Like a well-organized soccer team executing a precisely timed play on the field, linear transport systems deliver the coordinated motion manufacturers need for complex assembly tasks. A good example of this can be seen in the redesign of an automotive transmission pump assembly system performed by system integrator Eclipse Automation for one of its clients—a tier-one automotive supplier.
By deploying the eXtended Transport System (XTS) from Beckhoff Automation, along with PC-based control and high-speed EtherCAT industrial Ethernet communications, Eclipse was able to design a new assembly system in a compact footprint to make multiple automotive parts on one high-throughput machine with micron-level accuracy. With this new system, product changeover times plunged from one hour to one minute.
The base system features four separate cells with more than 50 stations for pressing, soldering, screwdriving, flatness checks with LVDTs (linear variable differential transformers), dispensing, plasma treatment, leak testing, inspection, and other processes. Some of these stations also require precise synchronization with robotics. With this setup, the new system can process two different pumps at the same time.
XTS plays a crucial role in the system. The adaptive mechatronics of XTS allow the automotive supplier to produce parts with different pitches without time-consuming changeovers or separate tooling at each station.
Electromagnetic propulsion
Eclipse constantly researches leading-edge solutions to help customers stay ahead of its competitors.
“We test all kinds of new technologies, including artificial intelligence, remote training, virtual reality for maintenance systems, and any components that add precision and flexibility,” says Jeff Werner, general manager for Eclipse, headquartered in Cambridge, Ontario, Canada. “One technology that has proven particularly important to us is linear transport systems.”
Combining the benefits of rotary and linear motion, Beckhoff’s XTS technology uses electromagnetic forces to propel movers along a track at high speeds with accelerations up to 100 m/s2. Movers with encoder flags operate individually or in groups, unlike rotary dial tables. Because each mover appears as an individual motion axis, it offers better traceability for each pump in each step in the process. The mechatronic XTS has built-in EtherCAT communication and therefore does not require separate I/O hardware for system communication.
Shrinking the footprint
This new XTS-enabled transmission pump assembly system is the second version Eclipse built for this supplier. The customer had requested the first system to replace several legacy machines that manufactured just one product type.
Though the new system replaced multiple older machines, the new machine could not achieve the throughput and quality standards the customer wanted to achieve for this high-volume product, according to Matthew Kelly, software design supervisor at Eclipse. “The previous machines used rotary dial tables and similar components. Each station only did one process and, if any station went down, it impacted the entire line.”
“The system allows operators to quickly release and replace the pallet with a second type. This new pallet indexes forward and its specific position is measured to determine an offset. We apply those offsets to each individual pallet and make sure that components and parts line up exactly for the processes. This allows the operator to easily load part type A, wait one cycle, and then load part type B with negligible downtime,” Werner says.
“Frankly, this design request seemed terrifying when we first concepted it because of the high accuracy requirements. When we presented the bold idea of suddenly taking a pallet off and putting on a different one, there was silence in the room,” he says.
Saving space
While increasing functional capabilities, the updated system from Eclipse needed to minimize footprint. “Floor space is always at a premium, but this customer’s assembly and process equipment is extremely consolidated. When we proposed the system, they said, ‘We like the concept, but make it 25% smaller.’ We didn't know if that was possible,” Werner says.
“XTS, along with the EtherCAT industrial Ethernet system and PC-based automation from Beckhoff, allowed Eclipse to concentrate an incredible number of processes in a small area and accomplish the dynamic motion control necessary to create the machine,” explains Andy Burleigh, Beckhoff applications specialist.
In the first three machine cells, operators place the pumps on pallets attached to XTS movers. The XTS systems are 12 meters long, with 18 movers in the first cell, six meters long with 12 movers in the second cell, and 10 meters long with 18 movers in the third. The pallets’ carefully calculated pitch enables micron-level positioning. When all assembly processes are complete, the operator moves the pump to the next cell. At the third cell, a small conveyor moves the pump to the fourth cell where a robot lifts the completed pump in front of two GigE cameras for a final machine vision inspection, then places it on a conveyor for outfeed.
“XTS transitions products from station to station very quickly and accurately; if there's an issue with a part at any point in the process, we can bypass other stations and simply remove it,” Kelly says. “We grouped multiple processes into a single station, which helped us further decrease footprint. With all the processes and tooling, it was the most condensed automation system I’ve ever seen.”
Changeovers: From one hour to one minute
With the innovative design by Eclipse, the updated transmission pump assembly system met the specified cycle time of 20.2 seconds per part with the micron-level accuracy required. Since commissioning finished in early 2021, the system has produced roughly 1,000 parts per shift, running part A and part B in separate batches. The easy release and attachment of pallets, along with the instant automatic indexing of XTS, almost eliminated changeover times, pushing them down from more than an hour to just one minute.
“The customer was absolutely overwhelmed by the ability to perform that changeover considering the system’s extreme compactness and complexity of process,” Werner adds. “It was a marvel of both controls and mechanical engineering to ensure easy release of these pallets without removing a single bolt.” Pallets simply move to a storage buffer and, if one is damaged, the operator can easily replace it.
Because the XTS movers are not linked as in traditional designs, they can freely move the pallets around the track to specific process steps as needed, even if the order is different between the two pumps.
