Do you ever wonder just what the heck is going on inside your stamping press? Maybe the parts are kicking up random burrs or that new coil of material likes to buckle unexpectedly. Or maybe there was a misfeed yesterday and even though the die survived the hit, something sounds a little bit off. If only machines could talk, right?
Jim Finnerty can give them a voice. A product manager with Wintriss Controls Group LLC, Acton, Mass., Finnerty says the company developed its first “super control” in 1985 – the Spectrum – and patented the first electronic die protection system nearly three decades before that, long before Industry 4.0 and the Industrial Internet of Things made machine monitoring systems an increasingly common and necessary investment.
touchscreen interface, dual-core processors, user-configurable dashboards, virtually unlimited
tool setup storage and the ability to share setups among networked SmartPac Pro units.
“Think about the cost of a progressive die, never mind the downtime and expense you’ll incur after crashing one,” Finnerty says. “If you knew there was a relatively inexpensive way to prevent that from happening, wouldn’t you want to know about it?”
Upgrade time
There are many shops that already do know about it, he says. They’re the shops that invested in the original SmartPac, introduced nine years after its Spectrum predecessor. And today, the SmartPac Pro is taking things even further.
“The SmartPac Pro press automation controller is the latest iteration of our flagship product, and a big percentage of our current business is helping shops that want to upgrade and take advantage of all the new features it has,” Finnerty says. “These are features that we’ve developed over the past couple of years in response to customer requests for additional functionality.”
The newest version provides “very comprehensive monitoring and control of a metal stamping press,” he explains. For instance, the system monitors discrete output sensors for die protection with up to 32 inputs as well as analog sensors for in-die measurement. It can also monitor press tonnage, either peak load monitoring or the full waveform monitoring that enables analysis anywhere within the stroke.
In terms of control, Finnerty adds that Wintriss has “the most powerful programmable limit switches available to put on a press with a host of new die protection features that are really cutting edge.”
Why bother?
Why is all this monitoring necessary? Finnerty provides several examples, beginning with one of the simplest yet most essential in any stamping operation: ensuring that parts leave the die as planned. Here, avoiding disaster is no more difficult than mounting a photoelectric sensor on the die and aiming it such that the part activates the eye upon ejection; if no part is detected, the press immediately stops.
In another application, the press operator needs to make certain that the strip feeds into the progressive die within 0.005 in. of its nominal length. Here again, it’s simple enough to install a photo eye to detect a hole, slot or other part feature that will activate it – or not. If the latter, the control stops the press before it makes a bad hit.
Does this level of sophistication imply that integration back to the feeder is needed, raising implementation costs? Not necessarily.
“Our control is resolver-based, so we always know the position of the crankshaft,” Finnerty says. “If the material is supposed to be in place when it hits top dead center, we just tell the die protection system, ‘Look, when this is at zero degrees, the sensor should be on. If not, then activate the emergency stop.’”
What about less obvious situations, such as the wrong material, unacceptable thickness variations or loss of lubricant? The sensor technology just described won’t detect such conditions, but a tonnage monitor will, and again, it can either stop the press or alert the operator to take corrective action.
Get a grip
Why not just rely on the latter and skip all this sensor-based die protection stuff? Simple, Finnerty says. “If you have a catastrophe, the tonnage will go through the roof and the machine will stop, but unfortunately, it’s too late at that point. You’ve already made a bad hit. That’s why we tell customers they need both types of systems.”
Die protection does all the heavy lifting, he explains. It helps to avoid the predictable, everyday occurrences that can cost big bucks and, potentially, weeks of downtime, such as material that doesn’t feed properly, a non-ejected part, a side-action cam that doesn’t return or a wayward slug sitting on top of the strip. Dedicated sensors within the die protection system detect these and many other problems before they affect production while the tonnage monitor prevents the myriad of situations that are less predictable and that you would never install a specific sensor to detect.
To illustrate his point, Finnerty offers an example from a customer that was just getting started with monitoring and was, as yet, unwilling to invest in more than a part ejection sensor. At the end of every day, the very experienced first-shift operator would make sure there was a full coil of steel ready to run and then put a pair of vise grips on the strip to hold it in place. A less-experienced second-shift operator would come in, pop off the clamps and get to work.
