Green Balancing

Knowledge is useful. This may not sound surprising coming from an academic. Or, if not knowledge, then at least start with data.  As we have been discussing in the last few postings, data and knowledge are critical to decision making on the shop floor. The more information you have the easier it is to understand what is going on and what you should do next. And, this simple statement lays out the basic strategy to green manufacturing - at any level.

The webinar just held on December 14th (see Future State Solutions website http://futurestatesolutions.com/ for archived material) covered some of the tradeoffs between lean strategies of reducing cost, lead time and waste and natural resource and energy use and carbon emissions while at the same time insuring that process capability is maintained (and product quality insured) as well as safety and profit margins. We also spoke about the need to include all the Scope 1 through 3 effects to insure that a full picture of your process or product impact is reflected in your analysis and decision making. For a refresher on that see August 25th posting - http://green-manufacturing.blogspot.com/2009_08_01_archive.html which discusses the three scopes of ISO 14064 (1- direct emissions from on-site/company owned assets, 2- indirect emissions  from energy generation or supply, 3- all others resulting from your business operation including business travel, shipping of goods, resource extraction and product disposal).

So - the data requirements can be over a broad range of your operations.

At a deeper level, reflecting our discussions in the last two postings, with data we can look at optimization of performance. Here we discuss this from the perspective of "balancing" resource use. I would like to go into two examples: balancing the operation of multiple machines in a production line and multi capability vs single use machines. In the December 9th posting I went into some detail about the operational peculiarities of a machine tool for illustrating how variations in process parameters could affect energy and resource consumption. The previous posting, December 3rd, defines some of the "in the box" inputs in a process, like a machine tool.

Being good engineers, we often try to coordinate (or synchronize) the actions in a production system so that all processes are operating at the same time completing their tasks. At the end of the cycle time the product, in whatever state of completion along the line is, is advanced to the next station for the next operation. Except for the bottleneck station (the one which, due to complexity or number of operations on the station, uses all the cycle time) there is usually some idle time at each station. Lean techniques try to eliminate this as much as possible but, usually, some still exists.

One solution is to adjust the start/stop time of each process at a station so that, when the line is humming along, all the process steps do not exactly occur at the same time. When all synchronized the energy usage of the line will be at a maximum. If they are staggered a bit, but not so much as to lengthen cycle time, decrease throughput or affect quality, we might be able to shave a bit off the "peak power consumption" of the line. The illustration below shows how this might work (and you might need to click on the illustration for a larger view).

This can have a significant impact on the line and, if applied to other aspects of the factory operations, the overall factory energy use. And it is free. But, you need to be able to see the energy variation within the process cycle so that you know how to stagger the process start/stops.

Another strategy, not so much balancing as compounding, is to look at the potential for multi-function machines. You might recall the discussion in the November 18th posting (http://green-manufacturing.blogspot.com/2009/11/is-green-lean-part-ii-of-iii-part.html) on "smart assembly" and the new multipurpose machine introduced for automotive production. The vendors of this smart machine touted a smaller footprint and faster changeover to each product variation (lean!). This strategy also can save energy and embedded resources (green!). There are a number of machinery builders who are introducing multipurpose machines...specially for machining processes.

If one takes a hypothetical production system with a number of separate conventional machine tools - say for drilling, turning, horizontal and vertical milling applications - and replaces them with one machine that is able to do all these processes, in one set up, with cycle time reductions thanks to reduced part handling, fixturing, etc., it can be argued that, in addition to time, we'll save energy and resources. Then, each process energy input, embedded energy and resources for each machine, embedded energy and resources and operational energy in the handling machinery are all collapsed into one machine. Granted, the machine is more complex - but, one machine never-the-less. The figure below shows this hypothetical comparison (and you'll need to enlarge this one for sure!).

The red line tracks the individual process machines in a sequence. The line goes up to the right to reflect the process energy and the "jump" is the handling machinery impact. The green line shows the operation of the multi-machine. And the hashed green box illustrates the energy savings. Likely cycle time savings are seen as well. Granted this is a simplified illustration but the potential savings are real. And this is an excellent example of one of those "technology" wedges that's been referred to before.

These two examples, one that is for existing machinery and requires little additional cost, and the second when machinery is replaced, are both enabled thanks to data on the process operation at the lowest level. And we can build other efficiencies on top of this.

In the next blog  we'll talk a bit more about Scopes 1, 2, 3 (and 4?).

And happy holidays!

