DMAIC Analysis of the Production Flow of a Steel Company (Reducing waste : inventory, waiting time & overproduction)

Project Name  

Improvement of the production flow. 


  • Manufacturing of steel 


  • Categorization of the product types and their respective Cycle Time.  
  • Data model generating impact on the production due to an improvement of the Cycle Time of machines. For example, a reduction of 10 seconds of Cycle Time from the bottleneck machine involves an increased production of nearly 5% in a month for the company.  

The Challenge

The client is a leading international manufacturer of steel products. The group has 2 plants in Belgium. The mission focusses on the production chain of one of them that is separated by two lines. On the production site, managers from both lines noticed that an overstock is generated at the end of the first production line generating waste (inventory, waiting time, overproduction…). 

Observing the process and using Lean principles in a DMAIC framework (Define, Measure, Analyse, Improve, Control) has allowed to: 

  • To identify that an overstock is generated at the end of the first line generating a bottleneck. This demonstrates the potential impacts on the production in term of Tons due to a variation of time on this machine (in term of Cycle Time).  
  • To define  solutions to fluidify the second line of production (in term of Cycle Time and production in Ton)…  

The Lean Solution  

Following the Lean methodology, Zerwaste took a Gemba approach (« the real place » in Japanese) to tackle this issue. We’ve visited the production lines to observe and understand processes. Data information has been collected to measure and analyse the AS IS production state.  

After deeper analysis of the data, it has been possible to demonstrate the main reasons generating the stock between both lines. Theses metrics helped the client to decide regarding the potential future investment regarding the bottleneck machine.  


This method has helped the client to have a clear view of the bottleneck machines in the production process. The products’ categorization   proposed influenced the planification team for future production planning. The decreased Cycle Time of the bottleneck (machine 3) implies a smooth production flow for the next machines. This optimization could avoid over-stock before the third machine. Moreover, this change could imply an increasing production in Ton of 5% per month.   

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