Leveraging Manufacturing, Part 3

The big finish!

That's a pun - gear finishing, leveraging, get it?! OK - blogger's license.

We will finish up our example of leveraging with this post. Although there was a long dead space in postings, recall that the example was from a recent paper from our research group and focussed on  the gear train as used in transportation. The premise was that the surface finish of gears contribute substantially to the efficiency of power transmission. Better surface finish yields better efficiency.

It was described that the gear manufacturing process chain is relatively complex with several options available to the manufacturer at each fabrication stage. In this example it is assumed here that the main process chain would be unchanged and that only gear finishing would need to be altered to produce gears with higher surface finish. For reference, the full citation to the paper on which this series is based is “Evaluating the relationship between use phase environmental impacts and manufacturing process precision,” CIRP Annals, 60, 1, 2011, pp. 49-52. I'll send you a copy if you want one.

The "leveraging" comes in with the expected fuel savings due to the better efficiency of the gear operation due to the better surface finish. We need to determine if the increased consumption of energy in finishing is paid back in the improvement in the operation of the gear train and accompanying reduction in fuel use. And a result of reduced consumption of fuel in the auto use phase we see reduced global warming potential (both from the reduced fuel used and the avoided impact of producing the fuel.)

Using the basic approach outlined in the last post, it was first necessary to determine the 'cost' of manufacturing improvements relative to surface creation. We do this by looking at the specific energy consumption requirements of the grinding process used in this part of the manufacturing process chain. From published data, for example from Professor Tim Gutowski at MIT, we know that the specific energy (meaning the amount of energy to remove a volume of material) for a grinding process assumed to be reflective of standard automotive gear finishing applications is about 200,000 Joules/cm3 for a process with a removal rate of about .01 cm3/sec. So, in English, if you want to remove a cm3 of material at this rate it will "cost" you 200KJ.

Using this approximation and the relationship between surface roughness and removal rate from earlier researchers we are able to estimate the increased specific energy required to decrease the surface roughness of the final gear drive reduction relative to the representative gear finishing process. This  estimate provides an upper bound to the manufacturing energy usage - meaning it should not exceed that since it is a convective estimate. Primary energy (energy needed for either the manufacturing process or moving the automobile) demand for the process and GWP emissions were then determined assuming a Michigan electricity mix (7015.2Btu/kWh and 0.7131kg CO2-eq/kWh, respectively. We assumed we were manufacturing the auto in Michigan.

The figure below shows the increase in PE demand and GWP emissions from electricity usage
in the manufacturing phase due to decreased surface roughness. This means, as we put more

energy into the grinding process to improve the surface roughness (recall, smaller is better in surface roughness) there will be a corresponding increase in global warming potential (GWP). Lower primary energy consumption is better for a given set of process conditions. In the figure we see two curves, one for the least sensitive relationship between process removal rate (x = 0.60) and the other for the most sensitive (x = 0.15). This shows the change (improvement) in surface roughness one can achieve by "spending" process energy - reducing surface roughness from the nominal by 50%, for example, will cost us 1.25MMBTU. (Read the graph as the x-axis at 100% is the typical surface roughness and moving towards 0 indicates reduced roughness or better surface.

Now to the automobile's primary energy consumption based on gear train efficiency. The fuel consumption of a vehicle is dependent on the power that the powertrain must deliver to meet the commanded acceleration while powering any accessories (e.g. air conditioning) and overcoming losses in the drivetrain and engine. Because this analysis considered only changes to the drivetrain efficiency, the power required for any accessories and frictional losses in the engine were neglected since neither would be affected.

The U.S. EPA Federal Test Procedure 75 (or FTP-75) emissions driving cycle was used to represent a standard driving scenario for this analysis. The decrease in fuel requirements was calculated for each surface roughness, Rq, of the gear pair in the final drive reduction. The resulting decrease in energy that must be provided by the fuel was then determined by integrating the decrease in fuel power. All deceleration events were removed from this calculation since a deceleration event does not require power from the engine. Modern engines are operated to fully combust fuel, and so the PE demand and GWP emissions were determined assuming that the fuel source was regular, unleaded gasoline (1184.8Btu/MJ used fuel and 0.0948kg CO2-eq/MJ used fuel, respectively.

The figure below details the relationship between the surface finish (stated in Rq, microns) of the gears in the final automotive drive reduction and the reduction in automotive primary energy demand (gas!) and the comparable reduction in global warming potential.

