Autodesk® Moldflow® Insight 2012
AMI Thermoplastics
Overmolding
Revision 1, 22 March 2012.
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Contents
Chapter 1
Overmolding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2
Thermoplastic Overmolding analysis types and analysis
technologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Chapter 3
Overmolding analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Overmolding analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Running an Overmolding analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Overmolding analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Process Settings Wizard dialog—Fill Settings for First Component Stage. . . . 5
Process Settings Wizard dialog—Fill Settings for Overmolding Stage. . . . . . . 6
Process Settings Wizard dialog—Fill+Pack Settings for First Component Stage. 7
Process Settings Wizard dialog—Fill+Pack Settings for Overmolding Stage. . . 8
Overmolding Second Component (3D) dialog. . . . . . . . . . . . . . . . . . . . . 8
Overmolding Advanced Options dialog. . . . . . . . . . . . . . . . . . . . . . . . . 9
iii
iv
Overmolding
1
Overmolding is an injection molding process where two materials are molded together. Types of
overmolding include two shot sequential overmolding, multi-shot injection molding or insert
overmolding.
Multi-shot injection molding injects multiple materials into the cavity during the same
molding cycle. Insert overmolding uses a pre-molded insert placed into the mold before
injecting the second material. Two shot sequential overmolding is where the molding
machine injects the first material into a closed cavity, and then moves the mold or cores
to create a second cavity, using the first component as an insert for the second shot using
a different material.
Materials are usually chosen specifically to bond together, using the heat from the
injection of the second material to form that bond. This avoids the use of adhesives or
assembly of the completed part. It can result in a robust multi-material part with a high
quality finish.
When designing an overmolded part, wall thicknesses of both the insert and the
overmolded component should be as uniform as possible to ensure an even and robust
bond. Avoid ribs and sharp corners to reduce flow problems.
Overmolded parts take longer to cool than single shot injection molded part, and cooling
systems are less effective. The insert acts as an insulator and heat is less efficiently extracted
from the part. However, optimising the cooling system can help reduce the cycle time.
1
Thermoplastic Overmolding
analysis types and analysis
technologies
2
The following table shows the available analysis technologies for a Thermoplastic Overmolding
analysis type.
Table 1: Thermoplastic overmolding process and analysis types
Analysis Type
Analysis Technology
Fill
Fill+Pack
Fiber Fill+Pack
Overmolding
Warp
Venting (Process Settings option)
2 | Thermoplastic Overmolding analysis types and analysis technologies
Overmolding analysis
3
An Overmolding analysis is used to analyse two shot sequentially overmolded parts.
Overmolding analyses consist of a two step process, where a Fill+Pack analysis is performed
on the first cavity (first component stage), and then a Fill+Pack analysis or a
Fill+Pack+Warp analysis is performed on the overmolding cavity (overmolding stage).
The overmolding stage on the second cavity uses a different material from the first
component stage. As the temperature of the insert, injected in the first component stage,
is not uniform, mold and melt temperatures used in the overmolding stage are initialized
by the temperatures recorded at the end of the first component stage.
NOTE: It is assumed that the material injected in the the first component stage does not
melt and flow when the second material is injected in the overmolding stage, even though
the temperature does rise.
TIP: You may find it easier to model your part in two separate studies, one for the first
component stage and one for the overmolding stage. You can then add these two stages
together in one model.
NOTE: Warp analyses on overmolded components on 3D models which contain part
inserts, take into account the influence of contact between the part inserts and the
overmolded component.
Overmolding analysis
When running an overmolding analysis, the different materials and injection
locations required need to be specified.
Running an Overmolding analysis
The Overmolding analysis consists of a 2-step process where a normal Fill+Pack
analysis is performed on the first cavity (first component stage), which is then
followed by a Fill+Pack analysis on the overmolding cavity (overmolding stage).
The consecutive overmolding stage on the second cavity uses a different material
from the first analysis, and the first component temperatures are used as the
initial temperatures.
NOTE: This topic assumes that you have prepared one study with a meshed
model of the first component, and another study with a meshed model of the
3
second component, and that you will create a new study for the
overmolding analysis of the two components.
1
Create a new project, or open an existing one.
2
Click Home tab > Import panel > Import, and then locate and import
the study describing the second component in the overmolding process.
3
Click
Home tab > Molding Process Setup panel, and select
Thermoplastics Overmolding.
