"Greening" the factory floor

The last blog took a view from a broader systems view of sustainability as it applies to manufacturing and business and focused on both upstream and downstream supply chain elements (that is, mine/well to consumer and consumer to reuse, respectively.) We also had discussed technology wedges in the September 15th blog and their application to greening manufacturing and closing the gap between present levels of consumption or impact and sustainable levels. 

At the higher levels in the manufacturing enterprise the facilities (office building and plant HVAC, administrative, employee services like cafeterias, etc., packaging and shipping) dominate. As we move down through the production systems and their associated consumables (with their energy, water, materials, compressed air, part and material delivery and removal, maintenance, etc.) and further down to the machine and process level (with the tooling, both work holding and process tools, machine operation, resources and consumables, part and material handling, etc.) we want to be aware of every aspect of production for applying our wedges. But, remember, planting grass on your plant roof should not be the end of your green manufacturing initiative!

That accounts for energy, material and other resource use in the direct production of a product. If we are heavily dependent on our supply chain we should take that into consideration as well although at present it may not seem to impact directly our energy or other resource consumption.

Here we'd like to take a look closer to the factory floor for opportunities to employ some of these wedges - where the "tool hits the metal" one might say. 

We can generally identify four distinct levels of influence with respect to greening production at this machine to part level - the system of machines making up a production line or cell, the individual machine tool or production machine itself, the overall operation of the machine and the detailed operation of the machine in production. 

Let me elaborate starting with the lowest level (and we'll rely on a machining analogy here):

- detailed machine operation (often called the process "microplan") represents the particular speeds, feeds, depths of cut (for a machining process) and tooling required to accomplish the operation on the machine.

- "macroplan" or process sequence which represents the order in which the operations are carried out with requirements for "what comes first"

- machine tool or production machine which represents the hardware (iron, actuators/motors and electronics) that provide the energy and coordinated motion for accomplishing the process sequence at the desired microplan, and the

- system, or assemblage of machines that comprise the production line or cell. 

At the lowest level, we know that the shape transforming operation that occurs (forging, machining, grinding, rolling, etc.) will consume energy and resources to convert the incoming material to a new configuration. 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. The term "specific energy" is often used here - implying how much energy is needed to accomplish a shape transformation of a specific volume or, if we include the rate of transformation, the specific power. Usually, very small volumes of material transformed require larger amounts of energy than would be proportionally determined from a  larger volume due to inefficiencies (that's why grinding heats up the metal more than a similarly scaled cutting process - the grinding removal is less efficient due to the small amount of material removed by each grain).

Moving up a notch, 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 matter.

The machine or production tool is the next level. (A word of caution - for some reason the words "tool and tooling" are used to represent a number of different elements in manufacturing. The machine is often referred to as a machine tool. The hardware that holds the part on the machine table during machining is a fixture or tooling. And the unique bit used to actually remove material (a drill or milling cutter, for example) is also called a tool. I don't know why. It's just that way.) 

The machine tool has both embedded energy and resources resulting from its manufacture (as does the fixture and and other tooling). It also consumes energy and resources during operation. In addition to moving the axes and rotating the spindle there is energy consumed in the tool changer (providing the correct cutting tool from step to step), powering the computer controller, rotating the spindle, lubricating the moving parts and removing the heat generated during operation (to keep the machine from changing shape and losing precision during operation), mechanisms to remove chips, provide cutting fluid or mist and so on.

We can envision improvements at all these four levels beyond that considered as part of continuous improvement:

- The machine tool can be designed to be more thermally stable without the use of complex cooling systems, materials with higher stiffness and damping per unit of embedded energy of production chosen, hydraulics and spindles configured for reduced energy, component configured for re-use or remanufacture after their end of life, etc.

- Operation of the system of machines can be optimized to better balance the power load over the individual machine cycles to avoid peak demand, multi-purpose machines might be used in place of a series of discrete machines to eliminate material handling and consumables and duplicate operations, power might be harvested from one machine to offset the needs of another as spindles are stopped for tool change, for example.

