Monday, July 25, 2011
Where does the material go?
California is used to the concept of getting more from less. We only have to recall now Governor Jerry Brown's comments when he was governor the first time from 1975 to 1983 and declared that University employees shouldn’t complain about low pay because, as academics, they were getting “psychic rewards.” As a UC faculty member we are now seeing dramatic reductions on state support of education as the campuses, specially Berkeley, charge forward to keep our programs strong. Psychic indeed!
We are not talking about psychic rewards here or starving critical institutions!
We've been talking about making better use of what we start out with (the yield or "buy to fly ratio" approach) as well as process and product design for better results with lower impact.
I have been making good use of Professor Julian Allwood's research at Cambridge University to make the first point. His WellMet 2050 study is inspirational. We'll see more from that below.
Others, like the Air Force SAMI as well as corporate programs are making inroads on this as we discussed in the last posting. TMS (The Minerals, Metals and Materials Society) has produced, with support from the DOE and a host of others, a report in January 2011 titled "Linking Transformational Materials and Processing for an Energy-Efficient and Low-Carbon Economy: Creating the Vision and Accelerating Realization." You can download this report from TMS.
The report presents a prioritized set of new products and technologies prepared by TMS working groups focussed on the following themes:
- Functional Surface Technology
- Higher Performance Materials for Extreme Environments
- Multi-Materials Integration in Energy Systems
- Sustainable Manufacturing of Materials
It is a comprehensive forward-looking review of technology.
There are some obvious (to me) gaps however. For example, in the focus on sustainable manufacturing of materials the group highlighted:
- Net-Shape Processing of Structural Metals (that means making things to a final or near final shape without removing material - such as forging)
- Additive Manufacturing of Components and Systems (combining process or materials in reduced number of operations; but not necessarily rapid prototyping - the term usually associated with additive manufacturing)
- Low Cost Processing and Energy Reduction Technology for Metals (reducing the energy requirements for primary processing of metals like titanium, aluminum and magnesium)
- Separation of Materials for Recycling (promoting increased recycling rates), and
- Real-Time Sensor Technology for Gases and Molten Metals (feedback for process optimization and control).
I did not see much reference to increasing yield (except in the net-shape area) but certainly not at the level of importance to address the tremendous losses pointed out by Allwood.
So, let's pick there from the part 2.
The last posting presented a graphical representation of the cumulative yield (output over input) through several process steps and the accompanying cumulative process energy (energy/ton of material input). During the process steps, typically, yield is reduced (meaning material ends up on the shop floor) and, due to processing and material loss, the cumulative energy increases. As noted in the WellMet 2050 report "Going on a Metal Diet" that is the basis of this discussion "…these graphs will show that the (already energy efficient) process of liquid metal production dominates the cumulative energy build-up but yield losses in the downstream supply chain can increase the embodied energy in the final component by a factor of up to 10." Up to 10x increase due to downstream yield losses!
I mentioned that Allwood's study had looked at four case studies. I don't want to repeat the report here (and encourage you read the whole report) but let's look at the cases for aluminum. The figure below shows the cumulative energy (reference to the original liquid aluminum) as a function of cumulative yield (actual product to input liquid metal) for three of the case study products (and click on the
image for better detail) investigated - car door panel, aircraft wingskin panel and beverage can. The various steps in production, from liquid, are shown by the open circles on the graph.
Lines connecting the circles going vertically (or more vertical) indicate processes that preserve yield (that is, less wasted material). Lines going horizontally, (or more horizontal) indicate processes that reduce yield (that is, waste material). This is not necessarily to imply that the material is wasted gratuitously but that the inherent aspects of the process are not able to make efficient use of the material.
For instance, the door panel example, indicates that from cast ingot to stamped panel there is a tremendous loss of material (yield from 1 down to 0.4 meaning 60% of the material not ending up in the product) The actual "buy to fly ratio" would be better than the 0.4 shown on the graph for door panels since the auto manufacturer is unlikely to by aluminum in liquid form. More likely the material enters production as cold rolled coil (at approximately .7 yield) and then is converted to the panel. So, buy-to-fly is closer to 50% form the auto manufacturers perspective.
