Can We Apply Just-in-Time Thinking to the Outbound Problem?
Most outbound warehouse operations routinely execute two independent processes: selection and loading, with staging in the middle. Selectors pick cases onto pallets (or carts, or other containers) and stage product on the dock. Later, a smaller number of loaders move product from the dock into the trailer.
Product staging before loading is generally used as a defensive measure, or buffer. Work can be assigned in advance, with minimal risk of falling behind and risking late dispatches.
For all its convenience, staging has several drawbacks, including:
- Staged product requires substantial dock space;
- Temperature-sensitive products are at risk; and
- Double-handling of pallets by both selectors and loaders adds labor time and can cause errors and damage.
However, warehouse managers are seeking ways to compress their response times and reduce their labor costs. Like many supply chain efficiency strategies, bypassing staging by loading products directly onto trailers after selection aims to:
- Limit the number of touch points for each item in the chain; and
- Execute each step just when needed, but not before (a just-in-time strategy).
Up-Front Load Planning
To more fully integrate selection and loading processes, each outbound trailer must have a good load plan with a pallet assignment for every case, and trailer position designated for every pallet. Load plans may incorporate compartment assignments, axle weight limitations, delivery sequence, product stacking and mixing rules, and so on. Planning should be as automated as possible. Letting loaders plan as they load by rebuilding pallets on the loading dock is both inefficient and costly.
A successful direct loading strategy demands a robust “command and control” system with three essential components:
- Visibility – The direct loading system must have in view the loads to be built (load plans), the dispatch schedule, and the labor pool assigned to carry out the work. A robust system will even learn from the experience of assigned employees, for instance, automatically recognizing that a new hire will take longer to execute a task than a seasoned veteran. To make it through the dispatch peak in a just-in-time environment calls for flexibility in labor scheduling, perhaps by overlapping shift schedules.
- Parallel Processing – Robust task and labor planning logic is needed that factors in warehouse rules and work standards. Planned start and stop times for every task and any task dependencies must be mapped in a timeline. To avoid staging, some selection tasks must be delayed to wait for available loading doors and equipment. Multiple loads are then selected and loaded simultaneously by multiple employees. The systems involved—WMS, load planning, labor planning, task management —should be tightly integrated.
- Dynamic Task Management – A direct loading system must be able to monitor the progress of all work tasks as they are executed by employees and dynamically assign tasks minute-by-minute (if not second-by-second). Work dependent on tasks completed late must be carefully accelerated when cleared to start. Work dependent on tasks completed early must be held back to allow other more critical tasks to take priority. Furthermore, voice is an ideal technology to enable realtime communication with employees in a just-in-time environment.
The staging process has existed for a long time. It provides a comfortable means of managing a labor pool, especially when manual systems are included in the mix. However, moving in the direction of direct loading may offer a reduction in the lead time for outbound processes, and a corresponding cost reduction. Such a trend will require real-time execution systems having the advanced planning logic necessary to build parallel tasks and labor plans, and the dynamic visibility to implement timely course corrections.