What’s on Your End of Arm?

Overall equipment effectiveness (OEE) is a crucial metric for any manufacturer using automated machinery. And for shops with CNC lathes, machining centers and electrical-discharge machines (not to mention press brakes and other types of sheet metal fabrication equipment), one of the most effective ways to improve OEE is with quick-change tooling.

SDC custom end-of-arm tooling equipped with pneumatic vacuum grippers. Provided by Steven Douglas Corp.

It’s nothing new. Lean practitioners tell us that Toyota Motor Corp. Machine Shop Manager Taiichi Ohno began using rapid die change systems in 1955 after visiting an American factory that used them on its Danly stamping presses. His contemporary, Shigeo Shingo, later claimed to have invented the technology, calling it single minute exchange of die (SMED).

No matter who deserves bragging rights, SMED is a lean concept that all manufacturers can and should apply wherever possible. Vises and fixtures equipped with zero-point clamping systems can potentially bring machining center setup times to near zero. The same is true for quick-change lathe chucks and, as Toyota learned nearly seven decades ago, stamping and forming dies. Then there are quick-change toolholders, which can be a game changer for in-process downtime reduction.

For those who’ve implemented one or more of these systems and are now bragging about the massive OEE improvements, congratulations! Now it’s time to make similar setup time reductions to robots and their collaborative counterparts, cobots.

Get ‘er Done

On a recent “Get it Done Friday” YouTube video, FANUC America Corp. highlighted Steven Douglas Corp. (SDC), where Project Manager and Senior Electrical Controls Engineer Tim Wilmot described how the SDC team used an off-the-shelf coupling system to affix a variety of custom grippers and other end-of-arm tooling (EOAT) to a heavy payload robot, all equipped with quick-change connections to expedite tooling changeover.

“The system has a master coupler mounted to the robot arm that interfaces to standard receiver units on each tool,” Wilmot says. “There are electrical modules available to power certain tools, as well as vacuum generators for part pickup, sensors to ensure proper gripping and, in one of the units, a servo unit that automatically adjusts the distance between multiple gripper heads to accommodate different part sizes. We also installed area scanners and safety interlocks to prevent human access, except through a special light curtain.”

SDC custom end-of-arm tooling showing a large-part-handling attachment. Provided by Steven Douglas Corp.

Two such systems have been delivered to a “large manufacturer of water treatment equipment,” with a third in the quoting stage, according to Wilmot. Furthermore, what was once an entirely manual production line with multiple stations is now tended by a single operator, which is said to significantly increase capacity and throughput.

“The parts are pretty large, so it was a cumbersome, somewhat messy process for the operators before,” Wilmot says. “Now, they are working on less menial tasks and the customer is enjoying far greater efficiency. It was a fun project.”

Time for a Change

With intuitive and ergonomic lever operation, the patent-pending MC-50 Manual Robot Tool Changer provides a simple solution for quickly changing robotic end-of-arm tooling by hand. Provided by ATI

The orange-anodized tool-changing units in the FANUC video came from ATI Industrial Automation of Apex, N.C., a Novanta company. ATI offers a full range of robot arm accessories, including multi-axis force and torque sensing systems, material removal tools, collision sensors, utility couplers and the automatic tool changers used by SDC, acording to Baron Kendrick, product manager for standard tool changers. A series of cobot-ready EOAT kits are also available for FANUC, Universal Robots (UR), Techman and others, each designed to provide “everything you need to get your cobot application up and running,” Kendrick adds.

This raises a question that anyone considering a robot should ask: “Do we need to hire an integrator, or can we install our shiny new bot without outside support?” Kendrick answers with a definite “maybe.”

“I’ve seen it both ways,” he continues. “With more advanced or highly customized systems like the one at SDC, we typically work closely with the integration company, after which they ship it to their customer, do the runoff and then hand them the keys.

“But there are plenty of simpler applications such as machine tending—which accounts for roughly 80% of all cobot installations—where the end user is often capable of installing and programming one on their own. We service both.”

OnRobot offers both single and—as seen here—dual Quick Changers, allowing the user to simply click end-effectors on and off their robot arm. Like all OnRobot products, the Quick Changer is compatible with all major robot brands. Provided by OnRobot

Kendrick points out that ATI’s EOAT kits support this function. “Shops frequently have to switch grippers or tools during a changeover, and, whether manual or automatic, these systems serve to reduce the downtime they would otherwise incur.”

There’s also a solution for what most machinists and sheet-metal fabricators consider necessary but miserable tasks: part deburring, chamfering and surface preparation. Here, the “material removal tools” listed on ATI’s website typically have a built-in force control element that makes it compliant enough to compensate for minor variations in part and process. For applications that require a more intelligent and human-like touch, a force/torque sensor can be installed between the tool and coupling.

“Consider weld preparation,” Kendrick says. “Push too hard and you might stall the grinding wheel or even damage the workpiece. Apply too little force and you lose productivity. You need to find the sweet spot. By working closely with robot OEMs like FANUC and others, we’ve developed the ability to feed the output from these sensors into the robot or cobot controller, delivering closed-loop feedback control for these types of applications.”

Get Savvy

Auburn Hills, Mich.-based DeStaco, a Stabilus company, offers a complete line of robotic tooling, some with colorful names such as the Spidergrip and BodyBuilder lines of end effectors. There are also automatic and manual tool changers, compliance devices that compensate for misaligned or inaccurately placed parts, and a host of cobot kits. Between these solutions and the others listed in this article, shops have no reason to settle for changeover-associated downtime or less-than-stellar droid performance.

