Conventional Palletizer or Robot?22-Nov-2011
*****This article discusses the diverse requirements of palletizing. It may help you decide whether to choose a robot or a conventional palletizer******
Technical advances increase palletizing possibilities: you can get flexibility and speed from the same system, but that may or may not be a robot. (Packaging Technology).
In the packaging industry, technology is not an end in itself, but a means to drive business forward. Obviously, moving toward higher tech palletizing solutions shouldn't be based on the latest fad. But, believe it or not, decisions based on what's "cool" have occurred in many plants that have erroneously adopted high-tech robots for their palletizing operations only to realize they didn't quite know what to do with them.
Today, the line is blurring between the flexibility you get with robots and the high speeds of traditional palletizers. Robots are more user friendly and continue to get faster, while traditional palletizers accommodate changes better than before. The challenge is deciding whether you want to upgrade to a new standard palletizing machine or if your operations--your line and personnel--would benefit more from using a robot.
No matter what products you package--foods, beverages, pharmaceuticals, medical items or health and beauty aids (HBA)--the requirements for efficient palletizing are similar everywhere: to build accurate loads, to stack damage-free product and to provide high process reliability and safe operation.
Take a look at what's been happening lately.
The old guard
Palletizing machines have seen two major operational developments over the years:
1. In the 1950s, palletizing was based on row forming, where you build a row of cases and push that row forward and then you build another row until you have a complete layer. Row-forming machines are still the most popular in the market but in the 1970s in-line palletizing was invented.
2. In-line, continuous-motion machines began to take up a larger segment of the palletizing business because they are capable of much higher speeds--some newer units can palletize up to 200 cases per minute. Currently in-line palletizers make up about 40% of the palletizing business.
Although these are two milestones in palletizing (sic), it's common for technological advances to occur with traditional palletizing machines every couple of years.
Recent developments are focused on increased speeds and the ability to handle smaller case sizes, which follows changing retail trends that emphasize palletizing the same package the consumer takes home instead of stacking and shipping secondary packages, which need to be unpacked at the store. Club stores such as Sam's Club and Costco require pallet loads that are display ready for the retail floor.
Costco require pallet loads that are display ready for the retail floor.
With that in mind, orienting smaller cases is a challenge. Retailers may want a specific side of the package displayed on all four sides of the pallet load. "Labels out" orienting may require additional equipment modifications but overall patterns can be changed via a programmable logic controller (PLC) and software allowing a range of customizable pallet patterns.
Though traditional palletizing machines may be considered low-tech workhorses, they are approaching a high tech level not too far removed from robotic palletizers by adopting computer controls and incorporating internal diagnostics and troubleshooting. Newer palletizing machines are being built with servo motors so you can control positioning, feedback and response times. This increases palletizer speed and flexibility.
Because plant space is always at a premium, palletizing machine foot-print is an important consideration. Smaller footprint machines tend to be slower while faster machines need a larger footprint. Currently, there are high-level infeed palletizers with small footprints. These machines focus on floor-level space constraints and free up floor space for personnel and fork lift traffic by elevating conveyors. High-level machines can rise 10 to 12 feet off the floor as opposed to low-level machines, which are typically about two feet off the ground.
Thanks to movies, television and science fiction novels, the robot plays on the imagination, encouraging dreams and "what-if" scenarios like, "wouldn't it be great if we could replace manual labor with a team of robots?"
But what once seemed like science fiction is, in fact, fast becoming truth. It's rare to see human beings pallerizing cases at the end of a packaging line. Most times, a traditional palletizing machine is doing this but, as robots have proven to be effective and efficient palletizers, they are starting to replace traditional palletizers. In fact, many manufacturers of standard palletizing machines are adding robots to their product line-up.
The trend toward multiple or unusual packaging options and mixed-case palletizing has helped convince companies that robotic systems make sense. And, when giants like Procter & Gamble use robots as viable palletizing options by rolling out robotic concepts that meet real business needs, this almost ensures the technology's success and acceptance. In fact, robots are starting to be seen as mainstream equipment and not something strange and different.
