WQ Review (Warehousing Quarterly Review):

Best Warehousing and DC Practices

Creating the Lean Warehouse

It’s an evolution, not a revolution.

Written by Chris Luery, President, LeanCor Canada Inc.,
and Robert Martichenko, CEO, LeanCor LLC

Creating a lean warehouse (or distribution center) is not something you accomplish overnight. It takes vision, planning, strategy, tools and tactics. With your people, you need to develop team members into problem solvers, and then provide a leadership infrastructure to support their efforts. Identifying and solving problems may seem fairly basic; however, experience would suggest it could prove elusive in application. The results achieved through your lean efforts can be quantum in nature. Improved customer fill rates, decreased inventory levels, decreased inventory carrying costs, improved inventory accuracy, and increased asset and team member utilization are all benefits of Lean Warehousing.

When Toyota Motor Manufacturing developed and shared its Lean manufacturing strategy (known as the Toyota Production System), many realized it had implications as an overall business system and not just a manufacturing system.  The principles of Lean are now being applied universally, including inside the warehouse. Some of these principles include team member training and development, standardization, visibility, quality at the source, continuous improvement, waste elimination, visual management, and problem solving, through a process known as the Plan, Do, Check, Act Cycle.

Starting with team member training and development, we understand that it is people who can identify problems and create sustainable solutions.  One of the lean tools that we can give our warehousing people is Value Stream Mapping.  This allows us to map out current processes on the floor and identify waste, and see where we can take non-value added activities out of the Value Stream.  The Value Stream is simply defined as the flow of activities that add value to the customer. The premise is that we should only be doing those things that add value. All other activities are considered waste and should be eliminated.

The concept of standardization is also a key lean principle for the warehouse. Creating standardization of processes is to create tasks are easily repeatable with planned zero waste.  The creation of standard work allows your team to understand processes from the point of view of inputs, procedures, timing and outputs. However, creating standard work is not about turning people into robots! It is about creating a baseline from which we can improve. Many warehouse operations are a series of manual processes. The unfortunate aspect of this is that people will do the same process in different ways. While this may lead to the same result, it is impossible to improve upon the process in the absence of a standard. Consequently, the lean thinker believes in standard work, as it produces the baseline from which we can improve.

Visibility of material flow, inbound logistics, internal warehouse flow and outbound logistics are critical to the lean warehouse. We need to understand the flow of material and be able to determine if we are supporting the “perfect order”: the right quantity, at the right place, at the right time in the right quality. The Lean concept of “visual management” allows us to understand the score of the game (i.e., the operation) so we can make decisions in real time that impact the overall flow of material to the customer. This is counterintuitive to many warehousing operations, where the operation simply reacts to what trucks (or orders) show up at the facility on any given day.

Building on the fact that many warehouses have manual processes, we need understand the Lean principle of “quality at the source.” To create quality at the source, we need to identify and isolate the key failure modes or areas of defects.  Then we need to implement Poke Yokes (error-proofing ideas) to eliminate the problems.  Further, we need to create a Quality Dashboard to ensure that we can track our improvement in establishing quality at the source and be sure to continue to improve upon past results.

Focusing on quality at the source in a warehouse environment can be very enlightening. For example, one organization realized it needed to do something about serious errors in picking performance. Once the root cause analysis was completed in the picking area, the team was surprised at the actual root cause. While they initially believed it was a training issue, they learned the real issue was picker interruptions. They learned that picking errors were being made because pickers were being interrupted by other members in the middle of their pick wave. This interruption made the picker lose track of where he was. The solution was that pickers should wear a green-colored vest while picking, and others were not allowed to interrupt them while they had the green vest on.

Material flow within the facility is often overlooked.  Is there a waste of conveyance taking place because the floor layout has not been correctly designed?  Experience has shown in Lean warehousing that simply putting your perceived fast runners (A items) will not necessarily provide the optimal warehouse layout. We need to consider material flow based on stability, as opposed to gross volume. In other words, what items do we pick frequently even though they may not be in large volumes? How have we designed the warehouse to facilitate this flow of stable material?

The Lean warehouse is about continuous improvement. Tools such as the PDCA (Plan, Do, Check, Act) cycle help us to identify and eliminate waste. What is the plan today? At the end of the day, how do we measure our actual performance to plan? What do we need to adjust to be better tomorrow? Answering these questions is the essence of the Lean warehouse. The goal is to create a warehouse where problems are visible and where we fix problems at the root cause, every day. Accomplishing this will in fact create a Lean warehouse and drive quantum business results.

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