface Milling Operations

[EN] Free form surfaces are commonly used to generate aesthetic parts. These parts can be manufactured directly by material removal techniques or indirectly with molding or forming techniques. In any case, these surfaces must be commonly machined with traditional processes, at least until certain degree of surface finishing, and the tool path must be generated with computer aided applications. In doing so, developers are implementing new theoretical strategy operations for controlling tool path and trajectories. These new options have so many combinations that it is difficult to know which is the best one to choose when defining the tool movements. Apart from the traditional strategies fixed angle method, principal axis method and multipoint machining, combined with tool orientation, there are many other strategies to explore due to machine tool and numerical control improvements. What is need now is a validation of these new strategies in computer aided applications regarding time minimizing and how the cutting parameters affects in the surface final result.The authors would like to thanks Universitat Politècnica de València, La Fondation Dassault Systèmes, Carolina Foundation and the National Polytechnic School for the support of this article through the 2017 call and project PIS 16-15 - PIS 16-22.Vila, C.; Ayabaca-Sarria, C.; Torres Carot, R.; Gutiérrez, SC.; Meseguer, M.; Yang, X. (2019). Analysis of Different Tool Path Strategies for Free Form Machining with Computer Aided Surface Milling Operations. Procedia Manufacturing. 41:843-850. https://doi.org/10.1016/j.promfg.2019.10.006S8438504

Determining Setup Orientations From the Visibility of Slice Geometry for Rapid Computer Numerically Controlled Machining

A method for rapid computer numerically controlled (CNC) machining is being developed in an effort to automatically create functional prototypes and parts in a wide array of materials. The method uses a plurality of simple two-and-a-half-dimensional (21/2-D) toolpaths from various orientations about an axis of rotation in order to machine the entire surface of a part without refixturing. It is our goal to automatically create these toolpaths for machining and eliminate the complex planning traditionally associated with CNC machining. In this paper, we consider a problem that arises in automating this process - visibility to the surface of a model that is rotated about a fourth axis. Our approach involves slicing the computer-aided design (CAD) model orthogonal to the axis of rotation. The slice geometry is used to calculate two-dimensional visibility maps for the set of polygons on each slice plane. The visibility data provides critical information for determining the minimum number and orientation of 21/2-D toolpaths required to machine the entire surface of a part

Multi-Axis Machining Project Development

Multi-axis milling is a manufacturing material removal process in which computer numerically controlled (CNC) tools cut away excess material through movement in four or more axes. Compared to traditional three-axis machining, multi-axis machining greatly increases the capability and accuracy of the CNC machining processes by reducing the amount of operations required to completely machine a part. Currently, the Industrial and Manufacturing Engineering Department at Cal Poly lacks an advanced CNC class that incorporates fourth and fifth axis CNC machining in the curriculum. This report describes the process behind creating a project for such a class. The class will demonstrate the increased capability of multi-axis machining through a multi-axis positioning machining project. To create the project for the class, a demo part was designed on SolidWorks to be machined on a multi-axis CNC mill. The part required initial operations to create a machining blank and workholding for the multi-axis mill, so these items were developed prior to the fabrication of the part. Each operation required a computer-aided design, computer-aided manufacturing, post-processing files, and engineering documentation. The project resulted in a multi-sided demonstration part that reflects the increased capabilities of fourth and fifth axis machining to be used in a class project in Cal Poly’s IME 336 Computer Aided Manufacturing II course