Lecture 1 Flashcards
Q: What is “Design” in the context of engineering?
A: The process of creating a solution to a specific problem by understanding parameters, required features, and user needs.
Q: What are the four stages of engineering design?
A: 1. Conceptual design, 2. Configuration design of parts, 3. Parametric design, 4. Detail design.
Q: What does DFM stand for, and what is its focus?
A: DFM stands for “Design for Manufacturing” and focuses on ease of manufacture for parts in a product.
Q: What does DFA mean, and what are its general guidelines?
A: DFA means “Design for Assembly.” Guidelines include minimizing part count, using subassemblies, mistake-proofing design, and reducing assembly surfaces.
Q: Define DFMA and its primary goal.
A: DFMA stands for “Design for Manufacture and Assembly,” aiming to address manufacturing and assembly issues early in the design phase.
Q: What is Concurrent Engineering, and why is it important?
A: Concurrent Engineering is a design philosophy where stakeholders and design engineers work together from the start, addressing manufacturing issues early.
Q: What percentage of product cost can design decisions influence?
A: Design decisions can influence 60% to 80% of a product’s cost.
Q: Name some DFM guidelines.
A: Minimize total parts, use standard components, simplify designs, avoid tight tolerances, and design for ease of fabrication.
Q: What are primary, secondary, and tertiary processes in manufacturing?
A:
Primary: main shape (casting, forging)
Secondary: main shape and features (machining, grinding)
Tertiary: finishing (surface and heat treatments).
Q: What is the DFA criteria for deciding if a part is necessary?
A: A part is necessary if it has relative motion, material difference, or needs isolation from other parts.
Q: What are some advantages of using DFMA in product design?
A: Reduced manufacturing costs, improved quality, reduced assembly time, and simplified products.
Q: How does Concurrent Engineering benefit design?
A: It enhances product quality, reduces lead times, and ensures that manufacturability is considered from the beginning.
Q: What is the main role of a manufacturing engineer?
A: To transition design specifications into a manufactured product by planning processes, reducing costs, and selecting tools.
Q: What is the Assembly Index formula?
A: Assembly Index = Theoretical minimum part count × Minimum assembly time per part.
Q: What is the “Over the Wall” approach in managing DFMA?
A: It refers to limited or no communication between design and manufacturing teams, often leading to inefficiencies.
Q: What are the cost implications of manufacturing decisions?
A: Costs include materials, cycle time, direct/indirect labor, special tooling, perishables, invested capital, and non-value-added activities.
Q: Define the term “Cycle Time” in manufacturing.
A: Cycle Time is the total time required to produce a product or component.
Q: What responsibilities does a Design Engineer have in manufacturing?
A: Responsibilities include material selection, setting tolerances, defining geometry, and designing components for assembly.
Q: What is the significance of “material selection” in product design?
A: It impacts the product’s durability, functionality, and suitability for specific manufacturing processes.
Q: List the basic principles of Design for Assembly (DFA).
A: Reduce part count, simplify parts, use subassemblies, and error-proof design to reduce assembly errors.
Q: Differentiate between manual, high-speed automated, and robot assembly.
A:
Manual assembly: Simple tools, economical for small production runs.
High-speed automated assembly: Uses specific mechanisms, suitable for high production volumes.
Robot assembly: General-purpose robots, adaptable for various tasks.
Q: What are the three main criteria of DFA methodology for part necessity?
A: 1. Relative motion, 2. Material difference/need for isolation, 3. Requirement for assembly/disassembly.
Q: Explain the “Theoretical Minimum Part Count” concept in DFA.
A: It is the smallest number of separate parts needed to meet design functionality, indicating potential simplifications.
Q: What is an example of DFA applied to a motor drive assembly?
A: Parts such as bushings and screws can often be combined or eliminated to reduce assembly complexity.
Q: What does the Assembly Index indicate in DFA analysis?
A: It reflects the efficiency of the assembly process, where a lower index suggests fewer, simpler parts and faster assembly.
Q: How can a product’s assembly time and cost be minimized through redesign?
A: By reducing part count, integrating functions, and eliminating unnecessary fasteners, which simplifies assembly.
Q: List some key guidelines for Design for Manufacture (DFM).
A: Minimize part count, standardize components, use multifunctional parts, avoid excessive tolerances, and limit secondary operations.
Q: Define “Design for Manufacture and Assembly” (DFMA) and its objective.
A: DFMA integrates DFM and DFA principles to optimize product design for cost-effective manufacturing and assembly.
Q: Describe the DFMA process steps.
A: 1. Create design concept, 2. Conduct DFA, 3. Select materials, 4. Perform DFM, 5. Build a prototype, iteratively refining the design.
Q: What are some advantages of DFMA for product development?
A: DFMA leads to lower costs, improved product quality, faster time to market, and simplified manufacturing processes.
Q: How does Concurrent Engineering relate to DFMA?
A: It involves collaboration between design and manufacturing teams from the start, integrating DFMA principles to improve product outcomes.
Q: What are potential risks of Concurrent Engineering?
A: Challenges include managing team dynamics, higher upfront costs, potential resistance to change, and time needed for team activities.
Q: What is the purpose of “Design for X” (DFX) in Concurrent Engineering?
A: DFX optimizes designs based on various stakeholder needs, where “X” can refer to manufacturability, assembly, quality, etc.
Q: What are “primary,” “secondary,” and “tertiary” manufacturing processes?
A
Primary: Shape creation (e.g., casting).
Secondary: Refining shape/features (e.g., machining).
Tertiary: Finishing touches (e.g., heat treatment).
Q: In DFA, what is “Mistake-proofing”?
A: Designing parts and assembly processes to minimize the possibility of errors during assembly.
Q: How does managing DFMA differ in various approaches like “Over the Wall” or “Concurrent”?
A:
“Over the Wall”: Little interaction between teams, often inefficient.
“Concurrent”: Collaborative approach with ongoing communication and shared responsibilities.
Q: What is “Standardization” in DFM, and why is it useful?
A: Using consistent parts and features across designs to reduce complexity, cost, and improve ease of manufacturing.
Q: What role do “Subassemblies” play in DFA?
A: They simplify final assembly by grouping parts, reducing the complexity and time required for the main assembly.
Q: Why is “Part Count Reduction” critical in DFMA?
A: Fewer parts simplify manufacturing and assembly, reducing costs and improving efficiency.
Q: How does DFMA impact a product’s time to market?
A: By optimizing designs early, DFMA reduces production delays, leading to faster product launches.
