Operational excellence in assembly through the implementation of lean manufacturing

Operational excellence in assembly is the result of a systematic and continuous improvement process that focuses all processes on efficiency, quality, and value creation. A key starting point is value stream analysis, which provides a holistic view of material and information flows. By recording all process steps in detail – from material provision to shipping – waste becomes visible and quantifiable. This allows typical sources of loss such as waiting times, unnecessary transport, excess inventory, search times, or quality problems to be identified.

ABC/XYZ analysis is recommended for further structuring and prioritizing optimization potential. It creates transparency regarding the quantity and demand distributions of assemblies and individual parts. While ABC analysis evaluates economic significance (sales or consumption volume), XYZ analysis classifies demand regularity. The combination of both methods provides a sound basis for designing efficient material flows and for differentiated control of pre-assembly and final assembly areas.

When restructuring the assembly organization, it often makes sense to segment the product portfolio—for example, into so-called fast-moving and exotic products. This separation allows processes to be targeted: while fast-moving products are assembled in highly standardized flow lines with clear timing, exotic or special variants can be manufactured in flexible assembly islands or one-piece flow cells. This requires a hall layout that is conducive to material flow, ensuring short distances, clear flow directions, and a clear separation of value creation and logistics.

A key challenge in the planning phase is cycle time design. Here, assembly content, cycle times, number of stations, and line length are coordinated in such a way that both ergonomic and economic requirements are met. The design of the individual workstations is based on the principles of lean ergonomics, i.e., a combination of increased efficiency and ergonomics. This is supported by a well-thought-out material supply system, for example, via picked sets, KLT flow racks, or driverless transport systems (AGVs), which ensure an uninterrupted supply.

Parallel to physical process design, establishing a lean management culture is crucial. Methods such as 5S (order and cleanliness), SMED (setup time reduction), Kaizen (continuous improvement), Jidoka (integrated quality assurance), and Andon systems (visual fault management) contribute to standardization, error prevention, and the active involvement of employees. Accompanying shop floor management ensures that performance indicators (e.g., OEE, cycle and throughput times, rework rates) are regularly monitored and deviations are analyzed immediately. This creates a learning organization that gradually improves its processes.

Digital support is also increasingly coming into play: assistance systems, digital assembly instructions, real-time data collection via MES systems, and automated feedback enable a high degree of transparency and flexibility. These digital tools complement the lean principles and make their effectiveness measurable and controllable.

Our project experience shows that operational excellence in assembly is never the result of a single measure, but rather of a holistic approach. Only the coordinated interaction of process design, layout planning, material logistics, IT support, and employee training leads to sustainable performance improvement. The transfer of best practices from other industries has proven successful in this regard—for example, the adaptation of automotive standards to assembly in medical technology or mechanical engineering.

Ultimately, operational excellence means designing the assembly process in such a way that it is robust, lean, flexible, and adaptive—thereby securing a long-term competitive advantage through superior process control.