Ch00fm-pgs-Martichenko/Goldsby
tải về 2.84 Mb. Chế độ xem pdf
|
- Điều hướng trang này:
- Six Sigma and the Logistician
| WHAT IS SIX SIGMA?
Six Sigma is a management methodology that attempts to understand and eliminate the negative effects of variation in our processes. Based on an in- frastructure of trained professionals (black belts), Six Sigma delivers a prob- lem-solving model armed with “voice of the customer” utilities and statistical process control tools. Define-Measure-Analyze-Improve-Control (DMAIC) is a map, or step-by-step approach, to understand and improve on organizational challenges (see Chapter 21). Six Sigma–trained employees will work on “projects” using the DMAIC model to reduce variation in processes and to attempt to achieve “Six Sigma quality,” a statistical reference to 3.4 defects per million opportunities. At the heart of Six Sigma is the principle of variation reduction: If we can understand and reduce variation in our processes, then we can implement improvement initiatives that will center the process and ensure accuracy and reliability of the process around customer expectations. For example, an average order-to-delivery cycle time of five days may reflect a variation between two and eight days. It is this variation that leads to customer nonconfidence and the resultant inventory buildup and/or loss of sales. Six Sigma and the Logistician The concept of variation reduction is paramount to the logistician. As stated above, logistics is about managing inventory, and managing inventory is about managing variance.* If we look at the different types of inventory, we will plainly see why variation plays such a vital role in how we manage inventories throughout the business and the supply chain. For example, safety or “buffer” stocks are inventories that we need to hedge against unknowns (i.e., the variations from the norm). That is, we maintain safety stocks because of variation in supplier quality, transportation reliability, manufacturing process capability, and customer demand patterns. In other words, if we can understand and control variation in our processes from supplier to * We use the following terms interchangeably throughout the book: variation, variance, and variability. 6 Lean Six Sigma Logistics customer, then we will be able to reduce our reliance on the buffers dramati- cally. In this regard, logisticians need to think of themselves as actuaries, like those who develop rates for automobile insurance. Actuaries look at key vari- ables — the age of drivers, gender of the drivers, types of vehicle driven, measures of past behavior (e.g., speeding tickets and accidents) — and then they determine insurance rates that reflect the variability in the data. This is precisely why the sixteen-year-old male who drives a sports car will have the highest insurance rates! Logisticians are no different than the actuaries in this analogy. For demo- graphics and sports cars, the logistician substitutes supplier competence, trans- portation reliability, and demand fluctuation. Then the logistician determines the “insurance rate,” using inventory as the unit of currency. The problem here, though, is that too many logisticians are treating their companies like teenage drivers when, in fact, the company performance is more like a middle-aged soccer parent who drives a minivan. A down-to-earth example of this is when a manufacturer has leveled demand from a supplier who is an hour down the road from the plant, yet the manufacturer continues to carry twelve days worth of that supplier’s parts in inventory! Why? Most likely the answer is twofold. The first reason is that the leveled flow (and therefore low variability of de- mand) is not understood; the second reason is more emotional. The emotional tải về 2.84 Mb. Chia sẻ với bạn bè của bạn:
|