Tuesday, November 24, 2009

Is green lean? (Last of a III part series)

(Or ... is lean green?)

We have been discussing the connection between lean and green. Lean has as its objectives removing everything and anything from the production process that does not add value (in the eyes of the customer) to the product.

If we recall Ohno's "seven wastes" to be avoided (see http://en.wikipedia.org/wiki/Muda_(Japanese_term)#The_seven_wastes) -

1. Overproduction and early production – producing over customer requirements, producing unnecessary materials / products
2. Waiting – time delays, idle time (time during which value is not added to the product)
3. Transportation – multiple handling, delay in materials handling, unnecessary handling
4. Inventory – holding or purchasing unnecessary raw materials, work in process, and finished goods
5. Motion – actions of people or equipment that do not add value to the product
6. Over-processing – unnecessary steps or work elements / procedures (non added value work)
7. Defective units – production of a part that is scrapped or requires rework

and, to extend the thinking, we can add in some of Deming's 14 points (see http://en.wikipedia.org/wiki/W._Edwards_Deming; and excluding for the moment the ones dealing mostly with management practice, work standards, and barriers). These include the need for constant improvement in production and service and less reliance on inspection as a means to insure quality - all for delivering more value to the customer (or the next downstream link in the supply chain).

Reviewing the list, and realizing that it was developed and promoted before the current concern about the environment and green manufacturing was so commonly of interest, we see many that map directly onto green manufacturing practice. Head of the list is producing more than is needed, or storing/inventorying more than needed, unnecessary transportation, unnecessary work steps or processes - all can be "converted" into wasted resources, energy, and other consumables or the indirect of these wastes (such as floor space and HVAC costs, additional tooling and the manufacture and operation of it, unneeded raw materials and the associated imbedded energy, transport, storage and recycling.)

It was on the basis of Ohno's and Deming's work that lean production was established.

In the last posting we introduced the value stream map (VSM) methodology commonly employed as a tool in lean production analysis. The procedures for VSM are well established and they are beginning to be introduced through a number of good starts in the market.  In this process a very detailed assessment of the present state of a production system is determined by identifying all the process boxes with all the inputs/outputs along with  critical process data for each box (cycle time, changeover time, uptime, production batch sizes, scrap rate etc.) This information would be used to assess the ratio of lead time to value added time (basically summation of productive to non-productive time using the definitions of a few blogs ago) to ascertain the efficiency of operation. This is represented in the figure below.

This information, on a process by process (or stage by stage) basis, can be used to identify points in the process or system for improvement.

There is much more to it but this forms the basis of the idea.

Now, recall the string of boxes used to represent a process in the first of this series on November 11. These were referred to as a "process box" similar to the ones to be analyzed in value stream mapping. For each of these boxes, the VSM analysis determines a number of specifics about the operation - the ones we mentioned above - and represents them with the process as shown in the figure below (except here we've added a box to represent energy, consumable consumption and waste - not usually tracked in conventional VSM.)

With this information (the "big picture of what is happening in the box) we are set for the analysis. But, we also know some important information that allows us to assess the impact of that process. With the motor power consumption on a per unit time basis during processing we can estimate the energy used in the process. And from the energy  (and the local conversion factor between energy and green house gases based on the energy supply, i.e. coal, hydro, solar, etc.) we can estimate green house gas generation.

We also know whether or not other consumables are used (water, lubricants, cutting fluid, cleaning solvents, towels/wipes, etc.) during the process. And, on a piece by piece basis, we know how much waste is generated either during processing or during changeover from one part type to another part type. (Remember, one of the key elements of lean production is balancing the flexibility of a production line with the required minimum lot size to meet "pull" demands of the customer or downstream supply chain - at some point changeover time exceeds the cycle time and we reach a point of diminishing return).

