When a new production line for airbag control sensors was required by TRW Systems, the company turned to Stäubli and its system integration partners, Grohmann and IPTE, to provide the robots required at the heart of the automated sequence of cells
TRW Systems located at Peterlee, County Durham, specialises in automotive safety – manufacturing intelligent systems for leading automotive OEMs that help to keep passengers, drivers and pedestrians safe.
TRW at Peterlee has been manufacturing airbag control systems for several years using a combination of in-house and outsourced components for the final assembly. Increased demand and an objective of bringing more of the supply chain in-house has generated the need for new investment in a dedicated manufacturing line. Initially, a manually-based system was considered but when TRW looked into the economics of using multi-axis robots, a decision to fully automate the new line with a combination of four-axis and six-axis robotics provided the best cost benefit solution.
The new manufacturing line consists of several connected cells each utilising Stäubli robots. The initial operation is to insert a metal bush into the PCB. This process is performed by two TS60 four-axis Scara robots – the first picking up the metal insert and placing into position, and the second pressing the bush securely into place on the PCB. Each board comprises an array of up to 48 sensor units.
The boards then pass into the adjacent cell where the electrical contacts are cut from an in-feed roll and inserted into the PCB. After this process the individual sensor components are separated from the board and proceed to a vision checking station handled by a TS60. The position of the electrical contacts is extremely critical and needs to be within +/- 0.1mm to ensure correct operation of the sensor.
After passing through a heating station, the sensor components enter the overmoulding cell serviced by two RX160 six-axis robots – chosen by TRW for their reach and speed of operation. The components are arranged into trays of eight and the first operation is to apply a thermoplastic elastomer followed by a second overcoating of glass filled nylon. The RX 160s execute the fast demoulding, positioning and placing required, all within the IMM cycle time of just 30 seconds. Each component is then fed by the robots into a final functional testing station which replicates the inertial shock that would be experienced in a crash – a response time of just 19 milliseconds for the airbag signal to be emitted is required for the components to pass the test. Failures at this stage are rare – less than 0.1% – a considerable improvement on the previous manual system using outsourced components. The final station applies the labeling and marking on each component ensuring 100% traceability.
Investing in robotics
This was the first investment in automation using multi-axis robots at TRW Peterlee, and initially there were some concerns about ease of use and the training that could be required. Their fears proved groundless with the operators quickly recognising and embracing fully the benefits of the new system. The new line has been operating 24 hours a day, six days a week for seven months without any major problems.
The new line has the flexibility to accommodate a range of different sensor models – currently 12 variants can be processed and has provided a manpower saving of 12 over a manual system. The ability to manufacture on a strict JIT basis has minimised inventory. With a payback of less than one year, TRW has been impressed by the performance of the automated line and particularly the Stäubli robots – so much so that they are now planning a second line with the same level of automation.
TRW Peterlee is now recognised in the group as a ‘Super Site’ and is its centre for manufacturing in Europe.
Stäubli Robotics’ input into the new system eased the path for TRW towards its first adoption of multi-axis robotics and clearly highlighted the benefits that can be readily achieved by the use of these advanced, user friendly machines.
Stäubli
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