Lots of shops say they want to automate operations, but how many actually have?
An article in the August 2017 issue of Manufacturing Engineering on linear pallet systems quoted an industry expert saying every shop he visits wants to automate. Yet Errol Burrell, product specialist for Okuma America Inc. (Charlotte, NC) recently said only 10% of all machine tools are automated. And, according to John Lucier, national automation manager for Methods Machine Tools Inc. (Sudbury, MA), the Robotics Industries Association reports that only 3–4% of new machines have a robot.
So whether we’re talking about linear pallet systems, simple pallet changers, or robots, it’s clear there is a huge opportunity to automate US machining operations. While horizontal machines are automated more often than verticals, vertical machining centers are more prevalent than horizontals so the greatest untapped potential is in automating verticals. No wonder Greg Feix, vice president and general manager of the automation unit at Gosiger (Dayton, OH), said his company has seen a five- to seven-fold increase in the automation of vertical machines over the last two years.
Good Old Pallet Changer
The simplest form of automation, whether on a vertical or a horizontal, is a rotary pallet changer. The operator loads parts onto a fixture mounted on the outside pallet while the machine works on the same arrangement inside. When the first set of parts is done, the pallets rotate and the operator unloads the finished parts.
Lucier said this level of investment fits the common practice of holding 10% of the value of the machine tool for vises and other fixtures, but it doesn’t really free the operator for long on a vertical since you can typically only machine a few parts on one pallet. So, while many people ask about such systems, very few buy it.
The economics are a bit different for horizontals, where the most common approach would be to put a four- to five-sided tombstone on the pallet to machine 4, 8, 16 or more parts at a time. But even then, it’s an expensive approach if you need to machine a variety of parts as they would each require different workholding.
Andy McNamara, director of sales, Doosan Machine Tools America (Pine Brook, NJ), said there’s another option becoming more common that offers a bit more capability than two-position rotary pallet changers: A work changer with an arm that lifts a pallet from an adjoining multipallet station and moves it into the machine. The pallet station usually features a rotary drum of 4, 6, 8 or more locations, the Erowa Robot Easy being a good example.
“It’s not really a robot, though the higher end systems may have a work scheduling system as well, making it closer to the capabilities of a linear pallet system.” McNamara said Doosan has received many requests for such systems on five-axis machines and they’re seeing interest in them for three- and four-axis machines in the mold and die industry to run electrodes and molds overnight, switching between parts as needed.
“You see lots of different versions of automatic work changers and rotary pallet systems on the higher end verticals in mold and die,” he said. “In job shops you see integral or add-on pallet changers most frequently.”
Integrating an articulating robot appears to be sweetest solution for verticals. Lucier went so far as to say that verticals are a much easier platform to automate in this way.
“At Methods, we see a higher percentage of verticals being automated than horizontals. Automating the door and integrating a robot is the same for either type of machine. The difference comes in when you consider the cost of the associated tooling versus the benefits.”
As discussed, the most popular use of a horizontal is machining parts on a tombstone. You could use a robot to load pallets with tombstones into a machine, and even use a robot on a rail to load a number of machines. But this approach would require a substantial robot and you’d still need an operator to affix parts to each tombstone.
If you wanted to automate the loading of the parts onto the tombstones, each vise would have to be piped for hydraulics or pneumatics, and a variety of parts would require a variety of such fixtures, further multiplying the high cost of this approach. In many cases the better approach, argued Lucier and Feix, is to use a smaller robot to load individual parts into an automatic vise on a less expensive vertical machine.
“We have such automation starting at under $100,000,” said Lucier, “complete with in-feed, out-feed, and robot with end-of-arm tool. Compare that to a pallet system where the robot itself costs $100,000, never mind the rail, the shelves, the control, and so on.”
Methods’ most popular cell has two vises in the machine (Op 10 and Op 20) and the robot services both vises. “More often than not, I put those two vises on a trunnion table so you can rotate up and down in a single axis to get three sides of the part in each gripping,” explained Lucier. “The robot flips the part, rotates it, and puts it in the second vise to get the other three sides. In this way, we’re able to complete a part in two operations and the robot does your flipping and repositioning.”