- The process operation level could benefit from work holding and work orientation for minimum energy machining,  process sequencing for minimum energy and consumables use finishing, etc.

- At the lowest level in the chain,  the process planning level,  machining feeds and speeds might be chosen for minimum energy machining or roughing and finishing designed for for minimum energy, consumables,  and finishing. We might try optimized tool paths for high productivity and minimum energy. 

We've tried many of these ideas - they work. And they are scalable and extensible to other processes. 

A future posting will go into more details - specially the more interesting ones like energy recovery from machines and design of "green" structures for machines.

Finally, in the "department of interesting stuff on the web" there is a flurry of information about manufacturers and their efforts to reduce emissions, consumption of energy or waste. Check out some of the links at the bottom - specially Environmental Leader (http://www.environmentalleader.com/) to see what others are up to.

Note: The "Why Green Manufacturing" webinar hosted by Climate Earth two weeks ago was a great success. The topic discussed the transitions in manufacturing first described in this blog back on July 27th and then covered some ideas about why industry should care about this and some metrics to track our progress. The archived webinar is available (or will be soon) on line at http://www.climateearth.com/webinar.shtml.

Sustainability Angst

In an earlier blog we discussed motivations for green manufacturing - basically why should you care about this (July 20 posting- "Why Green Manufacturing? (Part 1)"). We then went on in a later blog to tease out a bit more detail about green vs sustainability (see posting of August 4th - "Grappling with Sustainability").

Companies are becoming more and more aware of the issues and challenges but are often not sure how to proceed.

A recent report by the Sloan School at MIT along with Boston Consulting Group (see Env Leader for links - http://www.environmentalleader.com/2009/09/18/only-30-of-firms-have-a-business-case-for-sustainability/) presents the results of a survey of corporate executives. Guess what? Their answers agree with much of our list of motivations!

In order of importance, the "sustainability-related issues" that companies believe will impact their business organization include:

- government legislation

- consumer concern

- employee concern

- concern over environmental pollution

- depletion of resources (non-renewable and renewable, like water)

- societal pressures

- global political security

- population growth

- climate change

So the push of legislation and regulation along with the pull of consumer interest, market leadership, avoiding risk, etc. seems to be forcing more thinking about sustainability and, thus, green steps in business and manufacturing.

The report discusses the concerns about the gap between "intent and action" and indicates that there is not a lot of leadership towards addressing sustainability and a big shortfall when it comes to execution.

That's where we fit into the picture. Green manufacturing strategies, employing the "technology wedges" discussed in the last blog evaluated with solid performance metrics form the first steps in a strategy towards creating sustainable production. And, if we follow our scope of manufacturing encompassing all stages of product creation and distribution from raw materials through use and reclamation, we will correctly view the battlefield. The Sloan School study (http://sloanreview.mit.edu/special-report/the-business-of-sustainability/) said that many of the business leaders interviewed for the study recognized that the risks of not acting are increasing.

If we look we can find opportunity.

Sometimes it helps to take a bigger view of the situation. One that I like was presented by Ricoh, the copier company, some years ago as they started to define a sustainable business model. I've referred to them in an earlier blog (July 17th) when we started defining terms. Their "Comet Circle" represents their view of a sustainable society (see below from http://www.ricoh.com/environment/management/concept.html, accessed 9/21/09.)

The Ricoh comet circle is an excellent way to represent the “supply chain” feeding the consumer. You'll probably need to go to the link to see the details - this image is too small. The forward (counterclockwise loop) is from materials through production to delivery and use. The reverse (clockwise loop at the bottom) is after the consumer is done with the product back through recycling, recovery, and return to material supply chain. Usually when a green supply chain is mentioned it is in the context of the return loop - resource recovery. That is only half the battle and, if the forward loop is done correctly, is much easier.

The consumer can be you or me at home, or a company buying something (machinery, paper, electronic components). The key idea is that the closer to the consumer that the circle loops … the more sustainable/green is the scenario.