4
Click Home tab > Molding Process Setup panel > Analysis Sequence
and select either Fill+Pack + Overmolding Fill, or, Fill+Pack +
Overmolding Fill+ Overmolding Pack , depending whether you want
the packing stage included in the overmolding analysis.
5
Click Ctrl+A to select the entire model.
You will now need to apply the appropriate property to the model.
6
Right-click in the Model pane and select Properties, select the
Overmolding Component tab, set the Component option to 2nd shot
and then click OK. If the model consists of several types of entities, for
example, it includes beam elements describing the runner system for
the second component, select each entity type in turn and set the
Component option to 2nd shot.
7
Click
Home tab > Import panel > Add and then locate and import
the study describing the first component.
NOTE: Bodies or assemblies that are added to an existing model, are
displayed in a new layer.
TIP: After importing the two models into one study, it is a good idea
to give them different names in the Layers pane.
8
If necessary, click
Geometry tab > Utilities panel >
(Move tools)
> Translate to correctly position the first component relative to the
second.
9
Using the Layers pane, hide the second component, click Ctrl+A to
select the entire first component model, right-click in the Model pane
and select Properties, select the Overmolding Component tab, set
the Component option to 1st shot and then click OK.
As described above, you may need to repeat this step several times if
the model contains different types of entities.
10 Make the second component visible again.
11 Double-click Material A in the Study Tasks pane and select the
material to be used in the first component Fill+Pack analysis stage.
12 Double-click Material B in the Study Tasks pane and select the
material to be used in the second component overmolding stage.
4 | Overmolding analysis
NOTE: Alternatively, click and Home tab > Molding Process Setup
panel > Select Material > Select Material A/B to select the materials.
13 Click
in the study task pane, and set an injection location on the
first component model.
14 Click
in the study task pane, and set an injection location on the
second component model.
NOTE: Alternatively, click
and
Boundary Conditions tab >
Injection locations panel > Injection Locations to set the injection
locations.
15 Click
Home tab > Molding Process Setup panel > Process Settings
and specify the process settings for the first component stage and for
the overmolding stage on the respective Wizard pages, then click Finish.
The overmolding analysis is now ready to be launched via the Study Tasks
pane or the Job Manager.
Overmolding analysis
Use this dialog to specify settings for a Overmolding analysis.
Process Settings Wizard dialog—Fill Settings for First Component Stage
This page of the Process Settings Wizard, which can be accessed by clicking
(Home tab > Molding Process Setup panel > Process Settings), is used
to specify the filling phase simulation related process settings for the first
component stage of the overmolding analysis sequence.
NOTE: Some of the items listed below may not be available on the current
dialog. This is dependent on the mesh type, molding process and analysis
sequence selected.
Mold surface temperature
The temperature of the mold at the
plastic-metal interface, where the plastic
touches the mold.
Melt temperature
The temperature of the molten plastic,
or melt, as it starts to flow into the
cavity.
Filling control
Specifies the method by which the filling
phase of the analysis is controlled.
Overmolding analysis | 5
Velocity/pressure switch-over
The criteria by which the molding
machine will switch from velocity
control to pressure control.
Pack/holding control
Specifies the method by which the
pressure phase of the molding process is
controlled.
Advanced options...
Displays the advanced options for the
analysis.
Fiber orientation analysis if fiber
material
Enables a Fiber orientation analysis if
the material includes fiber.
Birefringence analysis if material data
includes optical properties
Produces stress-optical birefringence
results if the material has optical
properties.
Process Settings Wizard dialog—Fill Settings for Overmolding Stage
This page of the Process Settings Wizard, which can be accessed by clicking
(Home tab > Molding Process Setup panel > Process Settings), is used
to specify the filling phase simulation related process settings for the
overmolding (second component) stage of the overmolding analysis
sequence.
NOTE: Some of the items listed below may not be available on the current
dialog. This is dependent on the mesh type, molding process and analysis
sequence selected.
Material B
Allows you to select and/or edit the
material used by Controller B in the
analysis.
Mold surface temperature
The temperature of the mold at the
plastic-metal interface, where the plastic
touches the mold.
Melt temperature
The temperature of the molten plastic,
or melt, as it starts to flow into the
cavity.
Filling control
Specifies the method by which the filling
phase of the analysis is controlled.
Velocity/pressure switch-over
The criteria by which the molding
machine will switch from velocity
control to pressure control.
