Chris Munroe05.12.11
Lean manufacturing philosophy can differ widely between organizations. Electronics manufacturing services (EMS) providers face some of the greatest challenges because their diverse customer bases often drive tradeoffs in Lean implementation strategies. Correctly implemented, Lean manufacturing is an excellent tool in medical product manufacturing because it drives both efficiency and consistency in supply base management and production processes. This focus on elimination of waste helps reduce cost and ensure product quality.
This article will examinekey areas of Lean implementation focus and discusses the strategies used to maximize Lean implementation in each of these areas in spite of the challenges presented by a diverse customer base.
Large-scale Systemic Approach
While Kaizen events can drive focused improvements, true waste elimination requires an organization-wide focus. This EMS provider took that approach. Rather than optimizing the factory floor process by process, a large-scale systems approach can be implmented to drive focus on increasing factory throughput by optimizing and standardizing production. Key implementation elements include:
• Detailed process mapping to understand the key processes involved in transforming production inputs to customer-desired outputs;
• Identification of constraints in key processes that limit flexibility;
• Development of strategies to eliminate constraints which include working with equipment suppliers, material suppliers and employees to develop unique solutions for maximum flexibility;
• Standardizing the manufacturing solution through common equipment selections which further improves the flexibility of the assembly process; and
• Development of simple tools that ensure rapid exchange of real-time information.
Supply Chain Management
Properly implemented, Lean manufacturing minimizes raw material inventories, work-in-process and finished goods inventory. That said, creating a just-in-time (JIT) environment in a variable demand EMS business model can be challenging. The approach taken in this example focused on teaming with the customer and supply base to understand historical trends, and establish adequate bonds and replenishment streams. This resulted in a process which manages exceptions vs. constantly expediting to support “surprises” in demand.
From a supply base standpoint, this philosophy incorporates the following principles:
• Strong focus must be placed on developing and qualifying suppliers that embrace Lean manufacturing principles of short cycle times, flexible batch sizes and high quality;
• Suppliers must be responsible for managing production to forecast, yet deliver to “pull signals” vs. requiring firm release dates over an extended lead time;
• Appropriate buffer sizes for current production rates must be established, maintained and continuously monitored for adequacy;
• Material buffers should be maintained in close proximity to the manufacturing facilities to allow frequent release of small batches to the production floor and maximum flexibility in responding to changing demands;
• The material pipeline must be proactively and regularly monitored over the medium to long term horizon through bond reports to identify and resolve potential supply disruptions.
Epic, for example, uses a kanban “pull” system, postponement of commitments and Electronic Data Interchange (EDI). Strategic suppliers produce to the material requirements planning (MRP) forecast and ship to EDI release signals. Buffers are established at key locations in the pipeline and are regularly reviewed and revised as market and demand conditions vary. Consignment, in-house stores and vendor-managed inventory (VMI) programs are used with strategic suppliers to maintain buffers closest to the point of use.
Pipeline status or “bond” reports are regularly reviewed with supplier teams to ensure buffers and replenishment streams are able to support planned production within a range of variation levels based on past historical demand, current forecasts, customer service lead-time guarantees to their end market, manufacturing lead times and transit lead times.
On the factory floor, a two-bin system and color-coded cards identify raw material and work-in-progress status. Material shortages are easily visible on a walk-through of the material area. Between facilities, an “e-Kanban” system allows employees to electronically view the status of inbound material shipped from suppliers.
DFM/DFT Process
Design for manufacturability and testability (DFM/DFT) is a core component of a good Lean strategy, since designs that are inefficient to manufacture contribute to poor quality and increased costs. Medical manufacturers face a significant challenge in this regard, since once the product is approved changes may drive a re-qualification process. In this example, a formal analysis process and a ranking system for DFM/DFT recommendations is used to ensure that customers can see the impact of a recommended change to better understand its importance.
Customer data packages are analyzed during the project launch phase using advanced product quality planning (APQP) techniques. While APQP was developed by the automotive industry, its basic philosophy makes sense for any Lean product launch process.
Key points include:
• Understand customer requirements;
• Use a robust process for product design and development verification;
• Use a robust process for production process design and development verification;
• Validate both product and process; and
• Use a focused product launch process with feedback, assessment and corrective action mechanisms to ensure that the product meets customer requirements.