This approach is being proposed by, among others, Future State Solutions, Inc. (see http://futurestatesolutions.com/default.aspx) who have developed an integrated lean and green analysis tool called value stream enterprise management for assessing the "triple bottom line". They have a more detailed description of their approach to the lean and green tool on their site. (And, I will mention that I have no relationship with Future State Solutions but I found their information helpful in understanding the potential linkage between lean and green.)

But we can go deeper in this "lean and green" analysis. Inside the process box, tied to the peculiarities of the process (for example, the individual motions of a machine, or steps in an assembly, or actions of a complex process) there is more gold to be mined. Remember, Ohno and Deming were looking for wasted effort and resources at all levels.

Next time we will be boring deeper into the process box. But, for the moment, the linkage between lean methodology and green and sustainable production analysis is a promising collaboration that will offer valuable insight to process improvement that is both economically and environmentally sound - and would likely make the early proponents of lean production quite pleased.

Wednesday, November 18, 2009

Is green lean? (Part II of a III part series)

(Or ... is lean green?)

In the last posting we started the discussion about lean and green. Lean has for sure been a hot topic for some time and now it is being closely connected to green manufacturing by a number of solution providers and others - usually with good reason.

Oh, and you might notice that I have inserted another part to the series! We need more time on this one so it is now a 3 part series.

We started by looking more closely at a manufacturing system comprised of discrete processes (represented as boxes) assembled into a system (connecting a number of boxes). each process box had certain characteristics of inputs and outputs and was responsible for adding some value to the product moving through the system. It was apparent that some boxes don't "add value" for various reasons but are still included in the process.

This was the preamble to a discussion about using the cycle time as "productively as possible."  In other words - have as little or no waste as possible. Not surprisingly, this is the main objective of green manufacturing. But the definitions for "waste" may be a bit broader than those usually associated with lean manufacturing.

I  referred to a definition of "lean manufacturing" by Wikipedia as a production practice that "considers the expenditure of resources for any goal other than the creation of value for the end customer to be wasteful, and thus a target for elimination." Further to this, we know that there are a number of approaches to "lean."  First approach is nominally the elimination of waste and the tools that assist in uncovering waste in the process and system and getting rid of it. A second approach is more aligned with the Toyota Production System (TPS), which focuses on the the "smoothness" of production and constructing a process with the capability to produce the required results by designing out process inconsistency (or "muri"). This is to be done while trying to maintain as much flexibility as possible since excessive constraints or rigidity often induce waste (as in excessive set up/change over time, high minimum run lot sizes requiring extra inventory or inducing poor response to customer needs, i.e. poor response to "pull.") I listed the seven types of wastes used in TPS in the October 7th posting as part of an initial discussion of TPS.

As an example of the second type of lean manufacturing, Comau recently introduced a "smart assembly" cell focused on the production of high precision complex assemblies as in valve trains for auto engines (for all the details see http://WardsAuto.com/ar/comau_smart_assembly_091109/index.html). Citing the large number of individual machines and process steps used in traditional valve train assembly (some 72 parts in one case at a cycle time of from 25-30 seconds per machine) and several minutes per assembly in total along with a large capital investment), Comau's smart machine replaces the entire line by four operations and a total cycle time of 54 seconds. And, the cell, designed for 325,000 cylinder head annually, requires only 223 sq. meters of floor space compared to 753 sq. meters. And the machine can be reconfigured quickly according to the report.

Although I doubt that Comau was motivated by green manufacturing concerns in its cell design, the cell will have an impact on energy consumption by nature of the reduced number of stand alone processes and, importantly, the tremendous reduction in floor space. (Unless, of course, there is some requirement for "pre-processing" of components to feed into the cell and their accompanying energy and floor space requirements! But, that's why we need to do a careful analysis.)

One of the main tools for the "first type of lean" is the value stream map - charting exactly the material and information flow in the system (and, of course, this can be applied to a wide range of manufacturing and services - it is not restricted to mechanical parts manufacture.) One popular reference on this is the book "Learning to See" by Mike Rother and John Shook (see http://www.amazon.com/Learning-See-Stream-Mapping-Eliminate/dp/0966784308), a practical hands on implementation guide to value stream mapping (VSM). They define a value stream as "all the actions (both value added and non-value added) currently required to bring a product through the main flows essential to every product: (1) the production flow from raw material into the arms of the customer, and (2) the design flow from concept to launch."

