Quality in Product and Process Design Chapter 7 Quality in Product and Process Design S. Thomas Foster, Jr. Boise State University PowerPoint prepared by Dave Magee University of Kentucky Lexington Community College ©2004 Prentice-Hall

Chapter Overview Designing Products for Quality The Design Process Quality Function Deployment (QFD) Technology in Design Prototyping Methodologies Designing for Reliability Environmental Considerations in Design

Designing Products for Quality Each dimension of quality poses different design problems. Design is not strictly a technical decision to be made by engineers. Engineers need input from marketing and operations to understand customer needs, marketing requirements, and the realities of production.

The Design Process Slide 1 of 4 Project Development Process Figure 7.1

The Design Process Slide 2 of 4 Stage 1: Product Idea Generation External and internal sources brainstorm new concepts. Internal sources include marketing, management, R&D, and employee suggestions. The primary source for external product ideas is the customer. Stage 2: Customer Future Needs Projection This stage uses data to predict future customer needs. Stage 3: Technology Selection for Product Development Designers choose the materials and technologies that will provide the best performance for the customer at an acceptable cost.

The Design Process Slide 3 of 4 Stage 4: Technology Development For Process Design Designers choose the processes that will be used to transform the materials picked in the prior stage into final products. Stage 5: Final Product Definition Results in final drawings and specifications for the product with product families by identifying base product and derivative products. Stage 6: Product Marketing and Distribution Preparation Includes activities such as the marketing plan.

The Design Process Slide 4 of 4 Stage 7: Product Design and Evaluation Requires definition of the product architecture, the design, production, testing of subassemblies, and testing of the system for production. Stage 8: Manufacturing System Design Includes the selection of the process technologies that will result in a low-cost, high-quality product. Stage 9: Product Manufacture, Delivery and Use Finishes the process. The customer then enjoys the result of the design process.

Quality Function Deployment (QFD) Slide 1 of 2 Describes a method for translating customer requirements into functional design. Sometimes this process translation is referred to as the voice of the customer. Designers need a means for implementing customer requirements into designs. The house of quality (QFD) is used to accomplish this.

Quality Function Deployment (QFD) Slide 2 of 2 QFD Layout: The House of Quality Figure 7.2

Steps in QFD Slide 1 of 5 Step 1: Develop a list of customer requirements. Step 2: Develop a listing of technical design elements along the roof of the house. Step 3: Demonstrate the relationship between the customer requirements and technical design elements. Step 4: Identify the correlations between design elements in the roof of the house. Step 5: Perform a competitive assessment of the customer requirements. Step 6: Prioritize customer requirements. Step 7: Prioritize technical requirements. Step 8: Final Evaluation.

Steps in QFD Slide 2 of 5 Step 2: Develop a listing of technical design elements along the roof of the house. Step 1: Develop a list of customer requirements The list of customer requirements includes the major customer needs as they relate to a particular aspect of a process. These are the design elements that relate to customer needs.

Steps in QFD Slide 3 of 5 Step 3: Demonstrate the relationship between the customer requirements and technical design elements Step 4: Identify the correlations between design elements in the roof of the house The correlations can be identified through the use of symbols. A diagram can be used to demonstrate these relationships.

Steps in QFD Slide 4 of 5 Step 5: Perform a competitive assessment of the customer requirements Step 6: Prioritize customer requirements Articulate customer requirement priorities. Compare your product with those of your key competitors.

Steps in QFD Slide 5 of 5 Step 7: Prioritize technical requirements Step 8: Final Evaluation The relative and absolute weights for technical requirements are evaluated to determine what engineering decisions need to be made to improve the design based on customer input. Prioritize the technical requirements that fit your product design.

Technology in Design Slide 1 of 3 Computer-Aided Design (CAD) System These systems are used in designing anything from an ultralight airplane, to a hamburger, to a home, or to a new intersection that can handle higher volumes of traffic. Greatly improve the ability of designers to generate new and varied designs. Simplify the design process. Help to develop more reliable and robust systems.

Technology in Design Slide 2 of 3 Multiuser CAD Systems An important advance in CAD systems has been the advent of multiuser CAD systems. Using a common database in a network, multiple designers in locations worldwide can work on a design simultaneously, around the clock. Geometric Modeling Is used to develop a computer compatible mathematical description of a part. The image is typically a wire frame drawing of a component.

Technology in Design Slide 3 of 3 Engineering Analysis May involve many different engineering tests such as heat-transfer calculations, stress calculations, or differential equations to determine the dynamic behavior of the system being designed. Interference Checking Examining a design to see if different components in a product occupy the same space. Closed-Loop Systems CAD/CAM systems are often tied together in a closed-loop system with computer-aided inspection (CAI) and computer-aided testing (CAT) quality control systems.

Prototyping Methodologies Slide 1 of 3 Is an iterative approach to design in which a series of mock products are developed until the customer and the designer agree on the final design.

Prototyping Methodologies Slide 2 of 3 Types of Prototypes Basic prototype. The basic prototype is a nonworking mock-up of the product that can be reviewed by customers prior to acceptance. Paper prototypes. Consist of a series of drawings developed by the designer on CAD systems and reviewed by decision makers prior to acceptance. Working prototypes. These are fully working models of the final product.

Prototyping Methodologies Slide 3 of 3 Organizing the Design Team Perform design steps sequentially. Perform design steps simultaneously. Concurrent Engineering The simultaneous performance of product design and process design. Typically, concurrent engineering involves the formation of cross-functional teams. This allows engineers and mangers of different disciplines to work together simultaneously in developing product and process designs.

