Basics of Design I

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Basics of Design I
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Design For Assembly
Integrated Baffle, Oil Pick-Up Tube and Scrapers
Mains
Integrated baffle is captured and located by
lower skirt and cranks mains eliminating the need
for fasteners
11 parts Integrated Into one
Existing baffle oil pick-up tube w/gasket and
fasteners
Lower Skirt
Oil Pan
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Snap-Fit Opportunities

• Integrated Snap Fits
• No extra part
• Simple reliable
• Design freedom

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Snap-Fit Design
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Undercut Design

• Undercuts rounded to avoid tearing of part
  stress concentration.
• Ejectors should be large to avoid penetrating the
  part.
• Cycle time (specially hold pressure time) should
  be optimum to avoid excessive shrinkage.
• POM Undercut ((B-A)/B) 5

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Influence of notches on
Impact Strength
Break energy in J/m (Izod impact strength)
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Sharp Corners
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Wall Section Design
Non-uniform wall thickness
Wall Thickness Design
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Deflection Beam Case
Tensile E-modulus for some materials
210.000
Steel

70.000
Aluminium
55 GR PET
19.500
30 GR PET
11.000
3
B H
H
30 GR PBT
10.000
X
I
12
x-x
10.000
30 GR Nylon 6.6 (DAM)
30 GR Nylon 6.6 (Cond.)
7.500
B
3.300
Nylon 6.6 (DAM)
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F L
POM Med. Viscosity
3.200
d
3.100
POM High Viscosity
3 E I
Nylon 6.6 (Cond.)
1.600
x-x
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Profile Stiffness
Moment of
6.0
A
Inertia for
A, B and C
3
140
2520 mm
4.0
9.2
B
Compared to A
material
savings
up to 22.9
2.8
28
2.0
11.2
C
Compared to A
material
savings
up to 57.4
1.8
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Deformations with a Constant Load
Force
No deformation
Profile 1, deformation 1
Profile 2, deformation 2
W
H
t
H, W, t constant
1.00
0.62
0.48
0.44
0.57
0.46
1.12
0.33
Relative deformation value versus the reference
profile
Reference
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Relative Torsion Stiffness
Reference
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30
28
10.5
1.0
1.5
13.5
27.3
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Rib Designs
Rib Sink Marks
Alternative to ribs
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Ten rules for designers

• Aim for uniform wall thickness.
• Design wall thickness as thin as possible and
  only as thick as necessary.
• Use ribbing instead of greater wall thickness.
• Provide radiusing.
• Provide demoulding tapers.
• Avoid undercuts.
• Do not design to greater precision than required.
• Design multi-functional components.
• Use economic assembly techniques.
• Gate moulding on the thickest wall.

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A Polymer for Every Application