Assuming that these examples have convinced you that adopting lean is a good idea for those of us in the process industries, let us stop for just a minute and explore what is meant by “process industries” and why these industries need their special version of lean manufacturing.
Significant structural differences between the process industries and mechanical manufacturing substantially affect our ability to adopt lean practices in precisely the same way as our colleagues have done in mechanical manufacturing. It is valuable to understand these differences as we begin the discussion. There are three critical distinctions between process manufacturing and mechanical manufacturing:
1. In process manufacturing, the raw material experiences a transfor- mational change as it becomes a product as opposed to a reconfigu- rational change.
2. In process manufacturing, the manner of transforming raw materi- als into products is often indirect as opposed to the direct changes that occur in mechanical manufacturing.
3. In process manufacturing, the transformation of raw material is fre- quently dependent on time, but mechanical manufacturing is inde- pendent of time.
In the nature of process industry operations, each of these distinctions makes a very real difference in the way that we need to apply the theories and tools of lean practice in our plants when compared with mechanical manufacturing. I will discuss briefly here the differences from mechanical manufacturing, and then, throughout the book, I will describe the chal- lenges and benefits they offer for the adoption of lean in a liquid process.
transforming the raw material
The first distinction between mechanical manufacturing and process man- ufacturing is the way in which the raw material is changed as it proceeds through manufacturing. In mechanical manufacturing, the raw mate- rial is “reconfigured” but the material itself remains inherently the same. For example, when an engine block has holes drilled into the casting, the casting is reshaped, but the material itself is essentially unchanged. The same is true when copper tubing is drawn to size, when a chocolate bar is wrapped, or when a lawn mower is assembled. The raw material is recon- figured to become a finished product, but the material always remains the same material throughout the manufacturing activity.
In process manufacturing, the raw material undergoes an inherent “transformation” during manufacturing when it becomes an identifiably different material as a finished product. This is a very different manufac- turing outcome, achieved by a very different approach to manufacturing. Those differences necessitate a notably different practice of the lean theory and tools. The following examples illustrate how this concept of material transformation applies in different parts of the process industries:
Metallurgy:
• In metallurgical processing, heat-treating a block of steel will transform the crystalline structure of the metal so that it is either harder or softer or has less internal stress than the original block. Foods:
• In baking, a high-density liquid (cake batter) is transformed into a low-density solid (cake).
Reactive chemistry:
• In a polymer plant, individual molecules of mon-
omolecular gas (e.g., ethylene) combine to form a macromolecular solid (e.g., polyethylene). Alternatively, in a steel plant, coal, iron, and other chemicals combine to create a wholly new material.
Separation chemistry:
• In a petroleum refinery, a liquid stream com-
prising thoroughly commingled molecules of many different mate- rials is transformed into several streams, each with a relatively pure
composition of a single type of molecule. The chemical properties of the several new streams are individually very different from the properties of the original commingled stream.
Thus, although process manufacturing is normally associated with liq- uids or gasses, the differences between mechanical manufacturing and process manufacturing are more fundamental than just the initial state of the material. In fact, heat-treating a block of steel is an example of process manufacturing, and filling quart bottles with motor oil is an example of mechanical manufacturing.
The difference in the nature of the changes undergone by the material in process manufacturing leads directly to important differences in the manufacturing activities that produce those changes, which leads to dif- ferences in the way that we practice lean.
The first manifestation of this difference in lean practice is that mechani- cal manufacturers can rely on materials that are generally stable throughout manufacturing and therefore materials that are tolerant of interruptions to the manufacturing activity, but process manufacturers cannot. Thus, for example, the lean practice of andon5 or line stop practiced by frontline operators for quality improvement that is of great value to mechanical manufacturers cannot be used at all in most process manufacturing. In process manufacturing, when people stop chemical changes after they have been initiated, the product normally becomes worse—not better. The first distinction between process and mechanical manufacturing is the nature of the changes that occur as a raw material becomes a finished product.
Indirect material transformations
It follows that the second distinction between process manufacturing and mechanical manufacturing is the manner in which those changes occur. In mechanical manufacturing, the changes that occur in the raw material as it becomes a finished product are uniformly achieved quite directly by touching the raw material either personally, as in an assembly process, or mechanically, by using some sort of device such as a cutting tool or a wrapping machine.
By contrast, in process manufacturing, the raw material is normally touched only in order to contain it for processing or in order to create an environment within which the chemical transformation will occur. In many process industries, such as petroleum refining, the material of
production is so thoroughly contained that, in normal operation, the pro- cess operators never see the raw material, the work in progress, or even the finished product. In process manufacturing, the material literally changes itself once the proper conditions for the reaction have been established.
This distinction in the methods of manufacturing leads us to under- stand that mechanical manufacturers are relatively labor intensive and process manufacturers are relatively capital intensive. As a result, process manufacturers must focus much more on the equipment side of lean than on the labor side of lean. This change in focus has both advantages and disadvantages in our lean practice.
time as an Independent element of Production
The final important difference between mechanical manufacturing and process manufacturing is that two elements of time, often described as “residence time” and “persistence,” are necessary and independent ele- ments of process manufacturing.
In mechanical manufacturing, the changes caused by touching the material are generally both instantaneous and permanent. For example, when the drill touches the engine block, the reconfiguration of that engine instantaneously begins. Further, any physical change that occurs in mechanical manufacturing is permanent. Consequently, it is easily pos- sible to start and stop most mechanical manufacturing at any time or to vary the speed of manufacturing with few or no consequences. It is pos- sible to drill half a hole today and finish it in the morning with no degra- dation in the quality of the hole or in the quality of the resulting engine. Equally, it is possible to assemble a lawn mower partially now and finish it next year and the resulting lawn mower will be no different in any way. Time is required to do the work in mechanical manufacturing, but time is not generally an independent factor in the success of the process.
