Carter Paden freely admits that stamping houses aren’t high on his prospective buyer’s list for the company’s Smart Function Kit for pressing and joining applications. A sales product manager at Rexroth, a Bosch company, he’d say that automakers stacking lithium battery cells are a more likely fit. So are the coffee-making equipment manufacturers that need an efficient way to press seals and fittings into place by the thousands.
But there’s an application that hits closer to a stamping floor: the job shop that needs to press bearings into a large family of sheet metal housings and do so with minimal changeover time. Swap the tool tip and call up a different stored program and the same actuator in the kit handles the next bearing size that comes down the line. This is exactly the kind of secondary operation an OEM or one of its Tier suppliers might tack onto the back end of a press line.
It works the same as any other actuator, at least from a purely mechanical perspective: a rod extends and retracts under programmed force and position control. What’s different here is that Rexroth packages that actuator with its own drive, force sensor, cabling and software as one ordered unit. This is instead of a pile of components a buyer has to spec out and order – possibly from multiple suppliers – and then wire everything together to get it working.
“Think of it as the smart version of a rod-style actuator,” Paden says, “one designed to be a plug-and-play solution.”
Stacking blocks
Commissioning a pressing station the traditional way often calls for controls engineering, custom programming and days of integration. The Smart Function Kit compresses all of that effort into a wizard. The drive arrives pre-loaded with data about its own actuator – maximum force, safe-stop thresholds, and so on – so no manual calculation is needed and nobody from Rexroth has to come on-site. That said, the company backs the kit with video walkthroughs and phone support for anyone that runs into trouble.
That phone call to tech support is unlikely, however, because programming runs through a browser-based interface built around what Paden calls logic blocks.
“You basically just build it block by block,” he says. “It isn’t something that requires a huge amount of expertise to figure out.”
Simply put, the Smart Function Kit doesn’t require a college degree to program; enter a few values in the drag-and-drop interface and enter the path to more productive pressing and joining.
“You’re really just entering in a couple of parameters,” Paden adds. “It’s maybe three screens – next, next, next and you’re done.”
Assembled in the correct order, these logic blocks tell the actuator what to do and for how long. An operator drags a move block onto the screen, types in a distance, adds a dwell block and sets a hold time. Up to 99 motion profiles or unique applications can be stored at once, so a shop running mixed work can call up a different profile for each job instead of reprogramming from scratch. The software can also take a signal from an upstream station and hold the actuator until that step clears, meaning several operations can be chained together without anyone writing a single line of PLC code.
Force multiplier
Paden notes that metal stamping and forming shops aren’t unique in their struggle to find people who can program and maintain automated equipment. Rexroth built the Smart Function Kit’s interface, in part, so that gap doesn’t stop a shop from automating a pressing or joining step it otherwise couldn’t staff.
Solutions like this will only become easier to implement over time, in part because younger engineers don’t need much convincing to dive in. Paden says many came up through robotics courses that didn’t exist a generation ago.
“None of this is intimidating, even for those with little programming experience,” he says.
There’s a labor argument for going electric, too, separate from ease of use. A hydraulic press usually needs an operator standing there to feed it, pull a lever and move the part along; once set up, an automated pressing station runs on its own.
“Each operator can produce more,” Paden says. “Maybe you have one person running two, three or even four machines with less effort and more time to focus on part quality.”
For a shop already stretched thin on skilled labor, that multiplier can make a huge difference to the bottom line.
Retiring hydraulics
Before such kits existed, this kind of pressing and joining work usually ran on the hydraulic presses mentioned. Paden isn’t shy about what that means day to day: reservoirs to maintain, pumps and valves to service, oil that needs regular changing and a power unit that has to stay pressurized whether or not it’s actually pressing anything.
Hydraulics still win on raw force density, he concedes, but most everything else leans in servo’s favor. Electromechanical actuators only draw power on the stroke and they move quicker besides, picking up real throughput on the same job.
Even so, many purchasing departments still tend to favor hydraulics because they’re typically less expensive. But Paden contends the total cost flips in the other direction once the electromechanical actuator is installed and running. Over its lifetime, an electromechanical actuator typically delivers a better return on investment than a hydraulic cylinder, even though it starts as a pricier option.
The justification is simplest to make on a new line built from scratch; replacing a hydraulic system that’s already paid for is a tougher financial case because the supporting infrastructure is often a sunk cost. Despite this, Paden says inquiries about electric versus hydraulic actuators are among the most common reasons customers call.
Factory focus
Investment in smart systems like this is also an important step on the path to continuous improvement. Because every stroke gets logged, with the software plotting the force curve in real time and flagging anything that falls outside a defined envelope, defective parts can be sequestered for a closer look.
Several customers use that same traceability feed to assign each part a serial code for long-term recordkeeping. The Smart Function Kit doesn’t demand a particular control platform either – it connects into whatever fieldbus a shop already runs, from Profinet to EtherCAT, so a line doesn’t need a control overhaul just to upgrade an actuator.
“If you detect the issue upstream, you prevent a whole cascade of cost downstream,” Paden says.
At up to 70 kN of advertised force, with higher capacity units already shipping and a 250-kN version in development, plus IP65-rated cylinders and stroke lengths configurable to 400 mm, the kit is built for more than a demo booth.
“Some of these actuators have been running for 15, 20 years without any issue whatsoever,” Paden says. “I expect the Smart Function Kit will provide even greater performance.”
Don’t get behind on the stamping technology that advances the industry – stay informed with our extensive stamping archive.
