Lean Manufacturing, fundamentally tied to the history and evolution of Toyota, has proven to be much more than a collection of tools and methodologies for the effective management of factories and production lines. Today, its mindset and practices have been applied beyond the manufacturing sector, transforming the operations of various businesses across different industries [1].
In this article, we will examine the basic principles of Lean Thinking, as well as their application to warehouse and inventory management, also known as Lean Warehousing. We will discuss its benefits, how a company can leverage them, and finally, how Lean Warehousing meets the digital age through warehouse management information systems.
What is Lean Thinking and what are its basic principles?
Lean Thinking is centered around five principles [2] that are fully applied in warehouses as well [3].
The first step is identifying value. The company must determine what adds value to its products and services—that is, the needs and expectations of its customers.
The second is inextricably linked to the first and focuses on the identification of the value stream. Once the value has been identified, the company must define the sequence of actions that will efficiently bring the product from order entry through to completion and delivery to the customer’s doorstep.
The third is the creation of continuous flow. This means that the warehouse and the supply chain as a whole will organize and schedule their processes in such a way as to avoid any interruptions, delays, or obstacles in the movement of goods and employees. In the context of lean thinking, all of these are also referred to as waste, that is, activities that burden the company with unnecessary costs and wasted time, as they do not add any value for the customer.
The fourth is the adoption of a pull system. Simply put, this means that warehouse operations are always based on actual customer demand, avoiding excess inventory while ensuring there are no stockouts at the point of sale.
The fifth and final principle is a culture of continuous improvement. The company directs its energy and coordinates its resources toward the continuous improvement of its people and processes. Ultimately, the goal is for the former to be able to deliver quality work through the latter. The goal here is not major changes, but small and steady improvements, as well as the elimination of waste, which eventually accumulate over time and lead to tangible results.
Overall, we would say that Lean Thinking focuses on questions such as “How do we work now?” and “How could we do things more simply and, at the same time, more efficiently?” Employees are the bearers of technical expertise and process knowledge, as well as the driving force behind process improvement through their experience and active participation. At the same time, customers serve as the benchmark for defining value and coordinating warehouse operations.
How can we put its principles into practice?
The obvious question that arises from the above is how a company can actually put these principles into practice.
The answer has already been provided and structured by the Toyota team and the proponents of lean thinking through numerous tools that have been tested, implemented, and refined both within and, subsequently, outside the company on an international scale over the course of decades. Some of these are:
- 5S [4]: A visual workplace organization system (ranging from offices to warehouses and production lines). It aims to improve the order, safety, and efficiency of space, as well as to maintain it in that state through five distinct steps.
- VSM (Value Stream Mapping) [5]: A tool for mapping the value stream at each stage of every process. It aims to map material and information flows and identify steps that do not add value. Next, the warehouse team identifies which key performance indicators are linked to the problematic steps and prioritizes which improvements to implement based on importance. It implements the necessary changes to its processes and, after a certain period, repeats the process mapping to quantify and verify the extent of the improvement.
- Visual Management [6]: A system for managing tasks and workspaces through visual cues and markings. It aims to make locations and information visible, as well as to highlight any deviations from established standards. Typical examples include floor markings, route directions, color-coded markings for specific locations, defective items, etc.
- Standardized work [7]: A tool for standardizing tasks, which defines the most efficient and safest sequence of steps in a process, as well as the time and materials required to complete each step. The goal is to ensure the consistency and repeatability of a process. In practice, in addition to documenting the process, brief guides and useful checklists are created, and employees are trained on them.
- JIT (Just-In-Time) [8]: A comprehensive inventory management strategy that supports the pull system approach and the retrieval of products from the warehouse at the exact moment when there is actual demand. In practice, it is a strategy for managing minimal excess inventory that requires a WMS or ERP system. The reliability of real-time inventory data is what allows the business to place orders for the right quantities at the right time, ensuring that there will be no delays in fulfilling its customers’ orders.
Why should I train my personnel in Lean Thinking?
Training staff in lean thinking tools does not require any significant capital investment or physical infrastructure. The primary benefits stem, first and foremost, from reorganizing the management of existing resources, systematizing work processes, and identifying activities that harm the company and its offered value to the customer.
Many of the tools consist of structured analytical exercises that may already have been carried out to some extent by a warehouse team. At their core, the tools involve documenting existing processes, timing, observing and recording the movement of materials and people within the space, and identifying bottlenecks and errors. Their implementation primarily requires time, dedication, and a willingness to collaborate, so that the team’s actual work processes can be captured and an optimized plan developed for how they will operate moving forward.
At the same time, it is not necessary to implement them all at once. Change can occur gradually through targeted training and pilot initiatives, focusing on one operational issue at a time. Certainly, support and guidance from external consultants can accelerate and better organize such an endeavor at its outset. Additionally, a consultant is able to suggest changes based on best practices and insights from their experience with other companies. However, access to relevant knowledge and information via the internet and other sources allows businesses to operate more independently.