But you see how this does not tell the complete story - specially with respect to the cumulative energy - since most of that is in the liquid to cold coil processing.
Beverage cans are a similar story. Most material is "lost" from the ingot to cup stage. The can producer likely gets the stock as cold rolled coil. From there, the losses due to can production take the yield from approximately 0.7 to 0.55. From the perspective of the can maker, perhaps, this is a reasonable buy-to-fly ratio.
The figure below, from Kalpakjian and Schmidt's manufacturing text (presented on line), shows a schematic of can making from the original blank through the drawing process and the addition of the cap.
There are two major sources of process related material loss - the blanking of the disks used to start the forming process (think cutting circles out of square sheets) and the disk to first cup process due to the requirement to be able to hold on to the end of the disk during this first stage. There is some trimming at the end also. A similar process is required for the lid which, although not as deeply "drawn" still starts as a circle from a square sheet.
The least efficient from a materials efficiency point of view is the wing skin panel (and recall our earlier comments about aerospace buy-to-fly ratios). This ends up with an overall yield (from melt) of less than 10%. Assuming the manufacturer gets the material as rectangular plate (at about 45% yield) their part of the process yields a buy-to-fly of around 25%.
Recycling, oft mentioned with aluminum and other metals, will help, some. The problem is that with "low yield products" a lot of the material "going back into the pot" will not be post consumer waste but production waste. In the case of aerospace components most of that waste is in the form of metal chips removed to get the desired shape. Granted, aerospace is a special case due to the requirements of the product but this is a lot of material to leave on the shop floor. Composite materials will try to address this but they have material efficiency issues as well.
Next time we'll start the discussion about getting more from the material and, specifically, analysis tools to help us do that.
Monday, July 4, 2011
And now a word from the government!
In honor of the 4th of July celebration here in the US I am taking a break from our discussion about "less is more" to focus on major initiatives to move the cause of green manufacturing forward - these from the government. The discussion on "less is more" will continue with part 3 next time.
We've heard a lot about some of the major corporations and the initiatives they've taken to enhance the sustainability of their organizations and influence their supply chain. One of the first that comes to mind is Walmart and their efforts to insure the products they sell, and their operations delivering them, are "more efficient, last longer and perform better." There are many more players in this field and a simple glance at Environmental Leader or GreenBiz website will give a great introduction and allow you to track their progress.
For example, one recent item on GreenBiz refers to Marks and Spencers "carbon neutral bra" program which complements their "carbon neutral undies." These are, according to GreenBiz, "a way to showcase an energy-efficient factory in Sri Lanka that was built as part of Plan A. The factory is powered, in part, by solar energy and hydropower." (Plan A = Marks and Spencers sustainability effort; 'because there is no plan B'). It was also an exercise in carbon footprinting since the bra contains some 21 component parts from 12 different suppliers. The article states that M&S are offsetting the CO2 generated by the bra’s manufacturing and shipping by planting 6,000 trees in Sri Lanka. Since some of these trees are lime and mango trees there is the potential to generate income for farmers in the area.
Meanwhile, on the US fashion-eco front, one of our research collaborators Sarah Krasley, alerted me to the fact that Lady Gaga's infamous meat dress will become an exhibit in America's Rock and Roll Hall of Fame Museum. The "dress" from the 2010 MTV Video Music Awards will be part of a display at the museum in the 'Women Who Rock: Vision, Passion, Power' exhibition. Another reason to visit Cleveland this summer.
You will recall that the outfit was made entirely of raw animal flesh and generated an "environmental reaction" which I commented on. The dress has apparently been preserved to prevent deterioration so is, according to Sarah, likely to be rather like a "jerky dress."
But the story here is on government initiatives. First, one announced by President Obama recently on manufacturing.