‘Monkey in the Middle’
The inherent flexibility of a robot also makes it possible to service multiple machines. For example, Methods, Doosan and Okuma all field systems in which three machines form three sides of a square, the fourth side is the in-feed/out-feed station, and a robot plays “monkey in the middle,” as Lucier put it. “Once you go beyond three machines, you can’t really fit everything around the robot so we go to a robot on a rail, which can service any number of machines just by extending the rail.”
Naturally you don’t want any machines waiting for the robot, so the key factor is the part cycle time. Lucier’s rule of thumb is that if a part’s cycle time is 30-40 seconds, one robot can service one machine. For a cycle time of 60 seconds, one robot can service two machines. If it’s 90 seconds, three machines and so on. The same rule applies to a robot on a rail. Lucier offered the common example of a five-axis medical part with a six-minute cycle time, for which “a robot on a rail will service five or six FANUC Robodrills very nicely.”
Fast Changes, Robot Integration
Aside from the relatively low cost of vertical machine tooling, it’s easy to change. As Lucier put it, “Switching between part types on a vertical typically involves just changing the vise jaws. And second only to changing inserts, a vertical machine operator knows how to change vise jaws because he does it all the time.”
An even faster and perhaps more cost-effective approach is to use the zero-point clamping systems offered by Schunk, 3R, and Erowa. With these systems, an operator can set up the new vise outside the machine and switch it out in seconds without having to re-zero the position.
“You can switch these vises as quickly as you can change pallets in a pallet changer, albeit you have to do it manually,” said Lucier.
It’s possible to eliminate the manual workholding switch. Gosiger’s Feix said Schunk and ATI make automatic end-of-arm tooling quick-change units. Gosiger has installed custom automation in which the robot loads the part fixture into the machine, then changes the end-of-arm tooling, and then loads the parts for the machining process.
Jack Cardin, project manager for automation at Doosan, agreed. “If the change in size is too big for a gripper finger change, or you’re switching from ID to OD, you’re better off changing the whole hand from the wrist of the robot,” he said. “We have four to choose from, all from Schunk.”
Lucier said it’s this “surrounding” technology that has made the greatest improvement in recent years, “making automation more flexible, and therefore an easier choice to make.”
Setting up the robot for a completely new job takes an experienced operator about 30 minutes, said Lucier. If it’s a repeat job and you’ve saved the robot program, setup is only about 15 minutes. So when you consider that a typical job would run for a day or more, changeover time approaches insignificance.
Admittedly, the noncutting time for a system that moves a robot in and out of a machine for each part change is higher than a typical pallet changer arrangement with multiple parts on the pallet. But the flexibility of robotic automation allows users to automate a higher mix of low-volume jobs with minimal tooling costs.
In some respects the robot itself is the easiest part of the system to understand when you’re considering automation. Lucier said engineering the in-feed/out-feed system takes the bulk of his time. Methods partners exclusively with FANUC and its famously yellow robot. As Lucier put it, “The robot is yellow. I pick the right size for the job and that’s it.” The more challenging problem is whether the parts should be presented to the robot from a conveyor system, in a bin, in drawers, or another option.
Okuma’s approach is to supply a vertical machine with six-port hydraulic and pneumatic manifolds that make it easy to integrate automated fixturing, while relying on partners like Morris, Gosiger, and Hartwig to help the end user with automation solutions. Okuma also has a rapid deployment team at its US headquarters in Charlotte to modify any machine coming in from Japan with automated doors, lasers, and probes to enable automation integration.
“All our machines can also be kitted with an Anybus system so they can communicate with various automation systems, be it FANUC, Erowa, or whatever,” added Okuma’s Burrell. Anybus products enable industrial devices to communicate with any fieldbus or industrial Ethernet, whether wireless or cable. Anybus products are made by HMS Industrial Networks Inc. (Chicago).
