Product Design (ME-603 (C)) - Unit 3 Short Notes

UNIT 3: Product Design and Development

1.0 Introduction to Product Design

Definition & Scope:

Product design is the process of creating a new product for commercial sale, encompassing ideation, development, and commercialization. It integrates engineering, design, and business considerations.

Significance:

• Drives market competitiveness and customer satisfaction.

• Influences manufacturing cost, quality, and time-to-market.

• Addresses sustainability and regulatory requirements.

Objectives of Product Design & Development:

1. Meet user needs and expectations.

2. Ensure manufacturability and cost-effectiveness.

3. Achieve reliability, safety, and sustainability.

4. Facilitate ease of use, maintenance, and disposal.

Factors Influencing Product Design:

Characteristics of Successful Product Development:

• Clear market understanding.

• Cross-functional teamwork.

• Iterative prototyping and testing.

• Effective project management.

• Alignment with business strategy.

Challenges in New Product Development (NPD):

• Uncertain market acceptance.

• Technical feasibility and integration.

• Budget and timeline overruns.

• Rapidly changing technology.

• Supply chain complexities.

[!TIP]

Exam Focus: Be prepared to list and explain factors with examples (e.g., how user needs shape smartphone design). Challenges often relate to time-cost-quality trade-offs.

2.0 Product Planning and Strategy

2.1 Product Life Cycle (PLC)

Stages:

1. Introduction: Low sales, high costs, minimal profit. Example: First-generation electric vehicles.

2. Growth: Rapid sales increase, profit rises, competition emerges. Example: Smartphones post-launch.

3. Maturity: Sales peak, profit stabilizes, intense competition. Example: Conventional automobiles.

4. Decline: Sales fall, profit erodes, product phase-out. Example: DVD players.

Importance for Decision-Making:

• Guides marketing, pricing, and R&D investment.

• Helps plan product modifications or discontinuation.

• Manages cash flow and resource allocation across stages.

2.2 Product Strategy

Elements:

• Positioning: How product is perceived relative to competitors.

• Differentiation: Unique features/benefits (e.g., Apple’s ecosystem).

• Portfolio Management: Balancing new vs. mature products.

• Innovation Policy: Radical vs. incremental innovation focus.

Role: Aligns product development with long-term business goals, ensures resource commitment to strategic opportunities.

2.3 Organizational Aspects

Resource Allocation Process:

1. Idea screening → feasibility study → business case.

2. Stage-gate reviews with go/kill decisions.

3. Budgeting and team assignment per phase.

Organizational Policies:

• Standardized development processes (e.g., Stage-Gate®).

• Continuous improvement frameworks (Lean, Six Sigma).

• Intellectual property management.

Stakeholder Integration:

Collaboration among customer (needs feedback), designer (concept realization), material supplier (cost/availability), process planner (manufacturability) via concurrent engineering.

[!TIP]

Common Pitfall: Confusing PLC stages—remember Introduction has negative profit, Maturity has peak sales, Decline requires harvest/divest strategy.

3.0 Understanding Customer Needs

Importance:

• Prevents design failures due to unmet needs.

• Reduces redesign costs and time.

• Enhances user satisfaction and loyalty.

Customer Focus Definition:

Organizational culture centered on identifying, prioritizing, and fulfilling customer requirements throughout product lifecycle.

Methods for Obtaining Customer Information:

Involving Customers in Development:

• Co-creation workshops.

• Beta testing and pilot programs.

• User-centered design (UCD) iterations.

Competitive Benchmarking:

• Role in Planning: Identifies performance gaps and best practices.

• Assessing Rival Products: Compare features, cost, quality, usability, reliability, and after-sales service. Use tools like SWOT, feature matrices.

[!TIP]

Exam Tip: Link methods to design stages—e.g., observations in early concept, surveys in validation. Benchmarking should be continuous, not one-time.

4.0 Product Design Methodology and Process

4.1 Product Design Process Stages

1. Problem Definition → 2. Concept Generation → 3. Concept Selection → 4. Detailed Design → 5. Prototyping & Testing → 6. Commercialization.