This figure shows that decreasing surface roughness (Rq) lowers PE demand relative to a standard finished final drive reduction from 2-5MMBtu depending on the operating temperature, To. The earlier figure showed that a 20-60% reduction in roughness increases PE demand in the manufacturing phase by less than 0.5MMBtu. Comparing these analyses indicates that improving the manufacturing precision of the final drive reduction can provide a substantial reduction in the life cycle impacts of an automobile. Since the final drive reduction is one of several gear pairs in a vehicle, the impact of manufacturing precision on the entire vehicle drivetrain could be much greater.

This analysis showed that a relationship exists between the manufactured precision of a product and its environmental impacts over its entire life cycle. In the case of automotive drivetrain components, this relationship was found to be positive. However, it may not be true for every product and is largely dependent on the intended function of the product. Ultimately, if a manufacturer is concerned with environmental impact when considering a process or system design, then he should improve the manufacturing precision if the resources required for the improvement are less than the potential benefit of the improvement in the use phase of the manufactured product.

This is summarized in the figure below. The figure plots surface roughness (to the right is rougher) and the comparable primary energy demand difference between the use (auto operation) and manufacture (creating the surface by grinding).

You can see that, for the standard gear finishing operation at the right we set the difference (cost minus savings) at 0. Then, according to our analysis improved surface roughness, even though it costs something in the manufacturing phase, yields a good return (savings greater than cost - so negative delta) over a wide range of surface roughness (and corresponding process conditions). If we push it too far and try to get too fine a surface finish (going far to the left in the plot), the manufacturing energy needed outweighs the benefits in improved performance - it costs too much to do. The trick is, first, finding the relationship the allows us to define this curve and, second, determining when the lower limit is reached and it is no longer "environmentally profitable" to improve the process further.

Clearly there are things, some more important than others, that we are leaving out of this analysis. But, it is a pretty good, and accurate, example of leveraging. For example, we should measure other aspects of gear finishing processes so we can include other environmental impacts such as water, industrial fluid, and raw material usage. We might also consider other manufacturing and product effects such as increased or altered process consumables for the manufacturing process, will this more aggressive finishing process result in decreased process yield (that is, more rejects) and what impact does this change have on the service life of product. These could be additional benefits as well as offer some disadvantages.

I encourage you to read the paper if you want the full details. There is tremendous potential in this approach.

Finally, we just hosted at Berkeley the 19th CIRP Life Cycle Engineering Conference. We had almost 180 participants from all over the world and it was a great series of presentations and discussions on many aspect of life cycle engineering as it applies to manufacturing. The "theme" of the conference was "Leveraging Technology for a Sustainable World." You can read a short overview of the conference in a blog posting on the BERC blog space prepared by one of our lab members, Katie McKinstry. Katie's posting is titled: GLOBAL ENGINEERING CONFERENCE SHOWCASES SUSTAINABLE MANUFACTURING INITIATIVES 28 May 2012 | BERC News. Enjoy!

Leveraging Manufacturing, Part 2

Some details on processing

The last posting began to dig into the leveraging discussion and started to elaborate on this topic using an example. The example was  from a recent paper from our research group at Berkeley and focussed on an important aspect of vehicles and transportation - the gear train.

The efficiency of gear systems was described as deriving from a variety of factors including the surface roughness of the mating surfaces.  Other studies have shown an even greater dependence on the surface roughness of the mating surfaces for hypoid gear pairs, which are found in automotive differentials. And because the vast majority of environmental impacts of an automobile occur during the use phase  the impact of increased manufacturing precision through better surface finish on the final drive reduction of an automotive manual transmission drivetrain makes this an ideal example of leveraging.

The gear manufacturing process chain is relatively complex with several options available to the manufacturer at each fabrication stage. It is assumed here that the main process chain would be unchanged and that only gear finishing would need to be altered to produce gears with higher surface finish.

It might be helpful to digress a bit (I enjoy digressing!) to talk about this important manufacturing process that underlies the efficient operation of most machines and transportation. Gear finishing, essentially abrasive machining, is one of those seemingly small and innocuous steps in manufacturing that "gets no respect" (to quote Rodney Dangerfield). In the world of machining with hard tooling (meaning not using lasers or some other type flow process) cutting processes are categorized by the geometry of the tool used and according to whether or not the tool is stationary relative to the workpiece or if the tool rotates. There is a logical division of these processes that, at the highest level, distinguishes between cutting tools that have a “defined geometry” (meaning specific dimensions that determine the shape of the tool) and cutting tools that are not defined (meaning the shape is more random)—having an “undefined geometry.”

