Computer-Aided Assembly Sequence Planning for High-Mix Low-Volume Products in the Electronic Appliances Industry

Electronic appliance manufacturers are facing the challenge of frequent product orders. Based on each product order, the assembly process and workstations need to be planned. An essential part of the assembly planning is defining the assembly sequence, considering the mechanical product’s design, and handling of the product’s components. The assembly sequence determines the order of processes for each workstation, the overall layout, and thereby time and cost. Currently, the assembly sequence is decided by industrial engineers through a manual approach that is time-consuming, complex, and requires technical expertise. To reduce the industrial engineers’ manual effort, a Computer-Aided Assembly Sequence Planning (CAASP) system is proposed in this paper. It compromises the components for a comprehensive system that aims to be applied practically. The system uses Computer-Aided Design (CAD) files to derive Liaison and Interference Matrices that represent a mathematical relationship between parts. Subsequently, an adapted Ant Colony Optimization Algorithm generates an optimized assembly sequence based on these relationships. Through a web browser-based application, the user can upload files and interact with the system. The system is conceptualized and validated using the CAD file of an electric motor example product. The results are discussed, and future work is outlined

Robot trajectory planning using OLP and structured light 3D machine vision

This paper proposes a new methodology for robotic offline programming (OLP) addressing the issue of automatic program generation directly from 3D CAD models and verification through online 3D reconstruction. Limitations of current OLP include manufacturing tolerances between CAD and workpieces and inaccuracies in workpiece placement and modelled work cell. These issues are addressed and demonstrated through surface scanning, registration, and global and local error estimation. The method allows the robot to adjust the welding path designed from the CAD model to the actual workpiece. Alternatively, for non-repetitive tasks and where a CAD model is not available, it is possible to interactively define the path online over the scanned surface

Review on the leveraging of design information in 3D CAD models for subassemblies identification

In industrial manufacturing, both in the design and the production phase, the management of modern mechanical assemblies is becoming demanding due to their increasing complexity. The use of stable subassemblies concept constitutes a better alternative, which allows to independently treat smaller groups of the assembly's parts, also to achieve a parallel production. At this regard, several methods for automatic subassemblies identifi-cation, starting from the assembly CAD model, have been provided. However, most of the methodologies proposed rely on human intervention, especially in the model processing to make available essential data, while other details are ignored. After giving the definition of stable subassembly, this paper focuses on the application of stable subassemblies identification to industrial CAD models and highlights the issues arising. With the aim of ensuring a reliable CAD model analysis, starting point of the identification, the possible real engineering situations, both related to assembling methods and modelling techniques, are presented. Ap-proaches to algorithmically address them are then described, with the help of two examples of mechanical assemblies

Generación DELGRAFO de contactos para procesos de ensamble basado en extracción de datos: caso montajes de placas

Welding is one of the most fundamental manufacturing processes, is natural that companies and researchers develop new methods and tools to improve its productivity and flexibility (e.g., Robotic welding). Other manner to do it is the automated generation of the assembly plan for the product. This is a complex task mainly because the size of the configuration space of assembly states [1]  and the high dimensionality of the motion planning involved [2]. Researches like [1] and [3] worked to solve the configuration space problem through soft computing techniques, others proposed new methods base on the liaison graph, like the AND/OR graph [4] and a rule based assembly sequence generation system [5]. In the other hand [6] worked in the motion planning problem. Others start to use CAD files to obtain the assembly information as [7–9]. This work focuses in the developing of a method to generate the liaison graph LG in assemblies composed by prismatic plates which will be welded. The assembly geometric information will be gathered from a CAD file, the format ISO 10303 known as STEP [10]  was selected. The scope is limited to bodies with parallel positioning and rotation with a step angle of 90 degrees, this scope is sufficient to probe the approach, later extension for step angles between zero and 90 degrees is an implementation issue.La soldadura es un proceso de fabricación fundamental, las empresas e investigadores desarrollan nuevos métodos y herramientas para mejorar su productividad y flexibilidad (por ejemplo, soldadura con robots). Una forma de hacerlo es la generación automática del proceso de ensamble de producto. La tarea es compleja, por el gran tamaño del espacio de configuración de estados de ensamble  [1] y por la alta dimensionalidad de la planeación de movimiento [2]. Investigadores como [1] y [3] trabajaron para resolver el problema del espacio de configuración con técnicas de computación flexible, otros propusieron nuevos métodos base en el gráfico de enlace (LG), como el gráfico AND / OR [4] y un sistema de generación de secuencias de ensamblaje basado en reglas [5]. Por otro lado [6] trabajaron en el problema de planeación de movimiento. Otros han comenzado a usar archivos CAD para obtener la información de ensamble[7–9] . Este trabajo muestra el desarrollo de un método para generar el gráfico de enlace LG en ensamblajes compuestos por placas prismáticas que serán soldadas. La información geométrica del ensamblaje se recopila de un archivo CAD, se seleccionó el formato ISO 10303 STEP [10]. El alcance está limitado a cuerpos con posicionamiento paralelo y giros en ángulos de 90° suficiente para probar el enfoque, la extensión para ángulos de entre cero y 90° será el siguiente problema de implementación