De-palletizer à "unstacks" and separates a fully formed pallet. The purpose of a de-palletizing system is usually to unstack a homogeneous pallet so the products that make it up can be reformed into a mixed pallet. As you can see in the picture, the robot that is stacking the mixed pallet is also de-palletizing three other pallets. In some situations, the de-palletizing robot is also the palletizing robot, but in an Order Fulfillment system, the de-palletizing robot is most often a dedicated machine, handling only the unstacking of product that goes into creating the mixed pallet.

Source:http://www.material--handling--system.com/palletizing.htm