mpi 6.0 materials

8/14/2019 MPI 6.0 Materials

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From this it is possible to ascertain the direction of flow, position of weld lines and check for possible transient effects.

The basic concept underlying analysis software is that the way plastic flow in to the cavity has

a very significant effect on the properties of the final part. Therefore when optimizing a flow patternthe engineer must take in to account the criteria for mechanical performance. A significant factor ismolecular orientation.

In plastic material there is a direct relationship between flow shear stress and molecular orientation. Higher flow shear stress causes a greater alignment of molecules in the general directionof flow. The pattern of molecular orientation sets up internal stresses within the material. Themechanical properties are much reduced in the direction perpendicular to orientation so if there is adanger of the part being stresses across the orientation then during the design stage we shouldminimize the degree of orientation. Since the mechanical strength in the direction of flow is higher than across the flow, this can be used if the direction of mechanical load is known. Orientation can

be aligned in the direction of the principal stress.

It is also important to consider how flow affects the formation of weld lines. The extent towhich the two flow front join depends on conditions at the flow front and the direction of flow.Temperature is an important consideration so shear sensitivity and frictional heating are relevantfactors. So too is the structure of the material. The tendency of some additives to bleed out ahead of the flow front can give an interface between two joining flow fronts, which has poor strength.

This means that as well as being visually unacceptable, weld lines, regardless of how well theyhave formed will still give areas of local weakness in the part. Therefore it is important to positionweld lines away from areas of structural weakness.

The popular analysis software meant for flow analysis of plastic parts has a set of database of plastic materials from many of the international manufacturers. As many as 3000 to 4000 grades of plastics materials are available after characterizing the materials for the data as required by theanalysis programs. There are options available for the user to incorporate the material data for locally available plastic materials also, after conducting the tests in the prescribed manner. Thepopular software used for the purpose of analysis of plastics is

- C-Mold- Mold flow- Fill Calc- CAD Mould etc.

Why do we need flow analysis?

Identifying the molding problems at an early stage of the tooling can greatly reduce- Tooling lead times- Mould trials- Costly tooling and

- Product modifications

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What is happening at present?

With reference to the design of moulds, presently many of the parameters are either a guesswork or

based on existing empirical formula, which does not take in to consideration all the variables involvedin the process. For example, with the intention of ensuring a complete fill of the cavity, the designer always tends to oversize the runners and gates. This increases the wastage of material apart fromother likely moulding problems. Like this, the guesswork is generally carried out for determining thefollowing variables:

- Clamp tonnage- Product mouldability and quality- Cooling requirements- Injection time and pressure- Melt and mould temperatures- Pressure drop in the feed system- Position of weld lines and air entrapment- Areas of structural weakness- Surface areas, volume and shot weight prediction.

What is available through CAE analysis?

CAE analysis involves full range of programs, which calculates the various parameters for successfully moulding simple to complex parts based on complex equations of heat transfer and fluidflow. The features, which can be estimated using such CAE analysis programs, are:

- Mouldability of the part- Optimal Runner sizes- Number and position of gates- Temperature, pressure, fill time and cooling time required- Clamp tonnage requirement- Volume and shot weight- Optimum wall thickness- Stresses in the component part- Shrinkage and warpage prediction- Position and extent of sink marks

- Altering the material and verifying the mouldability for a different material using the materialdatabase.

About the Software

The modules available in flow analysis software are:

1. Filling analysis2. Packing analysis3. Cooling analysis4. Shrinkage and warpage analysis5. Stress analysis

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The main requirements for analyzing area as follows:

1. Description of the part geometry

The surface model with provision for modification of model for critical dimensions. The model of thedeed system-Sprue, Runner and Gate and suggested injection location for flow analysis. The modelof cooling circuit to be provided and the mould are needed for cooling analysis.

2. Raw Material Properties

The values of properties like Density, Specific heat, Viscosity and Thermal conductivity.

3. Molding conditions

Mold temperature, Melt temperature, Injection time or Flow time.

4. Process Machine Parameters

The injection pressure, clamping tonnage of the machine to be used. The flow rate of coolantsupplied the coolant inlet temperature.

Flow Analysis

Establish the filling pattern by Melt front advancement plots

Determination of the Optimum processing conditions

Determination of Runner and Cavity flow balance

Optimization of injection and Packing profiles

The position of weld and melt lines and nature of weld Finding out the optimum wall thickness of the part.

Packing Analysis

To check whether cavity is fully packed Accurate prediction of Clamping tonnage required The volumetric shrinkage of the part Elimination of post moulding effects Position and extent of sink marks

Cooling Analysis

Determination of total cooling time Efficiency of the cooling circuit Cooling network flow parameters

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Effect of mould features such as Inserts, Parting planes and Mould external surfaces on Mouldcooling

Effect of part design on Uniformity of cooling of Part and mould temperature distribution.

Shrinkage and Warpage Analysis

Factors affecting shrinkage Determination of Warped shape Identifying the nature of warpage Isolating the cause of the warpage Reducing the warpage to acceptable tolerance limit with the isolated cause

Stress Analysis

Using the load i.e. Point load, Edge load, Pressure load, Volume load, Thermal load Output result such as

Deflection in x, y, z axis

Deflection of the part Stresses Strains

Advantage of Computer Aided Engineering

The benefits of using CAE software to design and engineer components include: Improved and consistent component quality Lower costs associated with the need for less prototyping, rework and

lower product development cycle time Improved product design before the commencement of manufacturing Lower manufacturing cycle times.

Moldflow software

Moldflow produces CAE software for injection molded plastic parts and consequently helps bringthese benefits to the plastic industry.

Moldflow uses a structured design approach using a suite of programs to integrate mold and productdesign by modeling the cavity, selecting the appropriate material date and predicting pressure,temperature, shear rate, shear stress cooling times and a range of other outcomes.

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Flow simulation

Flow analysis requires model surfaces, which are meshed. The surfaces are meshed duringmodeling. The mesh comprises triangular elements, each element having three nodes. Thesimulation of flow is based on calculations performed for each node.

The total number of elements in the model determines the accuracy of the results and the duration of the analysis; more elements generally mean higher accuracy but longer computation time.

Control volume : Each node of the finite-element mesh is assigned a control volume. The sum of the control volumes equals the volume of the model.

The region formed by linking the mid-sides of a triangular element to its centroid by a straight linedefines the control volume. As shown in Figure 1, the shaded area is the control volume for node 1.

Figure 1

The time to fill a control volume is dependent on the resistance to flow (for example, the thickness of the elements and the flow rate ).

6

MPIMPI

ProjectManager ProjectManager

MFGMFGMaterialsManager MaterialsManager

Modeller Modeller

Material data base of plasticmaterials.

Modeling toolfor creating andmodifyingmeshed models

2D modeling andanalysis. Used todetermine moldingconditions

MPI/STUDIOFlow analysisMPI/STUDIOFlow analysis


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Flow front growth : In the following example of flow front growth, the resistance to flow isassumed the same in all directions .

For ease of reference the current flow front is shaded and a thick line encloses the predicted flowfront .