Ricoh lists the following components to a successful strategy:

- identifying and reducing environmental impact at all stages (this is Japanese continuous improvement at its best and is key to identifying elements of the operation that need to be identified, quantified, and reduced, eliminated or otherwise offset) putting priority on "inner loop" recycling (the highest value resources are those converted into product and used by their customers; try to minimize the resources, cost, energy that is needed to return a used product to "the state of highest economic value")

- institute a multi-tiered recycling program (reduces the consumption of new resources and generation of waste)

- more economically rational recycling system (to quote Ricoh - "A sustainable society must also establish a recycling system in which products and money flow in opposite directions in both post-product-use stages and original production and marketing stages. At the same time, it is important to establish a social system that helps people to be aware of environmentally-friendly business activities and buy products with less environmental impact.) This is important. This is part of establishing the business motivation for green manufacturing, including the original production stages in the equation. That is, the "green supply chain."

- finally, establishing a partnership at every stage of the supply chain. This partnership discloses materials used in production and in the product, transportation alternatives, etc.

Altogether, Ricoh hopes this strategy will reduce the impact of society as a whole leading to sustainable living. And it identifies many places in which our green technology wedges can be applied.

And this will help reduce any angst felt thinking about sustainability.

Green Manufacturing Technology Wedges

The last blog looked at the complete product life cycle to see the breadth of manufacturing  - from material extraction through production and distribution to end of life. We want to drill down a bit more on the production phase of that cycle.

In my lectures discussing green manufacturing I often use a “Google earth view” of manufacturing to zoom in from the enterprise level to the lowest levels on the shop floor – each step increasing the level of detail shown and, consequently, exposing more opportunities for improvement. (In fairness, this was originally the idea of one of my recent grad students – Athulan Vijayaraghavan). It’s a great analogy.
We’ve all used this feature on Google – put in a destination and with rotations and magnification the desired address moves into clearer and clearer view until we are staring at our destination with startling detail.

Same thing for manufacturing. We can start at the factory/enterprise level – move in closer to the production floor, then to the machine lines, on to individual machine tool, down to the spindle and table, and then, finally, to the tool-material cutting zone. (I’m a machining person by training so my analogies usually use metal cutting! But, this works with any enterprise to process zoom.) A representation of this zoom is below.

The interesting thing is that, if you look more and more closely, you see the many areas for “greening” the process. It’s like a tide pool at the ocean – you stare into it and there seems to be nothing there. But, bit by bit, you see little creatures moving around and, finally, are amazed at how much life is in that little pool.

I like to refer to these opportunities for greening as “technology wedges” after a concept proposed by Pacala and Socolow to address the big gap between the present trajectory and impact of CO2 on the atmosphere (business as usual – BAU) and a sustainable level – and how to close this gap in 50 years. (The full citation is “Stabilization Wedges: Solving the Climate Problem for the Next 50  Years with Current Technologies,” Science 13 August 2004: Vol. 305. no. 5686, pp. 968 – 972.) They reason that, rather than trying to find one “silver bullet” to correct this increasing mismatch between what we need and what we are doing, we should concentrate on “technology wedges” – small advances and improvements that, when added up, have the effect of a large change in the way we do business. 


Their wedges include efficiency improvements, carbon capture and storage from power plants, renewable power, etc. The specific wedges they propose are not the main interest here. But, the idea has real merit.

If we look closely along the view from enterprise to cutting tool, as in our zoomed view, we can see many opportunities for green technology wedges. Some are simple improvements. Others are more substantive and may require new technology or, for the entrepreneurs, offer opportunities for new businesses.


A complete discussion of this concept is in a paper I co-authored in 2007 (Technology Wedges for Implementing Green Manufacturing, NAMRI Trans., 35, 2007, pp. 193-200 – if you want a copy send me a note.)