Grinding uses undefined geometries - that is, the "tool" or abrasive doing the cutting does not have defined edges at all. Abrasive processes (grinding, sanding, polishing, etc.) use abrasive particles that are natural materials like sand, aluminum oxide, and so on, or materials made to appear as natural shapes. In typical grinding operations several abrasive grains (usually referred to as “grits”) are held together by a bonding material, as they would be in a grinding wheel or for abrasive (sand) paper. The shape of the grains is not defined but “random” depending on how the grain of abrasive was crushed to get the desirable size. If you've every sanded wood or other material or used an emory board on your finger nails you've been abrasively machining.

Importantly, as you observed when standing and noted that small grits gave you a better surface finish (meaning smoother or lower roughness), we control the desired process output by controlling the grain size and the way it moves through the material surface during grinding. Chip formation with an abrasive grain is illustrated in the figure below and shows the grit displacing/removing

workpiece material. The "v" is the velocity of the grit over the work and the arrow shows the relative movement between the grit and the work - the speed and direction. In grinding there would be hundreds of thousands of grits coming into contact with the work and each grit removing a small chip of material.

Thanks to many decades of research on grinding by engineers and academics (like Professor Steve Malkin of University of Massachusetts-Amherst) the relationship between grinding process parameters and material removal and, finally, surface finish is well characterized. We can summarize the gist of this rather simply as follows. We can describe a general empirical relationship that links the achieved average height surface roughness of a grinding process to the process specific volumetric
removal rate and the grinding wheel speed, the v in the above diagram, by assuming a direct correlation between the surface roughness and undeformed chip thickness.

Let me explain.

The undeformed chip thickness is the depth of cut of the grain into the workpiece. Seen in the figure above it would be the difference between the bottom of the grit in the work and the top of the work surface. Specific volumetric removal rate is the volume per unit time of material removed by the process - here dependent on the number of grains moving over the surface at the undeformed depth.  Each grain removes a small volume and the grains pass the surface at a specific rate. Surface roughness is a measure of the variation of the surface of a workpiece at a very fine scale, usually microinches or micrometers. The smaller the variation the smoother the surface. So small is good in the world of surface roughness!

OK … still with me?!

Then we can move on to the leveraging part. The figure below shows the link we are trying to quantify. This figure illustrates the discussion above about removal and surface effects but also shows where

the impact comes in. This figure is motivated by the work of another researcher at the University of Kentucky - Professor I. Jawahir. He studies the connection between process parameters, surface integrity and part function. The trade off between volumetric removal rate and surface roughness must be done understanding that if we adjust the grinding (or finishing) process to create a better surface finish it will cost us something. Here the cost is likely to be time (as finer finishing processes often take longer - remember how much time you need to sand with fine paper as apposed to rough sand paper to achieve a certain surface?). It will also cost us energy - we'll see why next time.

The "leveraging" comes in with the expected fuel savings due to the better efficiency of the gear operation due to the better surface finish. We need to determine if the increased consumption of energy in finishing is paid back in the improvement in the operation of the gear train and accompanying reduction in fuel use.

We'll "do the numbers" next time.

Leveraging Manufacturing, Part 1

First, some background

Where did March go?!

We finished a long set of postings on the power of the digital age in the form of software to connect the designer to the process with an eye to achieving all the normal requirements of a product but, in addition, incorporating measures to drive sustainable product design and green manufacturing. There is certainly more that can be said about that.

But, not now.

I'd like to get back to a subject that was mentioned first about one and a half years ago in an earlier posting - leveraging.

This was a follow on to a discussion centering on the "buy to fly" ratio concept used in the aerospace industry and discussed in another posting in November 2010 covering the impact of manufacturing on product performance.

That posting cited some results from VW on the role of manufacturing in the life cycle impacts of a particular VW automobile. It turned out that for a VW Golf example the data showed that there was a 20% manufacturing phase  versus 80% use phase contribution to the life cycle impact of the vehicle. I then did some simple calculations about the effect of some significant savings in one phase of manufacturing due to some "greening" efforts (like using lower energy machine tools, for example) and it turned out that, when this ripples through the production and use phases of the vehicle, we get, at most, single digit improvements in the lifecycle impact.

So, the question was, why bother?!

