Chapter 10 Managing Engineering Design

Advanced Organizer

Chapter Objectives Describe the phases or stages in systems engineering and the new product development process Recognize product liability and safety issues Recognize the significance of reliability and other design factors

Nature of Engineering Design Eng. Design Process Information: Statement of the problem Design standards Design methods Information: Drawings Specifications Financial estimates Written reports Oral presentations

Systems Engineering/ New Product Development The design of a complex engineered system, from the realization of a need through production to engineering support in use is known as systems engineering (especially with military or space systems) or as new product development (with commercial systems).

New Product Development - Stages Conceptual Technical Feasibility or Concept Definition Development Commercial Validation Production Product Support Disposal Stage

Systems Engineering Process (In each phase of development) Requirements Analysis: Analyze customer needs, objectives, and constraints to determine the functional requirements. Functional Analysis/Allocation Identify lower level functions needed to meet these functional requirements, and translate them into design requirements suitable as design criteria. Synthesis. Define the system concept, configuration item alternatives and select the preferred set of product or process solutions to the level of detail required in the phase being conducted.

Systems Engineering Process (In each phase of development) System Analysis and Control. Provide the progress measurement, assessment, and decision mechanisms required to evaluate design capabilities and document the design and decision data. Trade-off (trade) studies Risk management Configuration management Interface management Systems engineering master schedule (SEMS) Technical performance measurement (TPM) Technical (design) reviews

Quality Function Deployment (QFD) Quality function deployment is a team-based management tool in which the customer expectations are used to drive the product development process. Conflicting characteristics or requirements are identified early in the QFD process and can be resolved before production.

Quality Function Deployment (QFD) Key benefits: product improvement, increased customer satisfaction, reduction in the total product development cycle, & increased market share.

QFD: House of Quality Interrelationship between Technical Descriptors How: Technical Descriptors (Voice of the Organization) What: Customer Reqmts (Voice of Customer) Relationship between Requirements and Descriptors Prioritized Customer Reqmts Prioritized Technical Descriptors

4 Phases of QFD Phase I: Product planning Phase II: Parts deployment Phase III: Process planning Phase IV: Production planning

Classical Model of QFD How What Matrix Voice of Customer House of Quality Tech. Performance Measures Piece/Part Characteristics Tech. Performance Measures Subsystem Design Matrix Process Parameters Piece/Part Characteristics Piece/Part Design Matrix Production Operations Process Parameters Process Design Matrix

Portable Slide Projector QFD Example: Portable Slide Projector Engineering Metrics Brightness Weight Dimensions (girth + width) Time/Tasks required to start Distortion Distance from presenter Time to insert/pull-out slide Attractive product Customer Needs Good image Easy to transport Keeps present. flowing Image visible in bad conditions Minimizes unplanned interruptions Design makes the product attractive Device sets up quickly Works well for short present.

Portable Slide Projector—Phase I QFD Example: Portable Slide Projector—Phase I Engineering Metrics Brightness Weight Dimensions Time/Tasks Distortion Distance Time to insert/pull Attractive product Customer Weights 9 1 3 Customer Requirements Good image Easy to transport Device sets up quickly Works well for short present. Keeps present. flowing Image visible in bad conditions Minimizes unplanned interruptions Design makes the product attractive 9 3 1 Raw score 108 117 114 81 58 72 27 Relative Weight 16% 17% 12% 8% 11% 4%

Portable Slide Projector—Phase II QFD Example: Portable Slide Projector—Phase II Part Characteristics Top case Bottom case Lens Condenser Stand Heat sink Lamp Relative Phase I Weights 16% 17% 13% 8% 10% 4% Engineering Metrics Brightness Weight Dimensions (girth + width) Time/Tasks required to start pres. Distortion Distance from presenter Time to insert/pull-out slide Attractive product 9 1 3 Raw score 3.6 3.3 4.4 4.9 1.1 1.3 2.7 Rel. Weight 17% 15% 21% 23% 5% 6% 13% Rank 3 4 2 1 7 6 5

Phases in Systems Engineering / New Product Development (DoD) Pre-milestone zero studies Concept exploration & definition Demonstration and validation Engineering and manufacturing development Production and deployment Operations and support

Phases in Systems Engineering / New Product Development (NASA) Conceptual design studies Concept definition Design and development Fabrication, integration, test, and certification Pre-operations Operations and disposal

Phases in Systems Engineering / New Product Development (NSPE/NIST ) Conceptual Technical feasibility Development Commercial validation and production preparation Full-scale production Product support

Tasks Within Each Phases of Systems Eng. / New Product Development Approval to expend the resources / agreement on the work to be accomplished. Accomplishment of the work Compile the results: designs and specifications, analyses and reports, and a proposed plan for conducting the following phase if one is recommended. To cancel the development, To go back (recycle) and do more work in the present phase; or To proceed with the next phase.

