Throughput. It all comes down to this number. You want to increase it, but at the same time, you’re aware your customers want more product SKUs. You also have to be adaptable to change—while, of course, maintaining food safety. What to do?
- Where to implement robotics
- Controls: PLC, robotic or both?
- Let robots do their own control
- Get a grip, use a sensitive touch
- Speed and performance
- Rainbow palletizing
Maybe you have a line that’s completely manual or partly automated, and you need to take the next step. But what is it? Do you automate picking, packaging, packing or palletizing? Or do you scrap it all and start fresh with a totally new, integrated line? We asked system integrators, engineers and suppliers for their thoughts on bringing lines up to speed with robotics.
Turns out there’s no right answer for everyone. While robotics offers several opportunities to improve throughput and can be applied almost anywhere along your line, it should never be thought of as just a way to reduce head count. Question is: Does it make sense for your application? And, if so, where on the line should you implement it first?
“This is a complicated question because I don’t think there is one right answer,” says Daniel Labell, president, Westfalia Technologies, Inc. Some production lines are so complex that one integrator or manufacturer would not be able to handle the automation of them entirely. When this is the case, handling the integration in phases may be better since it can reduce downtime during the transition, and not all the pieces of the line can be tested under one roof. Alternatively, lines can be completely replaced. Often, lines have portions that are automated, like case packing, taping, etc., but palletizing is still manual, says Labell. “I believe too many factors go into this decision for you to assume one way is better than the other. Consequently, any single process in a line is normally evaluated for ROI and quality.”
“The correct answer really depends on the details of the manufacturing process,” says Brent Bell, engineering manager of the automation division of JMP Engineering. Diligence is required to truly understand the application and then deliver a solution that best benefits the food/beverage processor. Specific consideration must be given to factors such as throughput per operator, cost per operator, current packaging line OEE and intangibles including safety, cleanliness, the plant culture, level of technological competence and attitude toward change, adds Bell.
“At JMP Engineering, we work collaboratively with our customers to conduct a brief engineering study of each application to quantify improved throughput, reduced costs, improved quality and/or safety,” explains Bell. “Through this process, we find some applications where the most attractive ROI is in the downstream palletizing operations, whereas upstream package loading may be the most economically viable for others. Of course, safety and cleanliness can easily trump labor savings or increased productivity if there is an identified risk that robotics and automation can marginalize.”
“My suggestion in cases like this is not to automate the entire line at once,” says Bob Rochelle, Staubli Robotics segment manager, food and packaging. “Generally, if you do a complete line in pieces, production can be managed to minimize the interruption. Also, I would recommend automating the easiest process first where you have a better chance of success, and all parties involved can gain experience in robot and automation integration before tackling the more difficult processes.”
“Which areas to automate first depends upon which factor or factors are most critical,” advises Paul Santi, FANUC America account manager, North American Distribution. “For instance, if the company is losing productivity due to the manual end-of-line palletizing by people, robotic palletizing would be of great benefit. The most important factors should be used to prioritize where robotics can be of the most benefit.”
According to Jonathan Ferrell, ABB Robotics packaging market specialist, determining where to start is a decision based on a blend of ROI, risk, complexity and total cost. “The best place to start, however, is a conversation and site evaluation with an experienced robotic solutions provider.” Complete line automation usually is best left to greenfield sites, he adds, but for an existing line, a piecemeal approach usually makes more sense.
One incremental approach to automation comes from Rethink Robotics, and it’s named Baxter. This dual-arm robot can work next to people on the production line who manually execute the remaining tasks, according to Jim Lawton, Rethink Robotics CMO. The machine integrates quickly and effectively with other automation devices. A person “trains” Baxter by positioning it over an object that needs to be picked up and moving it by hand to its destination point while in the learn mode. The robot learns directly—not through a pendant.
“From a systems viewpoint, it may make sense to automate the entire line at once if you are planning on having all the robotic equipment operate on the same control system,” says Brian Roffers, Stellar packaging engineer, process engineering. “You also can have each robot function as its own system [if this makes more sense for your application].” Another option is to have a main control system designed with the capability to add robotic equipment systems in the future. This allows a processor to install the equipment where there is the largest demand for robotics, but leaves the door open for future installations as productivity increases or until the funds become available, adds Roffers.
Today, with PLCs assuming the general role of “automation controllers,” connectivity and integration are not as difficult as in the early days of robotics, when it was first being integrated into automotive industry systems. “Tie-in with existing line control is not difficult, given the flexibility found on both robot controllers and PLCs,” says ABB’s Ferrell. “A simple robotic system may be provided without a PLC, while a more complex, multi-robot system may very well have its own.”
