Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:1 Environmentally Conscious Design & Manufacturing Class 18: Recycle Prof. S. M. Pandit

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:2 Agenda Definition of recycling Hierarchy of recycling Design for recycling Recycling metals, plastics & forest products Economics

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:3 Definition of Recycling American Automobile Manufacturers Association’s definition A series of activities, including collection, separation, and processing, by which products or other materials are recovered from or otherwise diverted from the solid waste stream for use in the form of raw materials in the manufacture of new products.

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:4 Some Myths - 1 Recycling should pay for itself -Bias in data collected, and the inability to recognize large scale impact has led to reports of “expensive recycling” -$200 of energy is saved per ton of material recycled

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:5 Some Myths - 2 Environmental impacts of manufacturing are included in the products -Cost = function of: »supply & demand »governmental policy »problems with assigning cost

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:6 Source: Bishop, “Pollution Prevention: Fundamentals and Practice” Life Cycle of a Product

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:7 Recycling World Categories: -Portable high value (computers, auto parts) -Metals -Plastics -Paper -Chemicals & glass -Food waste -Used equipment -Building material

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:8 Typical Value for Vehicles

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:9 Hierarchy of Recycling Options Source: Bishop, “Pollution Prevention: Fundamentals and Practice”

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:10 Steps of Recycling For remanufacture and reuse: Disassembly Cleaning Sorting and inspection Part renewal Re-assembly

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:11 For material recycling: Separation Discrete subassemblies / joining techniques Sorting Group or classify Reprocessing technology Steps of Recycling (cont.)

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:12 Possible Separation for Materials Source: Bishop, “Pollution Prevention: Fundamentals and Practice”

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:13 Example: Polymer Recycling

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:14 Design for Recycling Multiple objectives Minimize variety of materials & components Avoid use of toxic materials Ease of disassembly of dissimilar materials

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:15 Disassembly Design for Disassembly (DFD) Ease of Disassembly -Preferred design: snap-fit, pop-in, pop-out, bolted or screwed components -Difficult design: welded, adhesive, threaded connections

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:16 Disassembly (cont.) Simplified Design -Reduce the number and types of parts -Reduce product complexity Modularity Design Material Selection -Facilitate identification of materials (e.g. Marking plastics) -Use fewer types of materials -Use similar or compatible materials

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:17 Disassembly (cont.) Non-Destructive Disassembly (NDD) -Minimize the destruction of the product -Maximize the potential of material resource and sub-component reuse Destructive Disassembly (DD) -Destroy one or more components so that the others can be disassembled -Save more expensive components -Recycle materials

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:18 Disassembly (cont.) Disassembly Strategy - Analyze feasibility of part reuse and materials recovery - Generate optimal disassembly sequence - Disassembly optimization (Lower disassembly cost, higher rate of component reuse, higher rate of material recycling, etc.)

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:19 Recycling Metals Mixed metals (plating) - expensive Pure metals - very inexpensive Separation techniques: -Manual -Automated magnetic separation -Chemical separation »Pyrometallurgy, hydrometallurgy, electrometallurgy

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:20 Recycling Plastics Thermoplastics - easy -Polyethylene terepthalate, polyvinyl chloride, low density polyethylene, polypropylene Thermoset plastics -Phenolics, polyesters, epoxides: - crosslinking, need pyrolysis / hydrolysis to reduce mol. Wt.

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:21 Recycling Rubber Mechanical Recycling Feed Stock Recycling Energy Recovery Use as is (Retreaded tired, fishing banks, etc.) Powdered rubber (Block, road paving, etc.) Reclaimed rubber (Devulcanization by the PAN reclaiming Thermal decomposition, etc Recovery of heat energy Source: Otsuka et al., SAE 2000 world congress

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:22 Recycling Forest Products Paper -Fibers get shorter with use & recycling »White bond »Colored bond »newspaper »grocery bags »toilet paper

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:23 Economics Recycling must be profitable Revenue from recycling: -High value, reusable subassembly and parts -Recycled materials and energy Cost incurred by recycling: -Investments in recycling equipment -Labor cost -Other cost such as transportation, equipment operating

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:24 Economics (cont.) Number of Disassembly Steps Cost Landfilling Cost Disassembly cost

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:25 References Graedel & Allenby, Industrial Ecology, html c.html html

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:26 Homework #6 1How is the manufacturing economics affected by environmental considerations? (Illustrate your answer by using machining as an example) 2What steps would you take in a quantitative decision making process? What are the different tools available in this process? 3Compare and contrast traditional and ECDM guidelines for material selection.

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:27 Homework #6 4Why is recycling of plastics so important for the ECDM efforts? Give relevant statistics to support your answer. 5What are the major hurdles in recycling of plastics? How can they be overcome?