In that paper we proposed a set of rules for applying technology wedges for green manufacturing:

1. the cost of materials and manufacturing (in terms of energy consumption and Green House Gas (GHG) emissions, etc.) associated with the wedge cannot exceed the savings generated by the implementation of the wedge (or wedges) over the life of the process or system in which it is employed.
2. the technology must be able to be applied at the lowest possible level in the process chain.
3. the cost and impact of the technology must be calculable in terms of the basic metrics of the manufacturing system and the environment. That is, cost and impact must be expressible in units of dollars (or euros, yen, yuan, etc), carbon equivalent, global warming gas creation or reduction, joules, cycle time and production rate, quality measures, lead time, working capital and so on relative to present levels of consumption, use, time, etc.
4. the technology must take into consideration societal concerns along with business and economy, and
5. there must an accompanying analytical means or design tool so that it can be evaluated at the design stage of the process or system. It must be an integrated approach.

These are general rules that should be considered when evaluating green technology solutions (wedges). Since the paper was written some refinement of these basic rules could be added but, overall, they are applicable.

I’ll include some applications of this approach to manufacturing systems in the future. In the meantime – take a close look at your product life cycle, or production system and processes, to see where green technology wedges can be implemented.

A reminder - "Why Green Manufacturing?" Join my webinar on September 17th - go to

https://www2.gotomeeting.com/register/187277227 to register.

Defining Manufacturing Lifecycle

We have been talking a lot about manufacturing (and related terms such as green, sustainable, low-carbon, clean-manufacturing) but it seems like we should spend a little time making sure everyone is on the same page with respect to what I mean when I say “manufacturing.”

Environmental Leader (see link at bottom of page) periodically "re-posts" some of my older blogs on their site. A recent re-posting covered a discussion I had about the differences in the CO2 impact of the embedded energy in manufacturing an automobile and how the location at which you produce a product can make a big difference (originally posted here on July 23rd). The blog then went on to discuss other aspects of manufacturing that need to be counted - including transportation. In response, a reader commented that there should be more attention paid to transportation (distance, mode and energy impact) in determining where something should be paid.

I agree fully and I've mentioned aspects of this before. But, this reminded me that we should define more specifically what we mean by manufacturing so that when we discuss impacts we are sure to include all the important stages and elements. So, that's our topic for today.

When I first started teaching manufacturing courses (back in the last century – I’ve been waiting for a chance to use that!), manufacturing was defined primarily as metal working using machine tools and conversion of materials by conventional processes (cutting, forming/forging, welding, etc.). Of course, that was a narrow definition then (it excluded most electronics - 30 years ago they did not play the role they do in our lives today; the topic probably touched on plastics a bit). That definition certainly is way too narrow now. So, thinking of all the products manufactured today (just look around your office or home for starters), how do we define manufacturing?

If you Google manufacturing you'll come up with a Wikipedia definition that works pretty well (I don't normally recommend this as a primary source to students but for this discussion it is fine - see http://en.wikipedia.org/wiki/Manufacturing):

"Manufacturing is the use of machines, tools and labor to make things for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale. Such finished goods may be used for manufacturing other, more complex products, such as household appliances or automobiles, or sold to wholesalers, who in turn sell them to retailers, who then sell them to end users - the 'consumers'."

This is usually restricted to “discrete parts manufacturing” (i.e. not refineries). The only part they miss in this definition is what happens after the consumer is done with the good, or the good is obsolete or worn out, and it is disposed of, recycled, re-manufactured/re-used, or discarded. That must be included since, more and more, it plays an important part in the manufacturing process and the company responsible for manufacturing the good may be required to take it back when the consumer is finished with it. We'll discuss this more in the future but check out some of the EU regulations, for example waste electrical and electronic equipment (WEEE) requirements.

A full picture of the product "life cycle" starts at the source of materials (mine, well, forest, ocean) and extends through conversion to processing to shipping to distribution to use to reuse/recycling - the whole nine yards. Think of a “simple” product like an aluminum beverage can. First, ore is mined, then converted to raw metal and formed into billets or plates and then sheets, then manufactured by deep drawing into cans, lids and pull tops and labeled, filled and packaged, transported to distributors, then to stores/outlets and customers, used and finally, recycled (back into the material flow).

