Robotic Palletizing: How the Technology Stacks Up

It wasn't that long ago that it was unheard of to see a robot at a packaging show. In recent years, however, show visitors find robots on display in virtually every aisle, usually performing palletizing operations.

Several reasons have driven the growth of the palletizing robot market.  Basically, it comes down to economics. A robot can work faster and with greater consistency than a more expensive human operator, withstands harsh environments better and is largely immune to injury.

Since users are just beginning to recognize the benefits of robotic palletizing, rapid growth is expected for the next several years. 'The market is just starting to be tapped,' reports Michael Crane, product manager at ABB, New Berlin, WI.

Driving the interest in palletizing robots is the tight labor market and a need for greater process consistency. As it has become increasingly difficult to recruit qualified workers in the United States, 'people are more willing to automate,' says Mark Handelsman, director of engineering at FANUC Robotics North America, Inc., Rochester Hills, MI.

Robots also can offer the flexibility needed to efficiently handle the wide variety of distribution packaging consumer goods makers must provide to satisfy their retail customers. 'The market is uneducated right now as to the flexibility robotic systems can offer,' he adds.

Indicative of the flexibility required today is a recent installation by ABB of a five-robot system at a pasta manufacturer. To handle the output of 12 lines and accommodate various pallet sizes and case styles, two of the robots are configured for three in/three out operation, while the other three work on a two in/two out basis.

There are two types of robots used for palletizing, articulated and gantry. The latter are suspended from an overhead rack. 'We're seeing more applications for gantry robots because of product size and work area requirements,' reports Mike Perreault, vice president at Midmac, a systems integrator based in St. Paul, MN. 'If you have the vertical space, a gantry generally is more efficient in horizontal space utilization,' he explains.

Encouraging the use of robots for palletizing are continuing improvements in capabilities related to payload, speed, flexibility, ease of operation and the ability to interface with line and plant controls.

Although the food and beverage industry has been a major user of palletizing robots, and interest from this sector continues to be strong, a growing number of units are being installed in plants producing personal-care, and paper products. Robots are particularly in demand in regulated industries like medical devices and pharmaceuticals where they can provide a higher level of cleanliness than a human operator and a greater degree of process control, thus simplifying the validation process, which ensures the system is operating within established parameters.

Some activity also is seen from soft goods, building material and petrochemical manufacturers. It should be noted that a high proportion of sales are generated by first-time customers.

In addition, 'We're seeing a lot greater interest on the distribution side,' says Handelsman. After watching the U.S. Postal Service (USPS) make a $101-million commitment to robotics in 1999, many companies, which are striving to reduce logistics and handling costs, are taking a look at robotic palletizing.

Worker safety, quality and cost control are the drivers behind the USPS investment. When the project is complete, trays of sorted mail will be loaded by robot into all-purpose mail containers for transport by truck or air. Although the material-handling system may vary depending on the building, the robotic cells and gripper configuration will be identical.

The robotic project is one step toward a 'lights-out' mail processing facility, which is being prototyped in Ft. Myers, FL. 'The robots will play an integral role in this facility,' says John Weller, program manager, USPS Material Handling Research and Analysis Engineering. 

A demand for high throughput has driven improvements in controls as well as interest in heavier payloads so product can be moved by the tier instead of case by case. FANUC Robotics, for example, has developed the M-410iWW, capable of handling payloads up to 880 pounds at more than 12 cycles per minute.

Heavier payloads also are spurring interest in gantry designs, which traditionally have been able to move more weight at faster speeds than an articulated robot. Toronto-based RMT Engineering Ltd. has installed gantry units capable of handling 100 cases per minute because it moves layers of cases as a unit rather than individual cases.

Another in-demand feature is the ability to interface with plant networks and different control systems. An example of a state-of-the-art system is a highly automated, five-robot system recently installed by FANUC. The units are controlled by a personal computer, which, in turn, interfaces with the plant control system, which resides on an IBM AS400 computer.

A similar interface between robot and plant business system is part of an upgrade to a two-year-old RL 80 palletizing robot from Reis Robotics, Elgin, IL, at Sandvik Chemical Products, Bristol, VA. Sandvik's goal is to track inventory of its mine bolt resins, a two-component polyester-based material used to strengthen mine roofs and prevent cave-ins. When the system was being designed initially, 'We thought the idea of tracking inventory was interesting, but we didn't think it would be necessary,' recalls Ken Monyak, production manager. 'Now that we understand how the system works, that's what we want to do,' he adds. 

Tracking will be accomplished by automatically updating inventory records each time the robot sets a corrugated box of product on a pallet. Since boxes could be dropped or rejected due to labeling problems, 'the robot only counts boxes it successfully places on a pallet,' he explains. 

In action, 40- and 60-pound boxes conveyed from Building 2 to Building 3 at Sandvik trip a photoeye, which starts a bar code scanner. The scanner sends label data including lot and sequential box number to the robot. The robot determines which of six pallet positions the product belongs in, the nest pattern and where the next box should be placed on the load, then picks up the case, sets it in position and transmits the part number to a database in a linked PC. As soon as interface software is written, the PC will be able to transmit case counts directly to the plant's AS400.

Harsh environments are another area where robotic palletizers make sense. FANUC is preparing to install what it believes will be the first North American placement of a palletizing robot in a freezer. Although the industry has been slow to accept robots in this setting, there are numerous advantages. First and foremost, it removes people from the freezer, an area where the cold temperatures make it more difficult to work safely and require added manpower to compensate for the more frequent breaks personnel need. This freezer installation at a large ice cream manufacturer will join one up and running for several months at a French fry producer in Europe.

Keeping some end users from considering a robot is a lack of familiarity with its control and programming. 'That's why we have worked very hard to make the systems easy to set up,' says Handelsman. For example, the operator interface features palletizing rather than robotic terminology. The idea is to 'make it as simple as possible on the operator level,' he adds.

To this end, ABB has developed PC-based software called PalletMaster and a color touch screen operator interface. To simplify programming of the robot itself, ABB offers another Windows-based program, PalletWizard. Both reside on the FlexPalletizer cell controller PC and interface with the robot controller itself.

Palletizing robots generally appeal to end users with mid-range needs. Low-end users often assume a robotic system is beyond their budget. While this may have been true a few years ago, prices, in general, have declined as hardware costs have dropped, and software has become more plug-and-play.

At the other end of the scale, high-volume palletizing still tends to be the province of hard automation. However, gantry robots like those from RMT are capable of handling many different products at relatively high speeds and can be equipped with a bar code reader so cases can be sorted as well as palletized.

Such multitasking is another feature robot users are demanding. Moving further upstream in the process, some systems like those designed by Midmac use a single robot to load the case before palletizing it

Other developments have to do with end effectors capable of handling a wide variety of case styles and devices to protect the robot and its human coworkers. Applied Robotics, Inc., Glenville, NY, for example, offers QuickSTOP collision sensors, which shut down the work cell and deflate to absorb the impact, thus minimizing damage to tooling and product.

Also becoming more advanced are the safety systems, which ensure no personnel get in the way of a working robot. Work cell perimeter guards like Smartscan L- and T-shaped light curtain units from Applied Robotics are sophisticated enough to differentiate between a pallet and a person. When a pallet is detected, a self muting feature allows it to pass, however, if a person tries to enter the work cell, equipment movement is halted in a split second.