We rationalized that if you are paying the electricity bill for the factory and this small technology wedge improvement is added to a lot of others in machine operation it can add up to real savings. But, maybe still not impressive compared to the full life cycle of the auto.

But, I reasoned, if we follow that logic we are leaving a lot of potential impact reduction from manufacturing "on the table."

Then I gave the example of something discussed in another prior posting on precision manufacturing about a major German auto manufacturer (but not VW in this case) who 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. And this was due to advanced manufacturing.

When we ripple that effect through the life cycle of the vehicle, the impact is enormous. Since most of the life cycle impact (think CO2, for example) is due to operation of the vehicle and the production of the fuel to consume in it, savings due to engine efficiency are highly leveraged.

And, the savings are attributable in large part to manufacturing.

There had been a similar example with respect to improved machining tolerances for airframe structural components in aircraft. Tighter tolerances due to improved machine tool control lead to less weight for the structural components (since we can still meet size/strength/performance requirements without "overbuilding" the component) and that means either more cargo per flight or lower fuel consumption due to decreased aircraft weight. Either one improves the performance of the aircraft. Another example of leveraging.

So, we need to look at this in more detail!

The example I'd like to use to illustrate the fundamentals of leveraging is from a recent paper from our research group at Berkeley. The full citation is “Evaluating the relationship between use phase environmental impacts and manufacturing process precision,” CIRP Annals, 60, 1, 2011, pp. 49-52 and I encourage you to look this up (or contact me and I'll send a copy) for all the details. It is co-authored by two of my research students Moneer Helu and Athulan Vijayaraghavan (now with System Insights).

The example focusses on another aspect of vehicles and transportation - the gear train.

We saw the example for the German auto maker how manufacturing precision can have a strong effect on the operational efficiency of an automotive engine. The operational efficiency of an automobile can be generally measured based on its fuel economy. The fuel economy is strongly influenced by the construction of the powertrain, where tight tolerances and high quality surfaces in the camshaft and crankshaft bearings are required to ensure relatively low losses. Tight tolerances are also required between the piston, piston ring, and cylinder surfaces to enable the use of lower viscosity oils that reduce frictional losses in the engine. In addition to the powertrain, the drivetrain is another component of automobiles that is vital to fuel economy.

Recent work has shown that the efficiency of gear systems is due to a variety of factors including the surface roughness of the mating surfaces, assembly errors (e.g. shaft misalignments), and other manufacturing errors (e.g. form errors). Because the vast majority of environmental impacts of an automobile occur during the use phase as we saw illustrated in the VW example, the impact of increased manufacturing precision through better surface finish on the final drive reduction of an automotive manual transmission drivetrain presents the ideal case study for this investigation.

For a good review of the terms powertrain and drivetrain I suggest any book in automotive engineering or our friend Wikipedia! The term powertrain usually includes the engine, transmission, drive shafts, differentials, and the final drive (drive wheels) but it sometimes refers only to the engine and transmission. Wikipedia sums up the case well-

"Competitiveness drives companies to engineer and produce powertrain systems that over time are more economical to manufacture, higher in product quality and reliability, higher in performance, more fuel efficient, less polluting, and longer in life expectancy. In turn these requirements have led to designs involving higher internal pressures, greater instantaneous forces, and increased complexity of design and mechanical operation. The resulting designs in turn impose significantly more severe requirements on parts shape and dimension; and material surface flatness, waviness, roughness, and porosity."

It's this last bit - about imposing stricter requirements on, among other things, surface features including waviness and roughness - that we are going to focus on here.

But, we'll start that in the next posting. Soon!

Tools of the trade, Part 6

Last Comments on Software

In the last posting I posed the question "suppose you want to take some action - either at the design end or the manufacturing end. What tools can you rely on after you've done the background work and now want to move on to execution?"

The simple answer I gave was "This is where software tools come in."

I then proceeded to go into details about some interesting software tools that aid the designer, or manufacturer, in decision making about green and sustainable actions to take.

Shortly after that posting, I was invited to participate in a live (and simultaneously web-broadcast) Sustainability Summit at Autodesk in San Francisco.

Not surprisingly, the event was well organized and attended by an interesting mix of media, industry and students (including a sizable audience "attending" via a YouTube live link). It was interesting to hear a large corporation with a number of software tools for designers and engineers in this field, like the Autodesk® Inventor® 3D CAD software, discuss where they think the market is going and what software tools will have to allow the designer, and manufacturer, to do.

