plastic fantastic - solid solutions · plastic fantastic • plastic parts must be geometrically...
TRANSCRIPT
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Agenda
Plastic Fantastic
• Plastic Fantastic?
• Challenges with Plastics
• Case Study – Plastic Razor
• Mechanical Performance of
Plastics
• Designing Plastic Parts for
Moulding
• Simulating the Injection
Moulding Process
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Fantastic?
Plastic Fantastic
Benefits of plastic moulded parts
• Complex shapes
• Net shape in one process
• Wide range of material properties
• Tight tolerances
• Economical for high volumes
• Little wastage / recyclable
Polyethylene usage predicted to increase by
100% from 2000 - 2020
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Challenges for Designers and Manufacturers
Plastic Fantastic
• Plastic parts must be geometrically capable of being
moulded easily – draft; parting lines etc.
• Injection moulding tooling is expensive
• Tools usually need development and often rework
• The ‘blame game’!
• Plastics behave differently from metals so need to be
designed and tested differently
• Many plastic parts snap fit together. Snap fits require
careful design so they work but do not break
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Case Study – Plastic Razor
Plastic Fantastic
• High volume part
• Complex shape
• Moulded body
• Over-moulded grip
• Cutter head snaps to body
• Moulded integral plastic spring for tension
• Plastic carrier
Will it fit together properly?
What will be the cycle time to mould it?
Can we mould it? Will it break?
Will there be
any surface
defects?
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance
Plastic Fantastic
FEA is widely used to predict mechanical performance. But plastics have special
considerations…
• They are typically much softer than metals. So the restraints have to be carefully
selected to suitably model how it the part is fixed.
• The shapes they form are usually complex shapes – meshing is more demanding.
• Plastics experience much larger deformations than metals – so the FEA solution is
usually nonlinear because stiffness changes must be taken into account
• Nonlinear simulation is commonly needed to model sliding “snap-fits” and “push-fits”.
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance - Static analysis
Plastic Fantastic
The razor handle has to be stiff enough not to bend when you
use it.
• Even on the thickest of moustaches!
• A 3-point bend test was performed to see how much it
would deform.
Fixtures
Load
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – Static analysis
Plastic Fantastic
• The curvature based mesh is ideal -
the element size adapts to fit into the
nooks and crannies!
• Results show that the
razor is very stiff!
• It takes around10 N to
give a 1mm deflection.
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – Nonlinear
Plastic Fantastic
The blade on the end of the razor is assembled
using a “push-fit” connection.
Due to this, the razor clip undergoes significant
large deformation and sliding contact.
To model this accurately, Nonlinear simulation will
be needed.
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – can it fit together?
Plastic Fantastic
When the component are assembled, we want to know..
• Is there physically enough space to fit the clip in-and-under the
blade groove?
• What force is required to push them together? – it should be
easy enough to push together by hand.
• More importantly, because it squashes when assembled, will this
cause the component to yield/fail?
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – can it fit together?
Plastic Fantastic
Using the Simulation tool we have been able to prove that..
• It is possible for the components to fit together.
• Even at the maximum inward angle, the clip of
the razor has enough room to fit under the
blade groove.
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – can it fit together?
Plastic Fantastic
Using the Simulation tool we have been able to prove that..
• The force required to push the handle into the blade
would be reasonable for someone to do by hand.
• The push force
required is around 20N
for half of the model
(40 N total).
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – does it break when assembled?
Plastic Fantastic
Using the Simulation tool we have been able to prove that..
• Some yielding does occur.
• Looking at an iso clipping, the yielded material penetrates
significantly into the depth.
• A redesign may be necessary!
• However since the mesh is very coarse, the stresses will
be more realistic after running a finer-high quality mesh.
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – tab spring stiff enough?
Plastic Fantastic
When in use, the blade oscillates back and forth within the
seat.
• Is the tab stiff enough to push the
blade back to the centre?
• If so, what force is required?
• Will it be long enough not to
unhook from the catch?