A cartoon of the full life cycle is shown in the figure above (you may have to expand this to get a clear view) and what is labeled as the “manufacturing” part is actually only a small part of all the processing, handling, transformation with accompanying energy, resources (materials and consumables) and environmental impact. So, to be correct, we really need to see manufacturing as including all these elements – except maybe the use phase (unless the product is a machine tool and you are a manufacturer using machine tools in your production!). Thus, transportation is a critical part of the resource use and impact analysis. But, so is “pre-processing” of materials used in the circled part. If you use a material which has been extensively processed before entering your facility (so you don’t need to) then you also need to count for the embedded energy, resources, and impacts of that pre-processing. From “cradle to grave” (or “cradle to cradle” as McDonough and Braungart suggest – see http://www.mcdonough.com/cradle_to_cradle.htm) the manufacturer must consider all the impacts. Else, when folks in other parts of the world start regulating embedded energy or cumulative impacts along the supply chain, you’ll be surprised at what’s in your product that you are accountable for!

There are a number of ways to account for all this embedded energy and resources and we’ll be speaking about them in the future. We are already doing simple tradeoff analyses for transportation and manufacturing. A recent study on supply chain optimization and planning for solar panel manufacturing shows the impact of efficient and inefficient means of transport as well as energy mix at different manufacturing locations showed that the energy payback time (time it takes to generate enough energy to offset manufacturing use) of solar panels can vary from 0.6 to 5 years depending on manufacturing locations (download the full paper at http://repositories.cdlib.org/lma/gmg/reich-weiser_08_5/).

If you look, and can measure and evaluate, you find opportunities!

We’ll be diving a bit deeper into manufacturing, and the opportunities for improving the footprint of manufacturing in the next posting.

Little things matter - precision manufacturing and green

Last time we discussed metrics and spoke about payback time or return on investment among others for assessing the best value for the money from implementing process improvements. We also introduced the idea of a "design space" where we needed to balance manufacturing capability, design and environmental impacts along with cost to achieve an ideal solution.

In preparation for my class on Tuesday I found an interesting discussion about the impact of the CARS program (aka "cash for clunkers").The motivation for this program was to stimulate the economy and to encourage the replacement of autos with poor fuel economy by those having improved fuel economy. We had discussed the need to measure, or at least estimate, the improvement from any plan for greening a process or product.

An article on an Automotive World website (http://www.automotiveworld.com/news/environment/77989--cash-for-clunkers-and-lifetime-co2-emissions) offers some insight into measuring the impact of a change. They compare data on the CO2 emitted during the manufacture of an auto (from Ford for small and mid size and Toyota for an "average" size). The figures range from 8.4% of lifetime emissions for a mid-size car that returns 17 mpg (US gallons) and 10.3% for a small car that returns 25 mpg for the Ford data and 18% for Toyota (which also takes into account the production of materials going into the vehicle). Then, considering scenarios of improvement due to replacing trade-ins with higher mileage vehicles (and an assumption for the amount of CO2 per volume of gas) they calculate the number of miles of driving needed (at the newer efficiency) to save the equivalent of the CO2 from manufacturing of the new vehicle.

Many assumptions needed of course but, bottom line, one of the best case scenarios yields payback in 20,000 miles (or about 1.4 years) if your average annual travel is 14,000 miles. A worst case scenario (either higher manufacturing emissions or smaller improvement in mileage when you swap cars) shows a break even at closer to 75,000 miles (or almost 11 years of operation). Depending on the specifics of your swap - this analysis suggests that the change may have accomplished the first motivation but falls short on the second. Read the article. This is an excellent example of using metrics in a tradeoff analysis.

Fuel economy in automobiles is a convenient transition to our discussion today - precision manufacturing and green. Time to "wax technical" a bit.

A well worn relationship for predicting the impact (in terms of environmental damage, consumption, etc.) is as follows:

Impact = Population x (GDP/person) x (Impact/GDP)

Population grows with time. Most countries strive to improve GDP/capita since that drives living standards, etc. The rate of consumption or environmental impact per unit of GDP is the "rate of damage" done as a result of the technology driving the growth in GDP.