The program was comprised of a series of discussions and panel discussion starting with company CEO Carl Bass in conversation with Marc Gunther, a Fortune and GreenBiz contributor, discussing the importance of sustainability in the future of design.  Although this conversation was design centric, it had a lot of leads into green and sustainable manufacturing.

Other participants included Clean Tech Partner Burt Hamner of Hydrovolts; myself representing our lab at UC Berkeley on green manufacturing; Daniel Talancon and Vince Romanin, UC Berkeley graduate students on their Eco-Fridge design using Inventor; and Ken Sanders of Gensler on their Shanghai Tower design and other sustainable building projects.

Rather than rattling on about the meeting here, I've decided to take the easy way out and post links to the recorded YouTube presentations and discussions. That is more effective and, to me, better to hear the participants speaking about their views in their own words.

As a set up to the recording of my comments as part of the panel discussion lead by Autodesk's Sarah Krasley, I was asked to describe our "spatial vs temporal" matrix of manufacturing activities. This was first presented in the January 21, 2010 posting as part of a "low hanging fruit" series.

As a quick refresher, in case you did not see this (or since it was over two years ago!), the matrix is designed to illustrate different levels of control and flexibility in manufacturing from a temporal view (ie what comes first, second, third, and so on) and spatial view (where in the enterprise - broadly viewed - can actions be taken). I had detailed the temporal configuration as including four levels, from product design at level 1 through process design and planning (manufacturing plan) to parameter selection and process optimization to post manufacturing operations (finishing, etc.) at level 4. It was noted that the flexibility to make decisions decreases as we move away from design towards manufacturing.

This makes sense. On the factory floor we are no longer able to change the product or component design, material or other features. We may not, at level 3, be able to do much about the suite of machines we intend to use to produce the part. We most likely can adjust some of the operating parameters or, at level 4, do some finishing or alteration to overcome a problem.

The spatial domains are defined along the same lines except they will move outward from production specifics in the plant to facility design, enterprise design, logistics (or inter-enterprise) and supply chain and distribution.

The figure below was included as a graphical representation of the matrix and is worth repeating here.

The temporal axis is horizontal and the spatial axis is vertical. As one moves up and to the right in the figure one can suffer a loss of decision making capability as all earlier decisions in the product design cycle, or lower in the supply chain, effect the ability to make decisions at higher levels.  How you affect what is happening at any location within this matrix depends on what information you have about the process or system represented there, what your understanding is of what this information says about what's going on, what ability you have respond to this understanding, if needed (or leave it alone if it is performing correctly), what "levers and buttons" you have at your disposal to make a response and, finally, what means you have to determine if your response had any impact and, if so, how much.

That is, with respect to our tools discussion here, how well the software you are using to integrate across these different levels includes all the critical information, reasoning, behavioral models, visualization, etc. to support your work and decisionmaking.

So, with that set up on the summit in general and the background on my particular contribution, the links to the different presentations are listed below. They are only 3-5 minutes in length so are easily digestible (with the exception of the interview with the CEO - which is much longer.)

Warning - this was a a commercial event so it is, not surprisingly, very professionally done and has a commercial message. But, the contributors are genuine in their enthusiasm are their messages are on target and worth listening to!

The links are:

- Overview of the program and Sara Krasley interviewing the panel

- UC Berkeley students on their Eco-fridge design

- Ken Sanders of Gensler speaking about green building design

- Dave Dornfeld speaking about the temporal - spatial matrix discussed above

- Carl Bass, Autodesk CEO, being interviewed (Careful- this is a long one! 34 Minutes)

Or you can see the complete "playlist" on line.

Enjoy!!

For sure, there is other software on the market that addresses many of these same issues. You should check that out on your own.

Finally, next time we'll revisit the leveraging discussion.

Tools of the trade, Part 5

Software to the rescue

In part 4 of this series (Back in December … it has been a busy start to the year!) I introduced the idea of the "design to production pipeline."  This was to illustrate the design to manufacturing continuum and show a strategy whereby the designer, looking into the pipeline from the design perspective, could see the follow-on steps and requirements for successful production. Although the process is rarely actually serial, it is clear that some things come first, like design, and others come later, like actual production. These days there is (or should be) a lot of iteration between the determination of the final design specs and the establishment of the process plan for manufacturing.

The point is, there needs to be an inclusion of green or sustainable requirements in the specifications of the design (like material selection, for example) and on to the manufacturing stage (like insuring efficient conversion of materials in to the product).

