The min/max at the item level is for primary locations only. The item min/max levels are used to calculate replenishment. Replenishment requires this information as replenishment is only calculated for primary locations. The replenishment dashboard will populate the primary bin locations requiring replenishment. 

The bin location min/max value is used for putaway calculation when an item does not have volume information entered in Item maintenance. We recommend setting volume on the item level and setting the max volume on the bin location level for putaway. To calculate a putaway list use the directed putaway dashboard and this will give you additional details for each line that the system recommends for putaway from a receiving staged location. These details are listed under the stats column in the directed putaway dashboard.