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DFE

(1) How does adding a Design for Environment capability to the Boothroyd Dewhurst, Inc., Design for Manufacture and Assembly (DFMA™) software help manufacturers achieve “green” or “sustainable” programs for their products?

This new DFE capability identifies and rates materials for their compliance to changing standards regarding toxicity and end-of-life destinations. Our motivation for adding this software enhancement largely comes from introduction of such EU legislation as the Waste from Electronic and Electrical Equipment (WEEE) directive and the Motor Vehicles directive. Manufacturers must demonstrate that their new products don’t contain certain banned materials—Restriction of Hazardous Substances (RoHS) compliance—and that a certain proportion of the product is reusable or recyclable at end-of-life.

DFMA software can be deployed at the earliest stages of product development when designs are often just rudimentary geometries without detailed computer-aided design (CAD) features. This is often the easiest and certainly the most effective stage for manufacturers to address the issue of DFE material selection.

Integrated DFMA/DFE analysis provides design and manufacturing cost savings, warns design teams about materials to avoid, and documents environmental compliance.

2) How does the DFE capability in the DFMA 2009 software release differ from sustainability efforts already underway in product engineering companies?

DFMA 2009 supports sustainability initiatives by raising awareness of recycling and remanufacturing options at the design level. The software currently does not include additional life-cycle analysis (LCA) costs or assessment of disassembly effectiveness.

DFMA product simplification with DFE capability helps compress greater performance into fewer parts—guiding design engineers to use the most sustainable and cost-effective materials and manufacturing processes. DFMA product evaluation opens numerous doors to sustainable, innovative design.

3) What information is in the DFE portion of DFMA 2009?

The DFE portion is integrated with the materials library of the DFM Concurrent Costing database of DFMA 2009. This library gives designers a comprehensive understanding of the costs to manufacture parts by means of turret pressworking, laser and plasma cutting, sheet metal stamping with a variety of dies, machining, structural foam molding, plastic extrusion, injection molding, thermoforming, blow molding, cold and hot die casting, hot forging, powder metal processing, sand casting, investment casting and metal injection molding.

Existing DFMA data for each individual material associated with the above shape-forming processes has been expanded to include DFE information. Materials in the software are now classified for the designer as ferrous metals, non-ferrous metals and other, and they are categorized as “preferred,” “non-preferred” and “avoid.” The “avoid” category will include materials on the EPA banned substances list, and─for European software─materials that will prevent RoHS compliance. The software estimates and designates the proportions of product that go to different end-of-life destinations, including reuse, recycling, landfill and incineration.

During DFE analysis, items in the product that are designated to be recycled, and that include mixed materials, are understood to be processed by bulk recycling. During bulk recycling, items are shredded; the resulting material mix is separated by magnetic and eddy current separation. The software assumes that ferrous and non-ferrous metals can be readily separated from the shredded-materials mix, while other materials cannot. Some stainless steels, although ferrous-based, are non-magnetic and consequently are designated “non-ferrous.”

Manufacturers can easily add their own preferred DFE materials to the DFMA database, or just to the specific project analysis they have underway in the software.

4) Who is the primary user of the DFMA-plus-DFE analysis and why?

The new DFE capability has been developed for easy use by the design engineer at his or her work station. No life-cycle data is currently generated by the software, so an LCA expert is not required at this level. Some input on the recyclability of various materials may be needed, depending on the specialization of the manufacturer.

The goal is to allow product development teams to make quick, basic decisions about environmental impact issues early in the process of defining products. This approach recognizes the challenges design engineers face integrating numerous product requirements, and it promotes the creation of “greener” products.

5) What does Boothroyd Dewhurst, Inc. bring to the field of DFE analysis?

Boothroyd Dewhurst has been in the Design for Environment (DFE) business for 15 years. Its development team has worked extensively with major manufacturers and researchers toward a fuller understanding of the role that product design and manufacturing can play in reducing negative environmental impacts.

DFE is not a start-up effort for the company. Depending on the readiness of the market to implement meaningful environmental programs, Boothroyd Dewhurst, Inc. will consider launching software upgrades based on its years of research in product disassembly methods and cost and end-of-life analysis.

