Standardization's role in Lean manufacturing. In two parts.

Most companies engaged in Lean manufacturing easily can discuss the changes they’ve implemented. But which changes really contribute the most? EPIC developed a list of the top 10 lessons learned in our Lean journey. This month, we review lessons six to 10; lessons one to five will appear in our next column.

10. Centralized AOI/AXI. Philosophically, EPIC prefers a robust electrical test over automated inspection methodologies. However, as an EMS provider, there is a need to support varying customer requirements. In some cases, customer products are not designed for a solid electrical test, which makes inspection necessary. However, because many products are electrically tested, EPIC has chosen to create centralized inspection test centers that include both AOI and automated x-ray inspection, rather than embed AOI/AXI equipment within each SMT line. Products requiring AOI/AXI run through the AOI/AXI inspection center. Those that do not require inspection go to electrical test. This strategy minimizes capital equipment expense and floor space requirements, as multiple lines feed a single center.

9. Standardized test platforms. Most EMS providers standardize on in-circuit test systems and fixtures. But when it comes to functional test, they either rely on or must accept systems developed by customers. That in turn means supporting a large number of unique functional testers, additional floor space allocation, increased training and additional maintenance support requirements. Additionally, customer-supplied test systems tend not to take advantage of the newest test technologies, and are rarely designed for a manufacturing environment.

EPIC began developing functional test platforms in the ’90s that were generic in scope, with the flexibility to test multiple customer products through fixture changeover. This was a big step to “leaning” floor space and test operations. 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 permits wholesale test improvements to be made concurrently across all platforms and products.

8. Optimizing the wave solder process. One area of focus in minimizing changeover time and floor space consumption was the wave solder process. EPIC worked with a Swiss wave solder equipment manufacturer to develop a duplex wave solution that supports both lead and Pb-free processes, while ensuring rapid changeover between the processes. The system architecture adapts to lean methodologies, saving floor space, utilities and resources. (For more on this, see my column from November 2008: “Leaning the Line”.)

7. Minimized changeover time. EPIC’s Synchronous Flow Manufacturing philosophy incorporates standard lean tools such as point-of-use stocking and single piece flow. The latter places a large demand on changeover quantity and time, while ensuring quality levels in production. When the placement industry was focused on chip placement speed in the mid-to-late '90s, EPIC selected Siemens placement equipment based on changeover flexibility. Changeover on Siemens can be completed with feeder exchange or full exchange of feeders by swapping the tables. Now in 2008, it is more common to find placement systems with changeover tables a key factor in the system design. The vapor phase reflow systems also offer advantages in changeovers, since there is no time delay in waiting for machine temperatures to stabilize. This, combined with the aforementioned standard array sizing, goes a long way toward reducing labor during SMT changeover. As we move downstream, we find our wave systems are considered zero changeover machines. Multiple products are produced across the wave systems without line interruption. This was, of course, until we introduced the duplex wave system, in which lead and Pb-free soldering requires a changeover process of about 10 minutes. Changeover is important, right down to the testing systems, whether we are dealing with board-level or box-build testers. Test systems are commonly changed three and four times an hour to best utilize floor space, equipment and operational efficiency demanded with single piece flow. Both hardware and software changeovers must be considered in the test changeover process.

6. Standardized chemistries. Another EMS challenge is to support a range of customer-preferred process and product application chemistries, such as solder flux, paste, conformal coating, etc. The EMS provider must drive standardization when it comes to materials and chemistries. Inventory management aside, factors such as supplier quality, material handling and floor control are all large issues that can directly impact quality to the customer and safety to the operations teams. Establishing relationships with key suppliers of chemistries, and knowing the performance of these chemistries, goes a long way toward optimizing process implementation and efficiency. Also, this standardization has a direct effect on changeovers, capital utilization and environmental safety. Another example is selecting chemistries that can bridge similar processes. Wave flux manufacturers today offer flux chemistries that are both lead and Pb-free capable, aqueous and no-clean compatible, or as we have found, one wave flux for all applications. The result is minimized maintenance, repair and operations (MRO) transactions, reduced MRO inventory and less engineering time spent supporting multiple chemistries.

Chris Munroe is director of engineering at EPIC Technologies (epictech.com); chris.munroe@epictech.com. His column appears bimonthly.