Conceptual stage Statement of the design problem, clearly defining what the desired intended accomplishment of the desired product Key functions Performance characteristics Constraints Criteria of judging the design quality

Conceptual stage Musts: requirements that must be met Must nots: constraints defining what the system must not be or do Wants: features that would significantly enhance the value of the solution but are not mandatory (to which an additional, even less compelling category of "nice to have" is often added) Don't wants: characteristics that reduce the value of the solution

Conceptual stage (Kano’s Model) Customer Satisfaction Delighters Satisfiers Actual Performance Dissatisfiers

Conceptual stage (Kano’s Model) Dissatisfiers Expected Quality Scratches, blemishes Smooth Surface Broken parts All parts work Missing instruction Clear instruction Function not provided Normal function Product is unsafe Product is safe to use Product is non-conformant Product conforms to std.

Conceptual stage (Kano’s Model) Satisfiers: Direction Performance Measure Desired Quality LargerTB Cubic feet of storage Capacity SmallerTB Dollars Price LargerTB MTBF Reliability LargerTB Transactions /second Speed

Conceptual stage (Kano’s Model) Examples of Delighters Sony Walkman 3M Post-it Cup Holder One-touch recording Redial button on telephone Graphic User Interface (GUI)

Results from Conceptual stage A set of functional requirements Identification of the potential barriers to development, manufacturing, and marketing the proposed product. Test-of-principle model to reduce technical uncertainties Order-of-magnitude economic analyses and Preliminary market surveys to reduce financial uncertainty.

Importance of Conceptual stage 1% of the cost of the product 70 % of the life-cycle cost

Technical feasibility stage The objectives of this stage are To confirm the target performance of the new product through experimentation and/or accepted engineering analysis and To ascertain that there are no technical or economic barriers to implementation

Technical feasibility stage Subsystem identification Trade-off studies System integration Interface definition Preliminary breadboard-level testing Subsystem and system design requirements (reliability, safety, maintainability, and environmental impact). Development of preliminary test plans, production methods, maintenance and logistic concepts, and marketing plans. Preliminary estimation of the life-cycle cost of the system. Preparation of a proposal for the development stage

Importance of Technical feasibility stage 7% of the cost of the product 85 % of the life-cycle cost

Development stage (Build-test-fix-retest sequences) The objective of this stage is To make the needed improvements in materials, designs and processes and To confirm that the product will perform as specified by constructing and testing engineering prototypes or pilot processes.

Commercial validation and Production preparation stage The objective of this stage is to develop the manufacturing techniques and establish test market validity of the new product. Selecting manufacturing procedures, production tools and technology, installation and start-up plans for the manufacturing process, and Selecting vendors for purchased materials, components, and subsystems.  Reproduction prototypes

Full-scale production stage Final design drawings, specifications, flow charts, and procedures are completed for manufacture and assembly of all components and subsystems of the product, as well as for the production facility. Quality control procedures and reliability standards are established Contracts made with suppliers Procedures established for product distribution and support. Manufacturing facilities are constructed Continuous process improvement (kaizen)

Product support stage Technical manuals for product installation, operation, and maintenance Training programs for customer personnel Technical supports Warranty services Repair parts and replacement consumables must be manufactured and distributed New procedures for operation and maintenance Improved parts for retrofit Notification of product recall for safety reasons

Disposal stage Every product causes waste during manufacture, while in use, and at the end of useful life that can create disposal problems. The time to begin asking, "how do we get rid of this" is in the early stages of product or process design.

CONCURRENT ENGINEERING AND CALS

Traditional Product Development System Level Design Subsystem Design Component Design Manufacturing Process Concept Development Manufacturing Process Development Delivery Development Service Development Delivery

Concurrent Processes System Level Design Manufacturing Process Concept Development Delivery Development Subsystem Design Manufacturing Process Development Service Development Component Design Production & Delivery

Definition of Concurrent Engineering A systematic approach to the integrated, concurrent design of products and their related processes, including manufacture and support. This approach is intended to cause the developer, from the outset, to consider all elements of the product lifecycle from concept through disposal, including quality control, cost, scheduling, user requirements. (Inst. For Defense Analysis)

Advantages of Concurrent Engineering The set of methods, techniques, and practices that: Cause significant consideration within the design phases of factors from later in the life cycle; Produce, along with the product design, the design of processes to be employed later in the life of the product; Facilitate the reduction of the time required to translate the design into distributed products; and Enhance the ability of products to satisfy users' expectations and needs.

