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Markets in Transition: Automated Pallet Handling and Pallet Quality - Anyone Behind the Wheel?
Columnist, Rick LeBlanc, explores the impacts of materials handling automation on pallet design and the importance of improved quality in modern systems.

By Rick LeBlanc
Date Posted: 12/1/2011

With the future trending towards the increased use of automation, are pallets positioned to carry the load? Like almost any good question in life, the answer seems to be, “Depends.” It depends a lot on the design and condition of the pallet.

             In a previous column, I interviewed Chris Delisle, senior engineer at Witron, and looked at pallets in the Dematic pallet runner system in an Australian installation for specialty wine distributor, 14 Degrees. Chris said that Witron’s systems typically relied on inbound pallets being doubled up onto wooden slave pallets. Witron did this for both white wood and rental situations because even rental pallets weren’t of a consistent enough quality to ensure smooth functioning in Witron’s automated systems. The slave pallet used is a block-style unit with a parallel base. This design had the load resting on the pallet stringer boards rather than the bottom deck to minimize the space loss of the doubled up pallet. In the Dematic case, the new white wood pallets utilized by wine producers worked splendidly in the 14 Degrees pallet runner system.                      

            Is the Dematic case study an exception to the rule? Can wooden pallets really work well in highly automated materials handling environments?

            Pallets certainly can be engineered to do the job, but not necessarily all are, according to David Noble, director of sales and marketing at Seegrid Corp. (www.seegrid.com). Unlike the automated storage systems covered in previous installments, Seegrid designs robotic vision-guided technology that performs much as manually operated equipment does, except with one minor omission - the operator. It transforms industrial vehicles into un-manned, automated pallet trucks and tow tractors that move unit loads from point A to point B.  And with its technology it achieves this without the need for wire, tape, laser or other costly guidance systems that are found in other automated guided vehicle (AGV) systems.

            I asked David if his technology would require any change in pallet design to work with the Seegrid technology. First of all, David stressed that the actual engagement with the pallet is no different than with manually operated equipment. In fact, at this stage of the technology’s evolution, an operator still steers the pallet truck into the pallet, before programming it to take the pallet away. That being said, the pallet truck has standard pallet truck forks. They will soon offer the technology on a forklift, but it will have standard forks. Bottom line, David stated that CHEP, GMA, PECO and iGPS pallets all work well with their automation, generally speaking, but all can have their challenges in a small minority of applications.

            One of those issues is pallet egress for loads under 200 lbs. While it doesn’t come up much, CHEP pallets can be a problem to pull out of for these really light loads, because of bottom deck board thickness. For pallet trucks or pallet jacks (which have front load wheels), they can get stuck in the pallet and not get out if there isn’t enough weight on the pallet, and if either the bottom boards are too thick, or are not chamfered. The interesting thing to me is that while GMA pallets typically have thinner boards, they oftentimes are not chamfered. None the less, David observed CHEP to be the pallet where they experienced this type of problem. In this case, plastic pallets such as iGPS provide a cleaner exit.

            At the other end of the scale, loads in the 2500 pounds and above range can also be a problem. Load deflection in the 1/4 to 3/8-inch  range can result in the top of pallet truck forks getting stuck when they are slightly raised as a result of driving over the bottom boards. David noted that this is more the exception than the rule, calling them rare occurrences. But he has seen lighter GMA pallets and iGPS pallets have such deflection issues.

            David is quick to qualify, however, that he likes the iGPS pallet. He said, “At the end of the day, they’ve got a good model, but they do have to work through issues, just like any other company. One of those is to improve stiffness.” Sometimes the deflection issue can be mitigated through load bridging techniques such as the utilization of chimney stacking, David noted.

            Aside from deflection, the largest pallet problem for Seegrid is the presence of broken boards, which can cause problems for both pallet entry and withdrawal. “Broken boards on wood pallets, and deflection on plastic pallets are the biggest issues we have with pallets,” David said.

            And to the extent that such factors can be a challenge for Seegrid, they are also a similar concern for operations with manually operated pallet trucks. It is no secret that broken pallets, and pallets without adequate stiffness should be a focus of concern for pallet users where applicable, emphasizing the importance of pallet inspection and maintenance programs, or alternatively, specifying plastic pallets with adequate stiffness to meet the needs of the application.

            Just because there is no one behind the wheel of a customer’s pallet handling equipment doesn’t mean its pallet management program can be stuck on auto pilot. At the very least, a company’s pallet program should be periodically reviewed to ensure enduring success.

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