Chapter 32

Question 1

Define: Rapid Prototyping

Answer 1

or (RP), is a family of technologies used to fabricate engineering prototypes of parts in minimum possible lead time based on computer-aided design (CAD) models.

Question 2

Define: Material Removal vs. Material Addition RP

Answer 2

Material Removal: Machining, primarily milling and drilling, using a dedicated Computer Numerical Control (CNC) machine that is available to the design department on short notice.

Material Addition: Machines that add thin layers of material one at a time to build the physical part from bottom to top. Helpful for complexity in part geometry.

Question 3

Define: Geometric Modeling

Answer 3

Modeling the component on a CAD system to define its enclosed volume. Provides exact representation of mass of part.

Question 4

Define: Tesselation

Answer 4

CAD models converted into a format that approximates its surfaces by triangles, with their vertices arranged to distinguish the object’s interior from its exterior.

Question 5

Define: Slicing

Answer 5

Model is sliced into closely spaced parallel horizontal layers. Each layer is saved as STL file.

Question 6

Define: Stereolithography

Answer 6

First material addition RP technology, dating back to about 1988. Processes of fabricating a solid plastic part out of a photosensitive liquid polymer using a directed laser-beam to solidify the polymer. Accomplished through a series of layers.

Question 7

Define: DDM

Answer 7

Droplet Deposition Manufacturing; Also known as ballistic-particle manufacturing, operates by melting the starting material and shooting small droplets onto a previously formed layer. Liquid droplets cold weld to the surface to form a new layer.

Question 8

Define: LOM

Answer 8

Laminated Object Manufacturing; produces a solid physical model by stacking layers of sheet stock that are each cut to an outline corresponding to the cross-sectional shape of a CAD model.

Question 9

Define: FDM

Answer 9

Fused Deposition Modeling; an RP process in which a filament of wax and/or thermoplastic polymer is extruded onto the existing part surface from a work head to complete each new layer. Slow Process.

Question 10

Define: SLS

Answer 10

Selective Laser Sintering; uses a moving laser beam to fuse powders in areas corresponding to the CAD geometric model one layer at a time to build the solid part. After each layer is completed, a new layer of loose powders is spread across the surface and leveled using a counter rotating roller.

Question 11

Define: Rapid Tool Making

Answer 11

When additive manufacturing is used to fabricate production tooling. Called RTM, split into two approaches:

1) Indirect RTM: Pattern is created by RP and the pattern is used to fabricate the tool.
2) Direct RTM: RP is used to make the tool itself