The client, Federal Mogul Friction Products manufacture brake pads and linings for original equipment vehicle manufacturers in the automotive and rail industries, together with manufacture under the Ferodo brand for the aftermarket industry.
To provide a fully automated product marking and inspection system that would mark unique part identification information such as part number and batch codes onto both sides of a diverse range of brake shoe linings with a cycle time of less than 3 seconds, whilst checking both sides of every part for correct marking.
The system was required to seamlessly integrate into an existing grinding process where parts were required to be automatically fed into the marking process from the previous grinding process. The grinding process produced parts at a rate of approximately 1 every 3 seconds and the marking process was required to match this cycle time whilst also providing a 20 minute buffer. Parts exiting the grinding process were very dirty and therefore the marking system was required to clean parts prior to marking. The client specified Tampo printing as the required print media. Printed parts were required to be inspected for full character recognition however part to part the substrate onto which the marking was applied was incredibly variable, thus making the inspection process highly complex. The marking system was required to feed good parts to a collection chute ready for pick and pack by the operator whilst containing any reject parts in a locked cage.
To achieve the cycle time of less than 3 seconds QM opted to use an eight station rotary indexing table with an infeed buffering conveyor, pick and place systems to load and unload the rotary table, two Tampo print systems to print both sides of the parts and two linked National Instruments based vision systems to inspect the parts for correct marking.
A buffering conveyor removed parts directly from the previous grinding process and fed parts to Station 1. In normal run mode parts were fed slightly faster to Station 1 than received from the grind process. In buffer mode the conveyor would store up to 20 minutes of parts allowing for short stoppages at the print system for ink replenishment, part changeover etc without the need to stop the grind process.
Station 1 utilised electronic pick and place actuators to transfer the part from the conveyor to the rotary table. The use of electronic actuators allowed for a diverse range of different parts to be accommodated whilst maintaining cycle time and robustness.
Between Station 1 and 2, during the rotary table index cycle the part was passed through an air knife and extraction unit to remove dust and debris from the part prior to marking
Station 2 utilised a Tampo based printing system that would apply the marking to the part. QM Systems adopted to use a system already employed within FMFP enabling common part stencils to be utilised.
Station 3 utilised a National Instruments based vision system. The NI vision studio suite was selected to allow the flexibility in design to accommodate the variations seen in the substrate. Here the substrate, dependant on processing could contain a high number of metallic particles and the vision system needed to be able to identify between a reflective metallic particle and a white printed character.
Station 4 utilised an electronic actuator combined with a rotation, self centering gripper to lift and rotate the parts through 180 degrees.
Station 5 utilised a Tampo print system identical to Station 2.
Station 6 utilised a Vision System identical to Station 3.
Station 7 utilised electronic pick and place actuators to transfer the part from the rotary indexing table. Good parts are passed to a collection chute ready for unloading and packing by the operator, reject parts are passed to a locked reject container.
Station 8 was unused providing future room for expansion and flexibility.
The system delivered provided an annual throughput of over nine million linings per year achieving a cycle time of less than 2.9.
Thoughtful design resulted in less than two minute changeover between lining types and flexibility to adapt the system to other products.
The fully automated system provided a solution that enabled the client to re-deploy 4 operatives to other areas of the factory, whilst significantly improving quality of print and accuracy of inspection.