The company’s particular expertise is in bringing environmental knowledge into the product design process very early, starting at the conceptual stage with raw shapes and continuing through the feature-building, advanced-costing stages of product design. This is what currently distinguishes DFMA 2009 from CAD/CAE/PLM product design tools that offer environmental compliance checks of Bill-of-Materials (BOM), or help create environmentally friendlier designs by targeting weight and material optimization. Such efforts generally take place after CAD models are extensively detailed. Likewise, proprietary internal LCA expert programs at leading manufacturers are often deployed as add-on requirements for the designer, usually after work on a BOM has already begun.

Boothroyd Dewhurst, Inc. feels that both environmental and product cost decisions need to be made together as early as the conceptual design stage.

6) What trends do you predict for the green product movement?

We expect considerable emphasis on the improved energy efficiency of products during use and manufacture, including resource conservation.

Companies are only beginning to address the ramifications of legislation, such as WEEE and RoHS, that will affect the marketability of future products.

Eventually, it is possible that DFMA approaches will work side-by-side in the future with PLM-based systems for design, optimization, visualization, and tracking of design and business structures.

MACHINING

1) How does the new Quick Estimator for machining differ from the full machining analysis available in the Boothroyd Dewhurst, Inc. DFM Concurrent Costing portion of DFMA 2009?

The difference lies in the way the machining process cost is estimated.

In a machining full analysis, the process cost estimate is based on the individual machining operations that are required to manufacture the part. Manually, the user adds each machine tool, individual machining operation and cut dimensions to the analysis. The cost for every movement of the cutting tool is estimated for each operation.

The machining Quick Estimator focuses on two factors: the volume of material removed during rough machining, and the surface area generated during finish machining. The user selects the volume of the finished part, the number of part features produced by various machining operations and the surface area of those features. The software chooses machine tools automatically, based on the weight of the work piece and classification of the machined part’s overall shape. For this data, the quick estimator software’s algorithms estimate cutting-tool movements.

The machining quick estimate requires less specific knowledge of machine tools and machining operations, and can be conducted more quickly than a machining full analysis.

When comparing overall part-cost estimates, smaller parts─toothpick-sized or so─tend to yield the largest errors but are still within 15 to 20 percent of a full analysis. As parts increase in size, the margin of error decreases rapidly.

2) Can this DFM Concurrent Costing Quick Estimator capability support overall supply-chain negotiation, or specifically help internal machining departments at OEMs and contract manufacturing firms?

OEMs have always wanted a tool that a less knowledgeable estimator can use to assess the cost of parts quickly. This translates directly into money savings and increased productivity.

Armed with costs for machined parts from the Quick Estimator, design teams can select an economic manufacturing process before designing the part. The same cost results also can inform supplier price negotiations and costing out competitors’ products.

The type and amount of information necessary for a machining quick estimate is similar to that required for the other non-machining processes in DFM Concurrent Costing. In comparison, machining full analysis requires the largest amount of process-specific knowledge and takes more time.

3) Is there a difference in the cost reports or other data outputs when comparing the new Quick Estimator with the full Boothroyd Dewhurst, Inc. DFM Concurrent Costing machining analysis?

With a full analysis, the cost of each individual part feature can be determined by totaling the cost of the operation required to make the feature. A quick estimate provides only the total cost of all machining operations.

CELL MACHINING

1) Explain cell machining and Boothroyd Dewhurst, Inc.’s new cost-estimation software.

In cell machining, two types of cells are used: dedicated cells and non-dedicated cells.

Non-dedicated cells are groups of machines set up to process families of related parts, reducing the non-productive time due to machine changeover in batch production. Individual parts may not visit every machine within the cell.

Dedicated cells are set up to process one part, in particular when processing on a single machine is not possible─for example, when milling and grinding operations are required. Used generally for larger quantity production, dedicated cells may also be treated as a single cost center for accounting purposes.

Previously, the software was used to estimate costs for individual parts in non-dedicated cells, with the addition of realistic machine-changeover times. By adjusting the responses suitably, costs for dedicated cell machining could also be estimated.

The new addition to the software makes this cost exercise for dedicated cells more transparent for the user by automatically combining individual processes, times and costs within the cell.

Boothroyd Dewhurst, Inc. added the dedicated-cell software at the request of users such as Harley-Davidson.