Injection molding Flashcards
1
Q
applications of injection modeling?
A
- toys
- household items
- automotive
- industrial and medical parts
2
Q
advantages of injection modelling?
A
- Mass production
- Flexible design for complex products
- Low labor cost
- Very good surface finish
- Large range of pure and composite materials
- High precision products at low cost are easily produced
3
Q
prosses of injection modelling?
A
pressure+material⇒mold cavity⇒soldifies⇒product
4
Q
what are the injection modeling properties?
A
- injection unit: holds molten material
- clamping unit: holds final product
- materials used: thermoplastics
5
Q
injection modelling cycle?
A
- close mold
- fill mold
- pack and hold
- part cooling(longest time)
- open eject
6
Q
screw zones?
A
- feed zone: plastic material is fed through the hopper and held in feed zone
- transition zone: holds molten material
- metering zone: compressing molten material
7
Q
injection modelling parts?
A
8
Q
types of molds?
A
- single cavity: large objects
- multi cavity: for every type of object to increase production
- 2 plate mold: staitionary and movable platens(runners attached)
- 3 plate mold: stationary platens and stripper(to remove runners) and movable plates
9
Q
mold filling simulation shows?
A
- pressure
- clamping force
- temp.
- time needed
10
Q
A
weld lines:
- seen on surface due to weak material bonding
- prevent by: increasing heat, pressure or redesign mold
11
Q
A
sink marks:
- shrinking before cooling
- avoid: redesign mold, increase cooling time, increase pressure
12
Q
A
Short shot:
- incomplete filling
- not enough molten material
- avoid: increase plastic volume and melting temprature
13
Q
A
flashes:
- extra seperation at parting line
- avoid: increase clamping pressure, decrease injection presure
14
Q
A
burn marks:
- air is trapped
- avoid: add vents, or decrease injection pressure
15
Q
A
warpage:
- cooling is not symetrical due to different wall thickness