“We don’t insist on any particular vendors for these systems,” he said. “A lot of people are battling for supremacy when it comes to workholding and robotics, just like we’re battling with many companies for supremacy in machines.”
Doosan’s approach is three-fold: It offers any robot interface required to help local integrators install automation on their machines onsite. It will also engineer a customized automation solution at its headquarters in New Jersey. Third, it offers end users standard, pre-built systems called DooCells that “give a job shop a cost-effective way to get into automation,” said McNamara.
Each DooCell has a robot and up to three machining centers or lathes in any combination. The in-feed/out-feed station is a drawer unit with three to five drawers, depending on the height and diameter of the part.
“The drawers open in both directions, so the operator is on one side loading raw stock or unloading finished parts while the robot is on the opposite side processing parts,” explained Cardini.
McNamara added that “many customers are in a rush and they are pursuing low-risk solutions they have used before and want to just get it done.” A simple, standard solution like DooCell fits that approach well.]\
A Bucket and Some Warm Water
Besides the ability to mix machine types like vertical machining centers and lathes, using an articulating robot to load individual parts gives you the flexibility to automate other tasks, like washing and deburring.
“Forget the $20,000 wash system,” said Methods’ Lucier. “Give me a bucket and warm water and the robot can do wonders for you. It’s an inexpensive way to wash parts. Next step: blow it off. More customers learn how to use their robot by programming a wash and dry cycle than anything else.”
Lucier cautioned against too much focus on eliminating idle time. “Let’s make sure we load the machine. If you have extra time, a little bit of deburring or washing isn’t a bad thing, but there’s no reason to be obsessed with that. If you didn’t have a robot you’d have an operator standing there that you have to pay for year after year. You buy the robot once and never have to pay for it again.”
Return on Investment
Okuma’s Burrell said “most people investing in automation technology are looking for a return on investment in 18 to 24 months” while being driven to adopt automation due to a lack of labor. But then they realize robots can fill that gap.”
Lucier said it’s easy to justify automation when its cost is roughly equal to the cost of the machine tool, and in most cases a small automation cell pays for itself in under a year.
“Start with basics,” said Lucier. “Half an hour lunch. Two 15-minute breaks. That one hour a day on an eight-hour shift adds 12% to your working day. What else can you do in your machine tool to increase your output by more than 10%?”
On top of that, he said, output will be higher even during hours in which an operator is available because robots change parts consistently all day.
“If a guy can change parts in 10 seconds first thing in the morning, he probably won’t still be changing them in 10 seconds at 3 pm. You can figure roughly 85% actual run-time with an operator, but the robot will yield up to 95% because the only time you need to stop is when changing tools. Add to this the possibility to make parts untended for hours after the shift.”
The degree to which Industry 4.0 and related concepts have been adopted is debatable. But if anything, it’s helping sell automation. “We love it when people implement systems that track machine uptime because they’re shocked when they realize the actual spindle utilization on their vertical machining center is only about 40%, on average,” said Lucier. “It’s not John Lucier the robot guy telling you how badly you need a robot—it’s your data.”
Burrell said he now sees automation being implemented in shops as small as 10 people and he predicts even job shops will consider it a “must have.” He added that these systems are decreasing in cost at the same time they’re increasing in intelligence, so he expects huge growth in vertical machine automation.
Finally, a case study from a contract job shop, related by Gosiger’s Feix. The shop wanted to use a vertical machining center for small-lot jobs during the day and automate a volume job during the night.
“They were considering a 30 × 16″ [762 × 406 mm] capacity mill and wanted a way to pull out the automated workholding and replace it with a vise each day. We suggested buying a larger mill, 40 × 20″ [1016 × 508 mm], and putting the workholding for automation on the right side of the table and vises they needed for day work on the left side, so they didn’t have to change over. You would never do that on a horizontal.”
But it’s the kind of flexible automation now readily available for verticals.