The developed portfolio of simulation tools (portfolio of ‘Pull’ KETs) enables a hierarchical decomposition of manufacturing system into the following critical modules which iteratively exchange their optimization results, design solutions a (Fig. 1): (1) System Feasibility & Configuration module determines an initial system layout and optimize cycle time and buffer sizes of a manufacturing system with embedded RLW technology and includes three simulation tools. (2) Workstation Planning and OLP module determines the detailed configuration of an RLW workstation and its operation, up to off-line programming (OLP) and is based on one simulation tool. (3) Process Design/Optimizer module sees that all technological constraints are satisfied by appropriate fixture layout and process parameters optimization and is based on three simulation tools. (4) Process Control module performs in-process weld quality monitoring, weld quality performance evaluation and correction to produce joints of required quality and is based on three simulation tools. (5) Process Assessment and Visualisation module allows for (i) eco-evaluation of energy use during RLW operations; (ii) product process resource costinf for RLW workstation; and (iii) RLW system 3D visualisation and includes three simulation tools.
Figure 1. The outline of the modules for rapid deployment of RLW process
Process Feasibility & System Configuration The goal of the “Process feasibility and System Configuration” module is to support the rapid earlystage design of the assembly system and to properly integrate RLW stations in the system, thus allowing to fully exploiting the potentials of RLW.This module provides the following main outputs and tools:
(i) System layout concept based on initial number and type of robots and workload as measured by number of joints (Assembly Layout and Process Estimator Simulation Tool)
(ii) Optimised cycle time and buffer size to ensure productivity requirements and also considering each machines’reliability for each of the evaluated configurations (System Configuration Optimiser Simulation Tool)
(iii) Integration of system layout and cycle time) (System Configurator Simulation Tool)
Process Design/Optimiser The goal of the “Process Design” module is to optimize the process performances to achieve optimum quality of the final RLW assembled product.This module provides the following main outputs and tools:
(i) Analytical model of geometric variation of a single or batch of deformable parts and using this model for variation
simulation analysis of assembly process (Part Variation Modeller Simulation Tool)
(ii) Fixture layout optimisation for assembly of a single or batch of deformable parts (Fixture Layout Analyser and
Optimiser Simulation Tool)
(iii) RLW joining process parameters selection and optimisation (Laser Parameters Optimiser Simulation Tool); which can also be interlinked with (i) & (ii) as iterative optimisation. The interlinked optimisation can be formulated as a single- or multi-objective decision problem with the following objectives: joint quality; product quality as defined by GD&T; or energy use. The simulation tools can support process development, installation & commissioning.
Workstation Planning and OLP The goal of the “Workstation Configuration and OLP” module is to determine the detailed configuration and operations of the RLW workstation including the generation of the executable offline
program (OLP). This module provides the following main outputs and tools
(i) Detailed configuration of the workstation, with the precise placement of all its elements and conducted
accessibility analysis for all the welding tasks
(ii) executable off-line program (OLP) of the RLW robot that completes all welding tasks with a minimum cycle time and complies with the kinematic model and the controller of the robot
(iii) 3D simulation of the workstation operations using advanced graphical user interface. This feeds into the Process Design simulation or can be used as interlinked iterative optimisation between Workstation Planning & Process Design.
Process Control The goal of "Process Control" module is to develop production tools for minimizing the ramp-up time and ensuring good weld quality during production through process monitoring and control This module provides the following main outputs and tools
(i) In-process monitoring of RLW process on the COMAU’s SmartLaser (SmartLaser Process Monitoring Integration Tool)
(ii) Inprocess weld quality performance evaluation (interface width) (Weld Quality Performance Evaluator Tool);
(iii) Root cause analysis and correction of process failures affecting product quality (Process Monitoring and Weld Fault Classification Tool). The crucial benefits of the toolkit is its capability for closed-loop quality improvement via adjusting joining process parameters.
Process Assessment and Visualisation The goal of "Process Assessment and Visualisation" module isTo develop a demonstration test-bed to prove the robustness and reliability of simulation tools against industrial standard.This module provides the following main outputs and tools:
(i) Eco-evaluation of energy use during RLW operations (RLW Eco Advisor Simulation Tool);
(ii) Product process resource costing for RLW workstation (Product, Process and Resource Costing (PPRC) for RLW Simulation Tool);
(iii) RLW system 3D visualisation (System Evaluation and Visualization Interface (SEVI) Simulation Tool).
The application of the simulation tools led to the first fully digitally developed Remote Laser Welding
automotive door assembly process. Then, the results were verified and validated by using the
developed physical demonstrator which includes pre-production tooling (welding and dimpling
fixtures; in-process monitoring of weld quality system) and selection of all joining process parameters
(robot OLP, laser welding process parameters). The final verification of the first fully digitally
developed Remote Laser Welding automotive door assembly process was conducted by building and
fully testing 12 doors. The developed simulation tools when compared with the best industrial practice
has led to reduction of unnecessary changes by: (i) 50% during fixture installation; and (ii) 75% during
welding parameters selection; what can result in 30% reduction of launch time.
Figure 2: Impact of simulation tools on new product introduction process