The key factor is the very mindset that companies are called upon to foster within their teams [1]. Issues, such as customer complaints about errors in their orders or delays in task completion by warehouse teams, must be managed by management as opportunities for improvement and not merely resolved as routine tasks. The commitment to continuous improvement must ultimately be an approach to daily operations rather than just another task to complete. The records created by the team each time, as well as the changes they implement, should be documented and retained by the company as operational knowledge.
Why should I combine Lean Thinking with Warehouse Management Systems (WMS)?
Information systems, such as a warehouse management system (WMS), do not replace these tools or their results. They can serve as complementary and supportive tools, as they offer numerous advantages.
A WMS provides real-time information on the fulfillment status of an order, available stock levels by SKU, their exact location within the warehouse, and more. In other words, it manages a very large volume of data centralized in one place, something that becomes increasingly difficult as a company continues to grow and expand its customer base. Features that are not adequately covered—or not covered at all—by other systems, such as the creation of optimal order-picking routes and warehouse mapping, demonstrate that a WMS already incorporates the principles of lean warehousing into its core [9]. For example:
- The elimination of waste is supported by the feature that creates optimal collection routes, as this ultimately reduces the time required for collection and minimizes unnecessary movement of employees and goods.
- Value stream visibility is enhanced through real-time tracking and historical data. Receipts and orders are also tracked and allocated based on both volume and the time required for completion. Users can view details such as how efficiently they are utilizing their warehouse space, which inventory items are sitting idle and for how long, and more.
- Continuous flow is supported through methods such as batch picking and cross-docking.
- The adoption of a pull system is supported by the real-time view of inventory and orders provided by the system. When combined with a system that supports the inventory replenishment process, such as an ERP, the business can perform this task more effectively and ensure that actual demand is met at the right time.
- The culture of continuous improvement is reinforced through reporting and data analysis, enabling the team to track past performance, plan future actions, and assess whether organizational, procedural, or layout changes truly deliver the intended results. Ultimately, decisions are not driven by intuition, but by targeted actions and measurable, documented outcomes.
It should be emphasized that the effectiveness of a warehouse system is directly linked to the existence of clearly defined procedures. Without these, as well as standardization, even an advanced system may lead to chaos and create additional errors and the need to manage them.
In today’s business environment, combining traditional methods with the digitization of processes is essential. Lean Thinking provides the foundation, while information systems offer visibility and real-time control. Decisions are based on data, and results can be measured effectively. Ultimately, organizational discipline combined with technological support can provide a strong competitive advantage [10].
For companies aiming to turn Lean philosophy into measurable warehouse results, selecting the right consultant and implementing a WMS are critical steps. Learn more on our Warehouse Management Systems (WMS) page.
Sources:
[1] Mourtzis, D., Papathanasiou, P., Fotia, S., “Lean Rules Identification and Classification for Manufacturing Industry “, Procedia CIRP, Vol.50, pp.198-203, 2016.
[2] Womack, J.P., Jones, D.T., “Lean Thinking”, Simon & Schuster, 1996.
[3] Baudin, M., Lean Logistics: The Nuts and Bolts of Delivering Materials and Goods, New York: Productivity Press, 2004.
[4] Sorooshian, S., Salimi, M., Bavani, S. & Aminattaheri, H., Case Report: Experience of 5S Implementation, Journal of Applied Sciences Research, 8(7): 3855-3859, 2012, ISSN 1819-544X.
[5] Rother, M., Shook, J., “Learning to See Value Stream Mapping to Create Value and Eliminate Muda”, Lean Enterprise, 1998.
[6] Mostafa, N. & Essam, Y., Using Lean Tools in Warehouse Improvement: A Case Study from Electronics Retail Sector, 7th European Conference on Industrial Engineering and Operations Management, Augsburg, Germany, July 16-18, 2024 , DOI: 10.46254/EU07.20240268.
[7] Franco-Silvera, N., Valdez-Yrigoyen, A. & Quiroz-Flores, J.C., Warehouse Management Model under the Lean Warehousing Approach to Increase the Order Fill Rate in Glass Marketing SMEs, International Research Journal of Economics and Management Studies, Vol.4(4), pp.379-387. DOI: 10.1145/3629378.3629385. (2023).
[8] Institute of Supply Chain Management, Just in Time: A Guide to Managing Inventory, https://www.ioscm.com/useful-resources/choices/post-16/ioscm_JIT_logistics_4.pdf
[9] Al Yaarabi, R., “The impacts of lean warehousing practices on the overall business performance”, Global Scientific Journals, Vol.12 (6), pp. 23-31, 2024.
[10] Achieng, O.H., Githii, W. & Ombati, O.T., Lean supply chain and performance enablers at Homa lime company. American journal of industrial and business management, 8(5), pp.1157-1171, 2018.