The design review summary lists the recommendations of the Design for Manufacturing Evaluation and scores each based on relative importance:
• 5 – Will not build the assembly with this issue unresolved;
• 4 – Major design issues. Can build product as designed;
• 3 - Issue should be corrected. Can build product as designed;
• 2 – Minor design issue; or
• 1 – Nice-to-have Item.
While the analysis is done using internal DFM/DFT guidelines optimized for the specific production environment, the foundation for those standards are based on industry-accepted guidelines including those published by IPC.
Standardized Manufacturing and Test Platforms
Standardized platforms, processes and chemistries for manufacturing and test are an important part of an enterprise-wide Lean strategy. The three biggest advantages are:
• DFM/DFT recommendations can be consistent companywide;
• Process improvements developed in one factory are easily transferred across the company; and
• Projects can more easily be ramped to multiple facilities.
Synergies in maintenance practices and equipment procurement/support negotiating leverage can also be developed.
The manufacturing equipment strategy uses standardized placement equipment that supports minimized changeover. Either feeders or the entire table of feeders can be swapped during changeover. Material is stocked on feeders near point of use to further reduce changeover time.
Vapor phase reflow is used because it has no time delay in waiting for machine temperatures to stabilize.
Further downstream, wave systems also minimize changeover time. For example, Epic worked with a Swiss manufacturer of wave solder equipment to develop a duplex wave solution that supports both lead and lead-free solder processes while ensuring rapid changeover.
The duplex wave system is a carrier-based system. There are costs associated with the carriers, but to minimize this, universal tooling has been designed for standard printed circuit board (PCB) array sizes. Multiple product types can be soldered collectively without system changeover and multiple production lines feed into a single machine.
Each carrier is barcoded with a unique ID that links to the duplex system for total profile control. A barcode reader on the conveyor signals the machine’s computer to change profiles as different products approach the input. Once the barcode is verified and accepted, and the product enters the machine, flux is applied based on the control settings for the product. The area and volume are predetermined during engineering development with control based on product complexity.
Most EMS providers use standardized in-circuit test platforms. However, in this example test strategy also addresses functional test. This provides the flexibility to test multiple customer products with just a fixture changeover. The platforms use a common test application and operator interface, further improving flexibility. The operators become well versed on the functional test platform and common software interface so minimal training is required as products are added. This systems approach also allows for wholesale test improvements to be made across all platforms and products concurrently.
Support for Variable Demand
Variable demand is perhaps the biggest challenge in any EMS system because it is often driven by multiple customers. The materials, DFM/DFT and minimized changeover focus strategies outlined above all help support variable demand focus. Two other areas which also contribute to robust variable demand support are operator cross training, and standardized work and flow.
Training helps ensure that the workforce has the ability to change work flow with changes in demand. Cross training starts with identifying a roadmap of qualifications for each operator and technical member, and a master matrix maintained to show competence of the staff and areas to improve flexibility. Operators are trained on a pull system and demand flow. When demand changes, these cross-trained and certified operators can be shifted to the work center with the highest demand.
Plant floor layout is also fundamental to supporting variable demand. When the manufacturing process flow can be visualized easily walking through the facility, it tends to have more efficient material flow. Operators understand the process flow, bottlenecks become very visible, and anything which is out of place can be seen and corrected quickly. Programs such as a well structured 5S program help drive a lean flow and improve the visual flow, and standardized floor models and flows within multi-facility operations set the tone for standardized work.
Continuous Improvement Focus
In addition to standard measures of quality, productivity and customer satisfaction, a Reliability Lab and Six Sigma practices are used to help rapidly implement continuous improvement efforts.
The fundamental difference between Lean and Lean Sigma is that while Lean manufacturing focuses on the elimination of waste by removing steps in processes, Six Sigma fine tunes processes by focusing on specific process improvement activities.
An in-house reliability laboratory supported new process definition and validation; new product process validation; and resolved internal, supplier and customer quality issues prior to implementation of Six Sigma tools. Now, Six Sigma’s define, measure, analyze, improve, control (DMAIC) approach has been added to enhance design for manufacturing/testability (DFM/DFT) analysis, process improvement and/or corrective action efforts.
In combination, these tools provide both a robust problem identification and resolution process, and the ability to clearly document the root cause and results of correction action.
There is no question that EMS providers deal with a greater set of challenges in implementing a strong Lean philosophy than those faced by OEMs. However, as these examples illustrate, these challenges can be met with a combination of off-the-shelf tools, customer and supplier partnerships, and internal creativity.
