Throughput Analysis of an Assembly Line
Assystem were commissioned by a major component supplier to the automotive industry to configure a new "mixed environment" system of manual and automatic work stations to assemble a new design of rotary connector for a major car manufacturer. The "Rotary Connector" is a device integrated into the cars steering system has seven safety critical components built into the assembly.
The system designed comprised two loops of a proprietary pallet transfer based conveyor system. Integrated into these loops were a number of manual and fully automatic work stations. The first loop, which comprised three manual and five automatic work stations, was used to assemble and fully test the flat flexible cable which is the signal carrying element of the device. The second loop was used for the assembly and testing operations. Automatic work stations were used to carry out a lubrication requirement, mechanical gauging out static electrical checks, full dynamic cycling and final electrical checking of the finished assembly. Only when all tests are satisfied is a bar code label issued and the build history of THAT assembly is accepted for lifetime records.
To confirm that the throughput would meet the specification requirements the system was modelled as a 3D kinematic simulation. Representative times for automatic actions and durations for manual tasks were input to the model as were machine availability and downtimes. This level of detail created an accurate model. Interrogation of the model demonstrated that the track layout was effective, the correct number of pallets had been selected and that when functioning correctly the designed output would be met.
During commissioning the simulation model was used to determine the process parameters. Actual data obtained from the installed equipment was input into the simulation to replicate what was occurring on the line. Variables for each station could be adjusted until the best settings were achieved. The system parameters then fine tuned to achieve a balanced product flow. The values obtained from the simulation were then used to set the devices or confirm that they were correct.
The simulation tool was invaluable during commissioning of the system because many process variations could be evaluated to find the optimum settings before implementation on the actual equipment. This approach reduced the potential number of hours of downtime and thereby saved many hours of lost production. View the movie.