“One day, the second-shift guy called in sick, so they put somebody with even less experience on the machine,” he says. “Of course, he didn’t know to remove the vise grips before punching the start button. They made it through the first five stations of a very expensive 10-station die before the part ejection sensor detected a problem and stopped the machine. That’s when I had the opportunity to explain to the machine’s extremely upset owner that there’s no such thing as a vise grip detection system and that if he had installed a tonnage monitor with the die protection system as I’d suggested earlier, the machine would have stopped on the first stroke.”
Control the process
There’s more to this than disaster avoidance, Finnerty notes. There’s also process control and part quality. A company using the same die to produce 2-, 3- and 4-position iterations of an electrical cover – a process that requires “gagging” in the die – can leverage the SmartPac Pro’s ability to monitor part cutoff and ejection even when it only occurs every second or third stroke.
In another use case, a manufacturer running high-speed stamping presses at 800 strokes per min. knows that the press needs a few seconds to get up to full speed. Concerned about part quality, they installed a programmable limit switch and “triggered cam input” that temporarily activates a diverter gate whenever an operator needs to stop the machine, allowing them to sequester the questionable parts made during this brief time.
“I recently had another customer running a 5-station progressive die,” Finnerty says. “They had a problem where a slug would sometimes come back up through the strip and land on the part after the initial hit, pretty much guaranteeing that the first part would be bad. By placing sensors under the stripper plate, they were able to detect this occurrence and automatically sequester that part and the next four after it. The SmartPac Pro makes it quite easy to solve this and many other common stamping problems – whatever the press type and regardless of whether it’s hydraulic, mechanical or servo-powered.”
You might be thinking that everything just described sounds quite complex from a programming perspective. How are we supposed to manage this when we can’t even find good operators? Don’t worry about it, Finnerty says.
“The interface is very easy to navigate with a context-sensitive help button that brings up instructions for whatever is currently on the screen and helps guide the operator through the programming process,” he explains. “If you have questions about the triggered cam input I just mentioned, you just hit the question mark and a pop-up menu will walk you through the different choices, explaining how and when to use each one.”
Keeping an eye out
Better process control, higher quality parts and robust die protection are all worthwhile goals, but so is the ability to collect and analyze the data coming off the stamping press and its various sensors. This brings us to the “if only machines could talk” part of the discussion. In addition to the SmartPac Pro, Wintriss offers ShopFloorConnect production tracking software, which gathers information on machine uptime, downtime and its various causes as well as overall equipment efficiency (OEE) or lack thereof.
“We offer a controller called the ShopFloorConnect Machine Interface that is mounted to the machine and continuously sends data back to ShopFloorConnect,” Finnerty says. “So let’s say you want to know the reason for any downtime event lasting more than 5 min. A screen prompts the operator to select the reason from a menu before proceeding, giving management visibility to problems that might otherwise go undetected.”
ShopFloorConnect goes well beyond downtime reasons, however. The system can monitor press tonnage and send alerts to a monitoring screen or mobile device. It can also gather data on maintenance activities and production rates, determine how long machines wait on first-piece approval and help uncover why some employees are more effective than others.
“I worked with a customer in Texas that was trying to reduce setup times and wanted to know why they were all over the map,” Finnerty says. “Because everyone has to log into ShopFloorConnect with an employee number, they quickly discovered that one operator could set up a press in a fraction of the time as everyone else. So they had him train the entire crew. And the only reason they knew it was because they had the data and were able to do the analysis.”
That scenario applies to jobs that might be less profitable than others, problematic dies and machines, a new coil of material, long-term quality trends and so on.
“It requires that someone take a look at the data and do a little bit of analysis, but it allows you to discover some surprising things,” Finnerty says. “For instance, we have several high-mix, low-volume stamping houses using it and they’ll tell you that, thanks to the increased visibility on OEE and setup times, they’re able to make more intelligent scheduling decisions than ever before. At the same time, their OEE levels have gone up significantly. It’s just a great tool.”