.1. Node 1 - the gate node - hasfilled. The first estimate of the flowfront is the line joining all nodes thatare attached to node 1 (nodes 2, 7,

5, 3, 6 and 4). This is the initial flowfront. Note that - being equidistantfrom node 1 - these nodes are allequally likely to fill at the same timeand very quickly.

7 1 6

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2. Assume that node 2, on theinitial flow front, is the first to fill.The flow front is now expanded byall the nodes connected to nodenumber 2. However - as flowalways takes the path of leastresistance, the shortest distance inthis instance - the nodes connectedto node 1 fill before thoseconnected to node 2. In any event,the nodes connected to node 2receive very little flow at this stage.With nodes 7, 5, 3, 6 and 4 stillfilling, one of these is the next to fill

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3. Assume that node 5 is thenext to fill. Its adjoining nodes arenow added to the flow front. Thenext node to fill - still on the initialflow front - is either 7, 3, 6 or 4.

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5. Assuming that node 7 hasfilled, the next node to fill is either 3

or 4

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4. Assuming that node 6 is thenext to fill, the flow front isexpanded as shown. The next nodeto fill is either 7, 3 or 4

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6. Assume that node 3 is thenext to fill.

7 1 6

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7. After the last node (node 4)on the initial flow front is filled, theflow front is as shown. One of thenodes connected to node 2 may bethe next to fill and the cycle of nodehopping continues until the part isfilled.

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MoldFlow design principles

The aim of the MoldFlow flow design principles is to get the simplest possible flow pattern; bypositioning gates, dimensioning the runner system and possibly modifying the dimensions of thedesign.A plastic paper clip is used here to demonstrate the principles. Note that, as principles, they are anideal. In practice you will have to decide which principle is the most important in a particular design,because achieving one principle will often prevent you achieving another.The most frequently used principles are balanced flow and, with runner systems, runner/cavityratio.

Balanced flowAll flow paths should bebalanced, that is, fill in equaltime with equal pressure.This may be improved bychanging the gate position,the thickness of one or moreflow paths, or a combinationof both. T M 0 0 6 P 3 0

1 s e c 1 s e c0 M Pa0 M Pa

1 0M P a

Balanced f low pa ths

Runner/cavity ratio

Design runners for highpressure drops. This minimizesrunner material by volume andgives a lower ratio of runner tocavity volume

TM006P38

Runn er/cavity rat io

8 cu.cm

8 cu.cm

Ratio 0.25:1

Ratio 1:1

2 cu.cm

8 cu.cm

Uni-directional flow

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Throughout filling the plasticshould flow in one direction andwith a straight flow front. Thisgives a Uni.-directionalorientation pattern.The flow pattern may beimproved by changing gateposition. However, this willaffect the balance of flow paths .

T M 0 0 6 P 3 9

Uni-direct ional f low

Flow f ront

The most efficient filling patternis when the pressure gradient(pressure drop per unit length)is constant along the flow path.This will give the lowestpossible volume for a givenpressure drop.A constant pressure gradient isonly possible if all flow pathshave the same length andthickness.

T M 0 0 6 P 3 1

Cons tan t p re s su re g rad i

1 0M P a

2 2 22 2

Shear stress during filling should beless than a critical value.A low shear stress will avoid exceedingany maximum recommended limit for the material and hence avoid possiblefailure in critical areas that are subjectto high structural stress when in use.Using a higher temperature, lower pressure, or a combination of both mayreduce shear stress.

TM006P32

Time

Shear stress

Maximumshear stress

Critical

Weld/meld lines

Pressure gradient

Shear stress

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Position weld/meld lines in the leastsensitive areas.Weld/meld lines are formed when twoflow meet. In multi-gated products theyare unavoidable.Apart from being areas of localweakness, they can be visuallyunacceptable. They can be repositionedby changing the location of one or moregates, or by flow balancing.

TM006P33

Weld/meld line

Weldline

Least sensitive area

Mostsensitive area

Hesitation

Position gates as far away as possiblefrom where the flow divides into thickand thin flow paths.Hesitation can occur when flow pausesin a thin path and is therefore losingheat, while a thicker path requiring onlythe current pressure is filling. By thetime full pressure is available, thehesitating plastic may have frozenwithout completely filling the thin path.

TM006P34

Avoiding hesitation

Thick

Thin

Thin

Gate

Underflow

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Frictional heating

Underflow occurs before the end of filling;when one flow (or more) meets another andreverses back under itself. Note that beforereversal the flow stops and loses heat.Flow reversal and therefore underflow givespoor quality products, both from surfaceappearance and structural viewpoints.Avoid underflow by positioning gates so thatflow front meets at the same time at the endof filling. TM006P35

1 sec

Avoiding underflow

Gate

1 sec

Design runners to increase melttemperature at the gates, by controlledfrictional heating. This achieves lower stress levels in the product without

material degradation due to longexposure at high temperatures.Frictional heating is increased andvolume reduced, by thinning therunners.

TM006P36

Frictional heating

90C

140C

140C

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Thermal shutoff

Design runners for thermal shutoff (freeze) whenthe cavity is just filled and adequately packed.This avoids overpack, a common cause of warpage, or flow reversal after the cavity is filled,both of which result in stressed products.The runners, rather than the gates, are used asan efficient flow control device. This is becausethey are much larger than a gate and thereforeless sensitive to hesitation and thermal effects.

TM006P37

Thermal shutoff

FilledGate freeze

MPI/FLOW

Moldflows flow analysis software (MPI/FLOW) predicts thermoplastic polymer flow effects inmolds for plastic injection molding. MPI/FLOW can be used as an evaluation tool for new designs or

as a diagnostic tool for existing designs. MPI/FLOW can be used to optimize design and processingconditions.

Identifying problems at an early stage can reduce tooling lead times, mold trials and costly toolingand product modifications. Production deadlines can be more easily met.

Specifically MPI/FLOW offers: Modeling / translation / editing of models Molding conditions and the effects of part geometry / polymer materials / gating on part

quality. Filling analysis predictions Packing analysis predictions Automatic runner balancing

These functions can be divided into two groups:

Processingincluding the analysis of filling and packing processes and runner balancing;

Pre and post processingincluding modeling (pre-processing), the graphical display of results and report generation(post processing).

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Chapter 2

MFP/FLOW Overview

MPI/FLOW follows the process below in examining a component model and analyzing it for partquality.

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Chapter 3

About Project Management in Synergy

The Synergy user interface incorporates a large number of design features to assist you inmanaging your work and to boost productivity. This topic describes the basic project managementfeatures in Synergy and how to get the most of them in your work.

Projects

A project is the highest level of organization within Synergy's project management scheme. Allinformation contained within a project is stored in a single directory. You can import and analyze asmany models as you wish within a project. Results within the same project can be compared with oneanother and also combined in a single report.

Study

A study is an analysis or analysis sequence based on one consistent set of inputs, e.g. mesh,material, injection location(s), process settings. Each study that you create is displayed in the ProjectView pane. If your project contains many studies, you can organize them into folders, for example bymodel (File->Organize). The bubbles displayed to the right of the study name in the Project Viewpane provide a visual indication of whether results are available for that study.

