Pallet-Based Automation Improves Flexibility, Speed
Traditional pallet-based automation systems can be a better choice than robotic automation for some applications
By Patrick Waurzyniak
With so many choices, manufacturers face tough decisions in choosing the right automation system. While robotic automation often is touted as a more flexible form of automation, many manufacturers continue to opt for more traditional automation approaches with pallet- or gantry-based systems that offer speed and high spindle-utilization rates.
Some newer pallet-based automation systems offer manufacturers substantial flexibility and the speed required by high-throughput operations, such as the manufacture of automotive powertrain components. Pallet-based automation systems are ideal for gear-cutting operations, and highly flexible manufacturing systems with pallet containers have been deployed extensively in the aerospace/defense industry.
Fast, Reliable Automotive Automation
Speed and throughput are key requirements for automating automotive powertrain manufacturing, noted Alois Mundt, managing director, Liebherr-Verzahntechnik GmbH (Kempten, Germany). “That is one issue,” Mundt said, “but the more important thing is reliability, reliability, reliability.”
Automation accounts for about €60 million of Liebherr’s annual turnover (total revenue), Mundt said, and automotive powertrain automation represents roughly 70% of the company’s automation turnover. “Nowadays, most of our program is automation of powertrain in the automotive industry, so we do material handling for big players in automotive,” he said. The company builds automation including gantry-style loaders for blocks, heads, crankshafts, camshafts, converter cases, and gearboxes.
For automotive powertrain, traceability is very important, noted Mundt. Many companies try to compete in automating automotive powertrain, Mundt said, but have difficulty providing the high reliability required by powertrain suppliers. “The big ones stay with the known suppliers, the big players,” Mundt said, “because they need reliability, and the system has to run 10–15 years.”
In working with the Detroit Three, Liebherr has installed roughly 14 miles of gantries in North America, said Peter Wiedemann, president, Liebherr Gear Technology Inc. (Saline, MI). The company’s systems have been highly installed at GM, Ford and Chrysler, and at truck and heavy equipment builders. In automotive, Liebherr integrates its gantry systems with its own conveyor technology as well as incorporating conveyor systems from partners. If required, the automation packages can be upgraded with robotic bin-picking systems to simplify loading of the lines with rough parts.
“Automation in gear manufacturing is quite easy,” Mundt said, “but it has to be fast.” In gear cutting for automotive powertrain, Liebherr’s machines use integrated automation with very fast ring or swivel loaders that can handle gear components weighing up to 800 kg from a handshake point outside of the machine directly on the fixture. This enables integration of various automation systems without influencing the machine. “Everyone thinks robotics is more flexible,” Mundt said. For some applications, however, he contends robots aren’t as flexible as conventional automation. “Definitely there are some limitations.”
With bigger parts and single or small-part batch manufacturing, a different automation method is necessary, Mundt said. “In this field, up to 50% of the processing time of the machine gets lost by setting up the part directly on the machine. Here the setup process of the parts needs to be decoupled from the machining process,” he said. Pallet-handling systems with independent setup can lower labor costs by getting up to 90% machine usage on expensive machine tools, Mundt said, and Liebherr employs a similar recipe to booth the efficiency of its own gear-cutting operations.
Boosting Spindle Utilization
For manufacturing processes that require very high spindle utilization, conventional palletized automation often can deliver parts quicker to machine tools than robots. Automation developer Fastems LLC (West Chester, OH), a subsidiary of Fastems Oy Ab (Tampere, Finland), offers manufacturers its Flexible Manufacturing System (FMS), a container-based pallet system that is considered a progressive alternative to older pallet-pool technology.
At IMTS 2012, Fastems showed its new FPC-3000 that provides a complete FMS installed in a pallet container. Fastems’ latest entry-level FMS solution, the system was demonstrated at IMTS with Kitamura’s new HX800iL horizontal machining center to show visitors a complete FPC and machining center in action.