We have been discussing the OECD (Organization for Economic Co-operation and Development) Sustainable Manufacturing Toolkit. In case you've missed the past three posting you can find details on the toolkit in an line Start-up Guide. This toolkit is well suited for organizing your strategy. But, what if you want to design or manufacture something and take green and sustainable principles into account?

Suppose you want to take some action - either at the design end or the manufacturing end. What tools can you rely on after you've done the background work and now want to move on to execution. This is where software tools come in.

As usual, it is not simple.

If you are a designer, and are beyond the function expansion stage and into more elements of the detail design, you are invariably led to consider some of the commercial software that is on the market for including sustainable (or at least green) constraints in the design.

As a green or sustainable manufacturer you usually have three basic "levers" you can adjust to optimize the production of a product or component - process technology, energy source and material. That is, you can improve the efficiency of the process in terms of energy or material consumption, you can reduce the embedded energy in the materials or use cleaner sources of energy, or you can introduce processing technology (remember the wedges?!) that are better suited to converting materials into product.

Let me state, at the outset, that I am not selling any particular piece of software! But, I am aware of some interesting developments in software that can get the designer (or manufacturer) moving in the right direction. And these offer insight (view down the pipe!) during the design process. This can be the design of a product or component, design of a machine used in production, or design of a factory.

First is material selection. Some time back we had a series of postings on "less is more" (see for example one on "how much less is less?"). In that series I mentioned software from Granta Design and their CES and  "Ecoselector" software. This particular software allows the designer (or manufacturing engineer) to consider energy (embedded and processing) and recycling potential along with other material properties in the course of designing a product or component.

The Eco Audit Tool is specially designed for this. It is an add on to Granta's basic material selector software that assists in meeting environmental objectives in engineering and design - objectives such as limiting the carbon footprint of a product, reduce the product's energy usage, limit wastes and emissions, or specify the details of its disposal at end of life.

First, Granta is clear about the components of the life cycle. In the figure below from the website linked above we can see the the different life stages of a product from material production through manufacture, use and end of life as well as the items tracked (energy, feedstocks and transport) and the environmental stressors. Stressors are the outputs of the cycle that impact the environment - e.g. greenhouse gases, particulates and waste.

Granta software makes an early analysis about where in the life cycle the major impact is seen (recall our discussion of use vs manufacturing phase impacts?). In the figure below, also from Granta, an example showing a product for which the use phase dominates in terms of energy consumption.

Then, in the lower boxes in the figure, different strategies are listed to minimize energy consumption. For the use phase these include minimizing weight, heat loss, electrical loss and systems losses. One can imagine this applied to an automobile where high strength to weight materials will offer enhanced fuel economy or, as a system, the powertrain is designed to reduce losses in power transmission. One can also envision this in the design of a machine tool for production for which the ability to idle machine components when not in productive use can save energy.

Interestingly, Granta has a link to Autodesk Inventor software. Or, perhaps better said, Autodesk Inventor has a link to Granta! This is shown on a clever (if not a bit commercial) Youtube video on how the CES software works and how they link into Autodesk for materials in sustainable design.

The Autodesk® Inventor® 3D CAD software, according to Autodesk's website info "offer[s] a comprehensive, flexible set of software for 3D mechanical design, product simulation, tooling creation, and design communication."

More on Autodesk and the Inventor software next time along with other commercial products that address this (like Solidworks design tools) and lifecycle assessment software for a deep dive in the impacts of the product or process.

Green Pot? Not!

Choice Items for the New Year

I've hit the pause button on the "Tools of the Trade" postings for the moment and, on the occasion of New Year, have included here a few items that seem a propos to green manufacturing - broadly interpreted- under the headlines 'green or not'? I know it sounds a bit like a Dr. Seuss book title - but read on!

The first one is thanks to Ralph Resnick and Corey Kovalcik of NCDMM.  It is a reference to a posting in the New York Times on the carbon footprint and environmental footprint of pot growing! I think they assumed that since I am at Berkeley with all those free thinkers that I had something to do with this.

I was a "child of the 60's" but was not a pot person (not even smoked but "didn't inhale" like our esteemed former President Bill Clinton!) As I explained to my dad many years ago when I joined the Berkeley faculty, every thing at Berkeley does not smell of burning hemp or involve overthrowing "the man."

