Lean manufacturing originally refers to the systematized production organization found by Womack/Jones/ Roos in their MIT study (1985 to 1991). Shah/Ward (2007), regardless of this definition related to the situation at the time, understand lean production as an “integrated socio-technical system whose core objective is the elimination of waste by simultaneously reducing or minimizing supplier, customer and internal fluctuations”. On the contrary, the function of lean manufacturing is the abolition of the principle of “shielding manufacturing systems against the contingencies of the market”. in other words, in the possibility of faster reactions to market changes, whereby the task of adapting and rationalizing production is decentralized with the help of standardized methods and hierarchically shifted further downwards. For the application of such lean manufacturing methods, the term “holistic production systems” has established itself in various countries.
Representatives of the future project Industry 4.0 explain that this approach supports lean production, as the transparency of networked systems supports the continuous improvement process. Others counter that Industry 4.0 as an automation concept entails the opposite of a streamlining of production because this is not based on the economic imperative, according to which effort and benefit should be in an economic relationship to each other, but the technological imperative, according to which available technology should also be used (cost, what it wants).
Womack/Jones/Roos already described more than just a production system. Thus, the term was soon framed by concepts such as lean administration or lean maintenance and extended to companies whose production is characterized by unique or small series production and finally further developed into lean management. This is now understood as a corporate philosophy of omitting (down to the smallest detail) all superfluous operations in production and administration through a more intelligent organization. It is based on innovative changes in the value chain and the actors accompanying it (such as customers, suppliers, trade unions, investors, municipalities) and on a partnership-based self-image of leading and executing actors.
Design Principles of Lean Production
In its early days, lean production was often associated with rationalization measures. This misinterpretation resulted in a loss of trust within the workforce. It quickly became clear that the methods of lean production systems only lead to sustainable success if the overall system is geared towards customer benefit with a consistent focus. This approach ultimately helped the Toyota Production System (TPS) to achieve a breakthrough. For the holistic orientation of a production system, the term holistic production systems (GPS) has prevailed in German-speaking countries. Holistic production systems provide for a company-specific orientation of the production system using the methods of lean production. A total of eight design principles of holistic production systems are distinguished.
The avoidance of waste is the fundamental goal of holistic production systems. This design principle aims to eliminate all non-value-adding activities within the production system. Value-adding activities are activities that increase the value of the product for the customer. Non-value-adding activities are therefore to be regarded as waste. However, it should be taken into account that there are non-value-adding activities that are necessary for the product development process, such as research and development activities, production planning or other indirect areas.
The avoidance or minimization of waste through lean production leads to more efficient processes and thus to less use of resources. The use of resources combines lean production with green management and supports the sustainable development of a company. A particularly lean company is also more resource-efficient and therefore green.
Continuous improvement process
The goal of a holistic production system is the pursuit of perfection. This requires a continuous urge to improve existing processes and systems. A prerequisite for this is the involvement of all employees in the improvement process. The personnel of a company should always question all methods, processes and tools and, if necessary, improve them. In this context, the design of in-house idea management is useful. With each improvement, errors, problems and waste are uncovered and eliminated.
Standardization deals with the definition of action steps about repetitive processes, workflows, production steps as well as planning and design tasks. Through standardization, the goal is to eliminate non-value-adding activities and to increase process stability.
The zero-defect principle aims to avoid passing on errors to subsequent work steps and thus to increase product and process quality. This design principle also contains methods for avoiding errors within a process chain and is closely linked to the methods of Total Quality Management (TQM).
The flow principle aims to realize a fast, consistent and low-turbulence flow of materials and information to achieve the lowest possible throughput time across the entire value chain. Products are to be transported from one process step to the next without intermediate storage, without restricting the flexibility of the company.
The pull principle is to drag a customer order through the production process. A counterpart is the push principle, in which production orders are pushed through the value chain based on forecasted customer requirements. The pull principle is thus based on specific customer orders and aims to minimize the control effort and inventories.
Employee orientation and goal-oriented leadership
Employee orientation and goal-oriented leadership in production companies must meet the requirements of holistic production systems. Within the framework of holistic production systems, the employees of a company are regarded as crucial resources for innovative concepts and continuous process improvements. The error-free and waste-free way of working of managers and employees must be ensured to obtain the desired result. The aspect of employee management concerns the daily interaction of employee and manager, whereby both parties benefit from goal-oriented leadership with clearly defined specifications and a consistent target structure within the GPS.
The main goal of visual management is the pictorial representation of information about processes and workflows. This is intended to create a high level of transparency about goals, processes and services within a holistic production system (GPS). This enables employees and managers to obtain information about production-relevant key figures in a short time. The transparency and the resulting involvement of employees should lead to a stronger identification with the workplace and the work task. In addition, problems and deviations from targets become immediately apparent, so that appropriate measures can be taken immediately. This also contributes to a reduction in waste and supports the continuous improvement process.