4.2 Creative Techniques for Idea Generation

• Brainstorming: Free idea flow, no criticism.

• SCAMPER: Substitute, Combine, Adapt, Modify, Put to another use, Eliminate, Reverse.

• Mind Mapping: Visual organization of ideas.

• TRIZ: Systematic innovation using patterns.

• Synectics: Metaphor-driven problem-solving.

4.3 Value Engineering (VE)

Definition: Systematic method to improve product value by optimizing function-cost relationship.
Significance: Reduces cost without sacrificing function/quality; enhances competitiveness.

Key Principles:

1. Function Analysis: What does the product do? (Not what it is).

2. Creativity: Generate alternative ways to achieve functions.

3. Evaluation: Select best alternatives based on value.

4. Development: Implement and validate.

VE Job Plan (Procedure):

1. Information Phase: Gather data on functions, costs.

2. Analysis Phase: Function analysis system (FAST).

3. Creativity Phase: Brainstorm alternatives.

4. Evaluation Phase: Screen and rank ideas.

5. Development Phase: Detailed proposals, cost estimates.

6. Presentation Phase: Recommend to management.

7. Implementation Phase: Execute changes.

Example: Redesigning a chair—function is "support user seated"; alternatives: fewer legs, different material, adjustable height.

4.4 Function Analysis

4.4.1 Function Analysis System Technique (FAST)

Definition: Diagrammatic method to define, analyze, and understand functions logically.
Diagram:

Basic Function: [e.g., "Transport Fluid"]  

→ How? [Sub-functions] → "Seal Leakage"  

→ How? [Sub-functions] → "Compress Gasket"  

→ How? [Sub-functions] → "Apply Pressure"  

Application in Automotive:

• Engine system: "Convert fuel to motion" → "Ignite mixture" → "Spark plug fires".

• Identifies over/under-designed components.

Implementation Difficulties:

• Resistance to functional thinking (vs. physical parts).

• Complex systems with many interdependencies.

• Requires cross-functional training.

4.4.2 Tertiary/Superfluous Functions

Concept: Functions that are not directly necessary for primary purpose but may support secondary objectives (e.g., aesthetics, brand signaling).
Role in System Performance:

• Can enhance user experience or market appeal.

• May add cost/complexity without functional benefit—target for VE elimination if value < cost.

4.5 Simulation and Analysis Tools

Role: Virtual testing of designs (stress, thermal, fluid flow) to predict performance, reduce physical prototypes.
Manufacturing Optimization with CAD/DFM:

• CAD-integrated DFM checks: draft angles, wall thickness, tool accessibility.

• Moldflow analysis for injection molding.

• CNC toolpath simulation for machining.

[!TIP]

Key Distinction: VE focuses on function-cost, while DFM focuses on manufacturability. FAST is the backbone of VE—practice drawing FAST diagrams for simple products (e.g., flashlight).

5.0 Design for X (DFX) Principles

5.1 Design for Manufacturing (DFM) and Assembly (DFA)

Benefits:

• Reduced production cost and time.

• Higher quality and yield.

• Simplified assembly, fewer parts.

DFM vs. DFA:

DFMA Approach: Combine DFM and DFA simultaneously; use tools like Boothroyd-Dewhurst method for assembly efficiency.

General Design Guidelines for Manual Assembly:

1. Minimize part count.

2. Design for symmetry and foolproof orientation.

3. Use snap-fits instead of screws.

4. Ensure accessibility and clear visibility.

5. Avoid sharp edges, tangling parts.

Techniques for Easy Assembly/Disassembly:

• Modular design.

• Standardized fasteners.

• Snap-fit and interlocking joints.

• Design for serviceability (e.g., replaceable modules).

5.2 Design for Specific Manufacturing Processes

Sand Casting Guidelines:

• Avoid sharp corners (use fillets).

• Provide draft angles (1–3°).

• Uniform wall thickness to prevent cracks.

• Position cores for easy removal.

