During previous industrial revolutions, new technologies and production philosophies have been developed and implemented in production to increase efficiency and productivity. With Industry 4.0, new advanced techniques in subjects such as simulation, optimization, and data analysis have been developed. These techniques can be combined with various production philosophies, such as Lean, to streamline the production systems of the future.

A way to depict how new simulation techniques can be combined with Lean. Furthermore, the Industry 4.0 technique Discrete-event simulation (DES) can be used in conjunction with Lean to increase efficiency in production systems. DES is an event-driven simulation technique where the focus is not on continuous review but on events that occur at specific times. Another argument to be made is that simulation can be combined with Kaizen, continuous improvement, to develop projects with the main focus on continuous improvement, increasing efficiency by reducing Waste, which refers to non-value-adding actions and processes. The use of simulation techniques like DES combined with the Lean production philosophy can lead to significant improvements in efficiency within industrial production systems. The main idea behind Lean is to eliminate all Waste.

One problem with implementing Lean in production systems is the time consumption. Lean is not a particularly quick solution but requires several years of production before improvement areas become apparent and Lean can shine. However, through the combination with simulation, this problem can be somewhat bypassed. With DES, a production system can be simulated comprehensively, with realistic stochastic variables, leading to improvement areas for Lean within the system becoming apparent much faster than manual operation of the system. Thanks to the speed of simulation engines, several years of production can be simulated in a fraction of the real-time, addressing one of the major problems with implementing Lean. This, in turn, raises the efficiency of production systems in a shorter time than if simulation were not used.

Furthermore, there are additional Industry 4.0 techniques that can be combined with Lean to streamline existing industrial production systems. One combination highlighted is Just-in-time through cyber-physical systems. The combination works by replacing the traditional Kanban system with vertical integration and machine communication. The purpose behind this is to establish a coherent flow of information with information about all parts of production, from order to delivery. This flow of information is maintained through the use of RFID chips, which automatically update the system, and the change becomes. A system of this calibre can, through data analysis, automatically create material orders if the data from the flow of information indicates a need.

This combination of Lean methods and Industry 4.0 techniques has a significant impact on the efficiency of a production system. Just-in-time alone has a significant impact, as clearly depicted by Ohno (1988) in his book Toyota Production System: Beyond Large Scale Production. The mindset behind Just-in-time, where materials are aimed to be provided only at the needed time and quantity, increases the efficiency of a production system, in part by eliminating inventory between different process steps. This, combined with Industry 4.0 techniques such as machine communication and vertical integration as mentioned before, can lead to a more efficient production system.

With the establishment of a coherent flow of information, similar to a digitalized Kanban system, a clear overview of production can be maintained. This, in turn, allows potential problems and material shortages to be detected much earlier before the problem can negatively affect production itself. With all information automatically updated by RFID chips and readers, erroneous information is minimized, further increasing safety within production and reducing the risk of problems arising. All of this leads to an industrial production system where there is a constant supply of accurate information and materials and a Just-in-time system, which through inventory reduction and increased productivity, leads to a more efficient production system.

Another combination of Industry 4.0 techniques and the Lean production philosophy is the use of optimization, specifically simulation-based optimization (SBO), to address issues within industrial production and contribute to more efficient production systems, specifically in combination with Lean. SBO can be used to analyze complex and dynamic systems and provide a variety of different solution options. SBO provides information about the system to be optimized and evaluates different variables in the system through a multitude of simulations. An argument to be made is that SBO, which provides solutions to complex problems with a large number of variables, combined with Lean, which can be used for continuous improvement within individual process steps, has enormous potential for streamlining industrial production systems.

The combination of these techniques and mindsets can lead to significant improvements in production, as they are fundamentally different. SBO focuses on larger parts of production with a large number of variables, requiring a large number of simulations to evaluate different solutions to the problem. However, this does not lead to constant improvements, but after optimization is completed, the optimal solution is implemented, and then the process is finished. This is where the combination with Lean begins to shine. After optimization is completed, and the optimal solution implemented, the central Lean method, continuous improvement, is used to maintain the solution and continue improving the system. This, in turn, leads to the optimal solution from optimization gradually becoming better and better thanks to Lean. This results in the system being streamlined, first by the implementation of the solution provided by SBO, and then continuously streamlined by the Lean mindset.