Diving Deeper - Green at the Process Level (Last of a 2 Part Series)

The more information you have the easier it is to understand what is going on and what you should do next. This simple statement lays out the basic strategy to green manufacturing - at any level. If you recall the major improvements (or leaps forward) in manufacturing we spoke about in an earlier posting (on July 27th to be precise - see http://green-manufacturing.blogspot.com/2009/07/why-green-manufacturing-part-of-next.html) you will remember that each of these "leaps" was based on observation of the process from a new perspective, data to document what was being observed and then a plan of improvement built on that observation and data. That's diving deeper in to the process at many different levels.

Last time we identified two distinct modes of performance of a manufacturing process (and, of course, there will be exceptions but in general this is a reasonable classification) that distinguished between processes (or machine or tools). One mode was  where the process energy dominates or, at least, is a significant component of consumption relative to tare energy, and another where the tare power dominates. And, depending on which "mode" you are in will determine what potential approaches you'll take to reduce energy, or consumption, during the process. The table below summarizes this (and recall that where the tare energy dominates, Et >> Ep and, when, Ep >> Et, process energy is much greater than tare energy.)

Depending on the units of measure (here meaning power or energy per unit of time or per unit of production) our strategies may be somewhat different, but, in general, our strategy for the tare dominant operation vs the process dominant operation are as shown in the table. I'll define some of the other terms as we go along.

For the operation of the machine under the tare dominant mode we should try to make the cycle time on the machine as short as possible (cycle time is tc) which will give the part produced the lowest energy footprint from the process. The machine itself (operation with out process) we need to look at ways to reduce the tare consumption. For a numerically controlled machine tool (following our milling example from part 1 of this posting) with reasonable precision we know that the main sources of energy consumption are related to the power for the controller itself, the control panel of the machine, rotating the spindle, table motion, and coolant pump. In fact, the coolant pump is a big one since machines of this quality need to be kept thermally stable to avoid thermal distortion. So idling the machine controller between process steps and finding a way to keep the spindle thermally stable (material? design? air cooling?) without the use of the coolant pump would be first on the list.

For operation under the process dominant mode we focus on optimizing the process itself. You may recall a posting on the 29th September on "Greening the factory floor: (see http://green-manufacturing.blogspot.com/2009_09_01_archive.html). In that I distinguished between different levels of machine operation from the "microplan" (the particular speeds, feeds, depths of cut (for a machining process) and tooling required to accomplish the operation on the machine), the "macroplan" (process sequence which represents the order in which the operations are carried out with requirements for "what comes first") and the machine tool or system of machines itself. Our interest here is on the first two, micro and macroplan.

For the microplan we know from research and experience that the choice of process settings will impact energy and resource use. It follows then that the correct choice will yield reduced energy consumption. This would be, for milling, the cutting speed (rate of rotation of the tool in the spindle translated to peripheral velocity), the feed rate (rate of advancement of the cutter through the work) and type of tools  used (for example, material type and any coating to reduce friction, resist temperature, etc.)

For the microplan (and still speaking about process energy) the process sequence level determines the path that a cutting tool takes across the workpiece and the sequence of operations. Machines use more or less energy depending on how their axes move, accelerate and decelerate, how many times the spindle starts and stops, tools are changed, etc. So sequence and paths can have a big effect.

As an example, consider a workpiece that requires motion of the machine table in two directions (two orthogonal axes) to produce. Usually, the machine is built with one of these axes stacked at a right angle on top of another - like a sandwich. The workpiece is fixed to a table on the top axis. But, if I need to move that workpiece in the direction of the bottom axis (that is at a right angle to the direction of the top axis) I need to move the bottom axis in the correct direction which also carries the top axis. Not surprisingly, it takes a lot more energy to move one carrying the other than to move the top axis by itself. So, a workpiece which has a lot of features that need to be machined using the bottom axis motion will consume more process energy than one that doesn't.

Make sense? So by either position the workpiece the table so that the maximum "top axis" features can be machined or, at least, adjusting the tool motion to incorporate as many top axis moves as possible as the tool sweeps over the part we can substantially reduce energy consumption. And that is both on a per part and a per unit time basis.

Machine "warmup" is also a big issue that requires the machine to operate much longer than needed for the specific process at the start of the production run. Strategies for minimizing that vary from thermal insensitive materials to special process plans that use the relative inaccuracy of the machine when it is "cold" to work on less accurate sections of the workpiece or for roughing cuts.

Embedded energy was a factor in either mode of operation since it accounts for the energy and materials used to build the machine in the first place. Here, we'd need to look at selection of materials for the machine (specially trade-off between "low embedded energy" materials and those that meet the structural or thermal requirements of the machine design) as well as ease of recycling or reuse of components, etc.

Whatever level of scrutiny we apply to the manufacturing process we can find potential for improving the energy or resource performance of the process or machine or system.