Die Casting vs. Sand Casting:

| Surface Finish | Smooth (Ra 1–2 μm). | Rough (Ra 25 μm).

| Cost | High tooling, low per-part. | Low tooling, high per-part.

| Design Rules | Thin walls possible, no cores needed. | Draft required, cores for cavities.

Design for Non-Metallic Products (Plastics, Composites):

• Mechanical Loads: Account for creep, fatigue; add ribs for stiffness.

• Thermal Loading: Consider CTE, thermal cycling; avoid stress concentrations.

• UV Exposure: Use stabilizers, select UV-resistant grades.

• Chemical Exposure: Choose resistant polymers (e.g., PTFE for acids).

5.3 Design for Environment (DFE) and Sustainability

Fundamental Ideas:

• Minimize resource use and emissions.

• Design for reuse, recycling, biodegradability.

• Lifecycle assessment (LCA) to quantify environmental impact.

Impact on Product Design:

• Material Selection: Recycled/renewable materials, non-toxic.

• End-of-Life: Easy disassembly, modular upgrades, take-back programs.

• Energy Efficiency: Low-power operation, efficient use-phase.

• Packaging: Minimal, recyclable, biodegradable.

Eco-Design Principles:

1. Innovation: New materials/processes (e.g., bioplastics).

2. Efficiency: Lightweighting, energy reduction.

3. Recovery: Remanufacturing, recycling loops.

4. Responsibility: Extended Producer Responsibility (EPR).

5.4 Robust Design

Concept: Design products insensitive to noise factors (manufacturing variations, environmental conditions) using statistical methods (Taguchi).
Objectives: Consistent performance, reduced variability, lower cost.
Challenges in Implementation:

• Requires statistical expertise and experimentation.

• May increase initial design complexity.

• Balancing robustness with cost targets.

[!TIP]

DFX Hierarchy: DFM/DFA are most common; DFE is increasingly critical. For non-metallics, always consider environmental degradation (UV/chemical). Robust design uses orthogonal arrays—know the term "signal-to-noise ratio."

6.0 Computer-Aided Design (CAD) and Manufacturing

6.1 CAD: 2D vs. 3D Modeling

6.2 Role of CAD in Manufacturing Optimization

• Generate CNC code directly (CAM integration).

• Simulate machining to avoid collisions.

• Optimize material layout (nesting).

• Create inspection programs (CMM).

6.3 DFM Tools within CAD Software

• Moldflow (injection molding analysis).

• Sheet metal bend allowances.

• Draft angle checks.

• Tolerance stack-up analysis.

6.4 Simulation and Analysis Tools (Link to 4.5)

• FEA: Stress, vibration, thermal.

• CFD: Fluid flow, heat transfer.

• Kinematics: Mechanism motion.

• Optimization: Topology, shape, size.

[!TIP]

Exam Insight: 3D CAD enables "design in the digital domain"—reduces physical prototypes. DFM tools are often add-ons (e.g., SolidWorks Plastics, Moldflow).

7.0 Rapid Prototyping (RP) Technologies

7.1 Importance and Advantages

• Fast concept validation.

• Complex geometries impossible with traditional methods.

• Reduced time-to-market, lower prototyping cost for low volumes.

7.2 RP Process: Five Steps

1. CAD Modeling: Create 3D model.

2. Slicing: Convert model to 2D layers (software).

3. Building: RP machine constructs layer-by-layer.

4. Post-processing: Remove support, finish surface.

5. Testing/Evaluation: Fit, form, function checks.

7.3 Classification of RP Methods

• Additive: SLA, SLS, FDM (most common).

• Subtractive: CNC machining (rapid, but material removal).

• Formative: Casting/molding from RP patterns.

7.4 Specific RP Methods

7.4.1 Stereolithography (SLA)

Process: UV laser cures photopolymer resin vat layer-by-layer.
Applications: Visual prototypes, dental/medical models, investment casting patterns.
Surface Finish: Smooth (Ra ~0.5–2 μm), but brittle.

7.4.2 Laminated Object Manufacturing (LOM)

Process: Layers of paper/plastic sheet bonded and cut by laser/knife.
Applications: Conceptual models, large parts, cheap prototypes.
Surface Finish: Stepped, paper-like texture; weaker bonding.