For more information, feel free to contact Chris Munroe, director of engineering for Epic Technologies at chris.munroe@epictech.com.
This article will examinekey areas of Lean implementation focus and discusses the strategies used to maximize Lean implementation in each of these areas in spite of the challenges presented by a diverse customer base.
Large-scale Systemic Approach
While Kaizen events can drive focused improvements, true waste elimination requires an organization-wide focus. This EMS provider took that approach. Rather than optimizing the factory floor process by process, a large-scale systems approach can be implmented to drive focus on increasing factory throughput by optimizing and standardizing production. Key implementation elements include:
• Detailed process mapping to understand the key processes involved in transforming production inputs to customer-desired outputs;
• Identification of constraints in key processes that limit flexibility;
• Development of strategies to eliminate constraints which include working with equipment suppliers, material suppliers and employees to develop unique solutions for maximum flexibility;
• Standardizing the manufacturing solution through common equipment selections which further improves the flexibility of the assembly process; and
• Development of simple tools that ensure rapid exchange of real-time information.
Supply Chain Management
Properly implemented, Lean manufacturing minimizes raw material inventories, work-in-process and finished goods inventory. That said, creating a just-in-time (JIT) environment in a variable demand EMS business model can be challenging. The approach taken in this example focused on teaming with the customer and supply base to understand historical trends, and establish adequate bonds and replenishment streams. This resulted in a process which manages exceptions vs. constantly expediting to support “surprises” in demand.
From a supply base standpoint, this philosophy incorporates the following principles:
• Strong focus must be placed on developing and qualifying suppliers that embrace Lean manufacturing principles of short cycle times, flexible batch sizes and high quality;
• Suppliers must be responsible for managing production to forecast, yet deliver to “pull signals” vs. requiring firm release dates over an extended lead time;
• Appropriate buffer sizes for current production rates must be established, maintained and continuously monitored for adequacy;
• Material buffers should be maintained in close proximity to the manufacturing facilities to allow frequent release of small batches to the production floor and maximum flexibility in responding to changing demands;
• The material pipeline must be proactively and regularly monitored over the medium to long term horizon through bond reports to identify and resolve potential supply disruptions.
Epic, for example, uses a kanban “pull” system, postponement of commitments and Electronic Data Interchange (EDI). Strategic suppliers produce to the material requirements planning (MRP) forecast and ship to EDI release signals. Buffers are established at key locations in the pipeline and are regularly reviewed and revised as market and demand conditions vary. Consignment, in-house stores and vendor-managed inventory (VMI) programs are used with strategic suppliers to maintain buffers closest to the point of use.
Pipeline status or “bond” reports are regularly reviewed with supplier teams to ensure buffers and replenishment streams are able to support planned production within a range of variation levels based on past historical demand, current forecasts, customer service lead-time guarantees to their end market, manufacturing lead times and transit lead times.
On the factory floor, a two-bin system and color-coded cards identify raw material and work-in-progress status. Material shortages are easily visible on a walk-through of the material area. Between facilities, an “e-Kanban” system allows employees to electronically view the status of inbound material shipped from suppliers.
DFM/DFT Process
Design for manufacturability and testability (DFM/DFT) is a core component of a good Lean strategy, since designs that are inefficient to manufacture contribute to poor quality and increased costs. Medical manufacturers face a significant challenge in this regard, since once the product is approved changes may drive a re-qualification process. In this example, a formal analysis process and a ranking system for DFM/DFT recommendations is used to ensure that customers can see the impact of a recommended change to better understand its importance.
Customer data packages are analyzed during the project launch phase using advanced product quality planning (APQP) techniques. While APQP was developed by the automotive industry, its basic philosophy makes sense for any Lean product launch process.
Key points include:
• Understand customer requirements;
• Use a robust process for product design and development verification;
• Use a robust process for production process design and development verification;
• Validate both product and process; and
• Use a focused product launch process with feedback, assessment and corrective action mechanisms to ensure that the product meets customer requirements.
The design review summary lists the recommendations of the Design for Manufacturing Evaluation and scores each based on relative importance:
• 5 – Will not build the assembly with this issue unresolved;
• 4 – Major design issues. Can build product as designed;
• 3 - Issue should be corrected. Can build product as designed;
• 2 – Minor design issue; or
• 1 – Nice-to-have Item.