Pack/holding control
Specifies the method by which the
pressure phase of the molding process is
controlled.
Cooling time
Specify a cooling time, or have it
calculated automatically during the
Fill+Pack analysis.
6 | Overmolding analysis
Advanced options...
Displays the advanced options for the
analysis.
Fiber orientation analysis if fiber
material
Enables a Fiber orientation analysis if
the material includes fiber.
Process Settings Wizard dialog—Fill+Pack Settings for First Component
Stage
This page of the Process Settings Wizard, which can be accessed by clicking
(Home tab > Molding Process Setup panel > Process Settings), is used
to specify filling and packing phase simulation related process settings for
the first component stage of the overmolding analysis sequence.
NOTE: Some of the items listed below may not be available on the current
dialog. This is dependent on the mesh type, molding process and analysis
sequence selected.
Mold surface temperature
The temperature of the mold at the
plastic-metal interface, where the plastic
touches the mold.
Melt temperature
The temperature of the molten plastic,
or melt, as it starts to flow into the
cavity.
Filling control
Specifies the method by which the filling
phase of the analysis is controlled.
Velocity/pressure switch-over
The criteria by which the molding
machine will switch from velocity
control to pressure control.
Pack/holding control
Specifies the method by which the
pressure phase of the molding process is
controlled.
Cooling time
Specify a cooling time, or have it
calculated automatically during the
Fill+Pack analysis.
Advanced options...
Displays the advanced options for the
analysis.
Fiber orientation analysis if fiber
material
Enables a Fiber orientation analysis if
the material includes fiber.
Birefringence analysis if material data
includes optical properties
Produces stress-optical birefringence
results if the material has optical
properties.
Overmolding analysis | 7
Process Settings Wizard dialog—Fill+Pack Settings for Overmolding Stage
This page of the Process Settings Wizard, which can be accessed by clicking
(Home tab > Molding Process Setup panel > Process Settings), is used
to specify filling and packing phase simulation related process settings for
the overmolding (second component) stage of the overmolding analysis
sequence.
NOTE: Some of the items listed below may not be available on the current
dialog. This is dependent on the mesh type, molding process and analysis
sequence selected.
Material B
Allows you to select and/or edit the
material used by Controller B in the
analysis.
Mold surface temperature
The temperature of the mold at the
plastic-metal interface, where the plastic
touches the mold.
Melt temperature
The temperature of the molten plastic,
or melt, as it starts to flow into the
cavity.
Filling control
Specifies the method by which the filling
phase of the analysis is controlled.
Velocity/pressure switch-over
The criteria by which the molding
machine will switch from velocity
control to pressure control.
Pack/holding control
Specifies the method by which the
pressure phase of the molding process is
controlled.
Cooling time
Specify a cooling time, or have it
calculated automatically during the
Fill+Pack analysis.
Advanced options...
Displays the advanced options for the
analysis.
Fiber orientation analysis if fiber
material
Enables a Fiber orientation analysis if
the material includes fiber.
Overmolding Second Component (3D) dialog
This dialog is used to specify the properties of the selected tetrahedral
elements of type Overmolding second component.
The collection of property values defined on the dialog are saved to a
property set with the description shown in the Name box.
8 | Overmolding analysis
Overmolding Advanced Options dialog
This dialog is used to specify the overmolding related advanced options
for the overmolding analysis sequence.
To access this dialog, ensure that you have selected the Thermoplastics
Overmolding process and an analysis sequence that includes Overmolding
Fill or Overmolding Fill+Pack, click
(Home tab > Molding Process Setup
panel > Process Settings), click Next to navigate to the Fill Settings for
Overmolding Stage or Fill+Pack Settings for Overmolding Stage page of
the Wizard, then click Advanced options for overmolding stage.
Additional injection controller
Allows you to select and edit an
injection controller for the second
component stage of the overmolding
process. You can control the filling
phase, velocity/pressure switch-over
point, pack/holding phase, mold
temperature and mold-open time.
Injection molding machine
Select and edit an injection molding
machine to simulate your molding
machine during the analysis. You can
configure the injection unit, hydraulic
unit, and clamping unit.
Mold material
Allows you to select and edit the mold
material to be used during the analysis.
You can specify the density, specific
heat, and thermal conductivity of the
mold material.
Solver parameters
Allows you to select and edit the solver
parameters to be used during the
analysis.
Overmolding analysis | 9