With robotic palletizing 4 applications, the driver is flexibility not speed. Some of the fastest robots work at only about 70 cases per minute. But robotics respond well to market needs for constant changeover. In the past, you may have had one type of container and one big palletizing machine. Now you might want many different package sizes palletized during the course of a shift and that's hard to do with traditional palletizing machines.
At many companies, key decisions are made by the marketing department. When marketing says its time to change a package--for instance, a product going from 12 to 16 ounces--manufacturing has very little say. Yet production departments still have to palletize the new package and a robot's flexibilty can accommodate changes in package cases, sizes and weights. Operators can do so using PCs and software programs that allow quick changeover virtually on the fly.
However, where robots may bring added flexibility, operators do need to have a basic understanding of how the robot works. The robot arm is controlled through the PC's central processing unit (CPU). But a PLC typically controls the rest--the peripheral equipment including the pallet dispensers, sheet dispensers and conveyors. Even though operators don't need to actually program the robot, they should understand the robot's palletizing software that comes with the unit.
Some manufacturers are trying to make this as simple as possible. Some robot software is equipped with a built-in CAD library of palletizing cell components, allowing users to easily create complete pallerizing cells, including defining parameters for unit loads, optimal paths and end effector (gripper) set-up--all in a graphical virtual environment. Most current robotic software can be used on a PC and is intuitive. The operator only needs to plug in how many pallet patterns you need for a run, how many cases and their dimensions and how many layers you want. After setting up pallet load criteria, the file is downloaded to the robot and it runs the file. There is no need to teach every point with the robot. It's a quick three minute set-up process with a PC, so there's little downtime. As new products come, there is no need to change any PLC commands. The main thing for case or product changes is whether they can fit within the conveyor system and whether the gripper can handle the cases. But, for the most part, end-of-arm tooling is customized to fit a range of case sizes.
Where standard palletizer machines are typically located in the packaging area or in an adjacent warehouse, robots are more flexible and can be found not only in the production environment but in distribution centers. These centers can be warehouses that receive full pallet loads of 4 specific products. Eventually a pick list is sent to the warehouse, which calls for a mix of products culled from several loads and palletized into one. Referred to as mixed-load palletizing--this type of palletizing has long been considered the "holy grail" of palletizing because standard machines have a difficult time handling such tasks.
However, because robots can be configured to differentiate light from heavy packages, they can palletize a range of case sizes on one pallet while ensuring that the pallet will be stable. With these mixed-load pallets, retailers can now get the exact number of products they want without having to store anything in the backrooms.
A downside to robotics may occur when a robot maker doesn't understand the dynamics of a packaging line. Many of them only produce robots so they may not have the expertise in applying the peripheral equipment around the robotic palletizer. Understanding palletizing and total packaging line equipment integration such as merging conveying systems, pallet dispensers and sheet dispensers are necessary factors for an efficient operation.
Palletizer needs are as varied as the materials handled. Whether you're palletizing bags at 10 to 40 per minute or cases up to 200 per minute, they all need to be palletized neatly, safely and efficiently. Palletizers, including traditional machines and robots, should be customizable to accommodate your needs.
This article originally appeared in Food & Drug Packaging magazine. For more information visit www.fdp.com
Choosing your robot
Okay, You've decided to use a robot in your palletizing operation. What next? Here are three attributes to consider that will help you select the type of robot that's best for your needs.
TYPE SPEED FLEXIBILITY PRICE
CARTESIAN Slow Generally handles Low price
(10 cases per minute) one load at a time
SCARA Medium Handles one to three Medium price
(20 cases per minute) loads at a time
ARTICULATING ARM High Handles one to five High price
(most popular robot for palletizing) (25 cycles per minute) loads simultaneouslyGANTRY Slow Can handle an Expensive
infinite number of
loads with extremely
Source: The Science of Palletizing, Columbia Machine Inc.