Self-contained manufacturing cells eliminate risk and increase predictability for customers and EMS firms.

The traditional perception of a Tier 3 EMS is that of a company that uses automated SMT and inspection equipment to build electronics assemblies in a high-mix/low-to-medium volume environment. Some Tier 3 EMS companies’ service offerings extend well beyond the completed printed circuit assembly; they have successfully developed expertise in complete order fulfillment, which includes the latter stages of final assembly (box build), final product test, packaging, shipping, logistics and distribution – all in a self-contained, dedicated manufacturing cell. The ability to execute in this area can significantly differentiate the EMS and offer benefits to the OEM not traditionally associated with a local EMS supplier.

Some progressive companies at this level have further positioned themselves into their customer’s value chain by acting as “virtual” manufacturing facilities, providing these services as well as reverse logistics for the products they have assembled. This function often is an afterthought to the OEM, but is a logical service to offload to an EMS provider. The EMS company typically would have parts on hand to support repair/replacement and has already invested in developing the expertise to assemble the product. Properly executed, it eliminates the need for the OEM to invest in logistics, supply chain or operational infrastructure.

In general, complete order fulfillment can often involve first assembly and test of printed circuit boards; integration of board assemblies into metal sub-rack or plastic housing; cable assemblies; thermal management units; cabinet integration, and direct shipment to the end-user. The EMS firm may also provide cabinet, rack and backplane wired assemblies, in-house FPGA and EPROM programming, assembly of complex cable forms and harnesses, potting, encapsulation and heat shrinking, as well as early-life final product testing, including ESS, vibration and pressure testing. Distribution and logistics support can entail stocking of inventory, delivery service relationships, packaging, consulting and depot repair.

Dedicated Manufacturing Cells

An EMS may have many different jobs in-house at any given time; it’s a high-product-mix environment. But a contract that involves complete order fulfillment is more complicated than simply building one component of a product, e.g., an assembled board. More parts, more disciplines and more elements are involved. To maintain optimum quality control in the manufacturing process, the EMS firm will employ dedicated manufacturing cells and a team of multi-skilled technicians and assemblers trained for and dedicated to that individual cell for the duration of the project – akin to mini factories within the factory. Each cell is optimally designed to support an individual product build process, and focuses exclusively on that customer or project. Machines or assembly equipment in manufacturing cells are located within close proximity to minimize product transportation (a form of manufacturing waste) and to maintain continuous flow with zero inventory between operations.

The manufacturing cell is operated by a team of multi-skilled operators who have complete responsibility for quality and delivery performance within the cell. Providing training on manufacturing concepts like Lean manufacturing, process flow, setup time reduction, total productive maintenance (TPM) and problem-solving/continuous improvement methodologies goes a long way toward building a high-performance manufacturing cell.

A prime example of this concept involved the manufacture of Ember Corp.’s EM250 “Jumpstart” kit, which provides the software and hardware to design Zigbee-based applications. In this case, Ember sought a complete turnkey manufacturing and distribution solution. Included in the milestones for selection were procurement strategies, manufacturing process capabilities, data collection, monitoring and measurement techniques, as well as distribution capabilities.

This involved the unique establishment of an in-house micro-facility at Sunburst EMS dedicated to Ember’s product, a standalone, vertically-integrated, dedicated workcell providing board-level functional test, sub-unit functional test, systems test, and final customer packaging for market distribution. Cell members – Sunburst personnel – took part in the planning process with direct customer interface to ensure customer expectations are met or exceeded with minimum resource allocation and maximum efficiency.

Box-build is an important extension of services, but the novel enhancement was complete order fulfillment inclusive of reverse logistics. This included design, planning, prototypes, production, test, integration, final product assembly, final product test, stocking distribution, drop ship, warranty repair, stocking repair and replacement, direct interaction with the end-customer, device tracking and reporting, and more. In short, anything the EMS firm does following the initial product shipment could be considered reverse logistics.

The manufacturing cell is completely self-contained both physically and logistically within the EMS facility (Figure 1). With the exception of electronics subassemblies built through normal manufacturing processes, there are no dependencies on any other aspects of the EMS team. This eliminates risk and increases predictability for the OEM and the dedicated manufacturing team. The manufacturing team is totally accountable to the OEM, which in turn has complete visibility into the project. In this particular case, the customer is also electronically connected to the EMS through a VPN. From the network, they can monitor functional test results in real time and adjust parameters remotely as required. This is also critical as a means of electronic transfer for logistics and distribution information, as this particular product ships directly to locations worldwide.

To achieve product conformity and consistent throughput, the process flow is set up in a continuously self-assessed system in which quality verifications are performed in a progressive manner and integrated into the build process. This is opposed to a tollgate/batch inspection system, which may require additional non-value-added resources. This concept ensures complete workcell accountability and comprehensiveness of all operations to be performed. One example is the “key characteristics” field, highlighted on each step of the assembly visual aids provided to the manufacturing team at each step of the process. These visual aids (Figure 2) are used during formal training sessions before validation and release of the process for product realization. This ensures continuous monitoring of feedback within the workcell, and appropriate adjustments are made when planned results are not achieved. If issues are identified, only one nonconforming opportunity at a time will require containment.

Implementing principles of Lean Manufacturing, all point-of-use inventories are replenished on a daily basis based on predetermined capacity levels by cell members. This ensures no interruption from material control or need for expediters to complete the day’s work, and further guarantees smooth delivery and quality. Finished product is released for delivery through EDI purchase orders that flow automatically through Ember directly to Sunburst for immediate shipment to the end-user. Finished product is built to a forecast and validated electronically via direct data transfer back to the OEM.

The custom cell is designed to function as an extension of the OEM’s business. The communication protocol is established straight from the OEM to the personnel in the manufacturing cell, with limited involvement from all levels within the organization. This makes the manufacturing team a virtual workforce for the OEM. In fact, a dedicated enclosure was built in the EMS facility to better conduct sensitive RF functional testing and provide a remote office for Ember personnel when they visit.

Tier 3 EMS providers seeking to increase their business and value proposition to their customers are offering a wider range of services and manufacturing solutions that include box build, integration, final assembly, rigorous testing and even shipping direct to the end user. Use of dedicated workcells is the best path to accommodate comprehensive manufacturing services for a customer, while maintaining quality, yields and on-time delivery in a high-mix manufacturing environment.

Dave Fahey is vice president of sales and marketing at Sunburst EMS (sunburstems.com); dfahey@sunburstems.com.