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Getting Lean

Filemon Sagrero

Correlating inspection trending with test data to fine-tune accept/reject parameters.

Industry 4.0 automated inspection technology opens the door to enhanced levels of process control. In addition to having to upgrade equipment, however, fully leveraging the power of this technology requires a strong team, an accurate program validation database, and a methodology to track trends in continuous improvement activities. Here is a look at an implementation process for inline 3-D solder paste inspection and 3-D automated optical inspection following reflow on SigmaTron’s SMT lines in Tijuana.

A planned phase two of this implementation includes adding 3-D AOI to secondary assembly operations post-SMT, plus correlating AOI trending with final test data to fine-tune AOI acceptance/rejection parameters. The facility is currently averaging 50ppm defect rates across its SMT lines. The goal of this greater inspection process is to drop that to zero defects; although, given material constraints are driving a defective component rate that represents a third of that 50ppm level on some programs, zero ppms may be unachievable until material availability returns to normal.

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Filemon SagreroLean Six Sigma training leads to effective, intrinsic problem-solving.

Much has been written on the “how” of Lean Six Sigma. This column discusses the “why” behind Lean Six Sigma. SigmaTron’s facility in Tijuana, Mexico, began implementing its Lean Six Sigma program in 2018 as a way to instill a focused process improvement methodology in its automotive and medical customer projects. A consultant was brought in for initial training, and I volunteered to be the internal champion after agreement that the necessary management support and resources would be put in place. The initial training sessions were designed to train the engineering team as Green Belts and select production personnel as Yellow Belts.

One challenge in an electronics manufacturing services company is each customer has control of their design. While some incorporate EMS-driven design for manufacturability (DfM) recommendations, others do not. Although SigmaTron’s production personnel wanted to solve production problems as they arose, the root causes were often difficult to identify using basic quality tools such as pareto charts without a strong problem-solving methodology. With Lean Six Sigma training, the team evolved from engineers and technicians trying to fix problems to a cohesive team with the necessary tools to rapidly identify issues, brainstorm possible root causes, test hypotheses, and implement the best solution. Issues that had taken weeks to analyze with prior methods were addressed in days or hours.

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Hom-Ming Chang

Using Lean Six Sigma to balance the increasing cost of solder.

While the death of through-hole technology has been predicted for decades, the reality is some applications have components that require a level of solder joint robustness that only through-hole technology can deliver. In low- and medium-volume operations, the cost-effectiveness of soldering those mixed-technology printed circuit board assemblies using a selective solder machine is an easy calculation because it may eliminate the cost of operating a wave solder machine. However, operations doing high-volume assembly of predominantly through-hole PCBAs may find determining the cost-effectiveness of selective solder is more challenging since their wave solder machines operate continuously. In those cases, the question becomes: What is the point at which use of wave soldering becomes inefficient when the percentage of through-hole components on printed circuit board assemblies drops?

The cost of solder, along with other material and production costs, is increasing globally. While these cost increases are unavoidable, implementing efficiency improvements can help balance these costs by reducing the amount of solder needed and eliminating solder dross.

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Allen Abell

A process for addressing RMA for multi-factory production.

In a normal business environment, the electronics manufacturing services (EMS) industry has more variation than that of a Lean original equipment manufacturer (OEM). This doesn’t mean EMS providers are disorganized. It simply highlights the challenges of an environment where customer inputs dictate supply-chain choices, processes and validation methodologies that would normally be optimized to minimize variation at a Lean OEM. Pandemic restrictions, supply-chain shortages, logistics constraints and demand spikes of 2021 have caused further variation at EMS providers and customers. However, those challenges serve as incentive to increase Lean discipline.

Past columns have highlighted Lean Six Sigma core tools such Gemba and the DMAIC process that help identify and correct quality issues that develop in manufacturing operations as project assumptions change. Lean Six Sigma is helping create an empowered, educated workforce at SigmaTron, capable of rapidly addressing unanticipated challenges found in today’s production environments. That said, defects can escape the factory or be induced by activities once product leaves the factory. Focusing on this area can have a long-term impact on eliminating another set of defect opportunities: muda (waste) and cost.

In SigmaTron’s model, field-service engineers work with customers that have higher volume or more technically sophisticated products to determine the root cause of field returns. While the company is achieving industry-standard low defect rates on some of its highest volume programs, even that low percentage generates monthly returns when the printed circuit board assembly (PCBA) count is in the millions.

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Jim BarnesLeveraging centralized resources for efficiencies across three facilities in as many countries.

Some industries have specialized end-market requirements. For example, corporate headquarters in fast food and fast casual restaurants dictate menu items and the equipment needed to support those items by region. Franchisees have choices in equipment configuration and a timeframe in which they need to buy it from a designated food processing original equipment manufacturer (OEM). They typically order very small quantities, however, making it challenging for a food-processing OEM to fulfill orders utilizing a single manufacturing location and centralized stocking model. There are also regional differences in input power voltages, cycles and plug styles. Preferred language for control overlays also varies. This creates a configure-to-order (CTO) dynamic that adds complexity to the variable demand model. Outsourcing adds flexibility to this equation because it gives food-processing OEMs access to shared production resources which help mitigate the production resource utilization inefficiencies that this type of high-mix, variable-demand production can create. It also helps OEMs more easily support a global customer base with minimal investment in production resources.

Regardless of whether the project is outsourced, when these units are manufactured in a single location, the wastes of overproduction, waiting, transportation and inventory are likely to be significant. At the same time, dividing variable-demand, small-lot production among multiple facilities has the potential to create inventory imbalances and production inefficiencies, particularly if the work is divided among contract manufacturers and managed separately by region. Lean manufacturing philosophy provides guidance on finding a balance that supports customer requirements while still leveraging some economies-of-scale.

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Filemon Sagrero

How to identify opportunities for improvement and enable corrections before the product is at risk.

The electronics manufacturing community is facing unprecedented challenges in 2021. Component supply and product demand are completely out of sync in many industries. Material constraints and transportation shortages are stretching lead-times even on committed orders. An economy flush with stimulus money and pent-up demand for products not available during much of 2020 has eliminated the ability of original equipment manufacturers (OEMs) to plan based on historical trends. In the middle is the EMS provider that sees material arriving later than planned, while at the same time experiencing unplanned increases in order volumes on many programs. Lean Six Sigma provides production teams the tools they need to identify issues, analyze potential improvements and implement changes that help keep production flowing on time even with changing production inputs.

SigmaTron International’s Tijuana, Mexico, facility utilizes teams of Lean Six Sigma Green and Yellow Belts in its continuous improvement activities. They use a variety of core tools in that process.  

One tool is the Gemba Walk. The term Gemba comes from the Japanese word for “the real place.” Taichi Ohno, a Toyota engineer and leader, is often credited with developing the concept of the Gemba Walk or the idea that leaders should regularly and frequently be present to observe the work of their organization when and where it takes place.

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