Next time we'll discuss some ideas about "line balancing" and the potential advantages of machines that do more than one process.

The webinar on Thursday, December 10, 2009 on "Built to Last:  Sustainable Manufacturing" is history. Go to the Future State Solutions website to see the archived webinar (http://futurestatesolutions.com/.) There will be a follow-on webinar on "Sustainable Manufacturing: The Details You Need to Know" that I will participate in on Tuesday the 14th December. Go to http://bit.ly/91eAfO to register.

Diving Deeper - Green at the Process Level (Part I of II)

In the last three postings we discussed the potential for combining lean approaches to manufacturing process optimization with green analysis to get a double hit. The basis of this is, of course, that both are seeking to eliminate waste in the process and the system so should have a logical link. I noted that the linkage between lean methodology and green and sustainable production analysis shows great promise and should offer valuable insight to process improvement that is both economically and environmentally sound.

A staple of lean manufacturing is the value stream map. A brief overview was given of that with some references for more details. But there is more to this and we need to bore deeper into the process box to see the full potential (or, make the case for a more detailed value stream analysis than is often done today.)

The posting on November 12 (part of the series on "is lean green" - http://green-manufacturing.blogspot.com/2009/11/is-lean-green-part-i-of-ii-part-series.html) illustrated the process box representing a manufacturing process. There were a number of inputs and outputs identified, including:

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

Outputs:
- Product
- Waste (heat, liquids, other consumables/tooling, etc.)
- Rejected/failed product

Later in that posting I linked several of these boxes together to create a system of production - that was the basis of our discussion on value stream maps. Many of these inputs are included in the value stream map for lean manufacturing analysis. Reviewing the list of inputs, and recalling the "Google earth view" of manufacturing that was presented in one of the earliest postings (see September 15th posting - http://green-manufacturing.blogspot.com/2009/09/green-manufacturing-technology-wedges.html), we know that we can look deeper into the process box than the rather summary data listed above. In fact, we can dig a lot deeper.

Allow me to elaborate! Take just two of the inputs - process energy and tare energy. This refers to the actual consumption of the machine but allocated to that which is associated with the actual production process (process energy) and that which is associated with the peripheral consumption just to keep the machine running (tare energy). This later one is called tare energy consumption from the similar concept of weight determination - the weight of the container holding the contents has to be accounted for when accurately determining the weight of the contents. The two will be dependent upon the process, the machine design, the sophistication of the control, the number of processes on the machine, the precision and accuracy of the machine, etc.

For the sake of simplicity, let's look at a machining process - like milling (but you can do the same for welding, injection molding, chemical vapor deposition, baking a turkey, etc.) We measure these two components by hooking up a power meter to the machine and noting the energy consumption when the machine is "on" but idle - not making any parts or, in the case of milling, cutting metal. We then start up the machine and begin cutting metal and again measure the power consumption during the cycle to create the part (or finish the process).

Interestingly, we can divide the performance up into two large camps - one in which the process energy dominates or, at least, is a significant component of consumption relative to tare energy, and another where the tare power dominates. We can represent these two regimes as in the figures below (and click on the figure to get a larger image).

We see in the figure on the left the circumstance where the tare energy dominates, Et >> Ep and, on the right, the opposite, Ep >> Et, process energy is much greater than tare energy. The strategies we'll want to follow to reduce energy will be entirely different! For the left case, our best interest is served if we try to make the part with the smallest cycle time possible since the process uses very little energy and slowing down only uses more. In this case we should focus on the machine design and operation to try to reduce the idle energy consumption.

In the right case where the process energy dominates, since the tare is much lower than the process energy, it will pay to look more closely into the details of the process to see how we can reduce energy consumption in the process.

There is also a small component labeled "embedded energy" that must be included to be complete. This represents the amortized "cost" of the energy it took to build, transport, and install the machine. We'll get back to this at a later date.

We''ll dig into these two cases in more detail next time. An important question we'll need to answer is - what is the unit of measure? Are we tracking power (or energy)/unit product? or power (or energy)/unit time?

(Blogger's note: I am liberally interchanging energy and power in this discussion. They are not the same of course but, I think, you follow the idea. I don't want to annoy the purists too much!)

Finally, in the last blog I mentioned that one approach to "lean and green" is offered by  Future State Solutions, Inc. (see futurestatesolutions.com). They have invited me to present a webinar on Thursday, December 10, 2009 11:45 PM - 12:45 PM EST. The topic is "Built to Last:  Sustainable Manufacturing" - go to  http://bit.ly/5RY3UC to register or you can register through the Future State Solutions website and see details of the webinar discussion.

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.

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!

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
- HVAC
- 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!

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!