Lean Manufacturing

Lean manufacturing (LM) also known as just-in-time (JIT) is one of the popular manufacturing methods these days. The history of Lean manufacturing started back in 1930 by Toyota. Since then, many industries have adopted the method and successfully increased their manufacturing efficiency. Throughout this article, the concept of Lean manufacturing will be explained and how the method has been popular for almost a century.

 

Concept of Lean Manufacturing

The purpose of lean manufacturing is simple, reducing wastes from each step of the manufacturing process to increase its efficiency. The wastes include time, human effort, resources, defective products (errors), equipment and space etc. The below two definitions show clearly what is the purpose of lean manufacturing. The early researchers on the lean method, Womack and Jones defined lean as the below [1];

 

 ... a way to do more and more with less and less - less human effort, less equipment, less time, and less space - while coming closer closer and closer to providing customers exactly what they want.

 

 

Another researcher, D. Rizzardo defined the lean method even simpler with a stronger voice as below [2];

 

 

The value of adding activities are simply only those things the customer is willing to pay for, everything else is waste, and should be eliminated, simplified, reduced, or integrated.

 

By forecasting potential errors and demands, production lines only operate based on build-to-order. The production line doesn't follow by its goal or target but by actual sales. By following this method, manufacturers don't waste their resources, labour, inventory, time and also not required an unnecessarily big production capacity. 

 

Reducing time and cost are the most important factors to achieve an efficient manufacturing process. There are case studies that adopted the lean method and accomplished the two key factors of the efficient manufacturing process. Rahani AR performed a study in the automotive industry and found improved productivity by eliminating overproduction [3]. Another study by Dhiravidamani PR also found improved performance by adopting the method into a foundry division of an auto parts manufacturing industry [4].

 

There are many techniques and activities to achieve the lean method depending on industries and applications, for example, Kaizen (continuous improvement), Value Stream Mapping (VSM), Total Productive Maintenance (TPM), Bottleneck Analysis and 5S System etc (figure 1). Nevertheless, their aim is the same, eliminating wastes to increase efficiency. 

  

Figure 1. The drawing shows the relationship between LM techniques [5].

 

Criticism

Lean manufacturing sounds like a perfect solution, but it has also significant drawbacks. Pressures onto workers are the biggest criticism. The workers always work under the pressure to produce flawless products with limited time and cost [6]. Throughout the COVID-19 pandemic, negative effects of lean methods also appeared. Less inventory, just-in-time delivery and limited outsourced suppliers caused global supply chain issues [7]. 

 

 

Conclusion

The lean manufacturing method can not be a solution for all different industries, but its principle is clearly beneficial to achieve an efficient manufacturing process by removing non-value wastes from each process step. As time goes by, the method tries to be more mutual. The fusion method called Lean Six Sigma was developed and used globally in various applications. Additive Manufacturing also shows benefits by adopting the lean method as well [8]. The positive side of the lean method has been proven through decades. The results depend on users/management selecting the method for the right industry and application to maximise the benefits and minimise the potential drawbacks.   

 

 

 

[References]

[1] Womack, J. P., & Jones, D. T. (2003). Lean thinking: banish waste and create wealth in your corporation (2nd.

[2] Rizzardo, D., & Brooks, R. (2003). Understanding Lean Manufacturing. Maryland Technology Enterprise Institute.

[3] Rahani, A. R., & Al-Ashraf, M. (2012). Production flow analysis through value stream mapping: a lean manufacturing process case study. Procedia Engineering, 41, 1727-1734.

[4] Dhiravidamani, P., Ramkumar, A. S., Ponnambalam, S. G., & Subramanian, N. (2018). Implementation of lean manufacturing and lean audit system in an auto parts manufacturing industry–an industrial case study. International journal of computer integrated manufacturing, 31(6), 579-594.

[5] Singh, A., & Ahuja, I. S. (2015). Review of 5S methodology and its contributions towards manufacturing performance. International Journal of Process Management and Benchmarking, 5(4), 408-424.

[6] What Is the Criticism of Lean Manufacturing?. (2011). Retrieved 12 January 2022, from https://www.brighthubpm.com/methods-strategies/105933-criticism-of-lean-manufacturing                       

[7] Evans, D. (2021). Coronavirus Shows That Supply Chains are Outdated and Unfit For Modern Manufacturing. Retrieved 12 January 2022, from https://www.forbes.com/sites/daveevans/2020/02/18/coronavirus-shows-supply-chains-outdated/

[8] Kohut, A. 5 lean manufacturing principles demonstrated by 3D printing. Retrieved 12 January 2022, from https://ultimaker.com/learn/5-lean-manufacturing-principles-demonstrated-by-3d-printing