3D Product Materials & Finishing 1 — Questions and Answers
Question 1: What is PLA filament and why is it commonly used for product prototyping?
- Polylactic Acid, a biodegradable thermoplastic that is easy to print, low-warp, and available in many colors (Correct answer)
- A carbon fiber reinforced filament for structural parts
- A high-temperature resin used in SLA printing
- A flexible TPU-based material for soft prototypes
Correct answer: Polylactic Acid, a biodegradable thermoplastic that is easy to print, low-warp, and available in many colors
PLA is a plant-derived thermoplastic that prints easily on unheated beds, produces little warping, and offers good detail — making it ideal for concept models and prototypes.
Question 2: What are the advantages of PETG filament over PLA for functional product prototypes?
- PETG has better impact resistance, moisture resistance, and higher temperature tolerance than PLA (Correct answer)
- PETG has a lower melting point making it easier to print than PLA
- PETG produces sharper details and finer surface finish than PLA
- PETG is biodegradable while PLA is not
Correct answer: PETG has better impact resistance, moisture resistance, and higher temperature tolerance than PLA
PETG combines PLA's ease of printing with better mechanical properties — higher impact and temperature resistance and food-safe characteristics for functional prototypes.
Question 3: What is 'Shore hardness' used to measure in product material selection?
- The hardness and stiffness of rubber and flexible polymers (Correct answer)
- The tensile strength of rigid plastics
- The surface roughness of a 3D-printed part
- The brittleness of ceramic materials
Correct answer: The hardness and stiffness of rubber and flexible polymers
Shore hardness (A scale for soft rubbers, D scale for harder plastics) quantifies material firmness, used to spec flexible components like grips, gaskets, and seals.
Question 4: What is 'anisotropy' in 3D-printed parts and why does it matter?
- The directional difference in mechanical properties — FDM parts are stronger along print layers than between them (Correct answer)
- A surface defect caused by incorrect extrusion temperature
- The variation in color between different material batches
- An optical distortion in transparent resin prints
Correct answer: The directional difference in mechanical properties — FDM parts are stronger along print layers than between them
FDM-printed parts are anisotropic because layer-to-layer bonding is weaker than in-plane strength, meaning part orientation relative to loads must be considered in design.
Question 5: What material property is described by 'tensile strength'?
- The maximum stress a material can withstand when being pulled apart before it breaks (Correct answer)
- The resistance of a material surface to scratching
- The ability of a material to conduct heat
- The flexibility of a material under repeated bending
Correct answer: The maximum stress a material can withstand when being pulled apart before it breaks
Tensile strength is the maximum pulling force per unit area a material can endure before fracturing — a key spec for structural product components.
Question 6: What is 'ABS' plastic and what are its main advantages for product prototyping?
- Acrylonitrile Butadiene Styrene, a tough, impact-resistant thermoplastic good for functional prototypes that can be sanded and finished (Correct answer)
- A biodegradable material derived from corn starch
- A flexible rubber-like material for soft-touch grips
- A transparent optical-quality polymer for lens prototypes
Correct answer: Acrylonitrile Butadiene Styrene, a tough, impact-resistant thermoplastic good for functional prototypes that can be sanded and finished
ABS is a strong, impact-resistant engineering plastic that can be machined, sanded, painted, and acetone vapor smoothed — widely used for durable functional prototypes.
3D Product Materials & Finishing 1
What is PLA filament and why is it commonly used for product prototyping?