In many cases, modern controllers like the Rexroth IndraMotionMLC can run several robots and accept incremental additions of robots without the cost of an additional controller, says Jim Hulman, Bosch Rexroth business development manager. An all-in-one device also synchronizes conveyors with robots and establishes common communications within the line and to external systems.
Some robotic systems, such as those from Adept Technology, have a distributed control architecture that allows a single controller to control multiple robots, says Adept’s Yan Banducci, senior product line manager. The architecture also allows robots to be more easily added to an existing system, as the controller already knows the specific locations and timing of the other robots in the work cell. Several software packages and additional hardware that facilitate PLC programming and control are available for anyone considering the use of a PLC as a robotics cell controller, says Banducci.
“Robots are very easily tied to today’s PLCs [and even some of the older ones],” says FANUC’s Santi. “But a food processor must make the integrator fully aware of the plant’s communication and controls architecture and protocols right from the first discussion on automating.” Controls interconnection and communication are key to ensuring all the tied-together equipment operates in harmony, is easy to troubleshoot and performs efficiently at high production rates.
Should a PLC control a robot? “In general, a PLC can’t control a robot,” says Craig Souser, president of JLS Automation. “Using a PLC as a gateway in a robotic system is a safe approach and keeps the robot code in the robot controller. But plant operations people should never program robots; they should make finite adjustments and select recipes, while a competent robotics provider does the actual coding.”
“Robots can be programmed through proprietary languages,” says Dean Elkins, senior general manager, Yaskawa America Inc./Motoman Robotics Division, “so they communicate with PLCs through EtherNet/IP or other communication protocols. However, a programmer must now learn the language used to program the robot and be conversant in PLC programming.”
Elkins notes a growing trend to employ a unified control strategy in robotics. So, some robot makers allow for robot motion to be programmed in function blocks or add-on instructions (AOIs), which are very familiar to PLC programmers. Robot programs and logic can then be stored on a PLC or machine controller, adds Elkins.
“Most robot controllers include some I/O that can be used to control simple cells,” states Staubli’s Rochelle. “But the majority of systems utilize a PLC because plant personnel, like maintenance and engineering, are generally more familiar with PLC logic and control than the individual robot controller programming systems.”
“The advantage of PLC-controlled robotics is that the end-user may already have expertise with PLC controls in house,” says Matthew Wicks, vice president, product development, Intelligrated. “This expertise can be leveraged to support the PLC robotic controls more seamlessly than native controllers.” However, the support engineers still need a good understanding of the fundamentals of the robotic system, as with any control system they support, adds Wicks.
Paul Moore, director, robotic & integrated systems at ARPAC, suggests it all comes down to cost. “We build PLC-controlled palletizers as well as robotic palletizing systems. There used to be a preference for the PLC-controlled palletizer [i.e., customers preferred a PLC machine]. Now customers look for the best price per application and will use a robot if it has a better ROI, even though a robot controller is involved. Furthermore, in 80 percent of the applications when a robot makes sense, they will not pay the premium for the PLC-controlled robot.”
Not all integrators, however, endorse PLC-controlled robotics, says John Schwan, director of sales and marketing, QComp Technologies Inc. “Until it is proven reliable to use a third-party control system for a robotic application, I would recommend using the robot manufacturer’s proven, engineered and robust controller and safety-rated system. The bigger the robot, the bigger the risk is to use a third-party system.”
“There is a great deal of hype around integrating a robot and PLC,” says Kevin Ackerman, controls specialist at JMP Engineering’s automation division. “But we usually want to keep them separate. Operators and maintenance can touch up points and jog through robot programs with ease; they just pick up the pendant and do what’s necessary with a robot. Alternatively, getting online with a PLC requires a laptop, which can become confusing since more coding is required.”
“The word control means many things to many people, and needs to be clarified when processors and integrators get together,” says FANUC’s Santi. “PLCs don’t really make robots move; that’s the duty of the robot’s motion controller or drive system. From a robot motion performance perspective, native controllers are the optimal choice. These have been specifically designed, built and tested to ensure robust, high-performance motion control, communication capability and integrated safety features.” Ideally, robots with native control can be networked seamlessly into a PLC-based control system, and will provide high-performance operation with a common look and feel on the plant floor, adds Santi.
Operators use this common look and feel on the plant floor to connect with the control system, says Jason Enninga, vice president of sales, Brenton Engineering. “With properly integrated robotics, a teach pendant, which can be intimidating to a machine operator unfamiliar with robotics, is not necessary to operate the machine.” Instead, all the robotic cell’s functionality is accomplished through the HMI, which most operators are accustomed to operating, with the PLC serving as the host to the robots in the cell.
