When discussing Value Stream Mapping (VSM), it’s easy to view the tool as a methodological exercise that can be conducted from behind a screen, relying on data from ERP or MES systems, or theoretical cycle times from manufacturing engineering offices. While these data points offer a valuable starting point to understand the overall performance of production processes, the real strength of VSM lies in its ability to map what actually happens on the shop floor. It is there, in the production environment, where value is truly created and where losses are hidden. It is precisely there that the flow must be observed and measured, in order to understand how it truly behaves and adapts to constraints and problems that are often invisible from the office.
I recently took part in an improvement project within a company that manufactures mechanical components for the agricultural sector. The production process for the selected product included multiple phases: reception and bending, machining, welding, painting, and finally assembly.
An obvious bottleneck uncovered in the VSM workshop
During the initial VSM workshop covering the full value stream, it became immediately clear that the assembly area was the bottleneck in terms of production capacity. The project had two main goals:
- To increase throughput without adding resources (labor or machines);
- To identify and reduce hidden losses and inefficiencies in production and internal logistics flows.
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In previous years, the area had already been analyzed and optimized by the time and methods department, and theoretical cycles appeared well-calculated. However, what was observed on the Gemba told a different story.
The assembly area was structured into three cells, each consisting of one pre-assembly station feeding two FIFO lanes, which served two final assembly stations.
The FIFO lanes were frequently congested, with accumulations of components and preassembled items. Pre-assembly operators were often idle, waiting for FIFO lanes to clear, while the assembly operators experienced frequent downtime due to setup or activities out of standard cycle. A spaghetti diagram revealed a high number of non-standard movements from the assembly operator, evidence of process inefficiencies not visible in the data.
In short: the data suggested a balanced line, but reality clearly revealed a mismatch between pre-assembly and final assembly.
These discrepancies must be interpreted with the trained eye of someone who truly understands the process and most importantly, by listening to those who experience it daily.
The Team: A VSM Conducted With the People Who Live the Process
This is why the improvement workshop was conducted directly on the field, involving a cross-functional team: the shift supervisor, five assemblers, one logistics operator, a safety representative, the quality manager, and a time and methods technician. Lean tools such as Spaghetti Diagrams, work sampling, and direct time observations were used to examine:
- The actual movements performed by operators;
- Value-added vs. non-value-added activities;
- Inefficiencies in both the physical and information flow.
Several key problems emerged:
- Frequent product changeovers, up to 14 times per day, causing setup downtimes of 15–20 minutes each.
- Inconsistent container sizes and non-standard quantities, which created leftover material at the end of each batch and increased the time needed to clean and reorder stations.
- Non-optimized workbenches, not suited for managing high variability in product codes, resulting in excessive setup times.
- Late preparation of tools and materials, often because the setup worker was occupied elsewhere with other changeovers.
Thanks to direct operator involvement and shared problem analysis, several actions were implemented:
- Standardization of containers to hold multiples of standard batch sizes, reducing residuals and speeding up replenishment.
- Reorganization of the supermarket area, integrating materials and setup equipment so the picker could prepare everything, including trolleys and setup kits, at once.
- Design of a dedicated workbench for high-rotation items, optimized for small batches and high product code variability.
- Elimination of non-standard activities causing off-cycle movements for assembly operators.
- Redefinition of operational roles, rebalancing workloads between pre-assembly and final assembly.
- Active training and participation of operators in designing the new layout and defining the future state.
This new structure led to:
- 35% reduction in average setup times;
- Improved FIFO lane flow, with reduced congestion and smoother handoffs;
- 10% increase in throughput, all achieved without additional headcount or machines.
Operators take ownership of improvements
However, the most valuable outcome was the operators’ ownership of the improvement. The VSM was not only a technical tool, it became a cultural enabler, helping operators visualize the flow and play an active role in improving it.
Operators also proposed a complete layout redesign, consolidating the six pre-assembly stations into a single centralized pre-assembly bench served by autonomous guided vehicles (AGVs). This centralized approach allowed better sequencing and kit preparation for high-rotation codes and simplified internal logistics. The solution is planned and budgeted.
Gemba: a transformative piece of value stream mapping
In summary, it is the presence on the Gemba that transforms VSM from a theoretical exercise into a real lever of change. Engaging those who work with their hands and minds in the process is essential to uncover the true root causes of waste, co-design sustainable solutions, and deliver meaningful and lasting results.
Large investments or revolutionary changes aren’t always required. Often, observation, listening, and structured involvement are enough. And when used correctly, VSM becomes the perfect bridge between technical analysis and hands-on process intelligence, a critical path to Lean transformation rooted in the reality of operations.
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