Destaco offers a variety of quick-change end-effectors for cobots and more, as well as a quick-change base for moving cobots to a different machine. Provided by Destaco

One of the problems is that many robot newcomers are less than automation savvy, says Gary Labadie, DeStaco’s global product manager. “There are a lot of accessories and tooling out there, some designed specifically for collaborative applications, while others are more for general purpose and industrial use.

“It can be confusing,” he continues. “Much of our product focus is on what are quickly becoming the most common automation devices—small payload robots and cobots—and knowing that a lot of these first-time users are mom-and-pop shops or those in the commercial space, we try to make the selection process as easy as possible.”

Some of this confusion revolves around the term collaborative. To help clarify its offerings, DeStaco has adopted the “small-payload” moniker, signifying bots capable of lifting 10 kilograms or less. Labadie notes that a truly collaborative end effector eliminates sharp edges and potential pinch points, and is often shielded with a plastic enclosure, making it suitable for use in close proximity to humans.

Most robotic applications don’t fall into this category. As ATI’s Kendrick pointed out, and Labadie agrees, the lion’s share of cobots spend their days and nights tending CNC lathes and machining centers. Here, the operator might drop by to check on things but, assuming all is going well, it will be a short visit. Therefore, there’s little need for kinder, gentler grippers; what’s more important is to have end-of-arm tooling that can withstand the oil, metal shavings and chemical agents common to the machining environment.

“It’s the complete opposite of many other applications, such as healthcare and pharma, electronics, cosmetics and food packaging, where the need to eliminate contamination is paramount,” he says. “As I tell our new employees, every day you will have used something handled, touched or moved by a robot, and we can only expect that to increase in the future.”

Get on with It

Kristian Hulgard, general manager of Denmark-based OnRobot Americas’ U.S. headquarters in Irving, Texas, seconds that statement. And like his contemporaries, he says quick-change EOAT brings “huge value” to robot and cobot users. “The ability to switch out tools quickly is a central part of robot OEE, which is why we as a company have focused heavily on the concept. In fact, one of our product lines is called “Quick Changer,” and utilizes the same click-on mounting interface.”

Yet Hulgard suggests that fast changeover is only part of the OEE equation. There’s also integration with the machine tool and, after that, programming. If these are cumbersome, cobot efficiency suffers.

“CNC machine tending has long been the bread and butter for collaborative robots, largely because they have a reputation as being easier to use than so-called industrial robots,” he says. “And while there’s some truth to this, it doesn’t change the fact that you still have to integrate it with the machine and get everything up and running—just because you might be able to find the right buttons easier, you still need to understand what those buttons do. You need to understand general robot logic, what signals perform which functions, and how to most efficiently move parts from point A to point B. That’s why we introduced D:PLOY.”

OnRobot’s D:PLOY is an automatic programming platform that slashes the time it takes to get automation up and running. Provided by OnRobot

D:PLOY is a platform for building, running and monitoring collaborative applications. It acts as a front end for all the different components in a robotic environment, using a centralized controller to “tie in” the robot, tool, sensors and even the CNC machine. This approach allows for automatic programming, signal exchange and logic creation based on minimal user input and a joystick interface to position the robot.

Hulgard admits that D:PLOY is not a cobot cure-all. It is currently limited to simple operations such as CNC machine tending, palletizing and picking parts off a conveyor, although Hulgard’s quick to point out that its capabilities will grow as a product matures.

“Let’s say you have a tray filled with 100 workpiece blanks arranged in a 10 by 10 pattern. D:PLOY will prompt you to show it three of the tray corners and tell it how many parts there are, and it figures out the rest,” Hulgard explains, noting the company has some videos on YouTube showing how it works. “I have to say, it’s pretty cool.”

Much More than Potatoes

Brian Havey also thinks his products are pretty cool. And like OnRobot’s Hulgard, he points to his company’s YouTube channel to promote them. The sales director at VersaBuilt Robotics, Havey says company founder Al Youngwerth began making aftermarket motorcycle clutches and accessories under the Rekluse Motor Sports Brand in 2002. Eventually, the production floor ran into the same problem plaguing most manufacturers: lack of skilled labor. “Off-road motorcycle accessory sales are very seasonal, so every fall we’d bring in a bunch of machine operators to keep up with the winter-to-spring demand, who then ended up making a bunch of bad parts.”

The ATI Robotic Tool Changer provides the flexibility to automatically change end-effectors or other peripheral tooling. Provided by ATI

Frustrated, Youngwerth turned to “one of the big players” for a solution. He received a quote for $250,000 to automate a handful of parts, not the several hundred Rekluse needed. Youngwerth politely declined and set about designing and building his own system. Several iterations of that first automation system later, a new company was born, VersaBuilt Robotics Inc., which Havey says produces numerous systems designed specifically for machine shops looking for a fast-yet-flexible way to automate high-mix CNC mills and lathes.

“To make automation effective in a high-mix environment, we faced two major hurdles: fast part changeover time and minimizing the time and cost of integrating hundreds of part numbers into the automation systems,” he explains. “The result was a new type of CNC automation workholding—the MultiGrip—and the VersaBuilt System Controller, or VSC for short.”

Similar to OnRobot’s D:PLOY system, VersaBuilt’s VSC “programming” is accomplished by “filling in the blanks” on the system controller. Havey notes that the software is parametric, and that once a job has been configured, changeover is largely a matter of selecting the part program from a drop-down menu, changing the workholding if necessary and pushing cycle start. “We have systems on our shop floor that easily have a hundred different part configurations. You don’t need a skilled setup person, there’s no tribal knowledge, and if you want to make a couple hundred parts this month and another couple hundred of the same part two years from now, it’ll make them exactly the same way. Problem solved.”

First published here: https://www.advancedmanufacturing.org/manufacturing-engineering/what-s-on-your-end-of-arm/