Using Lean Six Sigma to reconfigure assembly lines, boost capacity and reduce costs without adding new lines.
The need for flexibility is the one constant in the electronics manufacturing services (EMS) industry. Location preferences and volumes change over time. Lean Six Sigma provides the tools and principles needed not only to support these changes but to improve processes as they occur.
One such example occurred in SigmaTron International’s Chihuahua, Mexico, facility. A project’s volume was increasing due to a transfer of work from another facility. The final assembly portion is processed through two lines.
Instead of adding a third line, the facility’s manufacturing engineering team evaluated whether reconfiguring the existing lines made more sense. It developed a future state map of a simplified production flow that assumed changes in equipment capabilities to run all existing production on a single modified line, with a second similarly configured line added once the additional volume is transferred.
A Lean Six Sigma tool that can facilitate this type of analysis is the DMAIC (define, measure, analyze, improve, control) methodology.
In the define phase, a team develops a problem statement, identifies critical to quality (CTQ) and defect metrics, creates project objectives, determines the business case and financial impact of the desired improvement, determines customer impact, sets milestones and a timeline, defines the project scope and boundaries and assigns team responsibilities. In the measure phase, the team measures the variances they associate with the problem they’ve identified, utilizing core tools such as cause-and-effect diagrams and Gage R&R measurements. In the analyze phase, the team analyzes the data it collected to determine trends and possible corrective actions. In the improve phase, the team implements improvements and then utilizes design of experiments (DoEs) to determine if the proposed solutions are correcting the problem. In the control phase, measures to ensure continued achievement of desired metrics are implemented.
Value-stream mapping (VSM) also provides helpful tools for this type of analysis. VSM is a technique for visualizing and analyzing the flow of materials and information required to deliver a product or service to customers.
It starts with a visual representation of the current-state process, highlighting individual processes and cycle times, enabling a team to identify bottlenecks and unnecessary activities.
Areas of waste, such as excess inventory or work-in-process, excessive transport, or unnecessary steps, are identified and eliminated in a future state map. As part of a continuous improvement process, it helps ensure ongoing focus on improving process flow.
In this example, time studies were used to determine the equipment changes required to balance the line and avoid bottlenecks. The team found that if it changed the configuration in wave solder, modified production fixturing to run two products simultaneously and added two workers per shift to the line to increase the line speed, energy consumption, solder, total headcount and floorspace were reduced.
Additionally, changes included:
- Enriching the job requirements of existing production operators to expand the variety of tasks they performed.
- Automating the conveyor to achieve a paced line.
- Redoing visual aids to support changes in tooling and span of activities associated with each production operator.
- Redesigning individual workstations to support point of use stocking and expanded assembly activities for each production operator.
- Modifying the functional test fixtures and programming to reduce test time.
With the planned volume increase, one line became dedicated five days a week, and a second line was dedicated three days a week, with the remaining time allocated to other projects. The annualized savings exceeded the cost of the equipment and modified fixturing. Production operators no longer needed for the reconfigured line were deployed to other operations. The savings align with the customer’s requirement for annualized cost reduction.
Utilizing Lean Six Sigma tools to analyze production efficiency, particularly when variables such as increased volumes or changes in product mix are anticipated, enables teams to improve throughput and eliminate waste and inefficiencies through process improvements. In outsourced production, these improvements not only help EMS providers meet customers' flexibility needs but also align with agreements designed to achieve cost reductions over the life of the program.
Alvaro Grado is general manager at SigmaTron International’s Chihuahua, Mexico facility; This email address is being protected from spambots. You need JavaScript enabled to view it..