A central tab is needed to push it back after each stroke.
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – tab spring stiff enough?
Plastic Fantastic
The blade is rotated to it’s full travel, then allowed to recoil.
• Even at full tilt, results
confirm the razor remains seated.
It does not unhook!
• The blade is firmly pushed back to centre
with a force less than 1N.
• Results prove a re-design is not necessary.
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – will it come apart if dropped?
Plastic Fantastic
If the razor was dropped, ideally the blade
should stay on the handle.
• To simulate this, a drop test was conducted.
• One method that could be used is the drop test in Simulation
Professional.
• However in this case a nonlinear dynamic study was used. The
advantage is that it uses an implicit solver which gives a much
faster solve time.
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mechanical Performance – will it come apart if dropped?
Plastic Fantastic
• As a possible worst case, the razor was dropped on a corner
point.
• Looking at the results, dropping the
razor from a height of 1m shows that
the blade does not come off.
• Practical test on my bathroom floor agreed with the simulation
results. Although it did eventually break after about the 20th drop!
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mouldability
Plastic Fantastic
So we can predict how a plastic part will
perform under a variety of loading conditions
BUT ….
• Can we make it easily?
• Can we get the tool right first time?
• Can we minimise tool rework?
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mouldability with Mould Tools
Plastic Fantastic
SolidWorks Mould Tools helps you …
• Predict draft requirements and
undercuts
• Create parting lines
• Build shut off and parting surfaces
• Build the die and cavity
SolidCAM enables you …
• To CNC the tools
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
New for 2012 – SolidWorks Plastics
Plastic Fantastic
Enables you to ….
• Predict whether it will mould – even if you are
not an experienced mould designer
• See whether there will be surface defects
• Check where weld lines will occur
• Understand where the mould will be vented
• Predict cycle times and gate requirements
• Reduce tool development costs and lead time
2 Versions: Plastics Professional and Plastics Premium
Flow & Pack
Multi-Cavity Runner Balancing
Results vs. Time Shrinkage &
Sink Marks
Inserts &
Overmoulding Multishot & Co-
Injection
Gas-Injection & Valve Gates
Fibre Analysis &
Birefringence
Plastics Premium
Flow
Filling
Multiple Gates
Short Shots
Weld Lines
Air Traps
Plastics Professional
Plastic Fantastic
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Mouldability Case Study
Plastic Fantastic
We will predict the mouldability of 3 parts …
• The thin plastic razor carrier
• The main (bulky) body of the razor
• The over-moulded grip
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
SolidWorks Plastics – Key Features
Plastic Fantastic
Sophisticated shell, solid and mixed meshing
Guided set-up making it easy to use
Extensive libraries of plastic materials and moulding machines
Flow and Pack simulation – filling and cooling of mould
Extensive results types and display methods
In formative results ‘Adviser’
Report generator – outputs to Word and MS PowerPoint
Video output tools
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olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Short Shots
Plastic Fantastic
© S
olid Solutions M
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nt | 14/11/2012 | Confidential Inform
ation
Multiple Gates
Plastic Fantastic
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Conclusions
Plastic Fantastic
Plastics are exceptional engineering materials
with many valuable properties
Manufacturing requirements must be designed
into the parts ‘up-front’
Strength and performance simulations needs
special care; often using non-linear tools
Designing the part so that it can be easily
moulded will save tooling development costs
and time
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
How SolidWorks Can Help You …
Plastic Fantastic
SolidWorks has tools to help you design your
plastic parts …
• SolidWorks Mould Tools
• SolidWorks Simulation
• SolidWorks Simulation Premium
• SolidWorks Plastics Professional
• SolidWorks Plastics Premium
© S
olid Solutions M
anageme
nt | 14/11/2012 | Confidential Inform
ation
Further Information and Contacts
Plastic Fantastic
www.solidsolutions.tv
• Simulating Rubbers and Plastics
• SolidWorks Plastics
• Sustainable Design and Plastic
Injection Analysis