Study Task

The Study Tasks pane lists the tasks you need to perform to set up an analysis. The defaultaction for a task can be initiated by double-clicking the Study Task Node, for example, double-clickingthe Mesh node will launch the meshing utility, double-clicking the Analysis Sequence task allows youto change the analysis sequence. As you complete each task, a green tick will be displayed next tothat task. When all tasks have been completed, the Analyze Now will become active. You can thenlaunch the analysis by double-clicking the Analyze Now node. When the analysis has completed, theresults will be displayed in a folder in the Study Tasks pane.

Tip: Many useful tasks can be accessed simply by right-clicking on the Study Task node.

LayersLayers are an organizational tool that allow you to categorize components of your model. You

can use layers to visualize, manipulate, and edit your model more efficiently

Layers Pane

The Layers pane allows you to add, activate, delete, and modify the layers associated withyour model. Using the Assign button, you can assign model entities to individual layers

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Overview screen layout of Moldflow Plastics Insight

To create a new project

In MPI, a project usually consists of tasks relating to one part design. Before you can start workingin MPI, you must create a project first. To create a project, you must provide the project name, andthe location on your hard drive where you want the project to be stored.

1. Click (File New Project).The Create New Project dialog opens.

2. Enter the name of the project in the Project Name field. (eg. New.mpi)3. Select the location that you want the project stored in, either by typing the location into the

Create In field or browsing to the correct folder on your hard drive.4. Click OK.

The newly created project will open in MPI, with the project name appearing in the ProjectView pane.

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To open a projectOpening a project allows you to begin analyzing your part design for injection molding

problems. Once you have opened a project, you need to import a CAD model, or create a newmodel. Each model that you import into a project will become a separate study within the project.Note: The project will open automatically after creation, however, the instructions below show how tomanually open a project.

1. Click (Open Project).2. Navigate to the folder where the project is located.3. Click on the project file (*.mpi) to select it.4. Click Open.

The project and any associated studies open in MPI.

Tip: You can open a recently-used project from within the File menu.

To open a recently used project

In order to save time opening projects through the Open dialog, you can quickly open andclose recently used projects from the File menu. This option allows you to quickly load an existingproject, if it is one of the last four projects that you have worked on.Note: The loaded project will open in MPI. Only one project can be open at a time, so the newlyopened project becomes active. If you had a project open, it is automatically closed.

1. Select the File menu so that all of the options in this menu are visible.Below the Preferences menu options are listed the four most recent projects, including filelocations that you have been working on in MPI.

2. Click on the required project to load it.

To close a projectMPI uses projects as storage areas for all pre and post processing tasks for a particular part

design. Only one project can be open in MPI at one time; however, from time to time, you may wantto close the current project and open a different one to work on a different part design. You canautomatically close a project by choosing to open a new project. To close the current projectmanually, without closing MPI, follow the instructions below.Note: Ensure you have completed all of the required tasks in each included in the current project. Allstudies will be closed when you close the project.

1. Click File Close Project.

The entire project, including all studies, will close.

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To create a new folder You can use folders in the Project View pane as an organizational tool. If there are several

aspects of a part design that you wish to analyze, such as balancing runners and checking for part

warpage, you can create a runners folder and a warp folder, to keep relevant tasks in the samelocation within the project.

Tip: You can drag and drop studies into different folders in the Project View pane.1. Click File New Folder, or right-click in the Project area and select New Folder.2. A new folder is added to the project in the Project View pane.To rename the folder appropriately, either press F2, or right-click the folder and select Rename.

Note: Creating a new folder does not affect the disk location where studies are stored. All studiesstay within the project, and the folders you create also stay within the project.

To create a new studyIn MPI, a study is a subsection of a project. A study is used to investigate different aspects of

the same part design. Within the Project View, each study associated with the current project islisted. Each study contains its own geometry, mesh, process conditions, and, possibly, results.Multiple studies can be created from the same geometry (or CAD model). You must create a projectbefore you can create a new study.Tip: Importing a CAD model into MPI automatically creates a study.

1. Click File New Study, or right-click in the Project View pane and select New Study.

The new study is updated in the Project View pane, and the compulsory pre-processing tasks areupdated in the Study Tasks pane. The new study does not have a model associated, so you need toimport a CAD model or create a new model.

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To copy a study

In the Project View pane, you can make an exact copy of an existing study. It is useful to copy astudy if you want to re-run an analysis with some slight process changes and then compare the

results of both analyses. The duplicate study will automatically be updated with the name originalstudy [copy], so it is a good idea to rename the new study.

1. Click on the study in the Project View pane to select it.2. Right-click and select Duplicate.

MPI creates an exact replica of the selected study and updates it in the Project View pane.3. Rename the new study with a unique name.

To rename a study

The Rename function in the Project View pane allows you to give an existing study a differentname to the one it currently has. Correctly naming studies allows you to manage your projectefficiently and saves you time trying to find a particular item within a project.

Tip: You should rename a study if you have duplicated an existing study.

1. Click on the study in the Project View window to select it.2. Right-click and select Rename, or press the F2 button on your keyboard.3. Type the new name of the study.

Note: The name you give the study will also become its file name, with any blank spaces replaced byunderscore characters.

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To delete a study

The Delete function allows you to remove a study from a project when it is no longer useful.

Note: Ensure that you no longer need to retain the study in the current project, because you cannotretrieve a study after it has been deleted.

1. Click on the study in the Project View pane to select it.

2. Right-click and select Delete, or press the Delete button on your keyboard.3. Click OK to the prompt that appears.

The Study is deleted from the current project.

To save a model

In order to prevent data loss due to hardware/software problems, it is a good idea to save workregularly. The project state is maintained on disk at all times and does not require saving. Project-level changes, such as adding and deleting studies, are saved automatically. In order to save

changes to the study or studies; such as model changes, analysis and process setting changes, etc,you must save the model.

Click(File Save).

This will save the currently opened study.Or,

Click(File Save All).This will save any changes to all studies that are currently open in MPI.

Or, Click

(File Save Study As) and enter a new name.This will save another copy of the open study with the name you specify.

To import a CAD model

MPI allows you to import existing CAD model files to begin the part design process. If you attemptto import a CAD model before opening a project, MPI will prompt you to first open or create a project.When you import a CAD model, you will be prompted to select mesh type and the units that you wantto work with.

1. Click (File Import), or, right-click in the Project View pane and select Import.2. Select the correct file extension for your CAD model from the Files of type drop-down list.3. Navigate to the folder where your CAD model is located and select it.4. Click Open.5. Select the appropriate mesh type and units from the Import dialog that appears.6. Click OK.

Tip: A new study is created for the CAD model. The Study Tasks pane is updated with thecompulsory pre-processing tasks that guide you when preparing your model for analysis.

Note: To import an STL midplane

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An STL midplane mesh is not a standard format. However, if you need to import a midplane meshthat is stored in STL format, you should follow these steps.

1. Import the STL. In the Import dialog, set the model type to fusion, not midplane.2. Use Mesh Generate Mesh to create a new mesh. This process will remesh the STL surface

into a midplane mesh (but the type will still be set to fusion).3. After the meshing completes and the Mesh dialog is no longer visible, proceed to the next

step.4. In the study pane, change the mesh type to midplane.5. Assign properties (such as part surface) to the newly created mesh.

