“It’s a stretch forming press, a huge one. I mean, it can barely fit into an Olympic-size swimming pool, and it’s two or three times as deep. You look down from the edge and you feel dizzy.” Daniel Sion, senior programmer at hydraulic press manufacturer Macrodyne, based in Toronto, Canada, pauses to reflect on the seemingly impossible retrofit upgrade project that consumed weeks of his life (Figure 1).
“I heard that it cost $25 to $30 million back when it was commissioned in the 1980s, and it was controlled by this industrial PC with specialized I/O cards,” he continues. “But time went on. The parent company that made the press stopped making compatible equipment, and eventually the spare parts ran out. The owner was able to get things fixed by an electronics repair center, but there was no way to improve the press’s features or functionality. Finally, it just sat there gathering dust until they called us. And then we called Delta Motion.”
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Form(ing) and function
The press has a critical job: stretching metal alloy sheets to form parts for airplane wings. Workers keep parts in a freezer at a specific temperature; heat treat them for forming and then return them to the freezer. The entire process is complex and proprietary. Naturally, forming aerospace parts also demands a high level of precision, which played a crucial role in the upgrade’s planning.
“The press owner had been seeing an accuracy of a few millimeters in position deadband,” says Sion. “They wanted it to be a lot more accurate than that, at least keeping up with the press’s original specs. But that was a tough issue because of the technology they used, and the components are just getting old.”
In addition to accuracy, the owner also needed more force. Specifically, the machine’s light table, the component with the largest area and biggest cylinder mechanism, was designed to press 800 tons. With the existing pumps, the owner could only reach 540 tons. “The customer chose to keep the existing pumps,” explains Sion.
Ultimately, production had fallen behind, the press could no longer provide the necessary precision, speed or force, and presses at competing firms provided superior functionality. Moreover, the competitors’ presses could be serviced far more affordably.
It was up to Macrodyne to figure out how to breathe new life into this antiquated relic, and much of that task fell to Sion. Fortunately, he knew who to call for help.
Press control extraordinaire
“My first exposure to Delta Motion was in late 2005,” says Sion. “I was only using the basic RMC functionality, but, year after year, each new project got more complicated, and I used more of Delta’s capacity. Now, I believe they have the best motion control. And that’s not just me; ask any Delta user.”
Macrodyne certainly needed the best because the client’s press involved a total of 53 axes. Such a monumental task required substantial preparation and considerable programming and tuning. However, the challenges began early, because Sion went into the design stage half-blind. All he had were “some pictures of the hydraulic schematics and their electrical drawings,” which might or might not have reflected current reality. The original press manufacturer couldn’t offer any help and hadn’t dealt with press setup in decades. All Sion could do was make educated guesses.
To get started, Sion purchased the Delta RMC200 motion controller he expected to use at the press site. The RMC200 controls up to 50 axes of motion and comes loaded with a wealth of communication interfaces to different PCs, human-machine interfaces (HMIs) and programmable logic controllers (PLCs). Sion connected the RMC200 to a PLC and began programming. At the same time, the client maintained pressure on Macrodyne to complete it, as the company needed the press back in operation to fulfill pending orders.
Adding even more challenge, the customer requested adding a new press function that Macrodyne had never been implemented before (Figure 2).
“The table control has two cylinders, but they treat the entire table as one axis,” says Sion. “They don’t care that there are two physical cylinders. My program has to control each cylinder and make sure the average position (virtual axis), which is in the center of the table, is the one being controlled and has the force applied to that point. There’s one position, one tilt angle, one force, even though the cylinders are acting independently. It’s like lying to yourself.”
Many more cylinder motions had to be accounted for, as well—large cylinders, near and far, pushing and pulling from the left and the right, both inward and outward. Each cylinder functioned independently but might have to cooperate and act as a single axis, depending on the motion. It essentially was a research project for Sion and his team, who had never programmed something like this before.
Deploying into action
Incredibly, Macrodyne arrived at a fully functional solution from the outset without having to redo any work. Sion confirmed this when he arrived at the client site and got hands-on with the actual press. While no one would call the effort easy, Sion says Delta Motion was critical to the success of the project. He notes, “If the Delta didn’t have the capacity to handle this, I didn’t have a solution. There was no second option. It had to work.”
With the motion control system installed, the first order of business was to tune the press’s 53 axes across the RMC200 and accompanying RMC150 controllers (Figure 3). Moreover, the press’s process spanned a sequence of roughly 100 motions. Taken together, this amounted to a genuinely Herculean programming task.
Compounding the challenge even further, the age of the client’s equipment meant that sensors couldn’t be mounted within the press cylinders. Instead, the retrofit team installed external wire-draw encoders on the cylinders. The approach is less precise, but Delta’s polling rate and software programmability helped mitigate most of the sensor’s drawbacks.
Delta Motion sent two application engineers, David McNichol and Sean O’Banion, to the client’s site to assist Sion in reducing a tuning job that he says would have taken him two weeks down to “about two days.” The Delta engineers also validated the programs Sion and his team wrote.
The graphical interface of Delta’s free RMCTools software, Sion adds, made configuration impressively quick and easy. Part of Delta’s advantage in this scenario is its application-specific focus. Programmable logic controllers are well-suited for managing overall machine control, and electric servo systems are highly effective in motor control. Delta Motion does not attempt to replace PLCs, but rather complements them to optimize motion control for specific applications. While the RMC controls electric motors very well, Delta's primary focus is on hydraulic motion control, an area in which it demonstrates exceptional proficiency.
Outstanding outcomes
Throughout the weeks Macrodyne spent completing the press retrofit, technicians with the client worked and watched alongside Sion’s team. Substantial training would have been required in similar installations, but the Delta software's intuitive nature allowed most training to be done unofficially during the installation.
“From the first moment I started to jog the machine, people were with us,” says Sion. “I didn’t invite them, but they started to come and ask questions. Naturally, every answer led to more questions. It made my life a little more difficult, but it also turned into an advantage because the experience was very thorough for the client. In the end, they still asked for an official training period, even though they’d already been making parts for a month.”
In short, the aerospace manufacturer began this process with a machine that had been out of commission for six months, and no parts or expertise were available to fix it. Today, the company has its machine back, and it is working better than ever.
Before, the press had lacked precision and could not operate at its full tonnage. Budget restraints meant keeping all the original pumps, piping and cylinders; only the seals and valves were updated. Adding Delta motion control allows the position to be measured every millisecond and managed with superior accuracy. Greater accuracy allows for increased speed because now operators know precisely where parts are, so they don’t collide with other components and cause excess wear or damage to cylinders, valves or sensors.
The client now has its press operating at full capacity, with improved quality control and greater functionality. Placing leading-edge motion control at the center of the solution turned a seemingly impossible press upgrade into a satisfied, productive manufacturer.
