a pallet stacking assembly line having at least two pick - and - place robots are used . the first robot has a relatively low position . the second robot is in an elevated position . a pallet dispenser dispenses a first pallet onto a pallet conveyor the pallet conveyor moves the first pallet to a first build position in front of the first robot . the first robot picks products from a first pick position and stacks them on the first pallet . once the stack of products on the first pallet reach approximately half the finished stack height , the pallet conveyor carries the first pallet to a second build position in front of the second robot . at the same time , the pallet dispenser dispenses a second pallet which is carried to the first build position . the second robot picks products from a second pick position and places them on the upper portion of the stack on the first pallet to complete the stack . meanwhile , the first robot is picking and placing products on the lower portion of the second pallet . the process continues indexing , with both robots ideally being busy all the time . each robot builds half the stack on the pallet ,