Conveyors Support Robotic palletizing Operation

Compact and efficient automated system delivers a 30 percent increase in pallet-loading productivity over old manual process.

   In response to some tough productivity and materials-handling challenges, Jefferson Smurfit Corp. turned to high technology.  At its North Wales, Pa., manufacturing and distribution center, this leading producer of paper, paperboard, and packaging products selected two high-tech robotic stackers to load pallets as part of a highly efficient materials-flow system.  And key to that system is a series of integrated Hytrol conveyors.

    The North Wales facility ships cases of folding cartons and related products in a variety of pallet configurations that incorporate a mix of slipsheets and trays.  Until it implemented the automated system in the spring of 1996, pallet preparation was strictly a manual process.  But management felt there had to be a more effective, and ergonomically sound way of handling cases which can weigh as much as 65 pounds.  And there was.

    Working with STOKES Material Handling Systems, Hytrol's distributor based in Doylestown, Pa., Jefferson Smurfit developed a highly integrated materials-flow system that in addition to the two palletizing robots features the latest in ink-jet coders, UV-sensitive scanners, a sortation conveyor loop, automatic pallet transfer cars, pneumatic pushers, pallet conveyors, pallet dispensers, and a stretch wrapping machine.  STOKES Material Handling was the integrator for the whole system, which is run by a sophisticated computer controller from Allen-Bradley.

    In planning and implementing the system, Jefferson Smurfit wanted to increase throughput and productivity without adding any space to the existing facility.  It achieved both of these objectives and more.  The results, to date, have been nothing short of remarkable.  

• The North Wales facility now operates 24 hours a day with the two robots stacking as many as 14 cases a minute, combined.  This marks a 30 percent increase over the old manual process.

• Pallet automation and streamlined conveyoring reduced manning requirements, allowing the company to reassign these employees to higher skilled jobs.

• Loads are built more precisely.   The robots boast a replacement accuracy of 0.02 inch.

• Manual moving and lifting of heavy loads has been virtually eliminated.

Conveyors Form a Key Component

   The automated material-flow process begins with cases of product input from production via conveyor onto an oval sortation loop.  As the cartons travel around this oval, which contains approximately 140 linear feet of conveyor, they are scanned and coded with the appropriate information.

    After the coding process is complete, computer controls direct each unit into a conveyorized infeed lane.  The North Wales operation has eight infeed lanes, four for each of the robotic palletizers.  When the case reaches the predetermined lane, a pneumatic pusher from Hytrol pushes it into the lane.

    The first section of the infeed lane is a zero accumulation conveyor measuring 14 feet.  This leads to a 8- to 10-feet long positioning conveyor that moves the cases to a robotic palletizers.  The robots pick up the units one or two at a time.  Before stacking, they turn the open-top cases on their side and position them toward the center.  Some of the open-top units are also palletized upright with a corrugated tray separating them.  The pallets are built on a four-position rotary turntable precisely and accurately. 

    From the turntable, the full pallet loads move on a short transfer conveyor to the automated dual-lane transfer car, also manufactured by Hytrol.   Moving back and forth on an 80-foot track, this car transports the pallet loads to a transfer conveyor that leads to the stretch wrapping machine.  The transfer car also supplies empty pallets to the turntables, where the robots will build more pallet loads.  In addition, this car receives supplemental pallet loads four times an hour from a separate transfer car system.  All of this activity is controlled by signals from the robots. 

    Once the stretch wrapper utilizes the load, a forklift picks up the pallet and moves it to shipping.

A crisp, Compact Product Flow

   At first glance, the materials-flow system implemented at Jefferson Smurfit's North Wales plant appears complex largely due to the advanced computer controls and space-age robotic palletizing machines.  But in reality, the flow of cases from production to palletization is straightforward and direct.

    The 30 percent increase in throughput productivity was achieved without adding any additional space.  And the efficiency, accuracy, and speed of the robots enable the conveyors to do their job of moving product surely and swiftly.  In short, the flow process is crisp and compact with no wasted space or motion. 

    Not surprisingly, management at North Wales is pleased with the uniformly positive results to date.  Higher productivity, greater load accuracy, better use of human resources, enhanced worker safety, and a reasonably quick payback are among the advantages most often cited.  Then there's that all important benefit for customers, says Jefferson Smurfit:  A top-quality pallet load delivered on time every time.