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.
Case study: process improvement of a welding line
With the goal of increasing the EBIT, an analysis was conducted on the product portfolio. From the Pareto analysis (80-20), product X is the one with a higher weight than the others in terms of expected annual sales volumes.
A subsequent analysis selected the three major subgroups of Product X through the criteria: industrialization maturity, product complexities, and track of defects.
For the identified subgroups, using the Deming cycle approach (PDCA), a welding cycle analysis was performed to identify countermeasures to reduce operating costs.
Plan: AS-IS status
Through the time studies, the cycle times of the welding operations of the three subgroups were defined. During the observation for the cycle time studies, the activities of the production cycle that bring value to the customer versus non-value were identified.
In this case, eight different types of activities were identified to which each elementary operation could be clustered.
The activities defined as value-added (VA) are:
- part positioning
- welding (and spot welding)
On the other hand, the activities defined as non-value-added (NVA) are:
- inspection (using gauges);
- cleaning (performed with tools such as grinder, air blower, brush);
- handling of the workpiece by the operator;
- clamping;
- waiting or ideling.
A total time was calculated for each of the eight activity types, which related to the total cycle time to define the percentage.
It is observed that non-value-added (NVA) activities have percentage between 72% and 79% of cycle time, so are significantly higher in percentage than value-added (VA) activities.
A Pareto diagram analysis of the activity types was then performed for each subgroup. This allowed us to prioritize which of the eight types analysed had the greater impact i on the total cycle time for each product.
The Pareto analysis shows that a focused improvement is needed for the reduction of NVA, of the activities of cleaning, inspection, and clamping.
Then, to investigate the causes leading to the presence of these types of waste (NVAs) highlighted by the Pareto analysis, the 4M method (Ishikawa Diagram) was used preliminarily for the collection of all possible causes and then the 5Whys method for a more in-depth analysis and search for the root causes.
Do: implementation of the improvement activity
The first step of the improvement process was to create and optimize the existing standards.
Preliminary analysis using the “stopwatch” method led to break down the cycle into elementary activities, thus facilitating the drafting of the operations sequentially. In order to reduce variability (MURA), it is necessary to adopt the same cycle and thus the same methodologies for each operator, thus allowing the defined cycle time to be as effective as possible.
To allow that the defined methodologies could become a standard for the company it was decided to use two simple but effective tools:
- SOPs (standard operating procedures),
- OPL (One Point Lesson).
These tools also support the Training of new hires or operators with lack of knowledge by speeding up the learning curve and reducing the initial phase in which wastes and scraps can be created.
In addition, as analysed in the plan phase, the clamping operation represented a non-negligible part of inefficiency (NVA) and loss of time compared to the total amount of time available in the day. Through SOP, it was possible to standardize and optimize the activities for clamping and tooling the bench, getting the goal of reducing the time spent for these operations.
The application of these visual management tools allows the worker to an immediate assessment of the activity performed to correct actions that might create future defects or safety issues.
For each subgroup, the concept of poka yoke (error proof) solutions was applied to eliminate operator positioning errors, and secondarily to facilitate part positioning, clamping and reduce inspection and control, leading to a reduction in NVAs. For a subgroup, the poka yoke concept arrives to a re design of parts by a Design for Manufacturing perspective.
For the type of NVA manual cleaning, the countermeasure initially taken was to create dedicated OPLs that would highlight only the areas of the parts that needed the operation.
This initial quick and inexpensive solution was then improved with a modification to the process by adding a machine cleaning operation (operation done automatically) that reduced more than 70% of the activity thus reducing the cycle time and consequently the percentage of NVA on the total time (results verified in the check phase). This solution was validated by comparing the overall operation costs of the before and after state.
Check: TO-BE status
After the implementation of the actions described in the do phase, a new data collection and analysis was performed on the three subgroups considered.
With the improvement actions introduced there were savings compared to the initial AS-IS status of 84% in terms of bench tooling and clamping time and a reduction in NVA per cycle and thus cycle time ranging between -26% and -44% depending on the subgroup analysed.
These savings resulted in an overall reduction in manufacturing costs of product X of -5%.
Act: extension of corrective actions
In the last phase of the Deming cycle, after analysing the benefits gained from the improvement actions taken, the next targets to be achieved with a next PDCA cycle were set.
Based on the actions taken in the case study, the standards and solutions are extended to the remaining unaddressed products and a subsequent NVA cluster analysis of the remaining unanalysed work cycles is planned.
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As you can see, the benefits of value stream mapping go far beyond the theory—it’s about real results that drive impactful change. Our lean professionals have helped countless organizations streamline operations, eliminate inefficiencies, and achieve measurable gains. Ready to see what VSM can do for you? Book a meeting with our experts today to discuss your unique challenges and get hands-on with our VSM software. Let’s start mapping your path to lean success.