Speaking of HMIs and programming systems, several robotics suppliers offer software with 3-D graphics and simulation programs to simplify setup. ABB Robotics, for example, recently released its RobotStudio Picking PowerPac, which combines RobotStudio and PickMaster 3 into a single bundle. The software boosts the performance of picking lines, allowing systems to be optimized in the 3-D virtual world before being built in the real world; the risks in designing picking lines, such as variations in the product flow, can be thoroughly tested and refined before costly mistakes are made on the production line. Processors can also use the software on existing lines in conjunction with cameras to optimize their functionality.
Whether it’s a 100-lb. sack of flour, a 40-lb. case of soda or a 16-oz. cake with delicate icing, a robot has to be able to pick up the item and move it to another location without damaging it. While the robot arm itself has to be designed for the trajectories and weight/mass it will move, it’s the end-of-arm tooling (EOAT) that gives the robot the dexterity it needs. Often, the EOAT includes sensory systems that guide the robot to the target and establish a force that can be safely applied to pick up a product. (See “Robots have just the right touch,” FE, October 2014.)
But grip and touch aren’t the only concerns. “A robot is only as good as the design of the tool that is attached to the end of the arm,” says Sam Weller, Brenton Engineering mechanical engineering manager. “In raw food processing areas, end effectors more than likely need to be full-stainless steel components and guarded so nothing can drop off the tool and contaminate raw food traveling under it. Packaged products most likely do not need the full sanitary design.”
EOAT devices also must be cleanable. “For example,” says Mark Langenfeld, Spiroflow Systems manager of robotics and flexible automation, “meat requires a higher level of sanitation than cookies. This [sanitation] may vary from full high-pressure washdown with aggressive chemicals to dry environments that require only blow off and wipe down.”
On a production line, the sanitation requirements can be based on the type of operation being performed. Consider sliced deli meat in a tub. The robots that pick the sliced meat and load it into a form, fill and seal machine are located in a cleanroom that is fully washed down every evening. Once the meat is in the primary package or bag, it travels through a wall into the secondary packaging area where the bag is loaded into the tub, which is then case packed. (The secondary packaging area requires occasional washdown.) The cases of product are then conveyed to a dry warehouse environment for palletizing. Each area has different sanitation design requirements and associated equipment costs, says Langenfeld.
Vacuum technology provides the majority of today’s food handling on robotic lines, while a mechanical gripper and/or piercing is a safe plan B, says JMP Engineering’s Bell. “Custom-molded vacuum end effectors such as Adept’s SoftPic series combine suction and a pliable mechanical gripping technology for the high-speed pick and place of delicate and irregular-shaped products.”
While few major enhancements have been made to gripper technology over the last 20 years, some new technologies are being developed to handle application challenges where solutions previously didn’t exist. Grabit, a West Coast company, has applied a new technology called electroadhesion to pick up objects of varying sizes and, sometimes, delicate in nature. If you’ve ever had “static cling” in your clothes, you know the basic concept of electroadhesion. “The explosion of e-commerce order fulfillment has created a demand for flexible ‘each pick’ grippers that can handle a wide variety of SKUs including boxes, bags, wrapped products, and unwrapped fruits and vegetables,” says Steven Annen, Grabit vice president, marketing.
“Grabit, Inc. is currently developing flexible and part-conforming gripper technology that uses patented electroadhesion to gently pick and place a variety of products with a single gripper,” he adds. “One important consideration for handling unwrapped fruits and vegetables is how gripper technology bruises them. Any bruises that appear sooner than manual handling will be a show-stopper and prevent the adoption of robotics. But in independent lab studies, Grabit’s electroadhesion technology has shown no impact on bruising.” (Watch for more on this technology in a future edition of FE.)
“A new technology that is improving the functionality of end effectors is one that mimics the human hand,” says Stellar’s Roffers. “It is much more functional than some of the current end effectors, with a wider range of flexibility. It also has sensors on the fingertips so you can see where the hand is gripping your product.” A gripper solution designed for real-world applications is the piezoelectric-based device from Parker Hannifin’s pneumatic division, North America. While not yet commercially available, this gripper technology had its start as a pneumatic valve actuator, but Richard McDonnell, market development manager, asked his group of engineers whether it would be possible to use it to actuate a gripper to handle and move soft confectionery products. It offers tactile control and a burst of vibration to ensure product release. The piezoelectric device has a displacement of up to 0.125 in., provides up to seven pounds of force and uses 1.5mA at 6.8VDC. It can operate on up to 24VDC and works over a temperature range from -25°C to 85°C.
