Value Stream Mapping and A3 Methodology Drive Efficiency in Assembly Lines

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Welcome to our 'Lean in Action' series, where we bring you real stories from the field about the transformative power of value stream mapping (VSM). While we’ve taken care to keep identities confidential, the insights, successes, and lessons shared here are authentic accounts from lean experts and industry professionals across various sectors.?

Optimizing Plant Production with Value Stream Mapping and A3 Methodology

Massimo Zucchelli

In a manufacturing plant dedicated to the construction of industrial machinery, a project was initiated to improve efficiency and achieve budget goals. The analysis focused on machining, welding, painting, and assembly processes, to identify areas of inefficiency and establish focused improvements.

Analysis of Nonproductive Hours

The first step was to assess the contribution of each production area to overall efficiency by analysing nonproductive hours, i.e., hours of operator attendance that do not correspond to hours actually spent to production. These hours were deployed by department and analysed using the Pareto method, revealing that two assembly lines were responsible for 46% and 37% of the losses, contributing a total of 83% of the losses.

Value Stream Mapping for Identification of Causes and Improvement Projects

From the results of the analysis, two sub-projects were launched, each of which was developed with the A3 methodology to identify the root causes of losses and define countermeasures. One of these A3s was focused on one of the assembly lines and led to examine the value stream through a Value Stream Map. At this stage, it was found that a buffer of the machinery chassis upstream of the assembly line required one forklift driver per day.?

The buffer before the assembly line was able to be replaced with a FIFO lane, fed via trolleys which were moved by the line operators of the assembly line. This was done with sequenced scheduling and synchronized feeding of the bulkiest components.

The analysis of the individual line phases, through the Work Sampling method, allowed the quantification of non-value-added activities (NVAs) related to operator movements and component transport, amounting to a total of five equivalent operators. This analysis allowed focusing on key areas to reduce handling time and unnecessary activities.

Other types of assembly line inefficiencies found were related to rework caused by defects and missing components during assembly operations.

Using VSM and Countermeasures to Improve Assembly Line Efficiency

From the analysis of the inefficiencies of one assembly line and the causes that generate them, countermeasures were developed that involved different stakeholders in the process:

1. Mapping a Value Stream Map “To Be”: The goal was to eliminate the buffer and switch to a FIFO lane, improving sequencing and feeding between painting and assembly. This change involved managing components according to the feeding sequence in the assembly line, reducing lead time, and optimizing the flow through production phases, with the reduction of NVA transport.
2. Blitz Kaizen at Workstations: This project involved the implementation of the 5S and an analysis using the Spaghetti Chart, which is used to map operator movements. Workstation layouts were redesigned, and workbenches were redesigned to have tools and components within easy reach, improving ergonomics and reducing the time required for movement (NVA reduction).
3. Quality Improvement through Line feeding: To address issues of missing components on the line, an analysis with suppliers improved on-time delivery, while a reorganization of parts in Kanban on the line ensured the availability of the high frequency and cheaper components. The bulkiest and most critical parts – the machinery chassis – were fed sequentially from the warehouse, with a lead time calculated to ensure that the line was fed within the FIFO lane throughput time.
4. Collecting Data and Analysing the Root Causes of Rework: To further improve quality, data was collected on the main issues that required rework, and the root causes of each defect were identified. Pareto analysis allowed to classify the causes into a few priority clusters, addressing the 20% of the causes that caused 80% of the defects. The approach led to the definition of improvement actions, and the reduction of two “operator equivalents” previously dedicated to rework the products at the end of the line.

Project Results after Value Stream Mapping and Improvement Implementations

The A3 focused on inefficiencies on one of the two assembly lines led to an overall reduction in man-hours by 15% based on the same production volume, distributed among the logistics, rework, and assembly departments dedicated to the line. This improvement was possible by the collaboration and commitment of various Departments and the adoption of the systematic methods described for the analysis and elimination of losses.

The project demonstrated how a detailed analysis of inefficiencies, supported by methods and tools such as A3, Value Stream Mapping, and Work Sampling, can lead to a significant increase in overall efficiency. The results obtained not only contribute to the achievement of budget goals, but also lay the foundation for a corporate culture focused to continuous improvement, making loss reduction a key pillar for production.

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