While it offers robotic automation, Fastems primarily sells its FMS automation to customers, of which about 50% are in the aerospace/defense industry, noted Michael Bell, Fastems director of operations. “About 10% of the units that we sell involve an articulating robot, and that percentage is growing,” said Bell, noting that it doubled last year from 5% of sales. “We already have robots in Boeing, so they’re finally starting to use the articulating robots in some of their processes.”
Most of Fastems’ products are custom, but the container is a standard product for the company, Bell said. The FPC-3000 is designed to handle 800 and 1000-mm pallets with a 3000-kg capacity. Larger-capacity systems, such as the FPC-7500, offer a 7500-kg load capacity. “Setup time is key, because now we’re able to do multiple setups,” Bell said of the FMS systems. “We’re seeing about a 35% increase in spindle utilization from the cut on. This will get you to 75% spindle utilization.” With Fastems’ systems, spindle utilization has reached as high as 93%, Bell added, for an aerospace application for machining small titanium parts, with multiple setups per tombstone.
The Fastems Manufacturing Management System (MMS) software gives users highly flexible control over scheduling jobs in a single manufacturing cell or extended through the enterprise working in concert with ERP software systems. Now in its fifth generation, the MMS5 gives manufacturers predictive scheduling, employing intelligence derived from links to third-party ERP packages to shuffle job queues on the fly.
“The software is the key to the utilization rates. It plans your production,” Bell said. “The information can be downloaded directly from your ERP software system. It analyzes all that and it is able to come up with a plan.” Fastems’ software was written in-house using the C# (C Sharp) language. In the 1980s, the company used Siemens’ control system before developing its own software. “We monitor the tooling consistently and only send the tools needed,” Bell said. “We also warn the operator whether a machine has enough tooling to run.”
Aerospace accounts for about half of Fastems’ business now, Bell said, with aircraft customers including Boeing commercial aircraft, Spirit Aerosystems and Lockheed Martin, plus helicopter manufacturers Sikorsky, Bell and Robinson Helicopters. The FMS systems differ from traditional pallet pools by offering pallets in containers, a technology that requires less space.
“A pallet pool is essentially what its name implies, a pool of machines,” Bell said. “It generally has quite a large footprint. What the FMS brings to you is the ability to be completely flexible.” With the highly flexible system, an aerospace manufacturer might work on a wing spar program for 15 minutes, Bell said, then automatically cycle in the next part, such as a landing gear strut.
“I find that the pallet automation can be much more flexible than robots,” Bell said. “They’re [robots] excellent at doing repetitive skills, but those things have to be predetermined.” With Fastems' software, the user can completely change the mode, with analysis of the ERP information its connected to and with the push of a button. The software also has an FMS Autopilot feature that automatically selects the optimal jobs for loading stations and machines.
Modular Automation for Job Shops
Many pallet-based systems feature the high flexibility required by job-shop environments, where jobs routinely change quickly. With its Makino Machining Complex (MMC2) system, Makino (Mason, OH) offers job-shop operators and other manufacturers a highly modular automated material-handling system that achieves spindle utilization rates as high as 95%. The MMC2 links Makino’s horizontal machining centers, pallet loaders and operators using a servo-controlled, rail-guided vehicle (RGV) to transport material to and from machines, with little if any operator intervention.
“There’s quite a bit of market existing for what I call palletized part delivery,” said Jim Brown, Makino control software development manager. “The difference is that with palletized systems you can do a very wide variety of different-sized parts.”
Makino’s system includes its Makino Advanced System-A5 (MAS-A5) cell control software that helps job shops maximize production while effectively monitoring multimachine production requires. “We see it less in automotive, which is low-mix, high-flow. But there are plenty of other industries that have the mix, that are making a wider variety of parts. It’s likely to go into a job shop,” Brown said. “It’s the combination of the pallet delivery system and the software.”