CALS "Computer Aided Logistics Support," then "Computer-aided Acquisition and Logistics Support," "Continuous Acquisition and Life-Cycle Support," (1993, DoD) "Commerce At Light Speed" (U.S. industry)

Purposes of CALS To enable more effective generation, management, and use of digital data supporting the life cycle of a product through the use of international standards, business process change, and advanced technology application.

CALS Electronic storage, transmission, and retrieval of digital data Between engineers representing the several design stages, Between organization functions such as marketing, design, manufacturing, and product support, and Between cooperating organizations such as customer and supplier.

Commercial standards Computer Graphics Metafile (CGM) (ISO-8632): A standard means of representing line drawings in a device-independent way. Electronic Data Interchange for Administration, Commerce, and Transport (EDIFACT) (ISO 9735, ANSI X12): An international standard means for communicating commercial (trade) information. Initial Graphics Exchange Specification (IGES) (ANSI Y14.26M): A standard means of representing product data in a device-independent way.

Control Systems in Design Drawing/Design Release Version Control Product Data Management (PDM) Configuration (Design Criteria) Management Functional baseline (at end of conceptual stage) Allocated baseline (at end of validation stage) Product baseline (at end of development stage) Design Review

Special Considerations in Design Product liability Safety Reliability Maintainability Availability Ergonomics Producibility

History of Product Liability Caveat emptor (let the buyer beware) “Privity of contract” (Direct contractual relationship) 1916, MacPherson v. Buick (No need for direct contract) Plaintiff must prove negligence 1960, Hernington v. Bloomfield Motors,  implied warranty 1984, Greenman v. Yuba Power Product Strict Liability Absolute liability: “A manufacturer could be held strictly liable for failure to warn of a product hazard, even if the hazard was scientifically unknowable at the time of the manufacture and sale of the product.”

Reducing Liability Include safety as a primary specification for product design. Use standard, proven materials and components. Subject the design to thorough analysis and testing. Employ a formal design review process in which safety is emphasized. Specify proven manufacturing methods. Assure an effective, independent quality control and inspection process. Be sure that there are warning labels on the product where necessary.

Reducing Liability Supply clear and unambiguous instructions for installation and use. Establish a traceable system of distribution, with warranty cards, against the possibility of product recall. Institute an effective failure reporting and analysis system, with timely redesign and retrofit as appropriate. Document all product safety precautions, actions, and decisions through the product life cycle.

Designing for Reliability Definition of Reliability: Reliability is the probability that a system Will demonstrate specified performance For a stated period of time When operated under specified conditions.

Reliability Measures Reliability Failure CDF (cumulative distribution function): Failure PDF (probability density function): Failure or hazard rate:

Simple Reliability Models Simple Series Model S L Simple Parallel Model L

Simple Reliability Models Series- parallel model L S L S

Simple Reliability Models Bathtub curve Hazard Rate Life Infant Mortality Useful Life Wear-out

Designing for Reliability “Start with the best” Redundancy Factor of safety

Maintainability Maintainability is the probability that a failed system Will be restored to specified performance Within a stated period of time When maintained under specified conditions.

Maintainability Maintenance downtime Administrative & preparation time Logistic time Active maintenance time Types of Maintenance Corrective maintenance Preventive maintenance Predictive maintenance

Availability Inherent Availability (considers only corrective maintenance) Ai = MTBF / (MTBF+MTTR) Operational Availability (considers both preventive & corrective maintenance) Ao = MTBM / (MTBM+MDT) MTBM: Mean Time Between Maintenance MDT: Mean Down Time MTTR: Mean Time To Repair MTBF: Mean Time Between Failure (1/) BIT: Build-In Test

Other Considerations Human Factors Engineering (Ergonomics) Standardization Set of specifications for parts, materials, or processes intended to achieve uniformity, efficiency, and a specified quality. Producibility

Value Engineering A methodical study of all components of a product in order to discover and eliminate unnecessary costs over the product life cycle without interfering with the effectiveness of the product. What is it? What does it do? What does it cost? What does it worth? What else might do the job? What do the alternatives cost? Which alternative is least expensive? Will the alternative meet the requirements? What is needed to implement the alternative?