Product Life Cycle and Related Topics Slide 1 of 4 The Product Life Cycle (PLC) The product life cycle concept demonstrates the need for developing new products by showing product design, redesign, and complementary product development on a continuum. Product Life Cycle Imperatives First, product life cycles are becoming shorter. Second, as product life cycles shorten, product variety and change become much more important to the successful competitor as complementary products are needed to consume productive capacity

Product Life Cycle and Related Topics Slide 2 of 4 Complementary Products Are new products using similar technologies that can coexist in a family of products. Extend the life of a product line by offering new features or improvements to prior versions of a product. Design for Manufacture (DFM) Means to design products so they are cost effective and simple to build. Design for Manufacture Methods Intended to eliminate over-the-wall syndrome and radically reduce design cycle times.

Product Life Cycle and Related Topics Slide 3 of 4 Enterprise Resource Planning (ERP) System A system that integrates financial, planning, and control systems into a single architecture. Examples include the SAP R/3 system and Oracle. Product Data Management (PDM) Helps manage both product data and the product development process by tracking the masses of data needed to design, manufacture, support, and maintain products.

Product Life Cycle and Related Topics Slide 4 of 4 Design for Maintainability A concept that states that products should be designed in a way that makes them easy for consumers to maintain. Design for Maintainability Concepts Components that are easily replaced. Components that are easily removed with standard tools. Adequate space to perform the maintenance function. Nondestructive disassembly. Safe maintenance. Available adequate owners manuals and documentation.

Design for Reliability Slide 1 of 11 Dimension of reliability Failure rate Time Component Reliability Is defined as the propensity for a part to fail over a given time. System Reliability Refers to the probability that a system of components will perform their intended function over a specified period of time.

Design for Reliability Slide 2 of 11 Reliability Analysis Tools Failure Modes and Effects Analysis (FMEA) Fault Tree Analysis Failure Modes, Effects, and Criticality Analysis (FMECA)

Design for Reliability Slide 3 of 11 Failure Modes and Effects Analysis (FMEA) Method for systematically considering each component of a system, identifying, analyzing, and documenting the possible failure modes within a system and the effect of each failure on the system. Benefits of FMEA Improvement of product safety, quality, and reliability. Improvement of a company’s image and competitiveness. Increased satisfaction from a user standpoint. Reduction in product development cost. Record of action taken to reduce a product risk.

Design for Reliability Slide 4 of 11 Basic areas where FMEA can be applied Concept: FMEA is used to analyze a system or its subsystems in the conception of the design. Process: FMEA is applied to analyze the assembly and manufacturing processes. Design: FMEA is used for analysis of products before mass production of the product begins. Service: FMEA is used to test industry processes for failure prior to their release to customers. Equipment: FMEA can be used to analyze equipment before the final purchase.

Design for Reliability Slide 5 of 11 FMEA Steps Figure 7.18

Design for Reliability Slide 6 of 11 Fault Tree Analysis An analytical tool that graphically renders the combinations of faults that lead to the failure of the system. This technique is useful for describing and assessing the events within a system. Primary Symbols of Fault Tree Analysis Events Gates Link the faults to the undesired events within the diagram. Gates show how faults are related.

Design for Reliability Slide 7 of 11 Types of Events (in Fault Tree Analysis) Basic events are initiating faults that do not require events below them to show how they occurred. The symbol used for a basic event is a circle. An intermediate event is the result of a combination of faults, some of which may be primary events. This intermediate event is located in the middle of a fault tree. These events are described by rectangles. An expanded event requires a separate fault tree because of its complexity. For this new fault tree, the expanded event is the undesired event and would be located at the top of the fault tree.

Design for Reliability Slide 8 of 11 Fault Tree Diagram Figure 7.20

Design for Reliability Slide 9 of 11 Steps in Fault Tree Analysis Become familiar with the system. Define the undesired events of the system with the related contributing and initiating events. Develop fault trees for the undesired events. Obtain probabilities for the events on the fault trees. Evaluate fault trees. Analyze the results and proposals for system improvement. Change the fault trees to reflect proposed improvements and renewed fault tree evaluation. Perform a worst case analysis.

Design for Reliability Slide 10 of 11 Failure Mode, Effect, and Criticality Analysis (FMECA) An extensive, but simple method for identifying ways in which an engineered system could fail. Criticality In FMECA is important because it prioritizes how the design team should be spending its resources. In general, criticality refers to how often a failure will occur, how easy it is to diagnose, and whether it can be fixed. Critically assessment is somewhat subjective because it depends on the viewpoint of a service or field analysis.

Design for Reliability Slide 11 of 11 Product Traceability The ability to trace a component part of a product back to its original manufacturer. Consumer Product Safety Commission (CPSC) An independent federal regulatory agency that helps keep American families safe by reducing the risk of injury or death from consumer products.

Environmental Conditions in Design Slide 1 of 2 Importance Currently, society demands much more from product designers than just high-quality products. Many manufacturers have turned to a more environmental form of manufacturing that offers positive returns on investment. Green Manufacturing Movement that began in Germany with requirements for importers to remove packaging materials.

Environmental Conditions in Design Slide 2 of 2 Design for Reuse Designing products so they can be used in later generations of products. Design for Disassembly A method for developing products so that they can easily be taken apart. Design for Remanufacture A method for developing products so that they parts can be used in other products. Associated with green manufacturing.

Summary Designing Products for Quality The Design Process Quality Function Deployment (QFD) Technology in Design Prototyping Methodologies Designing for Reliability Environmental Considerations in Design