Sounds like a promising approach for introducing green manufacturing concepts to the enterprise. It starts with a very careful (and often tedious) assessment of the present state of your production system. This means outlining the process boxes (as illustrated in the last post) with the key interconnections and relationships, and collecting process data for each box. Rother and Shook give examples of this data as: cycle time, changeover time, uptime (on demand machine availability), production batch sizes, number of operators, number of product variations, pack size, working time (minus breaks), and scrap rate.

Many of these characteristics have green implications (meaning they are predictors of energy or resource consumption - like cycle time which can help define process energy. Or scrap rate which is an indication of efficiency of conversion of resources into product.

The procedures for VSM are well established. The use of VSM on green manufacturing analyses is not so well defined, although there are a number of good starts on the market. The best approach is to use the concepts of VSM and lean to compliment the development and operation of efficient manufacturing operations with the requirements of reduced energy and resource utilization - leading towards green and sustainable manufacturing. This will not always be a slam dunk analysis. There will be many aspects of lean (which requires or encourages exceptional levels of process flexibility) which will conflict directly with aspects of green. We can define some of these tradeoffs. Ultimately, the specifics will determine which wins out. But, importantly, this is an attempt to make the analysis more inclusive and systematic.

What we'll cover next time is a brief review of some of the approaches of "using lean to get green" as well as areas that may not be well covered by extending lean concepts to greening manufacturing. And these are usually related to the level of detail needed for tradeoff analysis and process design.

Stay tuned for part 3!

Thursday, November 12, 2009

Is green lean? (Part I of a III part series)

And ... is lean green?

Last time the topic was "stylish longevity" and  the role of style in people's choices for purchase and use of products. I introduced a scale of manufactured goods with function (over style or form) on one end and style (over function) on the other end. The concern was how to encourage longevity of a product (from auto to machine tool) for products that might be rendered obsolete by changes in style. In the middle of the scale I had listed a category  of "function and style".

Today in my graduate class on sustainable manufacturing I  had a guest lecture from someone working at "methodhome", a home care and personal care products company that makes and sells environmentally-friendly cleaning products that really are. And they are safe to use in the home and on yourself (see http://www.methodhome.com/). I think I found another example of a product that is both stylish and functional (I had referred to my MacBook in the blog last time as one example). In fact, according to Drummond Lawson, the speaker in my class, the company found a real niche in the market for these types of cleaning products that can compliment the home environment, and make people feel good and/or associate with the product, as a user. Take a look at their bathroom cleaning products to see what I mean. This is a great strategy ... and addresses the tension between style and function. Now, we need to get this kind of innovation into manufacturing (but more on that in weeks to come!)

Now ... back to the topic of today.

We will focus on lean and green for the next three blogs (this one and next two weeks). And, just in case you don't have a lot of time - the short answer is pretty much "yes" to the first question! But there are conditions and tradeoffs to consider when answering the second question.

First, some more background on manufacturing - specially close to the factory floor with the individual processes of production. You may recall the posting of July 27th (part of the "why green manufacturing" series) that spoke about the next great leap forward. This was not the next "five year plan" from some central government office but the movement to sustainable (or at least green) production. The argument was that this will follow the prior big leaps that accompanied the introduction of the assemble line, flexible production and the Toyota Production System or lean manufacturing.

Each of these changes or leaps occurred because of a realization that an improved system of manufacturing could be attained if the system was “designed and optimized” based on an understanding of some new criteria.  And, they all had a monetary value that could be assigned so that the required "cost-benefit" analysis could be done.

The discussion here is on how lean manufacturing lays the groundwork (or one might say offers a convenient platform or structure for) green manufacturing.