Although not new, Bernoulli-based EOAT devices have been used to move very delicate electronic parts without actually contacting them. When Brähmig GmbH, a German custom robotics and automation supplier, needed to design a pick-and-place robot with the capability to lift and move delicate cookies without damage, it chose a PEEK (polyether ether ketone) version of a non-contact transport (NCT) device from AVENTICS (formerly Rexroth Pneumatics). The device withstands CIP and SIP, and moves food products without contact, complying with EC and FDA guidelines. Sandro Claus, Brähmig sales and marketing, explains the reasons for choosing the NCT. “We need to make sure the chocolate coating on the pastry is not damaged by pressure points or scratches. Vacuum was eliminated as an alternative since, unlike the NCT, it required constantly exchanging the filter elements.”
“Robot manufacturers like to advertise their maximum rating for a pick and place per minute,” says QComp’s Schwan. “The industry standard is [to move] 25mm up, 300mm over, 25mm down and then back as one cycle, typically picking up a poker chip. But there are not many opportunities to pick and place poker chips in the packaging world. The best practice for any pick-and-place challenge is to run an actual test with the product.”
“A number of robots can perform over 120 simple pick-and-place cycles per minute,” says Langenfeld. “How fast it can actually pick and place a product depends on product weight, size, fragility, packaging and gripper reaction times.” Langenfeld recommends testing one robot to see if it meets your demands to keep your cost lower. If one doesn’t do the job, then consider a second robot.
At the end of the line, things are changing—mostly due to producing more SKUs and variations in product sizes and shapes. “Conventional case packing equipment has been around for a long time and can be much simpler than a robot,” says Westfalia’s Labell. “However, the more flexibility that is engineered into a conventional case packer, the more complicated and expensive it gets.” At some point, a robot begins to have advantages in its ability to move flexibly, which conventional case packing equipment simply can’t replicate. In addition, robots are fast and can pick up multiple loads at once.
“Although robot costs have dropped significantly,” says Langenfeld, “a robot solution still costs more than the custom two-axis packer. However, the cost of ownership of a robot is significantly less, making it the better economic option.”
ARPAC’s Moore sees significant changes ahead. “Robotic palletizing is one part of an integrated secondary packaging line. We build, control and support the entire line, making us better suited to ensure the robot has the flexibility to handle the customer’s current and future needs.” For instance, ARPAC builds a pallet dispenser, conveyor and stretchwrapper as one integrated robotic system.
“Rainbow palletizing,” the placing of several different SKUs on the same pallet, has become more common. Buffering systems leading up to the robot palletizer and more creative, easier-to-use software are making mixed SKUs on the same pallet much easier to accomplish. “Buffering systems play a large role in variety packaging,” says Hulman. “A robot has the flexibility to pick from several different locations and deliver multiple products of different shapes and sizes to fill a pallet layer.”
Rainbow palletizing isn’t likely to be done right at the end of one or two lines as it requires staging—whether for a robot or a gantry palletizing system. “Once product has been palletized within the facility and moved to a warehouse or storage area, rainbow pallets can be created with the use of a layer pick system, which is a combination of a heavy-duty, clamping and vacuum-based tool and a large, fast gantry,” says Derek Rickard, Cimcorp Automation distribution systems manager. “The bridge structure travels on two rails and can have multiple robots on common rails, each completing 20- to 30-second cycle times. The staging area under the gantry includes a pallet of every SKU the company offers stored directly on the floor.”
“When package types vary per layer, the problem becomes far more sophisticated,” says Westfalia’s Labell. The product has to be sequenced in the right order, and the entire pallet has to be programmatically pre-built before the picking process can begin. Staging requirements can be significant because of the need to sequence the right cases to the robot without starting and stopping the picking process.
“Custom palletizing software is used to ‘cube out’ the mixed-load pallet,” says Intelligrated’s Wicks. “This software determines the sequence in which the products are sent to the palletizing robot to create the mixed pallet.” The sequencing system stores and buffers individual cases and has a mechanism to release them in a unique order.
Third-party software exists to handle rainbow pallets, and some robot manufacturers provide some level of palletizing software. For example, Yaskawa Motoman’s PalletSolver allows processors to develop load geometries off line. “When addressing non-homogeneous layers or columns, more complicated algorithms must be employed to build out the pallet,” says Yaskawa’s Elkins.
Robotics is no longer the exotic solution it was in the 1980s when only car manufacturers were using robots. Food and beverage processors can enjoy the lower costs of robotics and allied technologies (e.g., sensors, materials and vision systems)—and take advantage of the 30 years of expertise offered by system integrators, machine builders and robotics suppliers.
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