Preliminary Design Report Cover letter Title page Executive summary Project description Proposed design describe how it meets your PDS provide sketches with dimensions bill of materials budget schedule (through project completion)

Preliminary Design Report (cont’d) Design analysis evidence of design calculations (e.g, appropriate structural analyses, thermal analyses, production rates, etc.) Discussion discuss design results using PDS discuss design approaches Bibliography Appendices include PDS, shop drawings, purchase requisitions, computer models, etc. DUE FEBRUARY 20th

Design Processes

Design Considerations Performance Environment Manufacture (DFM) Assembly (DFA) Life Cycle Value Use Reliability Safety Maintenance

Engineering Design Determine the most suitable functionality. Determine the most suitable geometry (usually a trade-off with industrial design). Determine the most suitable materials. Determine the most suitable combination of parts. Determine the most suitable methods of production. Determine the most suitable methods of testing.

Design for Environmental Friendliness Each engineer should be a good steward of the earth and its resources, not just a money maker for himself and the company. The "green factor" is becoming increasingly important in all industrial activities and product design is no exception. The advertising appeal of environmentally friendly products and packaging is increasing.

Design for Manufacturing Design parts for ease of fabrication. Simple geometry Few process steps Make with existing equipment & tooling or can be easily contracted out Geometry allows easy machine tool access to machined surfaced Not too small or too large for existing processes Usual tolerances (not too tight) Design parts for multiple uses.

Design for Manufacturing (cont.) Develop a modular design. Minimize part variations. Minimize the total number of parts. Minimize the number of moving parts to produce functionality. Use geometric dimensioning and tolerancing, and be complete in your documentation.

Design for Assembly Standardize designs. Avoid the use of parts that must be held in place manually for assembly. Avoid too many levels of subassemblies on the same product. Design parts so they are easy to handle. Design parts so they cannot be assembled incorrectly. Design parts to be self aligning. Avoid designs that require the alignment of several parts.

Design for Assembly (cont.) Eliminate adjustments as much as possible. Exploit symmetry or asymmetry Maximize compliance in assembly Minimize number of different assembly directions Minimize total part count Standardize frequently used small parts Avoid separate fasteners if possible Combine the functionality of several parts into a single part

Design for Assembly (cont.) Once a part is oriented, never lose that orientation. Provide through holes for shafts and fasteners in mating parts. Use fasteners that lend themselves to strip feeding (for automatic assembly). Use funnel-shaped openings and tapered protrusions to facilitate alignment in assembly. Use modular subassemblies. Bralla, James G., 1996, Design For Excellence, McGraw Hill, New York

Design for Cost The market determines the selling price of every product or process. Profit = revenues - costs ~70% of the final cost is set in the conceptual design phase. Learn to be frugal and control costs.

Value Engineering Developed by GE in the 1940’s For each feature of the product ask "What does it do?" This will identify all of the functions which may potentially add value to the product Identify the life cycle cost of each feature. Identify the worth of the feature to the customer through market surveys focussed on functionality.

Value Engineering (cont.) Form the value ratio of worth to cost for each feature. Be sure to keep the high value features because they are what gives your product its market share. Seek to strengthen the low value features to improve the product, or simply eliminate them to reduce cost. Ullman, David G., 1997, The Mechanical Design Process, McGraw-Hill, New York.

Design for Use Avoid deceptive marketing practices. False perceptions can lead to litigation! Keep it simple! Test the product thoroughly for anthropometric fit, natural function and usability -- by hand! Use "natural mapping" in the design process -- look at how the human body naturally tends to perform the required tasks and design the product accordingly.

Design for Safety Perceived safety problems lead to litigation! Anticipate potential safety hazards in each product. Design to eliminate or mitigate them as much as possible. Apply accepted analysis techniques to evaluate design. Conduct a design review by persons familiar with different aspects of the product life cycle. Design for reliability. Design to nationally recognized standards.

Design for Safety (cont.) Design to avoid assembly errors that might cause injury. Design to avoid operator entrapment in large products. Design products with high speed moving parts to avoid ejection of shrapnel or other projectiles should the mechanism break in service. Design products with moving parts to avoid entanglement with the operator's hair, body parts, clothing, and dangling jewelry.

Design for Safety (cont.) Develop unambiguous instructions for product installation and use. (NOTE: this is best done by someone who is new to the product and must learn how to use it.) Document the risk/utility & cost/benefit considerations encountered during the design process -- especially those that involve potential hazards.

Design for Safety (cont.) Encourage dealers, sales and service personnel to report problems, injuries and economic loss related to the product back to the engineering personnel. This information is useful in evaluating design decisions and improving the safety and quality of the next version of the product. Identify the necessary maintenance to keep the product working to specification. Include safety as a primary product specification over its entire life cycle.

Design for Safety (cont.) Inform the quality control supervisor about manufacturing and assembly error limits that may result in a hazardous product. Look at potential safety issues early in the design process. Make a failure and hazards study at each stage of the product life cycle. Make a permanent record of the history of product development.

Design for Safety (cont.) Make a pilot manufacturing run with production machines and tooling to look at the effects of mass production on product safety and quality before going into full production. Make a worst case design analysis. Make safety an integral part of the product design. As potential hazards are identified, incorporate the appropriate safety features into the design. Sometimes this means using an entirely new approach in the product. Provide warning labels and user instructions.

Design for Safety (cont.) Make the design documentation sufficiently detailed so that the final manufactured product has the characteristics specified during the design process. Minimize the operational noise and vibration. Place adequate warning labels on the product for hazards that still exist. Make the language VERY simple (6th. grade reading level or lower) and include standard icons where possible.

Design for Safety (cont.) Recognize that products may be used by people who won't read the owner's manual. Make the usage of the product as natural as possible. Review the total life cycle of the product, from initial production to final disposal, to uncover potential hazards. Ask yourself what kind of hazardous situations might arise during manufacture, storage, shipping, installation, usage, service & disposal. Look at the potential behavior of trained personnel, unskilled workers, casual users and bystanders including small children.

Design for Safety (cont.) Submit a prototype product to an independent testing lab for performance and safety analysis. Test the prototype using accelerated life tests. Use 100% inspection after manufacture, where feasible. Use compulsory (government) and voluntary (industry, ASME, SAE, ANSI, etc.) standards as a base line for the design.

Design for Safety (cont.) Noncompliance with compulsory standards will usually result in quick legal problems for you and your company. Remember that standards are usually MINIMUM levels of performance. Doing better than the standard is not usually a problem. Use "fail-safe" design methods -- simply avoid product failure modes where ever possible. Work with the advertising dept. to guard against overstatement or misrepresentation of product performance.

Design for Maintenance Many consumer products, such as vehicles, need to be maintained during their life cycle. Some consumer products are designed NOT to be maintained.

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