But first we need to define some of the terms and details about how the shop floor works. Let's start with a simple representation of a manufacturing line comprised of individual processes. We'll connect the process boxes to make a system.

First, we'll define a process (see the figure below).

This represents all the elements of a production process (such as a machine tool, or assembly robot, injection molding press, punch or forging press, cookie dough mixer, etc.) and includes:

- Process energy
- Machine/process “tare” energy
- Process chemicals
- Other process consumables
- Machine/process operation consumables
- Machine/process operation environment
- Operator consumables
- Operator operation environment

Not included in the box are the other "expenses" associated with utilization of the process, like
- Building
- Process input supply (water, compressed air, etc) infrastructure,
- Process output exhaust infrastructure

You can probably think of a few more.

Typical manufacturing involves a sequence of individual steps, machines, processes all with, often, distinct input and output requirements. We can illustrate this as in the figure below comprised of a string of the process boxes introduced above with inputs and outputs but, in this case, connected to the up-stream and down-stream processes.

This system of interconnected processes usually operates in either a synchronous or asynchronous fashion (meaning, all the parts advance from process to process at the same time in sync or they can advance to the next process when an individual process is complete, respectively). In the case of asynchronous production there is usually some requirement for a buffer or inventory storage/accumulator between stages to accommodate the different cycle times from process to process.

Between these processes there is some transport mechanism for moving the evolving part along.

Each process step takes time. The transport takes time. The accumulated process step times and transport times from the input to the system to the output of the system constitutes the production time (the inverse of which is the cycle time) and defines throughput, lead time, work in process, etc.

Of the time spent in production, there is productive time and non-productive time or, as I like to call it, value added time and non-value added time. If the resources being used are going to increasing the value of the component being processed in each "box" then we might call this productive time. This would be shape changes, added components, painting or coating, etc. If the resources are not adding value (for the customer) then this is non-productive time. This could include transport from process to process, tooling setup time, inspection, time spent in buffer storage, etc. They all add up to comprise the cycle time but don't all add to the product's value as it moves through the system.

The cycle time should be used as "productively as possible." That is the objective of manufacturing engineers. Our capacity in the manufacturing line should be used as completely as possible, be sufficient to handle our production requirements (throughput and batch or lot size). That is - as little or no waste as possible.

Now we get to the lean part! Lean is defined (see Wikipedia for starters, http://en.wikipedia.org/wiki/Lean_manufacturing) as a production practice that "considers the expenditure of resources for any goal other than the creation of value for the end customer to be wasteful, and thus a target for elimination."

There is a lot of information available on lean manufacturing and I don't intend to offer a detailed review here. Suffice it to say that "waste reduction thinking", on which the principles of lean production are built, goes back some distance (recall earlier blog references to Henry Ford in his factories and my father after the depression). Since this aligns itself extremely well with  green manufacturing objectives there should be, and I believe is, a natural linkage here.

That is, the practice of lean manufacturing or lean production, if properly applied at a sufficiently detailed level with necessary additional information and data available is to me, inherently, green manufacturing.

And it is to a number of others as well as we shall see next time.

Stay tuned for part 2!

Wednesday, November 4, 2009

Stylish longevity

I've had a lot of discussion recently with a number of people about green manufacturing and what can actually be done given the complexity of most manufacturing, the constant push to reduce costs and, importantly, the constant urge to "upgrade" products to the latest features and functions. One question that comes up is "how can we ever make product lifetimes long enough to amortize the embedded energy, materials, resources and their impacts to realize any gain?"

We'll cover some ideas about this below.

In the meantime ... I remind anyone who will listen that it is better to be aware of "the way the wind is blowing" (as we used to say when I was in college) than to ignore the trends.

I Illustrated this need to be aware in a presentation recently to a manufacturing conference in Orlando. I called it  the "Everett and Jones" philosophy.  There is a great bar-b-que place in Berkeley of the same name and, in addition to serving up fantastic ribs and a killer sauce, they have signs and bumper stickers posted behind the cash register.