While the analysis is done using internal DFM/DFT guidelines optimized for the specific production environment, the foundation for those standards are based on industry-accepted guidelines including those published by IPC.
Standardized Manufacturing and Test Platforms
Standardized platforms, processes and chemistries for manufacturing and test are an important part of an enterprise-wide Lean strategy. The three biggest advantages are:
• DFM/DFT recommendations can be consistent companywide;
• Process improvements developed in one factory are easily transferred across the company; and
• Projects can more easily be ramped to multiple facilities.
Synergies in maintenance practices and equipment procurement/support negotiating leverage can also be developed.
The manufacturing equipment strategy uses standardized placement equipment that supports minimized changeover. Either feeders or the entire table of feeders can be swapped during changeover. Material is stocked on feeders near point of use to further reduce changeover time.
Vapor phase reflow is used because it has no time delay in waiting for machine temperatures to stabilize.
Further downstream, wave systems also minimize changeover time. For example, Epic worked with a Swiss manufacturer of wave solder equipment to develop a duplex wave solution that supports both lead and lead-free solder processes while ensuring rapid changeover.
The duplex wave system is a carrier-based system. There are costs associated with the carriers, but to minimize this, universal tooling has been designed for standard printed circuit board (PCB) array sizes. Multiple product types can be soldered collectively without system changeover and multiple production lines feed into a single machine.
Each carrier is barcoded with a unique ID that links to the duplex system for total profile control. A barcode reader on the conveyor signals the machine’s computer to change profiles as different products approach the input. Once the barcode is verified and accepted, and the product enters the machine, flux is applied based on the control settings for the product. The area and volume are predetermined during engineering development with control based on product complexity.
Most EMS providers use standardized in-circuit test platforms. However, in this example test strategy also addresses functional test. This provides the flexibility to test multiple customer products with just a fixture changeover. The platforms use a common test application and operator interface, further improving flexibility. The operators become well versed on the functional test platform and common software interface so minimal training is required as products are added. This systems approach also allows for wholesale test improvements to be made across all platforms and products concurrently.
Support for Variable Demand
Variable demand is perhaps the biggest challenge in any EMS system because it is often driven by multiple customers. The materials, DFM/DFT and minimized changeover focus strategies outlined above all help support variable demand focus. Two other areas which also contribute to robust variable demand support are operator cross training, and standardized work and flow.
Training helps ensure that the workforce has the ability to change work flow with changes in demand. Cross training starts with identifying a roadmap of qualifications for each operator and technical member, and a master matrix maintained to show competence of the staff and areas to improve flexibility. Operators are trained on a pull system and demand flow. When demand changes, these cross-trained and certified operators can be shifted to the work center with the highest demand.
Plant floor layout is also fundamental to supporting variable demand. When the manufacturing process flow can be visualized easily walking through the facility, it tends to have more efficient material flow. Operators understand the process flow, bottlenecks become very visible, and anything which is out of place can be seen and corrected quickly. Programs such as a well structured 5S program help drive a lean flow and improve the visual flow, and standardized floor models and flows within multi-facility operations set the tone for standardized work.
Continuous Improvement Focus
In addition to standard measures of quality, productivity and customer satisfaction, a Reliability Lab and Six Sigma practices are used to help rapidly implement continuous improvement efforts.
The fundamental difference between Lean and Lean Sigma is that while Lean manufacturing focuses on the elimination of waste by removing steps in processes, Six Sigma fine tunes processes by focusing on specific process improvement activities.
An in-house reliability laboratory supported new process definition and validation; new product process validation; and resolved internal, supplier and customer quality issues prior to implementation of Six Sigma tools. Now, Six Sigma’s define, measure, analyze, improve, control (DMAIC) approach has been added to enhance design for manufacturing/testability (DFM/DFT) analysis, process improvement and/or corrective action efforts.
In combination, these tools provide both a robust problem identification and resolution process, and the ability to clearly document the root cause and results of correction action.
There is no question that EMS providers deal with a greater set of challenges in implementing a strong Lean philosophy than those faced by OEMs. However, as these examples illustrate, these challenges can be met with a combination of off-the-shelf tools, customer and supplier partnerships, and internal creativity.
For more information, feel free to contact Chris Munroe, director of engineering for Epic Technologies at chris.munroe@epictech.com.