In process manufacturing, the situation is quite different. Although some chemical reactions do occur at extremely high speed, all reactive transformations of material require a measurable amount of time—that is, “residence time”—for the chemical transformation to proceed from initiation to completion. Of equal importance, chemical reactions do not commence instantly and, once initiated, do not stop instantly. This char- acteristic is generally described as “persistence.”
Residence time and persistence are important to us because many reactive processes only produce the intended product when the proper conditions
for the transformation exist in a consistent and uninterrupted way for the entire period of the transformation. Starting, stopping, or otherwise alter- ing the conditions of the reaction while it is in progress will not simply start or stop the reaction, they will noticeably alter the outcome and it is unlikely that the resulting product will be the one originally intended. When process operations are disrupted, something will happen, and it is almost certainly something that is not good. As a result of these time constraints, process manufacturers are often inherently less flexible than mechanical manu- facturers. Therefore, they have both a greater need for and potentially can derive a greater benefit from the lean practices that enhance flexibility.
case study: a simple example in Process manufacturing
Baking a cake is a visible and commonly observed example of process manu- facturing and provides a good example of the impact of these differences.
The high-density liquid raw materials of a cake are fundamentally •
different from the low-density solid finished product. There is no pos- sibility that the baker can produce a cake by simply assembling the materials or by any direct form of labor. This process is transforma- tional rather than reconfigurational.
A cake results only when the raw materials are placed into an oven •
under the proper conditions for the appropriate period. Even the fin- est baker cannot produce a cake without an oven. This is a cap- ital-intensive activity where the manufacturing outcome is largely dependent upon the equipment.
When you first put the batter into the oven, it appears that nothing is •
happening. That observation is essentially correct. If you remove batter from the oven before the reaction temperature is reached, nothing per- manent will have happened. There has not yet been even a partial trans- formation of batter into cake. The batter is demonstrating persistence. Now consider what happens if you only partially bake a cake or •
attempt to start a cake one day and finish it the next or in any other way disrupt the normal time of manufacturing. Substantially inter- rupting the transformation from batter into cake once the process has begun will always result in a permanently damaged and often completely useless final product. The transformation requires unin- terrupted residence time appropriate to the desired reaction.
Each of these issues represents an important distinction between pro- cess manufacturing and mechanical manufacturing and each has a
substantial impact on the way that lean is practiced in the chemical and process industries.
special case: continuous Processing
Continuous chemical processes share all of the characteristics of the process industry generally and add the complicating factor of continuity because fresh raw material is constantly being introduced to the environ- ment of transformation and material that has completed its transformation is constantly being withdrawn. The entire continuum of the transforma- tion from raw material to finished product is continuously in progress within the same process.
case study: continuous Processing
At Suncor, we extract bitumen from Canada’s Athabasca oil sands and upgrade it into synthetic crude oil (SCO). The process for extracting the bitumen from the oil sand was first demonstrated more than 100 years ago. At that time, oil sand was placed in a pot of boiling water and, after some time had passed, the sand and oil separated. The oil floated to the top and the sand sank to the bottom. Although that simple batch-type process demonstrated that the separation was possible, it did not make it commer- cially viable. Remember that in order to be commercially viable the full combination of mining the sand, extracting the bitumen, and upgrading it to SCO—all under near-Arctic conditions—has to compete economically with the folks in the Middle East who simply put a hole in the ground and pump out oil.
Today’s commercially viable oil sand plants each produce hundreds of thousands of barrels of SCO each day using continuous methods. In the continuous process mode, oil sand and hot water continuously enter the reaction vessel. Bitumen continuously floats to the top and flows over a weir to exit the separation cell. Clean sand and water continuously flow out the bottom. It is a great process and one that has enabled Canada to become one of the world’s leading energy producers.
However, the continuous process is not without its unique difficulties. For example, if the sand and water slurry stops flowing or even if the flow rate slows below a critical velocity, the sand will fall out of suspension. At that point, instead of a pipeline of flowing slurry, we have a pipeline full of sand that will not flow again until it is taken apart and cleaned. Most continuous processes share this characteristic. They can enable a com- mercially viable business that would not otherwise be possible, but they are often surprisingly fragile when the continuity is disrupted. Therefore, as
we consider the practice of lean manufacturing in the process industries, we will need also to consider the special circumstances of continuous process operations.
Lean is appropriate to process industries and can be applied very success- fully. It is a great technology—one that I have deployed successfully for nearly three decades in discrete manufacturing and in process manufac- turing. In combination with some other tools of improvement—a great strategy and an industrial culture that supports an engaged workforce— lean will allow you to achieve performance that your competition simply cannot match.
notes
1. American Productivity and Quality Center.
2. I use the term “small event” improvement to distinguish the actions of engaged indi- viduals and teams at the frontline from the “big event” actions typical of engineers and managers. That distinction in no way implies that the improvements resulting from the actions of these workers are small. In fact, taken together, the business impact of many small event improvements is rarely small.
3. Donald Powell, senior vice president, Gilbarco (retired).
4. In my first book, A Culture of Rapid Improvement: Creating and Sustaining an
Engaged Workforce (CRC Press, 2008), I discussed both business strategy and
employee engagement in the rich detail that can be achieved only by devoting an entire book to the topic. Both of these concepts—strategy and engagement—are vitally important elements of business success as companions to lean practice. They are discussed in this book as part of the cultural enablers of lean, but there is much more information available in my first book that can be of great value to you as you adopt these capabilities in your business.
5. Andon is a Japanese term that refers to the warning signals on an assembly line when a defect occurs.