塑料件设计指导《Plastic Design Guide》

11
Shrinkage & Warpage
Good Flatness
Engineering Polymers / DuPont (Korea) Inc.
12
Shrinkage & Warpage Case on a ‘plate + rib’ profile
b a Gate L Gate h
w
Flow angle
36
Sinks
Ribs Design
should be improved
Better
Hale Waihona Puke Baidu
Best
37
Engineering Polymers / DuPont (Korea) Inc.
Good Design, Strength
Engineering Polymers / DuPont (Korea) Inc.
38
Good Design, Strength
1X
Relative Torsional Stiffness
Engineering Polymers / DuPont (Korea) Inc.
1.5X
13.3X
27X
30X
39
Bad & Good Design, Example
Engineering Polymers / DuPont (Korea) Inc.
Engineering Polymers / DuPont (Korea) Inc.
19
Shrinkage & Warpage
Non-uniform walls
Wrong
Right
Engineering Polymers / DuPont (Korea) Inc.
20
Shrinkage & Warpage
Isochrones
Engineering Polymers / DuPont (Korea) Inc.
13
Shrinkage & Warpage Glass reinforced materials
Deformation trend b
Shrinkage [%]
Transverse to flow In flow
77 103 32 23
97 52 86 34
Engineering Polymers / DuPont (Korea) Inc.
30
Weld Line & Strength Weld line, example
Flow
Flow
Engineering Polymers / DuPont (Korea) Inc.
Tensile Strength ZYTEL 70G33 23 C, DAM Engineering Polymers / DuPont (Korea) Inc.
4
Gate Location & Shrinkage
Flow Direction
Gate
Transverse Direction
Material Flow Affects Orientation
Shrinkage & Warpage Uneven Shrinkage
Engineering Polymers / DuPont (Korea) Inc.
10
Shrinkage & Warpage
Bad Flatness
Engineering Polymers / DuPont (Korea) Inc.
Sizing to Reduce Warpage
Bow-In
Max R
T 2 T
Reduce Stress Conc.
Reduce Warpage
Engineering Polymers / DuPont (Korea) Inc.
21
Shrinkage & Warpage Non-uniform Wall Thickness Contributes To
Engineering Polymers / DuPont (Korea) Inc.
8
Shrinkage & Warpage
Shrinkage Increases with Wall Thickness
Higher Shrinkage
Lower Shrinkage
9
Engineering Polymers / DuPont (Korea) Inc.
Mat erial Type
Filler Type
Tensile % St rengt h MPa R et ained One Two Gat e Gat e
N ylon 66 N ylon 66 Polyprop Polyprop
N one 40% Glass N one 30% Glass
79 199 37 69
27
Weld Line & Strength
1 Gate
2 Gate
Weld Line
Engineering Polymers / DuPont (Korea) Inc.
28
Weld Line & Strength
Tensile Strength Weld Line vs. Flow Direction
Engineering Polymers / DuPont (Korea) Inc.
7
Gate Location & Shrinkage
Mineral Reinforced
Flow Direction
Gate
Transverse Direction
Mineral Resists Shrinkage More Uniformly in All Directions
Design Guidelines
Version 1.0
Nov . 24 . 2004 Technical Center / Engineering Polymers DuPont (Korea) Inc.
Engineering Polymers / DuPont (Korea) Inc.
1
Design Flow
• • • • Higher Molded-in Stress Warpage Sinks Voids
Sink
Void In Thicker Section
Engineering Polymers / DuPont (Korea) Inc.
22
Shrinkage & Warpage
Outside Radius
23 C, 50% RH
180 160 140 120 100 80 60 40 20 0
Flow Direction Knit Line
MPa
ZYTEL 70G33
MINLON 22C
RYNITE 530
Engineering Polymers / DuPont (Korea) Inc.
29
Weld Line & Strength
33
Sinks
Ribs and Sinks
Engineering Polymers / DuPont (Korea) Inc.
34
Sinks
Ribs and Sinks
T
0.5 T (max. 0.75T)
R=T
3T
R max. 0.5T
D1
T
D2
Sink mark
should be improved
Deformation trend
b
Shrinkage [%]
Transverse In Flow
Shrinkage (S)
SThin Sin flow
S Thick
S
1 1.5 2 3 Wall thickness [mm]
4
a
Engineering Polymers / DuPont (Korea) Inc.
31
Weld Line & Strength
Weld Line
Gate
Engineering Polymers / DuPont (Korea) Inc.
32
Weld Line & Strength
Improved Design
Weld Line
Gate
Engineering Polymers / DuPont (Korea) Inc.
40
Bad & Good Design, Example
Engineering Polymers / DuPont (Korea) Inc.
5
Gate Location & Shrinkage
Unreinforced
Flow Direction
Gate
Transverse Direction
Higher Shrinkage in Direction of Molecular Orientation/Flow
better
35
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Sinks
Sink
Improved Sinks
Grained or Stippled Surface
Tooled Depression
Offset at Rib
Engineering Polymers / DuPont (Korea) Inc.
Cooling Side to Side
HOT
COOL
PART
TOOL
Engineering Polymers / DuPont (Korea) Inc.
25
Sizing to Reduce Stress Concentration Factor (SCF)
Stress Concentration Factor 3.0 2.5 2.0 P = Applied Load R = Fillet Radius T = Thickness
Engineering Polymers / DuPont (Korea) Inc.
6
Gate Location & Shrinkage
Glass Reinforced
Flow Direction
Gate
Transverse Direction
Glass Fiber Resists Shrinkage in Direction of Alignment/Flow
Shrinkage (S)
SThin Sin flow
S Thick S
1 1.5 2
3
4
Wall thickness [mm]
14
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a
Shrinkage & Warpage Unreinforced materials
17
Shrinkage & Warpage Glass reinforced materials
Gate
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18
Shrinkage & Warpage
Effect of Machine Settings on Shrinkage
Special applications
Engineering Polymers / DuPont (Korea) Inc.
3
Gate Location & Strength
Gate
300 250
MPa
200 150 100 50 0 Tension Compression
Flow Tranverse
Design Concept
CAE
CAD
Engineering Polymers / DuPont (Korea) Inc.
2
Typical Wall Thickness
For Engineering Polymers
millimetric scale
0
1 2
3
4 5
6
7
General applications
Follows
Inside Radius
Engineering Polymers / DuPont (Korea) Inc.
23
Good Design
Gate Bad 3T Gate Better T
Best
Engineering Polymers / DuPont (Korea) Inc.
24
Shrinkage & Warpage
15
Gate Location & Shrinkage
Bad Gate Location
Gate
Engineering Polymers / DuPont (Korea) Inc.
16
Gate Location & Shrinkage
Flow Steps
Engineering Polymers / DuPont (Korea) Inc.
1.5
1.0 0 0.2 0.4 0.6 0.8 R/T 1.0 1.2 1.4
26
Engineering Polymers / DuPont (Korea) Inc.
Sharp Corners
SHARP CORNERS
Engineering Polymers / DuPont (Korea) Inc.