In an ideal world, electronic products would never go into a landfill when they reach the end of their useful lives. Instead, all of the materials used to make them would be fully recovered and reused. The manufacture of electronic products, like organic farming, would be a sustainable activity that doesn't significantly deplete the world's natural resources.
We don't live in such a utopian world, of course, but a new directive from the European Union is moving us a little closer toward it. The directive on Waste Electrical and Electronic Equipment (WEEE) requires that nearly all electronic products sold in Europe be put to new good use when they reach obsolescence. Under WEEE, 75% by weight of an end-of-life product must be remanufactured, reused, or recycled. A maximum of only 20% can be sent to a landfill.
That's the good news. The bad news, for manufacturers of electronics, is that WEEE makes them responsible for recycling their own end-of-life products, thus increasing their costs, not to mention headaches. Some additional good news, though, is that engineers are learning to design products that are easier and less expensive to recycle, pushing costs back down.
Actually, WEEE permits not just recycling to reach it goals, but also remanufacturing and reuse. However, all require at least some systematic disassembly (also sometimes called demanufacturing or inverse manufacturing) of end-of-life products. Consequently, there has been a surge of interest in a concept called designing for disassembly, or DfD, that first sprang up about 10 years ago. DfD's purpose, quite simply, is to design products that are quick and easy to take apart.
Designing for Disassembly
Disassembly is already faster than you might think. In less than five minutes, trained workers at recycling centers can manually disassemble a computer and sort all of its plastics and its ferrous and nonferrous metals in preparation for recycling. (See sidebar, Recycling e-waste.)
At Intercon Solutions, a company that specializes in recycling computers and other electronic products, workers disassemble a CPU tower in a minute or two, a hard disk drive in another couple of minutes, and a monitor in another minute or so. "We literally take everything apart by hand," says Timothy Osgood, director of corporate recycling. The process eventually recovers steel from computer casings, aluminum from the platters in disk drives, and copper and other metals from circuit boards. The metals go to a refinery for recovery. Plastics, if pure enough, get processed and recycled. Otherwise, they're burned under controlled conditions for energy recovery.
Intercon is different from most electronics recycling companies in that it concentrates exclusively on recovering raw materials. It doesn't strip and resell components, and it doesn't send any e-waste to landfills or overseas. Nor does Intercon shred any e-waste, a common practice that makes material easier and less expensive to transport, but at the same time makes it more difficult to recycle.
For many companies, though, component resale and exporting are big parts of the business. Resale and exporting help make recycling less expensive, they say, and exported items such as used monitors and disk drives enable the production of affordable computers for populations that otherwise would have to do without. Critics counter, however, that exporting e-waste merely shifts environmental problems from industrialized nations to less developed ones, particularly in Asia. They site numerous reports claiming that e-waste containing hazardous substances has created dreadful environmental hot spots.
"It's time and money," says Intercon's Osgood. Labor costs are much lower overseas, he says, but "you don't have OSHA, you don't have EPA." And, he notes, a lot of exported e-waste contains no reusable components, but is merely a shredded mix of materials. "There are processes and shredders that separate out ferrous and nonferrous metals and plastics," he says, "but about 30% ends up as a mish-mash that's made up of everything else. There's really nobody in the United States that can profitably recover any of the materials that are in the mish-mash, so that 30% ends up going overseas."
Traditionally, shredding has been the easiest and least expensive way to deal with e-waste, even though it greatly reduces the materials that can be recovered, not to mention the components that can be saved and reused. The practices of designing for disassembly and designing for recycling aim to change that, however. Designing for disassembly makes electronic products easier, faster, and thus less expensive to take apart. Designing for recycling helps ensure that the materials in electronic products are compatible with recycling processes and are thus recoverable.
But manual disassembly may not be fast enough. Under WEEE, the cost of disassembly and subsequent recycling becomes part of a product's cost and thus affects the bottom line. Manufacturers will be motivated to reduce this cost, just like any other, and speeding up disassembly in any way can help do that.
And speeding up disassembly, for all intents and purposes, means speeding up manual disassembly. Automating the process is difficult and seldom cost effective. So-called active disassembly, in which products are designed to more-or-less fall apart upon application of some stimulus, such as heat, is still some ways in the future. Besides, designing products for easier manual disassembly is a good technology stepping-stone toward automated and active disassembly.
Faster disassembly, according to DfD experts, involves the selection of components, materials, and fasteners. You minimize components so that there are fewer pieces to take apart, and you minimize the number of types of fasteners so that disassembly is faster and requires fewer different types of tools. Minimizing the number of different materials makes it easier to sort the materials for the eventual processes of recovery and recycling.
Electronics engineers, of course, will be mostly involved in the selection of electronic components. Often, they will have few choices, although semiconductor manufacturers, in according with another European Union initiativethe Reduction of Hazardous Substances (RoHS) directiveare at least now producing many components without lead and some other harmful substances. That's important to design for recycling, because separating out harmful substances is often the first step of the recycling process. If there are no harmful substances to remove, the process becomes shorter.