One sign in particular sums it up well to me (and apologies in advance if you were in Orlando and heard this!).  It says

"There are three types of people in the world-

- those that make things happen,
- those that watch things happen, and
- those that say 'what happened?'"!

I tell my students that, at least, we should try to be in the first two categories. We've seen enough, and recently, that proves the last category doesn't work very well.

In the spirit to "making things happen" let's get back to longevity. One of the tenets of sustainable manufacturing is that more durable, longer lifetime products are more sustainable. And, if they are designed to be returned to productive use with the least amount of recycling or remanufacturing this seals the deal. Recall the Comet Circle from Ricoh and the loops closest to the consumer (see the Sept. 21st posting).

This is a challenging problem for many products. We can think about manufactured goods distributed along a scale of characteristics with "function" on one end and "style" on the other. Most products are sold based on a balance between function and style in the eyes of the consumer (whether that is a teenager ogling the latest MP3 player or a family considering a vehicle). Things that tend to be heavy on the style also tend to have short lifecycles (with some exceptions of course - see Louis Vuitton luggage for example).

In fact, the scale is really more like (from left to right) function ----- function/style ------ style.  There is a gradual transition along the scale from totally functional products with little "style" (a large metal forging press, for example) through those that have a balance (like the Mac laptop I am using to write this) to those for which style is everything (I don't know first hand but I'd guess a good example of this is women's shoes - see Jimmy Choo!).

Where our products lie along this scale informs us about ease of  "extending the  lifetime" of the product since it helps define the pressure to replace the product even if the embedded technology is sufficient for our needs (think of how often you need to upgrade software to give you some added bells and whistles that you will seldom, if ever, use - point made!).

So how do we approach this? We can first try to define where our products (or processes) fit along this scale. Most manufacturing machinery and processes fall near the "function" end of the scale. Meaning, if the function is appropriate for our processing needs the "style" of the machine is not so important. This also suggests, for most manufacturing, functional  upgrades can often be made, or should be made, without requiring major redesign of the machine itself - upgrade the controller on a numerically controlled machine tool, for example. Or perhaps a higher speed spindle on the machine.

There are limits of course. If a new technology for axis motion and control based on a linear motor is introduced for faster, more accurate machine tool motion and positioning then it may not be so simple. But, the machine could be designed to allow such upgrades. This would substantially extend the life of the machine and offer the machine tool builder a chance to keep supplying new technology to the market - just not always wrapped in a brand new machine.

This is being done already with some products, copier machines, for example, or large office printers. Without meaning to disparage anyone's products, I think it is fair to say that no one really buys a copy machine because of the way it looks. But we do expect a certain level of functionality and performance. And components of these machines are designed to be upgraded and swapped as new "engines" for the copier become available. Of course, for this business model, the copier company is leasing you the machine in most cases.

This is another business model for sustainable manufacturing, and includes the concept of extended producer responsibility, that we'll discuss in the future.

What about the middle and right end of the scale where the style is important to the consumer. That is a bit tougher. Trying to sell an automobile to a consumer that lasts a lifetime but can be "upgraded" with newer engines, drive train, brakes, or battery storage may be a bit more challenging.  The idea of upgrading a cell phone as technology advances (these, along with flat screen televisions have about a 6 month life time before new products are introduced) is provocative but hard to envision. Just recycling them has proven a challenge.

Or is it that hard? If you look at the evolution of styles of some of the commercially available hybrid vehicles over the past few years one might say, again not meaning to disparage anyone's products, that "style wise" there has been little change in appearance (body shape, interior layout, etc.) while performance wise there have been many improvements. So, perhaps, for "basic products" that we purchase with more function in mind - machine tools to hybrid vehicles - we may be closer than we think.

And, there is always Louis Vuitton or Tesla Motors (or Jimmy Choo!) for those who are more on the style end of the scale!

Oh, one last thing. Everett and Jones is on the corner of University and San Pablo in Berkeley if you are ever in that part of the Bay area. And, make sure to read the wall!