Assembly lines optimized for automotive displays

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Assembly line for automotive displays: Transfer position between Loop 1 and Loop 2 and commissioning phase of the line © Schnaithmann

Based on the already known or assumed process parameters, the assembly line was optimally designed using the Visual Components simulation software with regard to the required buffer spaces and workpiece carriers, among other things. The digital twin created during the design phase was adapted to the actual design as the project progressed. It can be further optimized after commissioning with the help of the real process sequences and times.

Line for the display assembly, shown with the Visual Components simulation software. © Schnaithmann

Schnaithmann has been using the Visual Components simulation software to plan and simulate assembly systems for three years now. The use of the software promises increased efficiency, savings in production costs and less time spent on project planning and design. Thanks to the extensive model library, which includes over 3,000 components from different manufacturers, visually appealing simulations can be created in the early project planning phase - even if detailed CAD files and information on all processes are not yet available. In the subsequent project phases, CAD data from the design and other detailed product and process information can complete the simulation.

At the beginning of the simulation process, the focus was on the following questions, as Wahl explains: "How many workpiece carriers are needed? Are there bottleneck stations and critical nodes in the chain? What are the effects of interruptions due to set-up work, maintenance or employee breaks? Where do buffer spaces need to be planned? How do the assembly lines influence the overall system effectiveness and system availability? And which work models, i.e. manual activities in connection with the line, are optimal?" Other points that had to be clarified with the customer as input for the simulation included the expected or estimated process times of the individual process modules, real process times from tests or reference systems and a worst-case scenario for failures or downtimes in individual processes.

Optimum number of workpiece carriers

On this basis, the simulation was used to determine the optimum number of workpiece carriers. In view of the desired diversity of variants - each line is to enable four different product variants - this is important to ensure that neither too many nor too few of the sometimes cost-intensive workpiece carriers are used later on. In addition, the necessary buffer spaces for a smooth material flow were determined and planned. "These optimizations result in the best possible availability of the system, even with short interruptions in individual processes, because buffers are built up and reduced again in a targeted manner," says Wahl. "In addition to the expected basic scenario, both a best-case and a worst-case simulation were carried out. On this basis, reliable statements can be made about system availability and the overall effectiveness of the system."

The digital twin, which was created from the simulation during the design phase, was adapted to the actual design as the project progressed. Extended requirements, additional findings and reliable data regarding the process sequences and times were added to the simulation software and the system was re-simulated in parallel. After commissioning, the digital twin can be further improved, for example with regard to the actual process times. "This means that even more reliable statements can be made regarding expected process or throughput times for subsequent optimizations or additional stations - in the spirit of simultaneous engineering," says Wahl.