Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New scheduling method raises efficiency of electronics recycling

15.10.2003


An industrial engineer at Purdue University has created a method to increase the efficiency, profitability and capacity of recycling operations for electronic products such as computers and television sets.



The work also promises to open up a new area of research in a field known as scheduling.

More than 1.5 billion pounds of electronic equipment is processed every year in the United States, and the quantity of discarded personal computers is expected to rise substantially over the coming decade.


While these products contain valuable materials, including copper, aluminum and steel, they also harbor hazardous substances such as lead.

Although certain recycling centers specialize in electronic products, there is no software designed for the efficient scheduling of jobs within electronics recycling plants. Such scheduling methods are commonly used to improve production in manufacturing plants, but the goals are different for recycling applications, said Julie Ann Stuart, an assistant professor of industrial engineering at Purdue.

She has developed a method for improving the efficiency of electronics recycling by better managing the flow of incoming products from storage to disassembly.

"In recycling you have a different objective when you schedule jobs than you do in manufacturing, and you need different key measurements to achieve that objective," Stuart said. "We created the key measurements, and we identified the new objective, which may open up an area of research for a whole new class of scheduling problems."

Findings about the new approach are detailed in a paper appearing this month in the IEEE Transactions on Electronics Packaging Manufacturing, published by the Institute of Electrical and Electronics Engineers.

Scheduling is a field in which researchers develop methods to improve efficiency by carefully timing the sequence of tasks in an operation, such as a manufacturing process, in which a critical objective is to complete a product on time. Manufacturers are expected to meet "due dates," or deadlines for the delivery of products.

The priorities, however, are different in recycling; there is no due date, and it often doesn’t matter how fast the final "products," raw materials such as copper and steel, are extracted from obsolete machines, Stuart said.

Far more important to the electronics recycler is keeping plenty of space continually available in an area of the plant where products are received and briefly stored immediately before they are recycled.

Electronics recyclers earn a portion of their income just for receiving shipments. Because the arrival of shipments is unpredictable, it is important to always have enough storage space available. If the receiving area – or staging space – is full, incoming shipments have to be turned away or stored in trailers, causing a loss of income or incurring trailer rental fees, Stuart said.

"The recycler wants to empty the staging space as fast as possible to receive more materials," she said. "That’s important because they may receive three truckloads this week, one the following week, two the next week and so on."

Recyclers currently try to keep their staging areas as open as possible by first moving the products that can most quickly be taken apart. But that is not the best approach, according to the research findings.

In the new method, the largest products that can be quickly disassembled are the first to be moved out of the staging space. Stuart compared the size-based method with two other strategies, one in which the most valuable products are moved first out of the staging area and another in which the products that can be most quickly disassembled are moved first.

She found that only the size-based method improved the system significantly.

"Moving the larger objects with quick disassembly times first enables you to operate with a smaller staging area," said Stuart, who tested her method with models that simulate recycling operations. "We showed that using our scheduling policy could lower the required maximum staging volume by as much as half. If you are able to reduce the staging space from 30,000 square feet to 15,000 square feet, that represents a considerable savings in overhead."

With increased efficiency also would come greater capacity because the recycler would be able to process a greater number of products within the same space.

Stuart grouped products into families – such as computer monitors and central processing units, television sets, office and kitchen electronics – and she used the turnover rate of products in the staging space as a key measurement, or metric. To determine which objects to move first, she created a technique in which the average size of a product family is divided by the time it takes to begin processing that product.

"If you have large products that don’t take very long to start disassembling and you start with those first, you are going to free up that space faster," she said. "This is very easy to implement because you determine an average size for such a group and an average time, and then you update those averages perhaps once a year. You can then use the size-based estimates for a year to schedule products at the recycling center."

Improving plant efficiency could become an issue in the future, as state and federal policy-makers consider how to control waste from electronic products. Certain electronic components contain hazardous materials, including mercury, lead and cadmium, making it important to recycle discarded computers so they are not dumped in landfills. The number of personal computers, televisions and other consumer electronics expected to become obsolete this decade may approach 3 billion units, according to the International Association of Electronic Recyclers.

The more than 1.5 billion pounds of electronic junk processed annually includes about 40 million discarded computer components like printers, monitors and CPUs, according to a report issued earlier this year by the association.

The association report estimates that about 1 billion units of obsolete computer equipment will become potential scrap between now and 2010, and about 3 billion units of consumer electronics will be junked during that time, including 200 million television sets. The increasing flow of e-trash is expected to drive a fourfold growth of the U.S. electronics recycling industry, currently made up of about 400 companies with more than 7,000 employees.

Currently, recycling computers and television sets is not required in most places. But if new requirements are instituted in the future, recyclers will face a significant challenge trying to manage the surging flow of high-tech junk.

"If it ever becomes law to recycle electronics, it would be a good idea to use this scheduling approach so that less costly, smaller recycling centers may achieve the same objective as larger ones," Stuart said.

The research was funded by the National Science Foundation.

Stuart began the work with her student Vivi Christina while she was a faculty member at Ohio State University and completed the research at Purdue. The paper will appear in the April 2003 issue of the monthly publication, IEEE Transactions on Electronics Packaging Manufacturing, which will be available in this month.

Emil Venere | Purdue News
Further information:
http://news.uns.purdue.edu/html4ever/031013.Stuart.recycle.html
http://www.iaer.org/communications/indreport.htm

More articles from Process Engineering:

nachricht Quick, Precise, but not Cold
17.05.2017 | Fraunhofer-Institut für Lasertechnik ILT

nachricht A laser for divers
03.05.2017 | Laser Zentrum Hannover e.V.

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>