Product Design and Development
8.1/ INTRODUCION
Conceptual design is completed.
A set of concepts has been evaluated to produce a single
concept or a small set of concepts for further development.
Embodiment and Detail Design: This is when we “put the meat on the bones”.
Next
What happens in this phase of your design process is that you:
Finalize product architecture.
Quantify important design parameters.
Determine form and shape of parts that will satisfy required
8.2/ PRODUCT ARCHITETURE
=> interactions between modules are well defined
Integral product architecture is often adopted when constraints of weight, space, or cost make it difficult to achieve required performance.
8.2/ PRODUCT ARCHITETURE
STEP 1: Create a
schematic diagram of the product
Example: Laser fusing Rapid Prototyping Machine
Making plastic 3-D parts quickly and directly from CAD files.
Some elements are physical
Some are still in functional form.
Generally no more than 30 elements.
Schematic diagram of a laser-fusing rapid prototyping machine
8.2/ PRODUCT ARCHITETURE
STEP 2: Cluster the elements of the
schematic
Example: Rapid Prototyping Machine
Five (5) Chunks
1. Laser table
2. Process chamber 3. Powder engine
4. Atmospheric control unit
8.2/ PRODUCT ARCHITETURE
STEP 3: Create a rough geometric layout
Example: Rapid Prototyping Machine
2-D drawings are adequate.
Decide whether geometric interfaces between chunks are feasible.
8.2/ PRODUCT ARCHITETURE
STEP 4:Define Interactions and Determine Performance Characteristics
The documentation on each module should include:
- Functional requirements
- Drawings or sketches of the module and its component parts - Preliminary component selection for the module
-Detailed description of placement within the product
- Detailed descriptions of interfaces with neighboring modules
There are four types of interactions possible between component
8.3/ CONFIGURATION DESIGN
In starting configuration design we should follow these steps:
-Review the product design specification and any specifications developed for the particular subassembly to which the component belongs.
-Establish the spatial constraints that pertain to the product or the subassembly being designed.
- Create and refine the interfaces or connections between components. Again, the product architecture should give much guidance in this respect.
- Before spending much time on the design, answer the following questions: Can the part be eliminated or combined with another part? Studies of design for manufacture (DFM) show that it is almost always less costly to make and assemble fewer, more complex parts than it is to design with a higher part count. Can a standard part or subassembly be used?
8.3/ CONFIGURATION DESIGN
8.3/ CONFIGURATION DESIGN
Four possible configurations of features for a right-angle bracket
8.3/ CONFIGURATION DESIGN
Progression of a design configuration
8.3/ CONFIGURATION DESIGN
8.3/ CONFIGURATION DESIGN
(move from an abstract to a highly detailed description)
8.3.1 Generating Alternative Configurations
Refining: is a natural activity as we move through the design
process in which we develop more specificity about the object as we move from an abstract to a highly detailed description.
Patching is the activity of changing a design without changing its level of abstraction
Refining and patching leads to a succession of configurational arrangements that hopefully improve upon the deficiencies of the previous designs
-Substituting looks for other concepts, components, or features
-Combining aims to make one component replace multiple components or serve multiple functions
- Decomposing is the opposite approach from combining
- Magnifying involves making some feature of a component larger relative to adjacent components.
- Minifying involves making some feature of a component smaller
8.3.2 Analyzing Configuration Designs
The first step in analyzing the configuration design of a part is the degree to which it satisfies the functional requirement and
8.3.3 Evaluating Configuration Designs
- Alternative configuration designs of a part should be evaluated at the same level of abstraction. We have seen that design for
function factors are important, because we need some assurance that the final design will work. The second most important criterion for evaluation is to answer the question, “Can a quality part or
assembly be made at minimum cost?”
- The Pugh chart or weighted decision matrix, as discussed in Chap. 7, are useful tools for selecting the best of the alternative designs. The criteria are a selection of the design for function
factors in Table 8.1 determined by management or the design team to be critical to quality plus the cost-related factors of design for
8.3.4 Checklist for Configuration Design
A checklist of design issues that should be considered during configuration design. Most will be satisfied in configuration
design, while others may not be completed until the parametric design or detail design phases.
Step 1. Formulate the parametric design problem Step 2. Generate alternative designs
Step 3. Analyze the alternative designs
Step 4. Evaluate the results of the analyses Step 5. Refine/Optimize
Systematic Steps in Parametric Design
8.4/ DESIGN FOR X (DFX)
See the example of Parametric Design of Helical Coil Compression Spring
-Design for manufacturing (DFM)
- Design for Assembly
- Design for environment
- Design for reliability
- Design for quality
- Design for reliability
- Design for safety
8.7/ Modeling
Many classifications of models used in design and engineering
Descriptive vs Predictive Static vs Dynamic
Deterministic vs Probabilistic Iconic (or physical)
Mathematical
Geometrical modeling on the computer
Representation of a system or a part of a system in physical or
mathematical form that is suitable for demonstrating the behavior of the system Engineers use models for
thinking
communicating predicting
controlling training
8.6/ Simulation
Subjecting models to various inputs or environmental conditions to observe how they behave and thus explore the nature of the results that might be
obtained from the real world system.
Hardware subjected to actual physical environment (prototype testing)
Mathematical models (apply inputs and observe outputs) Some common mathematical simulation tools
Finite difference method (FEM, CAE) Finite element method
Chapter 8-
Embodiment and Detail Design
37
The Manufacturing Process The Design Process
Synthesis
Analysis The CAD Process
The CAM Process
Design needs Design definitions, specifications, and requirements Collecting relevant design information and feasibility study Design conceptualization Design modeling and simulation Design analysis Design optimization Design evaluation Design documentation and communication Process planning Order materials Design and procurement
of new tools Production
planning
NC, CNC, DNC programming
Production Quality control Packaging
Marketing
Shipping
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