7.4.3 Selective Laser Sintering (SLS)

Process: Laser sinters powder (nylon, metal) layer-by-layer; unsintered powder supports.
Powder Handling:

• Preheated powder bed.

• Recoater spreads fresh powder.

• Excess powder recycled (but properties degrade).
  Material Considerations:

• Polymers: Nylon (PA11, PA12) – good strength, temperature resistance.

• Metals: Requires infiltration (bronze) or HIP for full density.
  Applications: Functional prototypes, end-use parts (e.g., drone components).

7.5 Surface Finishes Comparison

7.6 RP Data Formats

STL Format:

• Significance: De facto standard; represents surfaces as triangular facets.

• Limitations: No color, texture, or solid properties; facet approximation errors; no metadata.
  Other Formats:

• OBJ: Supports color/texture.

• STEP/STP: Full solid model, industry standard for CAD exchange.

• AMF: XML-based, supports color, materials, lattices.

7.7 Applications of RP

• Concept Modeling: Quick visualization.

• Functional Testing: Fit-check, wind tunnel models.

• Tooling: Direct molds/patterns (e.g., SLA for investment casting).

• Medical: Custom implants, surgical guides.

• Architecture: Scale models.

7.8 Validating Designs for Production Processes

• Fit/Form: Check assembly clearances, ergonomics.

• Function: Test mechanical properties (SLS parts can be load-tested).

• Manufacturability: Identify draft issues, thin walls via RP before tooling.

• Process Simulation: RP parts used to validate casting molds, injection molds.

[!TIP]

Critical Distinction: SLS uses powder bed (no supports), SLA requires supports (removal marks). STL is tessellated—facet size affects accuracy. For metal SLS, post-processing (HIP, machining) is often needed.

8.0 Ergonomics and Human-Centered Design

8.1 Ergonomics in Product Design

Principles:

1. Anthropometry: Fit human body dimensions (e.g., seat height, handle grip).

2. Biomechanics: Reduce physical strain (e.g., tool handle shape).

3. Cognition: Intuitive controls, minimal memory load.

4. Environmental: Lighting, noise, temperature.

Benefits:

• Improved safety, reduced fatigue.

• Higher productivity and user satisfaction.

• Lower error rates and training costs.

8.2 Elements and Concepts of Visual Design

• Aesthetics: Color, shape, texture, proportion (Golden Ratio).

• Usability: Affordances (e.g., button shape suggests push), feedback.

• Cognitive Aspects: Mental models, consistency, hierarchy (Fitts's Law for target size/distance).

[!TIP]

Example: Car dashboard—ergonomic placement of gauges (within 30° sightline), visual hierarchy (speedometer largest), tactile feedback on controls.

9.0 Special Topics and Applications

9.1 Power Transmitting Devices: Industrial Applications

9.2 Quality of Injection-Molded Parts

Factors Affecting Quality:

1. Material: Moisture content, viscosity, thermal stability.

2. Process Parameters: Melt temperature, injection pressure, cooling time.

3. Mold Design: Gate location, venting, draft angles, uniformity.

4. Design: Wall thickness (avoid sinks), ribs (avoid stress), draft.
   Defects: Sink marks, warpage, flash, voids.

9.3 Sustainable Product Design & Eco-Friendly Packaging Examples

• Product: Patagonia’s recycled polyester jackets, modular Fairphone.

• Packaging: Mushroom-based mycelium packaging, cornstarch bags, minimalistic cardboard (e.g., Apple’s compact boxes).

9.4 Manufacturing Optimization using CAD/DFM Tools

• DFM in CAD: Automatic draft checks, wall thickness analysis, manufacturability reports.

• Example: SolidWorks’ "Design Checker" enforces company standards; Moldflow predicts weld lines, sink marks.

• Outcome: Reduces tooling revisions, improves yield.

[!TIP]

Link Topics: Injection molding quality ties to DFM guidelines (draft, uniform walls). Sustainable design uses DFE principles—choose recyclable polymers, design for disassembly (e.g., snap-fits vs. adhesives).