This article is based upon the professional experiences of Bob Bilbrough, founder and president of Qualcon (Quality Contract Manufacturing, LLC) in Flowery Branch, GA USA. Mr. Bilbrough has capped a seventeen-year career in the electronics industry by pioneering continuous flow manufacturing in the EMS industry. Qualcon operates exclusively in continuous flow manufacturing mode. Despite being a relatively new entry in the world of EMS, OEMs seeking the valuable benefits of continuous flow manufacturing are flocking to Qualcon. Qualcon offers full turnkey assembly services, labor-only assembly services (customer consigned components) and test services. For more information on Qualcon, visit them on the World Wide Web at "www.qualcon1.com" or call them at 770-965-3300.

Continuous flow manufacturing has become the standard process among the best manufacturers in every industry --- except electronics manufacturing services (EMS). Electronic contract manufacturers have steadfastly maintained batch mode manufacturing (BMM) as their standard process despite a wealth of data supporting the efficiencies CFM. Strangely enough, many EMS providers tout CFM in their marketing pitches without actually employing it. In 1994 I spent a day with a large publicly held EMS provider. My goal was to qualify them to perform EMS for my company. They were doing quite well until we began the plant tour. The first words out of my host�s mouth were, "As you can see, we employ continuous flow manufacturing processes here." As I surveyed the manufacturing floor, I saw scores of carts containing work-in-progress (WIP) surrounding their "islands of automation". This BMM practitioner surrendered his chance of qualification on the spot. Other CFM wannabes are more clever. Consider the billion-dollar EMS provider who shows the single production line operating in CFM. Ask to see other production. Why? An EMS provider with an order for one product that consumes the entire capacity of several "islands of automation" will most likely run that batch in line, continuously. Our quite substantial EMS provider cannot demonstrate CFM anywhere else in their operations� I challenge you to review the marketing collateral received from your EMS providers. I�m sure you will note that many of them tout CFM, without actually providing it.

CFM provides many positive benefits to those who employ it and to their customers. Some of those benefits are:

Although it is evident that worker productivity increases in CFM, it can also be argued that worker satisfaction grows, as well. The PULL methodology of CFM shows increased respect for the production worker in two important ways. First, workers typically have only one piece of work before them at any given time, as opposed to the PUSH of BMM that may create a mountain of WIP before workers at production "bottlenecks".

The diagram demonstrates how the assembly operation is supposed to work: get a kit of parts, assemble them, and ship them. Obviously, all of the components must be present for this operation to work.

Without further process control, statistical probability dictates that there is a 98% chance of all the components being there at scheduled production start. In BMM the reality is that at least 75% of the time one or more parts will be missing at production start. So the work actually goes like this:

In the diagram above, steps above the dashed line are the real work. These are the only steps necessary in a CFM model. All the steps below the dashed line are complexity --- work that would not have to be done in CFM. Remember, in CFM, you don�t start until you can finish and you don�t stop until you�re done.

Let�s take the comparison a step further. We�re assembling a printed circuit board with SMT components, automatically inserted PTH components, hand-loaded pre-wave PTH components and a few components that must be individually soldered. Also required is in-circuit test and functional test.

The following diagram demonstrates the complexity of BMM in the EMS assembly process:

Anyone who has ever been a customer of a BMM operation understands the frustration of scheduling multiple production starts. In some cases EMS customers feel the necessity to place their own personnel in BMM shops in order to negotiate production starts and to monitor production progress through the shop. According to our customer surveys, the complexity of BMM creates an average manufacturing cycle time of 4.3 weeks --- with most of the time spent in Delay State (WIP).

Assuming the same assembly process in CFM, we have a single production start:

How simple! Customers negotiate one production start. The CFM shop plans for one production start. Manufacturing cycle time becomes takt time --- the time it takes to actually assemble and test the products. The real work is completed and the complexity is erased.