Engineers are most effective at changing technology that affects Impact/GDP. To the extent we can reduce that impact we are, effectively, greening the process.

Now, back to precision. The fuel economy discussion earlier points out one area that engineers, manufacturing in particular, have had tremendous effect. If you are familiar with the recent improvements in the internal combustion engine (yes...our old friend the IC engine) you can see how effective design and manufacturing changes can be in creating technology wedges to address the gap between business as usual and a more sustainable rate of impact.

Some examples. A major German auto manufacturer has been working to improve the "power density" of some of its diesel engines over the past years and has seen an improvement of almost a factor of 3 in power per unit of displacement. That means, for the same engine size (displacement) they have managed to squeeze three times as much power out. Coupled with advanced fuel injector systems operating at very high pressures (once thought absurd) they see enhanced performance in a small engine - increased fuel economy, improved acceleration (due to reduced mass), and reduced emissions.

If you add to that the recent improvements in "hybrid" valves (see, http://www.jobs.mahle.com/C125705E004FDAF9/CurrentBaseLink/W276TH5G611STULEN), which are composed of a laser welded hollow structure made from cold formed sheet steel parts, the valve train performance is substantially improved due to lower mass and higher resistance to combustion pressure and temperatures.

Another enhancement is assembled (rather than forged) camshafts formed of hollow rings friction welded together and shaped by hydroforming. This results in a reduction of part weight of 50% (and manufacturing cost of 15%).

In engines like these - reduced mass means higher acceleration and greater power per unit of displacement. And, improved fuel economy and lower emissions.

This is all due to the improvements in precision manufacturing - the ability to create incredibly small features, dimensions and shapes repeatably and reliably for low cost. The German engine relies on precision machining to create bearing surfaces and interacting parts with tight clearances, low friction and smooth operation. These are dimensions more typical of the semiconductor industry - not automotive. Ditto for the fuel injectors where micron sized injector holes with intricate patterns insure efficient combustion for maximum conversion of fuel to power and minimum emissions.

Don't write off the IC engine yet as part of the drive to reduced automotive energy consumption.

And we can see the impact of manufacturing technology on other products as well - not only for automobiles. The new Airbus 380 boasts better fuel economy and CO2 emissions (gCO2/passenger mile) than most European automobiles must achieve to meet regulations (this is a complex comparison - but humor me on this! and see http://www.enviro.aero/A380casestudy.aspx).

I also teach a graduate class on precision manufacturing and one of my favorite slides to motivate the students shows how improved machining tolerances on an aircraft airframe (a big one like a B747 or the A380) saves weight and, hence, fuel. If the machining process is under control and precision manufacturing principles applied, a reduction in machining tolerances from +/- 0.006 inches to +/- 0.004 inches on the features of the airframe can account for a weight reduction of 10,000 pounds/aircraft and substantial fuel savings (8%). This allows an increase of 10% in passengers (engines don't need to carry as much plane), and substantial reduction in manufacturing cost of the aircraft (less material and improved assembly). And less fuel consumption means reduced CO2 impact from operation. Think of the accumulated savings over the life of the aircraft - incredible.

All because of precision manufacturing technology. In all these above cases - metal cutting and forming!

Green manufacturing derives from an attention to detail and employment of the best engineering and process technology we can master. The examples above are not "rocket science". But they are achievable by precision manufacturing engineers, technicians and machine operators using state of the art precision machine tools and metrology.

We need to be able to confidently evaluate the impact of tradeoffs in design and production and the environment (as we saw in the figure in the last posting), and implement those by first class manufacturing practice.

The need to "green the process" will make many approaches thought to be unfeasible or too expensive very natural and cost effective. And make the manufacturer more competitive in the process.

Last word - for more info on precision manufacturing, I've written a book on the subject, see http://www.amazon.com/Precision-Manufacturing-David-Dornfeld/dp/0387324674/ref=sr_1_1?ie=UTF8&s=books&qid=1251867831&sr=1-1 or contact me if questions!