Autodesk Moldflow Insight 2012 AMI Thermoplastics Overmolding
Revision 1, 22 March 2012. This document contains Autodesk and third-party software license agreements/notices and/or additional terms and conditions for licensed third-party software components included within the product. These notices and/or additional terms and conditions are made a part of and incorporated by reference into the Autodesk Software License Agreement and/or the About included as part of the Help function within the software.
Contents Chapter 1 Overmolding.......................................... 1 Chapter 2 Thermoplastic Overmolding analysis types and analysis technologies.......................................... 2 Chapter 3 Overmolding analysis................................. 3 Overmolding...................................... 3 Running an Overmolding........................... 3 Overmolding...................................... 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
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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 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 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 Melt temperature Filling control The temperature of the mold at the plastic-metal interface, where the plastic touches the mold. The temperature of the molten plastic, or melt, as it starts to flow into the cavity. Specifies the method by which the filling phase of the analysis is controlled. Overmolding analysis 5
Velocity/pressure switch-over Pack/holding control Advanced options... Fiber orientation analysis if fiber material Birefringence analysis if material data includes optical properties The criteria by which the molding machine will switch from velocity control to pressure control. Specifies the method by which the pressure phase of the molding process is controlled. Displays the advanced options for the Enables a Fiber orientation analysis if the material includes fiber. 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 Mold surface temperature Melt temperature Filling control Velocity/pressure switch-over Pack/holding control Cooling time Allows you to select and/or edit the material used by Controller B in the The temperature of the mold at the plastic-metal interface, where the plastic touches the mold. The temperature of the molten plastic, or melt, as it starts to flow into the cavity. Specifies the method by which the filling phase of the analysis is controlled. The criteria by which the molding machine will switch from velocity control to pressure control. Specifies the method by which the pressure phase of the molding process is controlled. Specify a cooling time, or have it calculated automatically during the Fill+Pack 6 Overmolding analysis
Advanced options... Fiber orientation analysis if fiber material Displays the advanced options for the 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 Melt temperature Filling control Velocity/pressure switch-over Pack/holding control Cooling time Advanced options... Fiber orientation analysis if fiber material Birefringence analysis if material data includes optical properties The temperature of the mold at the plastic-metal interface, where the plastic touches the mold. The temperature of the molten plastic, or melt, as it starts to flow into the cavity. Specifies the method by which the filling phase of the analysis is controlled. The criteria by which the molding machine will switch from velocity control to pressure control. Specifies the method by which the pressure phase of the molding process is controlled. Specify a cooling time, or have it calculated automatically during the Fill+Pack Displays the advanced options for the Enables a Fiber orientation analysis if the material includes fiber. 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 Mold surface temperature Melt temperature Filling control Velocity/pressure switch-over Pack/holding control Cooling time Advanced options... Fiber orientation analysis if fiber material Allows you to select and/or edit the material used by Controller B in the The temperature of the mold at the plastic-metal interface, where the plastic touches the mold. The temperature of the molten plastic, or melt, as it starts to flow into the cavity. Specifies the method by which the filling phase of the analysis is controlled. The criteria by which the molding machine will switch from velocity control to pressure control. Specifies the method by which the pressure phase of the molding process is controlled. Specify a cooling time, or have it calculated automatically during the Fill+Pack Displays the advanced options for the 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 Injection molding machine Mold material Solver parameters 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. Select and edit an injection molding machine to simulate your molding machine during the You can configure the injection unit, hydraulic unit, and clamping unit. Allows you to select and edit the mold material to be used during the You can specify the density, specific heat, and thermal conductivity of the mold material. Allows you to select and edit the solver parameters to be used during the Overmolding analysis 9