The MAS-A5 software tracks tool management and does dynamic schedule, Brown said, to reshuffle jobs according to availability of tooling and other factors, which helps the system hit 95% spindle utilization rates. “In a practical sense, that’s probably as high as you’re ever going to achieve,” Brown said. “We actually have built into the cell control software what we call unattended mode, for lights-out machining.
MMC2 cells use a single-rail system for material transport with its RGVs that draw power from an overhead power rack, Brown said. “It has a computer on the vehicle ready to receive commands that are transmitted to the vehicle by an infrared optical link,” Brown said. “In previous designs, these types of systems had a cable system, and they’d wear down over time. It’s a very well-proven system in which we’ve kept the vehicle simple and located the smarts in the software—there’s nothing complicated about it.”
Using automation lowers manufacturers’ costs and decreases setup times, noted Mike Kerscher, product manager, machining centers and Palletech, Mazak Corp. (Florence, KY). With Palletech’s pallet-based automation system, one of four levels of automation offered by Mazak, multitasking machining centers help manufacturers cut costs and boost machining efficiencies.
The Palletech system allows using multiple types of machining centers and lathes in the same cell, including systems like Mazak’s Orbitec aimed at larger parts. “The reason you use Palletech is to minimize your downtime and decrease your setup,” said Kerscher. “That’s what separates North American manufacturing from the rest of the world, and this is really where we push our customers to consider this technology.”
Palletech is very modular in its construction, adding multiple load stations, the ability to store material, tilt load options and it has an adaptable footprint, Kerscher said. The system features automated cell-management capability with Mazak’s controls and a third-party Sail software package from CMS Software (Oshkosh, WI).
“We provide systems that automatically build the schedule for the Palletech from a higher-level MRP system to the manufacturing system,” Kerscher said. “I think it’s important to understand that we provide a spectrum [of automation]. Automation is the statement of ‘I don’t need a man to intervene.’ You have to have a predictable known process that develops a quality part. Once you get that, you move on to the question of how do I get material in and out of the system. The process will determine the rate at which you move the material.”
Where Hybrid Automation Makes Sense
In some cases, going to a hybrid mix of palletized automation combined with robots makes sense, and many pallet automation suppliers offer such systems. With its FANUC RoboDrill machines, Methods Machine Tools Inc. (Sudbury, MA) can supply customers with a pallet changer or instead they can opt for robotic automation for loading/unloading the drilling machine, according to John Lucier, automation manager, Methods Machine Tools.
When comparing pallet changers to robots, it really depends on the parts, Lucier said. “When producing small short-cycle time parts, it can make sense to load multiple parts at a time on a pallet, in turn sharing the pallet change time over several parts, and resulting in better spindle utilization,” Lucier said. An option from Methods is the company’s JobShop Cell, consisting of the RoboDrill coupled with robotic automation including a six-axis FANUC Robotics (Rochester Hills, MI) LR Mate 200iC robot.
Employing a hybrid system with both a pallet changer and robotics pays dividends, according to Lucier. “That is kind of the best of both worlds,” said Lucier. “I’m minimizing the door open time and I don’t have the labor for loading the parts.”
Robot builders are helping automation integrators by developing newer robots geared toward new material-handling applications, noted Bill Natsch, director, Robot Integration, Intelligrated (Mason, OH). “Our product line includes both conventional and robotic palletizers,” said Natsch. “We can look at the job and determine which type solution works better. In some instances, a combination of these solutions are the best fit.”
Intelligrated's automation includes conventional palletizers, robotic palletizers, and hybrid solutions. Each has characteristics that can make them better suited for certain installations, said Earl Wohlrab, Intelligrated palletizing product manager. “Currently, conventional in-line palletizers are capable of the highest speeds, while robotic palletizers are great for handling multiple production lines, as well as certain product types such as bags, while hybrid machines are ideal for complex patterns and small packages.” ME
This article was first published in the August 2013 edition of Manufacturing Engineering magazine. Click here for PDF.