In the past, we engineers were charged with considerations such as Design for Manufacturing, Design for Assembly, cost targets, production targets, margin targets, tooling considerations, lead-time and other factors. Now, the new consideration is Design for Disassembly, sometimes referred to as Design for Destruction. Just as manufacturing or assembling is a process to be optimized, disassembly or destruction of products to be recycled is a relatively new process and needs to be optimized.
Professor Tim Gutowski of M.I.T. suggests the following ‘top 10 list’ of considerations during
design to help with later disassembly for recycling:
1. Reduce the number of components
2. Reduce the number of separate fasteners
3. Provide open access and visibility for separation points
4. Avoid orientation changes during disassembly
5. Avoid non-rigid parts
6. Use common tools and equipment
7. Design for ease of handling and cleaning of all components
8. Reduce the number of different materials
9. Enable simultaneous separation & disassembly
10. Facilitate the sorting of non-compatible materials
Eric Leafquist, Product Manager at SolidWorks, suggests the following procedures, and notes that his firm offers design tools to help.
Minimize material types and maximize the use of these materials. After European Directives mandated the recycling of automobiles, the manufacturers drastically reduced the number of plastics used in order to simplify recycling. In SolidWorks, the manufacturer can create its corporate ‘allowed materials’ database with all the structural, physical, thermal and other properties. These data are available for determining things such as weight and cost of the part. These data are also available to feed the SolidWorks Simulation tools to use finite element analysis (FEA) to help ensure material need and part strength. This shorter list of available (allowable) materials may initially make engineers feel constrained in their design options but simulation can help optimize parts. For molded plastic parts, Solution Partner products help simulate the manufacturing of these parts to speed part design and refinement and help develop key aspects like mold runner designs to reduce waste and the need to reprocess post-molding materials.
As designs are required to be packaged more efficiently, tools such as COSMOSFloWorks enable heat transfers checks to ensure proper thermal performance.
Hold products together: Eliminating fasteners typically speeds assembly and disassembly. SolidWorks includes an assortment of Fastening Features to speed the design of snap fit features, alignment bosses, etc – well suited for molded part design. Molding in fastening features often speeds assembly, disassembly and eliminates the cost and complications of metallic fastener and molded-in inserts. A product called Toolbox provides a library of fasteners and standard hardware. Design management can customize this to help control and limit the range of fasteners available for use by engineers in their designs. This helps ensure use of existing parts already qualified for design for disassembly.
Workflow management and design tracking: PDMWorks Enterprise is a product data-management tool. This enables the enterprise to track CAD data and manage the workflow in the product-development process. Materials recycling considerations for key products such as batteries and PCBs can be added to the components. PDMWorks Enterprise can track hazardous substances. This data can be shared with ERP/MRP systems and can further streamline certification processes like RoHS, ISO, and environmental compliance.