BMW – Robotic Bolt Fixing

BMW is a global automotive giant, with over 130,000 employees BMW have manufacturing operations in Germany, Brazil, China, India, South Africa, the United States, Mexico and the United Kingdom. The UK has played an important role within the BMW group with it being the only place in the world where all three of BMW Group’s brands – BMW, MINI and Rolls-Royce Motor cars are represented by manufacturing operations. The growth of BMW Group’s UK operations has been significant with the MINI plant in Oxford, the heart of MINI operations, producing MINI’s since 2001 and has produced three million to date.

Requiring a productivity boost, a KUKA LBR iiwa was deployed at the manufacturers plant in Oxford to assist MINI with the bolt fixing of their anti-roll bars. The application capitalises on human-robot collaboration with its process design allowing operator and cobot to work together in close proximity due to the sophisticated safety configurations that were developed. The integration of this cobot increased productivity for MINI enabling operators to perform more cost-effective tasks for the business.

The Original Process
MINI were looking for an automated solution to their bolt fixing process within anti-roll bar assembly as a means of boosting productivity. Their original process saw operators manage a section of the production line where they would place the part onto the anti-roll bar assembly, line up the bolts, then fix the bolts with an overhead Cleco system which was manually controlled. As this process required operators to carry out each step, there was opportunity to improve productivity by reducing waiting time between tasks. With an automated bolt fixing system operators would be able to let the cobot complete the fixing process whilst they prepare the next part, reducing time spent waiting and improving overall utilisation of time.

Reeco RB base series

Reeco’s Solution
To increase productivity within this process a collaborative application incorporating the KUKA LBR iiwa has been developed. The cobot works alongside the operator by fixing bolts into place and reducing process down time. The heart of the application is its internal electrical components and hardware which allow the cobot to communicate with the rest of MINI’s production line, as well as the application tooling for maximum integration. These components are housed in one of Reeco’s Robot Bases which are made bespoke for each project.

The cobot starts its operations by moving into its ‘home safe’ position and waits for the arrival of the part via conveyor, at this stage the cobot will look for signals that the Cleco tools are active, which are now mounted to the cobot arm. When the part arrives, the conveyor sends a signal to the cobot which confirms its arrival along with the size of the part. The cobot then moves into its ‘home fast’ position and awaits further signal that the operator has fitted the anti-roll bar, whilst in this position an output is triggered which temporarily disables conveyor movement so the cobot can work safely. After the anti-roll bar has been fitted the operator returns to their workstation and presses a button to start the process. Starting with the left bolts the cobot moves into position ready for bolt fixing, its positioning over the bolts will signal the Cleco tools to being driving, fixing the bolts. When the tools reach the correct torque, this information is relayed to the cobot allowing it to move on to the right-hand bolts. This same process is repeated and once the right-hand bolts have reached the correct torque, the cobot will move back to the ‘home safe’ position which allows the conveyor to move again. Moreover, the home safe position is assisted by external proximity sensors which constantly monitor the cobots position, ensuring safe operation.

When the anti-roll bar program was produced an additional function was created for the safety configuration of the system. The configuration utilises the KUKA’s ability to be self-aware of its location by placing itself in a virtual cage with several predetermined areas. Each area can be defined individually, for example one area could be a working space and another could be a protected space. This function, along with the ability to monitor the spaces, provides the cobot with information which tells it where it can and can’t operate, thereby preserving the safety of the operator and meeting human-robot collaboration (HRC) requirements ISO/TS 15066:2016.

The integration of this cobot has provided MINI with improved productivity through the utilisation of time after an effective HRC application. Its proven that where factories implement automation solutions they receive a productivity boost, this remains true for MINI as the better utilisation of time has provided them with improved product throughput.

Issues Solved

  • Automation of bolt fixing within anti-roll bar assembly

  • Efficient integration of Cobot into the production line

  • Safe and easy to use in workplace

  • Reduced the risk of RSI

Value Added To The Process

  • Bespoke safety configuration for full human-robot collaboration

  • Easy to meet manufacturing requirements through precise and repeatable torque levels

  • Minimises repetitive tasks

  • Increase product throughput due to a productivity increase