To export a project, including a CAD model

You can export an entire project, including model and results files, into a *.zip file for use at a later date. Once you have completed the analysis of your part design, you can save your changes andexport the entire project from MPI into the archival location of your choice.

1. Click (File Export).2. Navigate to the location where you want to store the archived project.3. In the File name field, enter the name of the *.Zip archive file to contain your project.4. Click Save.5. Select Entire project from the Export Project to Archive dialog.6. Select Include result files in archive if required, and click OK.

The Archival process will take a couple of moments.7. Click OK to the Project Archived Successfully prompt.

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To append entities to a modelMPI allows you to append existing model entities to your CAD model to save modeling time. If

you have existing model entities that you want to add to a model, such as cooling lines, you can addthem to the study that is associated with your CAD model.Tip:

1. Ensure that you have a model open in the display area.2. Click (File Add).3. Navigate to the directory where the required model entity is located.4. Select the correct file extension from the Files of type drop-down list.5. Click on the file to select it.6. Click OK.

The model section that you appended to the current model is updated in the display window. Youmay need to use the MPI modeling tools to correctly join the two model sections.

To Organize Project

In MPI, the Organize Project allows you to control the structure of your project when itbecomes too large to maintain efficiently. A project can be organizing by either model, material,injection location or shared results.

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To Compacting the Project

In MPI, the Compact project allows you to condense the project by removing redundant restart files.Removing restart files will result in any subsequent analyses starting from the beginning of theanalysis sequence.

To edit preferences

1. Select File Preferences from the menu.2. Click on the required dialog tab, and make the necessary changes.

Note: You can change the screen display, units, internet access, animation parameters,mouse modes, system defaults, MDL, Increment, and Help System preferences. Use thecontext-sensitive help in the Preferences dialog to learn more about the individual settings.

3. Click OK.

To exit the program

Once you have completed all of the required tasks for a project, you may want to exit MPI. In order toclose the current project and exit the application, do one of the following below:

Note: Ensure that you have saved all tasks within the current project.

1. Select File Exit from the menu, or click X in the top-left corner of the application.

To display the context menuMany actions that you can perform in the program can be selected very quickly by right-

clicking on the particular aspect of Synergy on which you want to perform the action and thenselecting an entry in the menu that appears.

For example, here are some of the aspects you can right-click on or within to display a context menu: the model window a study name in the project view window a task in the study tasks window a result name displayed in the study tasks window

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a toolbar

To undo or redo an action and view the action history

Click UndoThe last action will be reversed.

Click RedoThe action of the undo button will be reversed.

1. You can view the Action History for the active study by clicking Action History .2. The Action History dialog will open, displaying the actions you have performed on your study.

The most recent action you performed will be at the end of the list.3. To undo a series of actions, scroll to the bottom of the list in the Action History dialog, and click

on each action in the list that you want to undo.4. The actions you click will be highlighted.5. When you are finished selecting actions, click Undo, and the actions will be reversed.6. Click Redo to reverse the undo action.

7. Once you perform a new action on the study, you cannot Redo the list of actions.To select and deselect individual entities

You can use the Select tool to select and deselect individual entities on your model and mesh,and select more than one individual entity.

To select individual entities:

1. Click Select.2. Click on the feature in the display that you want to select.

To select more than one individual entity:

1. Click Select.2. Click on the feature in the display that you want to select.3. Hold down the Ctrl key.4. Click on the next feature in the display that you want to select.

To deselect an individual entity:1. Ensure that the Select tool is still active.2. Hold down the Shift key.3. Click on the feature in the display that you want to deselect.

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Tip: To expand the selection, use the Expand Selection dialog.

To select and deselect groups of entitiesThe most efficient way to select and deselect groups of entities is by using the Select By dialog.

To select groups of entities:

1. Click Edit Select By, and the Select By dialog will open.

2. Use the dialog to choose the types of elements you want to select.3. If you want to select the nodes associated with those elements, click Select Associated Nodes

Also.4. If you want to add the selection to entities that you have already selected, click Add to the

Current Selection.If you do not click this box, any entities already selected will be deselected.

To deselect groups of entities:

Click Edit Deselect All.

Or

Repeat steps 1 through 4 above, being sure not to click Add to the Current Selection.

Invert Selection

In MPI, the Invert Selection allows to reverses a selection, so that all the elements you haveselected become deselected and vice versa.

Expand Selection

In MPI, the Expand Selection tool allows you to expand the selection you have made by theamount specified.

To use banding selection tools

Using the Banding Selection tools, you can select groups of entities on your model that do not

share an entity type or property assignment. The Banding Selection tools act as filters to control howmany entities are selected. Both Banding Selection tools can be used simultaneously.

To use the Enclosed Items banding selection tool only

1. Ensure that the Select tool is active.2. Click Edit Banding Selection Enclosed Items Only.3. On your model, use the crosshair pointer to draw a rectangle around the entities you want to

select.4. Only the entities that are fully enclosed within the rectangle will be selected.

Note: All entities through all thickness of the part that are within the rectangle will be selected. Rotatethe model to see all of the selections.

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To use the Facing Items banding selection tool only1. Ensure that the Select tool is active.2. Orient the model so that the entities you want to select are facing you.3. Click Edit Banding Selection Facing Items Only.4. On your model, use the crosshair pointer to draw a rectangle around the entities you want to

select.5. Entities on the face of the model that are enclosed within and touched by the rectangle will beselected. Entities through the rest of the thickness of the model are not selected.

Note: If the rectangle includes an edge of the model, some of the shared elements along the edgemay be selected. This may result in some elements on the other, non-facing side of the edge beingselected. You can manually deselect these elements by holding down the Shift key and clicking onthe elements individually.

To use the Enclosed Items and Facing Items tools together

You can use both tools together, to further refine your selections.1. Ensure that the Select tool is active.2. Orient the model so that the entities you want to select are facing you.3. On your model, use the crosshair pointer to draw a rectangle around the entities you want to

select.4. Entities on the face and through the thickness of the model that are fully enclosed within the

rectangle will be selected.

To customize the toolbars1. Click View Toolbars Customize, or right-click in the toolbar area and select Customize.

The Customize Toolbars dialog opens.2. Click a checkbox in the Toolbars window to display that toolbar.3. Select any options that you require in the area to the right of the Toolbars window.4. Click the Commands tab.

This tab allows you to customize toolbars by moving buttons to different toolbars.5. Select a category, and then click on a button to read its description.

If you want to move a button to a different toolbar, select it in the Customize dialog and move itto the required toolbar location in MPI.

6. Click OK when you are finished.

To display and hide toolbars

1. Display the list of toolbars, which you can do in two ways: Click View Toolbars. Right-click in the toolbar area.

2. Select the names of the toolbars that you want to display or hide.

Note: Toolbars that are displayed have a check mark next to them.

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To display and hide model entities

1. Click(View Layers).The Layers dialog opens.

2. Select a checkbox in the Layers window to display that entity.3. Perform any other tasks that are required, such as making a layer active, assigning entities to

a layer etc.4. Click Finish to close the dialog.