You can find the full story on this at the NYT link. I don't know Dr. Evan Mills from Lawrence Berkeley Lab, the author of the study quoted in the article, but he seems like a serious researcher to me. The report is enlightening and will pose a dilemma for many folks (theoretical as well as practical - maybe even Ron Paul supporters!). His full report can be accessed on-line.

The last such dilemma I faced was not paper or plastic bags but natural versus artificial trees! This was first reported (or my first observation) in a Science 2.0 posting in December 2007 titled "The great debate: Real vs artificial Christmas trees." The article states "While chopping down a living tree may see like the most un-environment friendly thing you can do, in this situation it actually appears to be the “greener” choice. Because it’s not so much about how many uses you can get from your tree … as it is about what the tree is made of, and what it does to the environment when it is created and when you dispose of it."

"Artificial trees are manufactured using a polyvinyl chloride (or PVC), which is a petroleum-derived plastic. The raw material for fake Christmas trees is both non-renewable and polluting. Furthermore, PVC production results in the unhealthy emission of a number of carcinogens, such as dioxin, ethylene dichloride and vinyl chloride."

"Additionally, in order to make the PVC needles on artificial trees more malleable, the manufacturers use lead and other additives that have been linked to liver, kidney, neurological, and reproductive system damage in lab studies on animals. The Children’s Health Environmental Coalition warns fake trees "may shed lead-laced dust, which may cover branches or shower gifts and the floor below the tree.""

Wow. Check out that article … the comments are rich and numerous too.

USA Today weighed in on this last December, 2011 in an article that focuses on the dispute between manufacturers of artificial trees and the National Christmas Tree Association. Not surprisingly each side sees the other as spreading misleading info. Up to you to decide if you have a need for a tree next year!

But, back to the pot.

The article starts out with the statement "indoor marijuana cultivation consumes enough electricity to power 2 million average-sized U.S. homes, which corresponds to about 1 percent of national power consumption." A lot of production is indoors these days using high intensity lights - resulting in an approximate $5 billion dollar annual electricity bill. According to Mills that contributes the equivalent in green house gas emissions to about 3 million cars on the road.

It gets worse. The smoke from consuming all that marijuana further complicates the issue. Report author Mills said a single marijuana cigarette represents 2 pounds of CO2 emissions, an amount equal to running a 100-watt light bulb for 17 hours.

Don't try going "off grid" to raise your pot and expect to save the planet either. Mills stated "for off-grid production, it requires 70 gallons of diesel fuel to produce one indoor cannabis plant, or 140 gallons with smaller, less-efficient gasoline generators."

And then there is all the water! Each marijuana plant needs between 3 and 5 gallons of water per day to grow to "harvest".

Dr. Mills' report is comprehensive and contains detailed graphics and tables of impact.  Table 4 is specially intriguing. Did you know that "one Cannabis cigarette is like driving 15 miles in a 44mpg car emitting about 2 pounds of CO2?" Which is where the equivalent to operating a 100- watt light bulb for 17 hours comes from.

It also includes suggestions as to how you can improve the energy efficiency of cannabis cultivation. I will not be using this as a case study in my graduate Sustainable Engineering course this semester but it is an exceptionally well done, and complete, study.

Finally, Neil Duffie (a friend and professor in Mechanical Engineering at UW-Madison) reminded me of this poem on the "one hoss shay" following a presentation I gave in Madison late last year on sustainable manufacturing and design for sustainability.

This is a poem by Oliver Wendell Holmes about a deacon who, apparently concerned about designing things with some components that wear out or fail faster than others (hence "wasting the over designed components and the material and effort that went into them), designed a one horse shay of components and materials that lasted exactly 100 days and then totally disintegrated all at once.  For your information, a shay is a light, covered, two-wheeled carriage for two persons, drawn by a single horse - thanks Wikipedia!

I believe the horse was fine however!

The poem starts with the following lines:

"Have you heard of the wonderful one-hoss shay,

That was built in such a logical way
It ran a hundred years to a day,
And then, of a sudden, it - ah, but stay,
..."

And ends many lines later with:

"How it went to pieces all at once, 

All at once, and nothing first,
Just as bubbles do when they burst.


End of the wonderful one-hoss shay, 

Logic is logic. That's all I say."

You can find the whole story (or poem) on-line (and I know that other links can be found by searching.)

No mention of the carbon footprint of the shay unfortunately.