Berkeley will be one of the six universities in the US participating in the Advanced Manufacturing Partnership (AMP). The AMP is being developed based on the recommendation of the President’s Council of Advisors on Science and Technology (PCAST), which released a report June 24 entitled “Ensuring Leadership in Advanced Manufacturing.” The PCAST report calls for a partnership between government, industry and academia to identify the most pressing challenges and transformative opportunities to improve the technologies, processes and products across multiple manufacturing industries.
According to the PCAST report, manufacturing has been declining as a share of U.S. GDP and employment, and the loss of U.S. leadership in this domain has not been limited to low-wage jobs in low-tech, conventional industries; the United States is also trailing in high-tech industries that employ highly-skilled workers. The U.S. trade balance in advanced technology manufactured products shifted from surplus to deficit starting in 2001, according to PCAST.
The report lays out three compelling reasons why the US should strive to revitalize its leadership in manufacturing, and in particular advanced manufacturing, as:
1. Jobs: Manufacturing that is based on new technologies, including high-precision tools and advanced materials, can provide high-quality, good-paying jobs for American workers.
2. Innovation: It is not enough to invent in America and manufacture abroad. By keeping manufacturing local, a number of synergies ensue through which the design, engineering, scale-up, and production processes feed back on the conception and innovation sectors to generate new ideas and novel second- and third-generation products.
3. Security: Domestic manufacturing capabilities using advanced technologies and techniques are vital to maintaining national security.
One of the specific program goals is increasing the energy efficiency of manufacturing processes; and developing new technologies that will dramatically reduce the time required to design, build, and test manufactured goods.
First of all, anything that shines a little more light on manufacturing is great. Second, one of the objectives is energy efficiency of manufacturing processes. To me, this includes all of the approaches to green manufacturing we've been discussing here. The "design to production" element is also good for greening manufacturing if we can insure that sustainable design decisions are made early in the process and, to re-iterate Walmart's focus, make sure products are more efficient, last longer and perform better.
For our part at Berkeley we'll make sure that green manufacturing, as part of jobs, innovation and security, is an integral part of the discussion.
But there is more, also from a government organization. This time the Defense Department.
The Air Force has launched a sustainable manufacturing initiative. This in response to the 2010 Department of Defense Strategic Sustainability Performance Plan (SSPP). The SSPP identifies goals for meeting the intent of Executive Order 13514 “Federal Leadership in Environmental Energy and Economic Performance.” An essential component to sustainable acquisition and procurement is sustainable manufacturing.
A white paper on line gives a lot more detail on the Air Force ManTech Sustainable Aerospace Manufacturing Initiative - acronym SAMI. From the white paper, the purpose of SAMI is to "fulfill Department of Defense (DoD), AF, and industry strategic intent for sustainability by maturing sustainable manufacturing practices that will enhance the production capability necessary to process and fabricate DoD weapons systems with optimized energy footprints and environmentally sustainable processes while preserving performance requirements." SAMI operates out of the Wright-Patterson Air Force Base Materials and Manufacturing Directorate.
Specific program goals include:
- Develop assessment tools for identifying manufacturing process step-changes
- Demonstrate sustainable technologies in military unique process
- Design for sustainability
- Produce military systems with less energy
- Minimize environmental impacts
- Reduce environmental footprint associated with manufacturing without compromising capability or end product performance
The Air Force is partnering with a number of organizations on this including the LMAS of UC-Berkeley (my lab), the NCDMM in Pennsylvania, and several organizations in the supply chain such as General Dynamics Ordnance and Tactical Systems, Remmele Engineering, and GKN Aerospace in addition to others.
The importance of all these initiatives, from Walmart and Marks & Spencers to the Air Force, is that they are laying the groundwork for systematically designing, procuring and manufacturing, distributing, selling and, eventually, recovering products covering a wide range of "consumer needs."
Big organizations driving big effects. That's worth some fireworks!
Next time we'll continue with "less is more" part 3.