Prototyping / Manufacturing Process
What is the purpose of prototyping?
To test, evaluate, and refine design concepts before final production.
What is the purpose of Design for Assembly?
Reduce assembly time, cost, and errors
What does GD&T stand for?
Geometric Dimensioning and Tolerancing
What is a stakeholder?
Anyone affected by or having influence on the product.
What is a manufacturing defect?
A flaw that causes a part to deviate from specifications.
Give one example if a variable cost.
Material selection,
Labor per part
An important DFA principle that reduces assembly time?
Minimizing part count
What is the purpose of GD&T on engineering drawings?
To clearly define allowable geometry and ensure proper function
What is one characteristic of a good engineering requirement?
Measurable and testable
Parting line
porosity
What are some considerations when selecting a manufacturing process?
Material, Tolerance, Surface Finish, Production Volume, Part Geometry, Cost
Why is part symmetry important in DFA?
Reduces orientation errors and assembly complications
Name three categories of hole/shaft fits.
Clearance
Transition
Interference
What is the purpose of a Pugh Chart?
To compare design concepts against a baseline.
Why are tolerances important?
They define acceptable variation and ensure parts function properly.
What are some common prototyping methods and their advantages?
3D printing, relatively fast and cost effective depending on filament used.
wood / foam mockup/prototype - can be made with easy to source household items, very quick to acomplish
Important DFA principle that improves manufacturability?
Avoiding sharp internal corners to allow for machining tools.
What is an advantage of an interference fit?
Strong permanent joint without additional fasteners.
What does Grueblers equation determine?
The degrees of freedom of a mechanism
Why does injection molding become cheaper per part at higher production volumes?
Tooling costs are spread out across many parts, allowing the total price per part to decrease.
What is the difference between machining and metal casting?
Machining - tight tolerances, higher starting cost (machines), very fast, normally have better surface finish.
Casting - allows for complex shapes, lower cost per part, can produce higher volumes.
Explain how Design for Assembly can conflict with Design for Manufacturing, and how they can be balanced?
DFA often simplifies assembly and reduces part count, while DFM can require added features, but these can be balanced by weighing the cost, function, and manufacturability of the product.
For an RC1 close sliding fit with a 0.5 in nominal hole, what is the design intent of this fit?
Precise alignment with minimal clearance allowing for smooth sliding motion.
What is the difference between a grashof and non grashof mechanism?
Grashof mechanisms allow full rotation of at least one link and determines motion capability and motor compatibility.
Compare machining and injection molding from a cost perspective across low and high production volumes.
Machining is cheaper at low volume, injection molding is cheaper at high volume due to the tooling cost being spread out.