1. It Starts With Parts PART 2 PART 1 PART N Product is made up of parts
You create parts, then do things with them
Fundamental info is stored as part geometry and info, everything else is derived from this
Change the part, the dwg and assemblies automatically update
Parts are 3-D!
A car: 10,000 parts
ASSEMBLIES
DRAWINGS
ANALYSIS

2. Parts have features SLOT or CUT CHAMFER PROTRUSION
Rounds, chamfers, holes, threads, cuts, ….

3. Build up part by creating base, then adding features
Base parts are usually slabs, cylinders, cones or simple variants.
Build features on top of base parts

4. Assemblies are collections of parts

5. Drawings are generated from parts
We’ll get into dimensioning later.
Dimensions (size) is specified **at part creation time**, not at drawing time.
Can change whenever.
Can link dimensions so that if you change the side of a hole, you automatically change the size of a pin.

6. Machining Assembly 2-D drawing Costing/Purchasing Engineering analysis
1400 lbs
3-D solid model is the heart of the part database
Everything flows from the database
Internally, stored in proprietary format, visual (shaded, wire-frame) is just for humans
2-way Associativity: changing dimension on assembly or on drawing will change dimension on 3-d part. Thus, everything stays up to date.
A key feature when handling assemblies with thousands of parts (e.g. auto, plane, ship…)
Costing/Purchasing
Engineering analysis

7. CAD determines design intent
This?
…or this?
CAD package vs general drawing package.
CAD tries to determine your intent.
When you enlarge a part, will guess that you don’t mean to enlarge the hole

8. Constraint-based modeling
6.00
2.00
This?
4.00
6.00
3.00
Constraint-based modeling
You can either constrain hole to be:
(1) always 2 inches from the edge, or
(2) always in the center
Constraint remains no matter how you change dimensions of the part
For assemblies, constrain parts to each other, e.g. faces match or left sides align.
Parametric modeling: The dimension drives the geometry. You can change the dimension and the geometry changes.
…or this?

9. Relations to fix intentD1 D2
D2 = SQRT(D1) 1 4 2
Relations
Dimensions are related (by any mathematical function), so that a change in one dimension affects other dimensions in such a way that preserves design intent.
Equations can be of arbitrary complexity and and relate an arbitrary number of dimensions.
Goal: Set up constraints and relations so that you only have to change one thing, and intent is maintained.