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Basics of Design I

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Design For Assembly

Integrated Baffle, Oil Pick-Up Tube and Scrapers

Mains

Lower Skirt

Integrated baffle is

captured and located

by lower skirt and

cranks mains

eliminating the need

for fasteners

Oil Pan

Existing baffle oil

pick-up tube

w/gasket andfasteners

11 parts

Integrated

Into one

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Snap-Fit Opportunities

Integrated Snap Fits

No extra part

Simple & reliable

Design freedom

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L

h/2

h

f

Q

F

Alpha

f = 1.09 es L

h

2

[mm]

Es = [MPa]sses

Es = Secant Modulus

Snap-Fit Design

HeightWidthDeflection lengthDeflection undercutAngleDeflection forceEngagement force

mmmmmmmmdegreeNewtonNewton

hbLfAlphaQF

POM High Viscosity 8

POM Med. Viscosity 5Nylon 6.6 DAM 2-3Nylon 6.6 Cond. 4-6GR Nylon DAM 0.5-1.2GR Nylon Cond 0.9-2.0

PBT

GR PBTGR PETTPC-ET

3-4

0.7-1.50.5-0.815-20

General case

Approx. valuesfor

e [%]

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Undercuts rounded to

avoid tearing of part &

stress concentration.

Ejectors should be

large to avoidpenetrating the part.

Cycle time (specially

hold pressure time)

should be optimum to

avoid excessive

shrinkage.

POM Undercut = ((B-A)/B)

5%

Undercut Design

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Break energy in J/m (Izod impact strength)

V(r = 0.023 mm) U(r = 3.2 mm) UV

Nylon

Dry as moulded

28 740 26 : 1

Nylon

Cond. 2.5 % RH

34 1340 40 : 1

POM 36 310 9 : 1

Influence of notches onImpact Strength

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Stress

Concerntration

Factor

3.0

2.5

2.0

1.5

1.00 0.2 0.4 0.6 0.8 1.0 1.2 1.4

R/T

P = Applied Load

R = Fillet Radius

T = Thickness

Sharp Corners

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Wall Thickness Design

Non-uniform wall thickness

Wall Section Design

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Steel

Aluminium

55% GR PET

30% GR PET

30% GR PBT

30% GR Nylon 6.6 (DAM)

30% GR Nylon 6.6 (Cond.)

Nylon 6.6 (DAM)

POM Med. Viscosity

POM High Viscosity

Nylon 6.6 (Cond.)

210.000

70.000

19.500

11.000

10.000

10.000

7.500

3.300

3.200

3.100

1.600

Tensile E-modulus for some materials

F L

3 E I

3

x-x

d =

I =B H

12x-x

3

X

Force

x

x

L

B

H

Deflection Beam Case

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140

2.8

1.8

4.0

2.

0

6.

0

9.

2

11.

228

Moment ofInertia forA, B and C

2520 mm3

Compared to Amaterialsavings

up to 22.9 %

Compared to A

materialsavings

up to 57.4 %

A

B

C

Profile Stiffness

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1.00 0.62 0.48 0.44 0.57 0.46 1.12 0.33

Force

W

H

tH, W, t = constant

Profile 1, deformation 1Profile 2, deformation 2

No deformation

Reference Relative deformation value versus the reference

profile

Deformations with a Constant Load

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1.0 1.5 13.5 14 27.3 30 28 10.5

Reference

Relative Torsion Stiffness

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Rib Designs

Rib & Sink Marks Alternative to ribs

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Aim foruniform 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.

Ten rules for designers

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A Polymer for Every

Application