Oh, one more item! Karen Tworsey brought to my attention a recent posting on her site on the
"10 Wackiest Ideas Ever for Improving the Environment."Everyone has their own definition of "wacky" but, for me, the human powered floating gym is enough. And there is one with kangeroos but modesty prevents me from any more details on that one!

Best wishes for a prosperous and happy New Year!

Tools of the trade, Part 4

Building the green manufacturing pipeline

It has been a busy month of December so I am a bit behind in this posting. The good news is some of my activities helped me to frame this and the next few discussions!

In a post on October 14, 2009 I discussed the concept of "ubiquitously green" as we were getting into the green manufacturing subject in greater detail. I cited Miriam Webster (aka "the dictionary") for a definition of ubiquitous as "existing or being everywhere at the same time;  constantly encountered; widespread" and they give the example "a ubiquitous fashion." The adverb ubiquitously means, essentially, in a ubiquitous manner. Another term that could be used here is holistic - meaning incorporating all aspects.

The topic then was expanded to a discussion of the terms "design for manufacturing" (or DfM) and "manufacturing for design" (MfD). These terms are commonly used in the semiconductor industry where manufacturing restrictions often limit the capability of designers in chip design. The concept is that, from the perspective of the designer, she should be able to look down the product development and manufacturing pipeline and anticipate problems and challenges to manufacture the design or some particular feature. It's the reverse for the MfD side. The manufacturing engineer should be able to look up the pipeline and see design features and elements that are going to cause challenges. Or, ideally, see the requirements of design in advance so that the capable manufacturing processes or systems can be in place when the design rattles down the pipe to production.

This view works well with a temporal representation of the design to manufacturing to distribution to use and end of life treatment scenario. And, hence, the requirement is that throughout all the stages from extraction of materials through the process of their conversion, to manufacture and assembly of the product, its distribution and delivery, use and eventual  reuse, remanufacture or recycling, the principles of green and sustainable manufacturing should be "everywhere at the same time; constantly encountered."

I like this view. It creates a clear mental image of the various actors, almost in relay race style, handing off their piece of the process to the next person in the pipeline with the coordination and competence typical of a relay team competing in a race.

Tools to help with the design to production pipeline. I've used the image shown below to delineate the critical elements in the pipeline from a production process development and implementation view (remember I am a manufacturing engineer and the blog is titled "green manufacturing"!).

This view starts with a functional model of a process for creating the features of the part or workpiece and then continues through the prototype building (or at least solid conceptualization from the process model output) through integration with the computer aided design (or CAD) capability to insure that process scale-up can be achieved and then the details of production line layout (design and optimization), supply chains with the requisite quality gates and, finally, but not necessarily lastly, the integration of the environmental impacts, social effects, energy, material utilization, etc. for green manufacturing.

What makes this so "connected" so that the person on the process model end of the pipe (and with the specification of the part from the design team in hand) can see down the entire length of the pipeline and envision the opportunities and problems to be taken or avoided (respectively) while doing his or her part?

Simple answer - data. Data on the design; data on the materials available and their usage; data on the impacts of the process steps; data on efficiency of the factory layout; data on the distribution network and supply chain; data on the consumer usage and re-use potential; data on the recovery of materials from the product at end of life; and so on and so on.

The tools we are referring to should allow this "temporal" representation, or time dependent sequence of stages, to be compressed into the frame of view of whomever is working along the pipeline. That is, we should need no longer wait for action and reaction, then assessment and correction and repeat the process.

That's the kind of tools I am referring to. Pipeline at the speed of light - or data transfer and representation in real time.

Then we need to step back from manufacturing. What comes before? Should this be linked in to the pipeline? Meaning, should we "add some pipe" to the front of the manufacturing image illustrated above?

You bet we should!

Here is a representation of the "design to manufacturing" steps I've used before. It starts a long time before a designer starts inputting data to the CAD system. In an idealized process, we speak to the

customers to understand what they want, need. We write design specifications. We do a conceptual and then detailed design. We then hand this off to manufacturing. Actually, today, there is a lot more feedback between all these steps and, again, not as sequential as we might think.

But, the important idea is that this product creation "pipeline" is on the front of the manufacturing pipeline shown earlier.

Same story. Same need for data instantaneously available at all stages of the pipe. Same ability to see what the effect of one's impact is "downstream" in the pipeline. But, it is not a real impact if we do this right - only a potential impact. An impact we can amplify or attenuate depending on what we are trying to achieve.

Next time we'll look at some of the tools already available to enable big chunks of this pipeline and the kind and sources of data to drive this.