Note: The Layers dialog provides you with a list of all of the entities present on your model. You candisplay and hide entities, as well as create, rename and delete entities.

To display online helpThere are several ways of accessing the on-line help.

1. Click Help Help Topics, or click (Help Topics) in the Standard toolbar.

2. Double-click on the required book, chapter and topic.3. The selected help topic will appear.

To display help on a particular analysis result:1. Display the result you want help with by selecting it in the Project Pane or clicking Results

Create New Plot.2. Click in the result window to activate it.3. Click F1.

To fit to window Click (Fit to Window).

The display will zoom in or out on the model, without changing the model rotation, so that it just fits inside the current window .

To center a model1. Select in the Viewer toolbar.2. Click the cursor on location in the display where you want to set the center of rotation.

The cursor will then change to the rotation tool, and the location you clicked will be centeredon the screen.

3. Hold and drag to rotate the model with the new center of rotation.

To measure distances on the model

Use this tool to find out the coordinates of a point on the model, or to measure the distance betweenany two points.

1. Click Measure Distances .2. To find the XYZ coordinates of a point, click on a point. While you hold down the mouse

button, the coordinates appear in the Measurements dialog.3. To measure the distance between two points, click the first point on the model, hold down the

mouse button, and drag to the second point. While you hold down the mouse button, thecoordinates of the second point, the distance between the two selected points, and the vector between the two points appear in the Measurements dialog.

4. To exit Measurement mode, click the Close button in the Measurements dialog.

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To use the cutting planeThe cutting plane appears to cut away the model, allowing you to see inside a 3D model. Use this

function to look at geometry and results in difficult-to-see areas in solid models. You need to specifythe cutting plane first, and then you can move the cutting plane through the model. The "cuttingplane" can be specified in either the XY, YZ, or XZ planes.

1. Ensure that a 3D result is displayed.

2. Click Edit Cutting Plane in the Viewer toolbar .3. In the Create/Modify Cutting Plane dialog, select the plane(s) that you want to set for the

cutting plane.4. Click Close.

The cutting plane will be indicated on the model.5. Click Move Cutting Plane in the Viewer toolbar.6. Hold and drag the left mouse button up and down the screen to move the cutting plane(s)

along the model.7. To de-activate cutting plane mode, click Edit Cutting Plane the Viewer toolbar.8. In the Create/Modify Cutting Plane dialog, deselect the plane(s) you set.

9. Click Close.

Database

Moldflow Plastics Insight (MPI) uses two types of databases; the System Defaults databaseand the Personal database. You can gain access to all database properties through the Tools menu,and also from a variety of right-click functionality used throughout the program.

After you create a Personal database, access to it depends on the type of database you have createdand how the feature is used. The following Personal databases can be created: Material; Parameters;

Process Conditions; Mesh Properties and all.

Creating a personal database

1. Click Tools New Personal DatabaseThe New Database dialog appears.

2. Select the Category.

3. Select the sub category of database you want to create from the Property Type box.For example, Thermoplastics material.

4. Click (Browse).The Database Name dialog appears.

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5. Enter a suitable name in the File name box and click Save.

6. Click OK.The Properties dialog appears ready for you to begin the process of building the personaldatabase.

7. Click Databases.The Properties dialog expands to reveal all the System database entries relevant only to thecriteria you have set previously in steps 2 and 3 above.

8. Select a Database, Description entry, and click Copy.The entry will be copied from the System Database into your New Personal Database.

9. Click OK.

Editing the default properties database

All System Default Database properties provided with Moldflow Plastics Insight (MPI) can be edited.These are supplied in a (*.udm) file format and stored in your MPI Projects\udm folder,where is the MPI version number you are using.

1. Click Tools Edit Default Properties Database....The Properties dialog appears and indicates all database properties in the default udm folder.

2. Select a Description, and then click Edit.

3. Make any required changes in the dialog that appears, and click OK.

4. Click OK again to close the Properties dialog.

To tile all windows

The tiling of windows is a useful feature when post-processing in Plastics Insight. Some modelscontain complex geometry, which is impossible to view completely from one window viewpoint. Toview various sections of a model simultaneously, for example, to check fill pattern, you can tilewindows. If you have already split a single window, this function will evenly distribute the split windowin the display area.

1. Ensure that you have more than one window open in the display area. If not, this function willoptimize the display area with the single window.

2. Select Window Tile.All open windows are evenly tiled in the display area.

To cascade windows

The MPI display area allows you to view multiple window instances at the same time. Due to thefact that the actual display area is relatively small, MPI provides you with options for organizingwindows. One method you can use to organize multiple windows to make them easier to use is tocascade them. Cascading windows allows you to quickly compare values between tworesults/models etc.

1. Select Window Cascade.All open windows are cascaded from the top-left of the display area down.

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To create a new window

The New Window option within the Window menu allows you to open the selected model into anew window without creating a new study. This is useful for viewing different aspects of the samemodel at the same time, which could not be done within the single window. After creating the newwindow, the window titles will change to study name :1, study name :2, etc. to indicate the originalmodel and the duplicate window(s).

1. Open a model into the display area.2. Select Window New Window.

Tip: If you want to view both windows simultaneously, click Window Tile.

To arrange iconsIn cases where you have several study windows open, you may want to minimize some windows.

Icons for the minimized windows may be scattered around the main window, and you may need toreorganize them so that you can see the main window more clearly.

Select Window Arrange Icons.

To split a window

The Split Windows option in MPI is a display feature that allows you to divide the current windowinto smaller windows. The model present in the original window will be reduced and included into allof the newly created windows. You can split the current window into either two or four smaller windows, allowing you to inspect different aspects of the model more closely.

1. Select Window Split.Cross-hairs will appear over the window, allowing you to split the window into four smaller sections.

2. Click the location in the window where you want to divide the window.

Tip: The Split Horizontal and Split Vertical buttons in the Viewer toolbar can also be used to split awindow.

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Chapter 4

Modeling Entities

To create nodesA model node is a special coordinate position in space. Nodes, along with curves and regions,

are the building blocks of a model. Nodes acquire special significance when you assign boundaryconditions (for example, injection locations) to them.

1. First, make sure that your modeling workspace is open, as follows: If you plan to add to an existing model, make sure that model is open. If you plan to create a new model, make sure you have created a new study.

2. Click (Modeling Create Nodes...) to open the Create Nodes dialog.

3. Click the tab that corresponds to the node creation method you plan to use. For example,Divide creates the number of nodes you specify, on the curve you select, at equal intervals.

4. Use the Create Nodes dialog to proceed. Make sure to use the easiest method to select a coordinate, curve, or other entity. Use the appropriate Filter. Keep in mind that the new nodes will be created in the active local coordinatesystem. The values shown in dialog input fields always reflect the active localcoordinate system.

5. Click Apply to create nodes.Click Close when you finish creating nodes.

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To create curves

A curve is a geometric line on your model. Curves can be straight lines between two points, or arcs made of three or more points. Curves, along with nodes and regions, are the building blocksof a model.

