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Software enables component reincarnation
Programs give engineers a peek at disassembly costs, and options for reusing/recycling parts
By Marne Turk, New Products Editor -- Design News, July 7, 1997
According to the American Plastics Council (APC), 12 states recently reported having less than a decade of disposal capacity left. As reported by the Department of Applied Research in Anthropology at the University of Arizona, by the year 2,000, 55% of the total municipal solid waste will end up in landfills; only 30% will be recycled.
While these numbers represent an improvement over recent years, much remains to be done to tame our throwaway society. Stricter environmental requirements, including ISO 14000, the growing number of eco-labels such as the German Blue Angel and the Nordic Swan programs, and an increase in requests for environmental guides as part of customers' procurement processes will help. But is it enough? The engineering community doesn't think so. In fact, governments, companies, and universities have quietly researched how engineering can become more eco-oriented.
Software solutions. A major factor in this drive involves designing for recyclability. To aid in this attack, Boothroyd Dewhurst Inc. (BDI), Wakefield, RI, and the TNO Institute of Industrial Technology, Delft, Netherlands, have introduced Design for Environment (DFE), version 1.0. This Windows-based software involves product engineers and concurrent engineering teams at the earliest stages of designing automobiles, computers, and other industrial, military, and consumer products.
The DFE software analyzes and optimizes the disassembly sequence of products for end-of-life recovery. The resulting data reveal cost benefits for various options, such as material recycling, part re-manufacture or reuse, and disposal through land filling or incineration. Designers can also pinpoint the disassembly sequence where major economic and ecological benefits end or where further disassembly proves of no benefit financially or environmentally.
The Product Stewardship Group at Digital Equipment Corp., Maynard, MA--working to minimize product impact on environment, health, and safety throughout the entire life cycle, while maintaining price/cost, performance, and quality standards--has been part of a consortium to help develop this software over the past two years and has evaluated several pre-release versions. "This tool provides a fast, cost-effective way to compare different design alternatives," explains Larry Nielsen, product integration manager at Digital. "We use it to give us a reliable standard on time to disassemble."
"We are working to design product stewardship features into all of our products, and that includes design for recyclability," notes Nielsen. "We see the BDI tool as a good way to show the designer how to change certain characteristics in a product that will shorten time to disassemble, making recycling much easier."
To facilitate recyclability, Digital engineers design products for easy and fast disassembly and recovery of components and raw materials after the products' first useful life. Modular product design allows for easy functional upgrade to extend product life and recovery and reuse of modules. Examples include: modular CPUs, memory, I/O, and communication and graphics options. Plastic parts are marked to identify polymer, additives, and reinforcing materials in accordance with ISO 11469, a widely recognized standard from the International Organization for Standardization. This type of marking facilitates recycling when the product reaches the end of its life.
Design for disassembly has been used on all recent Digital high-volume PC desktop products, including the new Venturis FX family. "By designing these products with disassembly in mind, end-of-life disposition allows greater recovery of materials."
Plastics progress. In other recycling efforts, The American Plastics Council (APC), Washington, DC, has teamed with MBA Polymers, Richmond, CA, to introduce a comprehensive research facility to study the recovery of plastics from computers, automobiles, refrigerators, and other durable goods. The facility integrates an array of plastics recovery, recycling, and identification technologies, and it can process more than 10,000 lbs of material per hour.
The new operation offers two processes, that according to APC are critical to effective, economical, yet complex plastics recovery: distinguishing between the many types of plastic, and separating the plastics from non-plastic materials.
The pilot line incorporates various stages in a sophisticated recycling process. It includes a size-reduction operation that can accommodate foreign materials such as metals; a state-of-the-art, multi-stage-air classification system that can produce up to four different material streams using air; and a low-energy, high-throughput wet grinding system. Once sized, the materials pass through a series of hydrocyclone separation systems to remove the remaining foreign material and to separate plastics by density.
The facility's Plastics Identification Laboratory features a collection of prototype plastic identification instruments. "Just five years ago identifying durable plastics took several minutes. For recyclers to devote minutes to identify each part isn't profitable, but that's changing. Today, the minutes have turned into nano-seconds and large, awkward equipment that was too difficult to transport has given way to hand-held instruments," says Jack Benson, chairperson of APC's Information Technology Industries Subcommittee. "We may see automated plastics identification lines with parts on conveyor belts being identified by infrared scanners in a matter of seconds," adds Benson, who is also the business development director for Dow Plastics. That vision is already coming to pass. APC plans to purchase such a system for light-colored plastics.
"The progress we've made in identification has encouraged us to believe that there will be substantial growth in the small number of product-specific streams presently being economically recovered at a purity level high enough for recycling back into durable goods," notes Benson.
If there is to be further progress in the effort to design for recyclability, economics will certainly be a driving factor. Such products as the BDI Software and more research from the likes of the APC will help provide a catalyst for a strong future.
Designing for the Environment embraces numerous Design for the Environment (DFE) principles. Some of the recommendations:
When using multiple materials, designers should ensure that all materials can be easily separated from the primary plastic.
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Using fewer materials reduces both the use of natural resources and the amount of material that needs to be recycled.
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When using more than one type of plastic, make sure they are compatible for recycling together.
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Designers can facilitate recycling by selecting materials that can be used in internal "closed loop" recycling processes. Plastic parts and enclosures should be designed to be recycled into the same part or into a different part within the same product whenever feasible.
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Whenever possible, designers should select resins and design techniques to avoid using materials that may become contaminants in the plastic recycling process.
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To facilitate product recycling, designers should avoid the attachment of plastic and non-plastic parts, as well as the attachment of parts made from different plastic materials.
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When metal fasteners are to be used in a product, carbon, or magnetic stainless steel should be preferred over non-magnetic stainless steel, aluminum, or brass.
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Once molded, engineering plastics become very difficult to identify. Testing the material is time consuming and not always conclusive. At a minimum, plastic enclosures and significant sized parts should be marked according to ISO Standard No. 11469.
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