This section discusses three different approaches to managing and improving business processes—Lean Production, the Theory of Constraints (TOC), and Six Sigma. Although each is unique in certain respects, they all share the common theme of focusing on managing and improving business processes.

Lean Production

Traditionally, managers in manufacturing companies have sought to maximize production so as to spread the costs of investments in equipment and other assets over as many units as possible. In addition, managers have traditionally felt that an important part of their jobs was to keep everyone busy on the theory that idleness wastes money. These traditional views, often aided and abetted by traditional management accounting practices, resulted in a number of practices that have come under criticism in recent years.

In a traditional manufacturing company, work is pushed through the system in order to produce as much as possible and to keep everyone busy—even if products cannot be immediately sold. This almost inevitably results in large inventories of raw materials, work in process, and finished goods. Raw materialsMaterials that are used to make a product. are the materials that are used to make a product. Work in processUnits of product that are only partially complete and will require further work before they are ready for sale to a customer. inventories consist of units of product that are only partially complete and will require further work before they are ready for sale to a customer. Finished goodsUnits of product that have been completed but have not yet been sold to customers. inventories consist of units of product that have been completed but have not yet been sold to customers.

The push process in traditional manufacturing starts by accumulating large amounts of raw material inventories from suppliers so that operations can proceed smoothly even if unanticipated disruptions occur. Next, enough materials are released to workstations to keep everyone busy. When a workstation completes its tasks, the partially completed goods (i.e., work in process) are “pushed” forward to the next workstation regardless of whether that workstation is ready to receive them. The result is that partially completed goods stack up, waiting for the next workstation to become available. They may not be completed for days, weeks, or even months. Additionally, when the units are finally completed, customers may or may not want them. If finished goods are produced faster than the market will absorb, the result is bloated finished goods inventories.

Although some may argue that maintaining large amounts of inventory has its benefits, it clearly has its costs. According to experts, in addition to tying up money, maintaining inventories encourages inefficient and sloppy work, results in too many defects, and dramatically increases the amount of time required to complete a product. For example, when partially completed goods are stored for long periods of time before being processed by the next workstation, defects introduced by the preceding workstation go unnoticed. If a machine is out of calibration or incorrect procedures are being followed, many defective units will be produced before the problem is discovered. And when the defects are finally discovered, it may be very difficult to track down the source of the problem. In addition, units may be obsolete or out of fashion by the time they are finally completed.

Large inventories of partially completed goods create many other problems that are best discussed in more advanced courses. These problems are not obvious—if they were, companies would have long ago reduced their inventories. Managers at Toyota are credited with the insight that large inventories often create many more problems than they solve. Toyota pioneered what is known today as Lean Production.

The Lean Thinking Model   The lean thinking modelA five-step management approach that organizes resources around the flow of business processes and that pulls units through these processes in response to customer orders. is a five-step management approach that organizes resources such as people and machines around the flow of business processes and that pulls units through these processes in response to customer orders. The result is lower inventories, fewer defects, less wasted effort, and quicker customer response times. Exhibit 1-6 (page 14) depicts the five stages of the lean thinking model.

The first step is to identify the value to customers in specific products and services. The second step is to identify the business process that delivers this value to customers.⁵ As discussed earlier, the linked set of steps comprising a business process typically span the departmental boundaries that are specified in an organization chart. The third step is to organize work arrangements around the flow of the business process. This is often accomplished by creating what is known as a manufacturing cell. The cellular approach takes employees and equipment from departments that were previously separated from one another and places them side-by-side in a work space called a cell. The equipment within the cell is aligned in a sequential manner that follows the steps of the business process. Each employee is trained to perform all the steps within his or her own manufacturing cell.

The fourth step in the lean thinking model is to create a pull system where production is not initiated until a customer has ordered a product. Inventories are reduced to a minimum by purchasing raw materials and producing units only as needed to meet customer demand. Under ideal conditions, a company operating a pull system would purchase only enough materials each day to meet that day's needs. Moreover, the company would have no goods still in process at the end of the day, and all goods completed during the day would be shipped immediately to customers. As this sequence suggests, work takes place “just-in-time” in the sense that raw materials are received by each manufacturing cell just in time to go into production, manufactured parts are completed just in time to be assembled into products, and products are completed just in time to be shipped to customers. Not surprisingly, this facet of the lean thinking model is often called just-in-timeA production and inventory control system in which materials are purchased and units are produced only as needed to meet actual customer demand. production, or JIT for short.

The change from push to pull production is more profound than it may appear. Among other things, producing only in response to a customer order means that workers will be idle whenever demand falls below the company's production capacity. This can be an extremely difficult cultural change for an organization. It challenges the core beliefs of many managers and raises anxieties in workers who have become accustomed to being kept busy all of the time.

The fifth step of the lean thinking model is to continuously pursue perfection in the business process. In a traditional company, parts and materials are inspected for defects when they are received from suppliers, and assembled units are inspected as they progress along the production line. In a Lean Production system, the company's suppliers are responsible for the quality of incoming parts and materials. And instead of using quality inspectors, the company's production workers are directly responsible for spotting defective units. A worker who discovers a defect immediately stops the flow of production. Supervisors and other workers go to the cell to determine the cause of the problem and correct it before any further defective units are produced. This procedure ensures that problems are quickly identified and corrected.