1. First, make sure that your modeling workspace is open, as follows:

If you plan to add to an existing model, make sure that model is open. If you plan to create a new model, make sure you have created a new study.

2. Click (Modeling Create Curves...) to open the Create Curves dialog.

3. Click the tab that corresponds to the curve creation method you plan to use. For example,Connect creates a curve that connects two existing curves. It is commonly used to modelcooling hoses.

4. Use the Create Curves dialog to proceed. Make sure to use the easiest method to select a coordinate, curve, or other

entity. Use the appropriate Filter. New curves will be created in the active local coordinate system. The valuesshown in dialog input fields always reflect the active local coordinate system.

5. Click Apply to create curves.

6. Click Close when you finish creating curves.

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To create regions

1. First, make sure that your modeling workspace is open, as follows: If you plan to add to an existing model, make sure that model is open.

If you plan to create a new model, make sure you have created a new study.2. Click (Modeling Create Regions...) to open the Create Regions dialog.

3. Use the Create Region dialog to proceed. Make sure to use the easiest method to select a coordinate, curve, or other entity. Use the appropriate Filter. Keep in mind that the new regions will be created in the active local coordinatesystem. The values shown in dialog input fields always reflect the active localcoordinate system.

4. Click Apply to create regions.

5. Click Close when you finish creating regions.

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To Create Inserts

Inserts Insert is modeled with flat shell surfaces representing each of the faces on the inserts. Thecomplete insert (six surfaces in its simplest form) is effectively a closed volume defined by the sixsurfaces. Inserts can have complex cross-sections to match features on the cavity model, in whichcase they consist of more than the basic six surfaces. Inserts can be added to inserts to create morecomplex inserts shapes. When small inserts about onto larger inserts, the surface of the larger insertsmust have an internal boundary for the smaller inserts to connect with.

When the edge of a plastic surface runs across an insert surface, the insert surface shouldhave an internal boundary added to ensure that the mesh on the plastic surface and the mesh on theinsert surface are compatible. Inserts must not contact the mold outer surfaces or the origin point of the model (that is, 0 in X, 0 in Y and 0 in Z).

Note: Each insert must be meshed and correctly oriented.

Local Coordinate System

When loads or constraints on the part act in a direction other than the X, Y and Z directions of theglobal coordinate system, using a local coordinate system can greatly simplify the settings of suchconstraints or loads.

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Move/Copy Entities:To translate the model

1. Click (Modeling Move/Copy Translate...) to open the Break Curves dialog.2. Select the entities you wish to translate.3. Specify the vector.4. Specify whether to move or copy the entities.5. Click Apply.

To scale the model1. Click (Modeling Move/Copy Scale...) to open the Break Curves dialog.2. Select the entities you wish to scale.3. Specify the scale factor.4. Optionally specify a reference point.5. Specify whether to move or copy the entities.6. Click Apply.

To reflect the model1. Click (Modeling Move/Copy Reflect...) to open the Break Curves dialog.2. Select the entities you wish to reflect.

3. Choose the mirror plane4. Optionally specify a reference point.5. Specify whether to move or copy the entities.6. Click Apply.

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Query EntitiesIf you know an entity identifier, such as T123 (triangle 123), and you wish to locate it on the

model, use Modeling Query Entities.

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Cavity Duplication Wizard

The Cavity Duplication Wizard allows you to create a standard multi-cavity layout. You can then usethe Runner System Wizard to connect all the cavities, or model the runner system manually.

Creating a runner system using the Runner System Wizard

1. Click (Modeling Runner System Wizard).

The first page of the Runner System Wizard appears.2. Step through the pages making any property changes as you go, and click Next to proceed.

3. Upon reaching the final page, click Finish to close the Wizard.The newly created feed system will appear on the model.

Creating cooling lines using the Cooling Circuit wizard

The Cooling Circuit Wizard can be used to create a pair of serial cooling circuits above and below

your part.

Mold Surface Wizard

The Mold Surface Wizard is a tool for quickly modeling a cuboid mold outer surface around theexisting model for the purposes of improving the accuracy of a cooling analysis.

The Mold Surface Wizard determines the dimensions of the required mold surface from the suppliedinputs, creates a region for each face of the cuboid, assigns the property Mold block surface to theregions, and then meshes the regions. The mold surface regions and elements are assigned toseparate layers so you can control their visibility and properties.

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Chapter 5About part model mesh

Before you can run a Plastics Insight analysis, you must have a meshed part model. The meshis a web composed of elements, with each element containing a node at every corner. The meshprovides the basis for a Moldflow analysis, where molding properties are calculated at every node .

Midplane meshThe midplane mesh provides the basis for the MPI/Flow analysis. This mesh consists of tri-

noded triangular elements that form a 1 dimensional representation of the part, through its centre.The midplane mesh supports every molding process.

Surface mesh

The surface mesh provides the basis for the MPI/Flow-Fusion analysis. This mesh consists of amixture of different types, including regions with traditional Midplane elements and surface (double-skin) shell elements. The surface mesh can be 3 or 6 noded plane, straight-edged triangles.

Volume mesh

The volume mesh provides the basis for the MPI/Flow3D analysis. This mesh consists of 4-noded, tri-element, solid tetrahedral elements. The density of the mesh is the number of elements per unit area.In general, the more elements there are in the mesh, the more detailed the analysis results, but thelonger the analysis time.

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Mesh ConsiderationsThe density or coarseness of the mesh, and the shape of the triangular elements within the

mesh, affect flow analysis results. Ideally each element should form an equilateral triangle. As ageneral rule the ratio of the longest side to the height (aspect ratio) should be less than 6:1, or 4:1 for a gas-assisted flow analysis. Aspect ratios greater than 6:1 (4:1 for gas analysis) should not be used.

Long thin elements should be avoided when the pressure, temperature and velocity of the flowmight vary rapidly. High aspect ratios can cause the program to run poorly.An additional consideration is the mesh match percentage, or the percentage of surfaces elements inthe model that match on each side. A model with a mesh match percentage of 85% or higher isacceptable for a flow analysis; however, for a warp analysis, the percentage should be even higher.

Tip: After meshing a model, it is a good idea to check the mesh for uniformity and any problem areasusing the mesh diagnostics tools in Plastics Insight.

To mesh the model

After you create or import an unmeshed geometry model in MPI, you must mesh the modelbefore running an analysis. The mesh is comprised of triangular elements joined with nodes, andprovides the basis for a Moldflow analysis. The three finite element mesh types that MPI supportsare: midplane, fusion, and 3D. The mesh type that you create depends on the model that you use.

Note: Click (View Layers) and select the model regions that you want meshed. Only the visible modellayers are meshed.

1. Click (Mesh Generate Mesh).The Mesh dialog allows you to preview the mesh, and to change the default meshingparameters.