Materials and Fasteners
The more significant choices, however, are in the areas of materials and fasteners. It can be said that the choice of fasteners is at the heart of design for disassembly, and it can equally be said that the choice of materials is at the heart of design for recycling. Fasteners present myriad opportunities to make products easier to disassembleand to assemble, for that matter. And many materials that may seem similar, aren't similar at all when it comes to recycling processes and therefore can't be processed together.
In the disassembly of electronic products for recovery and recycling, materials fall into the categories of plastics, ferrous metals, and nonferrous metals. After a product has been disassembled, large magnets can separate out the ferrous metals. Separation of nonferrous metals from plastics is made possible by fairly large differences in density.
But not all metals, or plastics, are created equal when it comes to recycling. Aluminum, for example, is more difficult to recycle if it has been contaminated, even slightly, with any copper, lead, magnesium, iron, or steel. Likewise, the recycling of steel suffers from contamination by aluminum, copper, tin, or lead. Consequently, plated metals are more difficult to recycle, and therefore have lower value in the recycling market, than unplated metals.
A mix of different types of plastics also presents difficulties in recycling. Many seemingly similar plastics can't be recycled together, and many plastics in electronic products are also painted, which introduces contamination. According to the Systems Realization Laboratory at the Georgia Institute of Technology, even 1% of paint contamination can ruin a batch of plastic for recycling.
When it comes to the nuts and bolts of choosing fasteners, a primary goal of design for disassembly is the elimination of nuts and bolts. DfD experts often recommend using snap-fit fasteners, for example, that work without the use of tools. The Minnesota Office of Environmental Assistance, which provides guidance to Minnesota businesses, notes that snap-fit fasteners come in a variety of types and that many are suitable for repeated assembly and disassembly. The snap-fit flaps found in radio and calculator battery compartments are good examples.
If you do need to use a fastener like a screw, Georgia Tech recommends creating a hole for it that goes completely through the material to which it's attaching something. That way, it can be tapped out during disassembly instead of being unscrewed. Better yet, says Georgia Tech, use a molded-in fastener or a separate fastener made of the same material, so that fastener removal might not even be necessary before recycling. Next in priority would be to use a fastener made from a ferrous metal. Very often, all or parts of equipment being recycled goes through mechanical shredders; ferrous fasteners can be pulled from a mass of shredded material by means of magnetism.
Adhesives, unfortunately, are a bad bet as fasteners. They make disassembly difficult, and they can contaminate any plastics they fasten, making them unsuitable for recycling. Experts caution that if you do use adhesives, make sure they're compatible, in the recycling sense, with the materials they fasten.
Instead of adhesives, the Minnesota Office of Environmental Assistance recommends ultrasonic welding. It's important, however, that any plastic parts to be welded together are the same resin type. If the welded parts are made of dissimilar plastic resins, they probably can't be recycled.
A list of DfD tips could go on and on. Many universities, in fact, now offer entire courses in DfD. This is especially true in Europe, where environmental mandates are generally more prominent and strict than in the US and where WEEE will affect almost every electronic product sold.
The "how to" aspect of designing for disassembly and recycling can never take a back seat to economics, however. With manufacturers now bearing the cost of recycling their products, disassembly and recycling have to be not merely possible, but also cost effective. That means trying to minimize disassembly time while more completely separating the various recovered materials, thus increasing their value. Finding a good balance, experts say, can be difficult.
Unfortunately, automating the process of disassembly is seldom a viable option. "It is incredibly difficult to totally disassemble most electronic products with automation," according to the Department of Design and Technology at Loughborough University in the U.K. The department's Web site on WEEE also notes that automation requires disassembly of many similar products, preferably of the same make. In addition, automated disassembly typically produces "cruder fractions"materials that aren't well separated and thus have lower value.
In the long term, automation and greater efficiencies will probably come about through what's called active disassembly, in which products partially disassemble themselves. Products manufactured for eventual active disassembly contain fasteners, usually made from shape-memory alloys, that release when exposed to an appropriate stimulus, such as heat. Application of the stimulus is to an entire product or component, not to specific fasteners, so one automated action can replace numerous manual steps. Nokia has built a prototype mobile phone using active-disassembly fasteners, and in one experiment disassembled the phone in two seconds, compared to 100 seconds manually.
For now, though, designers have to learn to make their products easier and faster to disassemble manually. They also have to learn to use materials that are easy and economical to recycle. Both requirements can have a negative effect on product performance and cost.
But designing for recycling, and particularly designing for disassembly, can actually lead to improvements and savings. Designing for disassembly in many ways is similar to designing for manufacturability, which can reduce production costs. The careful selection of materials can result in more materials recoveredand resold or reusedduring the recycling phase.
There's little time to waste, though, in learning the ins and outs of designing for recycling. WEEE, scheduled to go into effect in August throughout Europe, has been delayed by bureaucratic holdups in some countries, but probably only for a few months. Soon, as noted by an executive at an American company that specializes in recycling electronics, "it's going to change the way companies do business."
About the Author
Gary Legg is a Boston-based freelance writer. He holds a BSEE degree and is a former editor and executive editor of EDN magazine. He can be reached at firstname.lastname@example.org