The lean thinking model can also be used to improve the business processes that link companies together. The term supply chain managementA management approach that coordinates business processes across companies to better serve end consumers. is commonly used to refer to the coordination of business processes across companies to better serve end consumers. For example Procter & Gamble and Costco coordinate their business processes to ensure that Procter & Gamble's products, such as Bounty, Tide, and Crest, are on Costco's shelves when customers want them. Both Procter & Gamble and Costco realize that their mutual success depends on working together to ensure Procter & Gamble's products are available to Costco's customers.

The Theory of Constraints (TOC)

The Theory of Constraints (TOC)A management approach that emphasizes the importance of managing constraints. is based on the insight that effectively managing the constraint is a key to success. As an example, long waiting periods for surgery are a chronic problem in the National Health Service (NHS), the government-funded provider of health care in the United Kingdom. The diagram in Exhibit 1-7 illustrates a simplified version of the steps followed by a surgery patient. The number of patients who can be processed through each step in a day is indicated in the exhibit. For example, appointments for outpatient visits can be made for as many as 100 referrals from general practitioners in a day.

The constraint, or bottleneck, in the system is determined by the step that has the smallest capacity—in this case surgery. The total number of patients processed through the entire system cannot exceed 15 per day—the maximum number of patients who can be treated in surgery. No matter how hard managers, doctors, and nurses try to improve the processing rate elsewhere in the system, they will never succeed in driving down wait lists until the capacity of surgery is increased. In fact, improvements elsewhere in the system—particularly before the constraint—are likely to result in even longer waiting times and more frustrated patients and health care providers. Thus, to be effective, improvement efforts must be focused on the constraint. A business process, such as the process for serving surgery patients, is like a chain. If you want to increase the strength of a chain, what is the most effective way to do this? Should you concentrate your efforts on strengthening the strongest link, all the links, or the weakest link? Clearly, focusing your effort on the weakest link will bring the biggest benefit.

The procedure to follow to strengthen the chain is clear. First, identify the weakest link, which is the constraint. In the case of the NHS, the constraint is surgery. Second, do not place a greater strain on the system than the weakest link can handle—if you do, the chain will break. In the case of the NHS, more referrals than surgery can accommodate lead to unacceptably long waiting lists. Third, concentrate improvement efforts on strengthening the weakest link. In the case of the NHS, this means finding ways to increase the number of surgeries that can be performed in a day. Fourth, if the improvement efforts are successful, eventually the weakest link will improve to the point where it is no longer the weakest link. At that point, the new weakest link (i.e., the new constraint) must be identified, and improvement efforts must be shifted over to that link. This simple sequential process provides a powerful strategy for optimizing business processes.

Six Sigma

Six SigmaA method that relies on customer feedback and objective data gathering and analysis techniques to drive process improvement. is a process improvement method that relies on customer feedback and fact-based data gathering and analysis techniques to drive process improvement. Motorola and General Electric are closely identified with the emergence of the Six Sigma movement. Technically, the term Six Sigma refers to a process that generates no more than 3.4 defects per million opportunities. Because this rate of defects is so low, Six Sigma is sometimes associated with the term zero defects.

The most common framework used to guide Six Sigma process improvement efforts is known as DMAIC (pronounced: du-may-ik), which stands for Define, Measure, Analyze, Improve, and Control. As summarized in Exhibit 1-8, the Define stage of the process focuses on defining the scope and purpose of the project, the flow of the current process, and the customer's requirements. The Measure stage is used to gather baseline performance data concerning the existing process and to narrow the scope of the project to the most important problems. The Analyze stage focuses on identifying the root causes of the problems that were identified during the Measure stage. The Analyze stage often reveals that the process includes many activities that do not add value to the product or service. Activities that customers are not willing to pay for because they add no value are known as non-value-added activitiesActivities that consume resources but do not add value for which customers are willing to pay. and such activities should be eliminated wherever possible. During the Improve stage potential solutions are developed, evaluated, and implemented to eliminate non-value-added activities and any other problems uncovered in the Analyze stage. Finally, the objective in the Control stage is to ensure that the problems remain fixed and that the new methods are improved over time.⁶

Managers must be very careful when attempting to translate Six Sigma improvements into financial benefits. There are only two ways to increase profits—decrease costs or increase sales. Cutting costs may seem easy—lay off workers who are no longer needed because of improvements such as eliminating non-value-added activities. However, if this approach is taken, employees quickly get the message that process improvements lead to job losses and they will understandably resist further improvement efforts. If improvement is to continue, employees must be convinced that the end result of improvement will be more secure rather than less secure jobs. This can only happen if management uses tools such as Six Sigma to generate more business rather than to cut the workforce.

⁵ The Lean Production literature uses the term value stream rather than business process.

⁶ Peter C. Brewer, “Six Sigma Helps a Company Create a Culture of Accountability,” Journal of Organizational Excellence, Summer 2004, pp. 45–59.