2. Click Advanced, and then make any required changes to the global edge length and mergetolerance.

3. Click Mesh.The model will be updated immediately with the new mesh.

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Mesh Density

Increasing/decreasing mesh density along edges

Before you define your mesh size, it is important to understand the starting point, as different model

types allow the use of different functionality in the Define Mesh Density dialog. For example, (*.stl)models are imported as a solid model, whereas (*.iges) models contain separate surfaces andentities, and make definition in localized areas more feasible

To create beam elementsBeam elements are often used to represent cooling channels. Two beam elements are available:

BEAM2 and BEAM3. These are 2-noded and 3-noded beams respectively. The longitudinal axis of the elements is straight, so that when modeling curved beams, they provide a "faceted"approximation to the true geometry. Currently, the beam is assumed to have a circular cross-sectionof constant radius. However, the cross-sectional radius of adjacent elements may be different.

1. Click (Mesh Create Beams).

2. In the Create Beams dialog, enter the number of the first node to use as an end of the beam,or click on the model to select the node.

3. Enter the number of the second node, representing the end of the beam, or click on the nodeto select it.

4. Enter the number of beams to be created along the length. If you enter a number greater than1, the beam will be divided into even portions totaling the number you enter.

5. To change the properties of the beam element, click Change, and select the appropriateproperty from the Assign Properties table .

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To run mesh diagnosticsOnce you have meshed your model, it is a good idea to run a series of diagnostic checks onthe mesh.

1. To see a text report of various types of diagnostic data, select Mesh Mesh Statistics from theMPI menu.

2. To see graphical or text reports of specific types of diagnostic data, from the Mesh menu,select Aspect Ratio, Overlapping Elements, Orientation, Connectivity, Free Edges, Thickness,

or Occurrence Number.

Mesh Repair Wizard

The Mesh Repair Wizard tool is used to diagnose and automatically repair a number of common problems with the mesh. The Mesh Repair Wizard allows you to repair several types of mesh defect. You can make changes on each page, or skip the pages that do not concern you.

Use the Stitch Free Edges page to join nearby edges that are not quite connected. You can choose

either the default option (0.1 mm) or select a specific distance. Any edges that are closer together than the specified tolerance will be stitched.

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To check the mesh for defects

In order to determine whether your meshed model is suitable for Moldflow analysis, you shouldcheck the mesh for errors. Imperfections such as high aspect ratio, overlapping elements, incorrectmesh orientation, and unconnected elements can be identified and removed, ensuring an accurateflow simulation.Before running a 3D analysis on the model, create a Fusion mesh, diagnose and correct meshingissues, and then create a 3D mesh.

To check the mesh for defects, follow these steps:

1. Ensure that you have a meshed part model open in Plastics Insight.2. Select Mesh Statistics from the menu.

This will provide you with a text-based report on the mesh. The report includes the mesh entitiespresent, and also provides you with mesh-edge, orientation, intersection, aspect ratio and meshmatch details.

3. Study the report to check the state of the mesh, and click Close.

Any problems with the mesh will be indicated here.

4. Select (Mesh-Mesh Tools), select the appropriate individual tool(s), provide input whererequired, and click Apply to repair mesh problems.

To repair the meshTo repair mesh problems, such as poor aspect ratios and connectivity, use the tools on the

Mesh Tools dialog.

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To squeeze the meshIn order to perform a successful analysis on your meshed model, every node and element must

be consecutively numbered. This can be achieved by the Purge Nodes function. Removing gaps in

numbering will also ensure that modeling limits, for the surfaces and the mesh, are not unnecessarilyexceeded. This function also performs the following:

Deletes any nodes not connected to the mesh. Merges any nodes that are closer than the nodal tolerance. Issues a warning if any points are closer than the point tolerance. Deletes any elements with repeated nodes, e.g. 3 3 2. Deletes surfaces or points with the construction display attribute. Deletes fully overlapping elements (elements that share the same three nodes). Applies the display attribute gray to overlapping elements that share two nodes.

Select Mesh Mesh Tools Purge Nodes from the MPI menu.

To orient the meshMPI cooling analysis requires the mesh to be oriented

1. Select mesh orient all from the MPI menu.2. If you've diagnosed orientation problems that you wish to correct manually, use Mesh Mesh

Tools orientation.

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Chapter 6

AnalysisAbout MPI analysis

Plastics Insight includes a suite of flow analysis products that are used to predict thermoplasticpolymer flow inside the mold. The programs simulate flow by calculating a flow front that grows from

node to connecting node, starting at the injection node. The cycle continues until the flow front hasexpanded to fill the last node.Further more, it uses a packing analysis to determine whether a cavity will be completely filled and arunner balance analysis that ensures equal pressure is delivered at each cavity.

Features of the analysisThe product used to predict flow, will determine the meshing technology that should be used

for your model. If you have all three, select the most suitable application for each situation as follows:

MPI/Flow predicts material behavior during the molding cycle by analyzing a midplane shell mesh of a 3D part model. The mesh is comprised of triangular elements. Each element has three nodes. Ingeneral the more elements there are in the mesh the more detailed the results, however with morenodes the analysis time is also increased.

Setting up and running a analysisBefore you can run a analysis, there are a number of modeling and model setup prerequisites

that need to be fulfilled. They are as follows,

About part model meshBefore you can run a Plastics Insight analysis, you must have a meshed part model. The meshis a web composed of elements, with each element containing a node at every corner. The meshprovides the basis for a Moldflow analysis, where molding properties are calculated at every node.The mesh types supported by Plastics Insight are:

Midplane meshThe midplane mesh provides the basis for the MPI/Flow analysis. This mesh consists of tri-

noded triangular elements that form a 1 dimensional representation of the part, through its centre.Every molding process is supported by the midplane mesh.

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About thermoplastic materialsThis topic describes some important material characteristics to consider before selecting a

material grade. The material that you select will depend on the characteristics that you require. A linkto Moldflow's material testing service is also provided.

AmorphousAmorphous polymers are a family of polymers that are characterized by entangled polymer

chains that are loosely bound. The term amorphous indicates that there is no preferred orientation of the molecules, relative to each other, without external force. During injection molding amorphouspolymers have orientation . Amorphous polymers are in a super-cooled liquid state and generallyshrink less than semi-crystalline polymers.

CrystallinityThe crystallinity of a material identifies the state of the polymer at processing temperatures,

and can range from amorphous to crystalline states. Amorphous polymers are devoid of anystratification, and retain this state at ambient conditions. Crystalline polymers have an orderedarrangement of plastic molecules, allowing the molecules to fit closer together. Therefore, they aredenser than amorphous polymers. The rate of crystallinity is a function of temperature and time.Rapid cooling rates are associated with lower levels of crystalline content and vice versa. In injectedmolded parts, thick regions cool slowly relative to thinner regions, and therefore have a higher crystalline content and volumetric contraction.

Composite materials

Composite materials contain fillers that are added for injection molding. Adding a filler to apolymer can increase the strength of the polymer and ensure that good quality parts are produced.Most commercial composites contain 10-50% fibers by weight, which are regarded as being

concentrated suspensions, where both mechanical and hydrodynamic fiber interactions apply. Ininjection-molded composites, the fiber orientation distributions show a layered nature and areaffected by the filling speed, the processing conditions and material behavior.

Viscosity

The viscosity of a material is a measure of its ability to flow under an applied pressure.Polymer viscosity is dependent on temperature and shear rate. In general, as the temperature andshear rate of the polymer increases, the viscosity will decrease, indicating a greater ability to flowunder an applied pressure. The material database provides a viscosity index for materials, in order tocompare ease of flow. It assumes a shear rate of 1000 1/s and indicates the viscosity at thetemperature specified in brackets.

