Quality Palletizing Operations

Written By: Marvin Logan

By Marvin Logan, BMH Indianapolis Systems Sales Consultant

A client of mine recently asked us to examine their shipping operation to see if there were any changes that could be made in the palletizing area to improve quality. This customer batch picks cases from a pick module and then has a conveyor system that sorts the cases to shipping lanes where they are palletized by customer order. At the end of the lanes, the operators build 6 orders at a time by reading the ship-to address and placing the cases on the pallets. The problem that they were having is that the operators were putting the cases on the wrong pallets.

Here are the options that we came up with to improve the quality, in the order of increasing effectiveness and cost.

1. Pallet count audit – After the system says that all the cartons for an order have been sorted, the operator (or an auditor) can do a count of the all the cartons on the pallet and compare this to the expected quantity. Granted, this is can be hard to do, esp. with various sized cartons. Also, it will not help in the situation where two cartons were “swapped”, making the counts right, but the order wrong.

2. Use a check-off sheet or peal-away tab – If the system is pre-assigning which cartons will go on which pallet, a list of all the carton id numbers for each pallet could be generated. The operator would then check-off the carton id number as they place the carton on the pallet. This really bogs down productivity. Another slight variation of this is where the carton label has a peal-away tab, showing the carton id, which can be stuck on the pallet list. If you really want to get clever, the list could then be OCR scanned into a system that can recognize if any of the carton ids don’t belong on the list.

3. Scan to the pallet – You can use RF scanning to improve quality. There are two variations of this method. The first is when the WMS or WCS pre-assigns cases to pallets. In this method, the operator scans the barcoded carton ID number and then the barcoded pallet id (usually hanging from the ceiling, right above the pallet).

A variation of this method is when the WCS or WMS does not pre-assign the cases to pallets, but allows the operator to build a pallet on the fly. Cartons are continually added to the order pallets until they are all accounted for or when the operator believes that the pallet is “full” and starts another pallet for the same order.

In either case, the system makes sure that the scanned carton belongs on the pallet. If it doesn’t, the RF unit beeps or makes some annoying sound.

4. Voice Direct Put – Instead of looking at the RF unit to determine what pallet the scanned case belongs on, a voice directed system could be used. Operators wear head sets that “tell” them the pallet ID number to put the cases on. When the operator scans the barcoded carton ID number, the system tells them the pallet number. Once the case is put on the pallet, the operator confirms the put by saying a check digit or some other confirming code to the system.

5. Put to light – Instead of looking at the RF unit to determine what pallet the scanned case belongs on, a put-to-light system could be used. Light indicators are hung over the pallet spots and when the operator scans the barcoded carton ID number, the appropriate light illuminates. If multiple operators are sorting to the same area, multiple colored lights can be used with a different color assigned to each operator. To confirm that they put the cases on the correct pallet, the operator “extinguishes” the light by pressing the lighted button.

6. Build one pallet per sortation lane – A good way to remove the human error is to reduce the variability. The system could be redesigned so that there is only one pallet at the end of the sortation lane – making a one-to-one sort. If there are not changes made to the equipment side, this would require batch picking in significantly smaller waves – increasing operational costs. Otherwise, either more sortation lanes are needed or some type of buffering and sequencing system is needed between picking and sortation – increasing capital costs.

7. Robotic Palletizing – The best way to remove the human error is to remove the human. Mixed case palletizing has come a long way. Robots are better, end-of-arm tools are better, vision systems are better, and warehouse control systems are better – making this technologically feasible. The capital costs are definitely higher than the other options, but the quality results are also much higher while improving the labor and ergonomic costs associated with palletizing operations.

These are the options that I came up with. I would love to hear from anyone that can think of others!

Posted by Marvin Logan on 4/23/2010
mlogan@bastiansolutions.com

Marvin Logan is Director of Consulting Services at Bastian Solutions. He and his team of consultants provide engineering studies, system simulations, slotting analysis, and system layout and design.

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