PVT data To account for material compressibility during a flow analysis, Moldflow provides PVT models.

A PVT model is a mathematical model using different coefficients for different materials, giving acurve of viscosity against pressure against temperature. An analysis based on PVT data is moreaccurate but computationally intensive - through iterations for temperature and pressure per node.However, this makes it particularly suited to complex models that have sudden and large changes inthickness.

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Mold and melt temperatureThe mold temperature is the temperature of the mold where the plastic touches the mold. Moldtemperature affects the cooling rate of the plastic, and cannot be higher than the ejection temperaturefor a particular material. The temperature of the molten plastic is the melt temperature. Increasing themelt temperature reduces the viscosity of a material, which also reduces shear stress. This results inless material orientation during flow. Additionally, the material is hotter which decreases the frozenlayer thickness. Decreasing the frozen layer means that shear is less since the constriction to flow is

less.

ShrinkageAs plastics cool, there is a significant change in their dimension, due to volumetric shrinkage.

The main factors that affect shrinkage are cool orientation, crystallinity, and heat concentrations. AShrinkage Summary Report is provided for each material in the Moldflow Materials database thatcontains shrinkage data.

Material Testing Service

Moldflow Centre for Plastic Testing and Research and C-MOLD's Polymer Laboratory havebeen brought together to form Moldflow Plastics Labs (MPL).With a combined experience of 25years and more than 4,000 grades, MPL is the leader in material characterization for plasticsprocessing. MPL offers a comprehensive range of both standard and innovative tests to providecomplete and accurate material characterization data for use within Moldflow and C-MOLDsimulation software.

About injection locations

The injection location represents the position where polymer is injected, allowing the softwareto simulate the flow pattern inside the mold cavity. This help topic describes some injection locationconsiderations when running a flow analysis in MPI.

In order to mold the best part possible, you must identify the optimum injection location for your part.The optimum injection location creates balanced flow, allowing the extremities of the mold to fill at thesame time and pressure. Choose the number and position of injection locations such that thevolumetric shrinkage at the end of flow is close to the design value using the optimum holdingpressure.

The position of an injection location is an important factor in determining an acceptable fill pattern. If your initial analysis indicates that the fill pattern is unbalanced, altering the injection location, or

adding another one, may solve the problem. There may be instances of thick and thin sections whereit is desirable to position the injection location near thicker sections to achieve uniform packing. Itmay be necessary to use several injection locations, or to even change the type of gate being used,for example to a fan gate, to produce more uniform orientation effects in the product.

Gate Location analysis

The Gate Location analysis can be used to identify the best place to inject on your part. If there are no injection locations specified, the Gate Location analysis will determine the best place for a single gate, given the selected material. If one or more injection locations already exist, the resultsuggests the best place for the next gate location given the selected material.

You can iterate the injection location(s) using the Gate Location analysis as many times as requireduntil a suitably balanced flow path is determined by the proceeding flow analysis.

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About pressure control points

IntroductionDuring the injection molding process, there is a point where the velocity phase control changes

to pressure phase control. The pressure control point is an optional prerequisite that you can setwhich triggers the program to switch control, once a specified pressure at a node is reached.

What is a pressure control point ?When you wish to simulate the workings of an injection molding machine as closely as

possible, the process requires extra information about the molding machine settings. The softwareshould be provided with the time and pressure at which you wish to switch from velocity to pressurephase control. The pressure control point is one option that you can use to specify the switch-over.

The pressure control point is a sensor that is used to detect pressure values during ananalysis. If you specify a pressure control point at a node, you can specify a pressure, at that node,that the algorithm changes from velocity phase control to pressure phase control. Once the pressure

specified at the pressure control point is exceeded, the algorithm will change from the velocity phaseto the pressure phase control, and packing will begin. Selecting a suitable switch-over pressure Theswitch over pressure can be higher or lower than the fill pressure, but in general the following ruleshould be observed

If the fill pressure is close to the pressure/clamp ceiling for the machine, then the switch over (packing) pressure should be less than the fill pressure to prevent the mold from flashing. If the fillpressure is substantially less than the pressure ceiling for the machine, it may be possible to use apacking pressure which is greater than the fill pressure, to ensure a product with a good surfacefinish while not exceeding clamp tonnage limits. Selecting a transition point for small, thin-walledparts

If a part is small and thin walled, as in a connector part, the molder may set up the machine to fill thecavity quickly using the ram displacement control and then switch to pressure control, either justbefore or just after the part has volumetrically filled. (The molder will not be aware whether or not thepart has in fact filled by the time he switches to pressure control because of the melt compressibilityeffects described earlier.) This may cause a rapid escalation in pressure, but because the machinemay have a reserve of clamp tonnage, the molder does not have to worry about the resulting highclamp opening forces.

Selecting a transition point for large, thick-walled parts

By contrast, if the part is a thick-walled, large-area molding, such as a large rubbish container,available clamp tonnage may be the critical factor and so the molder will set an injection time (ramforward velocity) that he knows will not fill the part. Then when the mold is only partially filled he canswitch over to pressure control, to prevent the part from flashing. In this case, if the switch over pointis set close to the instant of fill, the pressures and clamp tonnages may appear unreasonable in theflow analysis software. This is because the software has not been run in the way the molder sets upthe machine.

The choice of the transition point can influence the calculated values of pressure at theinjection node, and the clamp tonnage prediction. Consequently, if these are of interest, the flowanalysis software must be set up in a realistic way to represent what happens in an actual injection-molding machine. This is best done by thinking how the molder is likely to set up the machine inpractice.

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About occurrence numbers

Occurrence numbers can be used to simplify the amount of modeling required for a flowanalysis by specifying the number of times that a given flow path is repeated in a model.

Warning:1) If you intend to proceed to a cooling, warpage or stress analysis, you cannot use

occurrence numbers to simplify the amount of modeling required. You must model the fullpart.

2) Occurrence numbers can be specified for surfaces that have both symmetrical geometryand the same plastic throughput.

Occurrence number considerations

Occurrence numbers are used to specify the number of times that a given flow path isrepeated in a model. They can be used as a shortcut to reduce the amount of modeling and analysistime required for models with symmetrical flow paths. Identical flow paths are defined to havesymmetrical physical geometries and identical volumes of plastic flowing through them. Occurrencenumbers are very helpful, especially in multi-cavity modeling, where only one cavity needs to bemodeled and the other identical cavities can be referenced in the analysis by occurrence numbers.

Symmetrical Flow Paths

Before we consider modeling simple parts using occurrence numbers, it is helpful to understandthe concept of "symmetrical flow paths". Flow paths are said to be symmetrical when the physicalgeometry of the flow path is symmetrical and when the volume of plastic flowing through the paths isidentical.There are 3 main combinations of parts and runner systems:

1. Direct injection into a cavity2. Injection via a runner system into a multi-gated cavity3. Injection via a runner system into multiple cavities.

Of course there are many other possible combinations apart from these three basic combinations, butfor simplicity they will not be described here.

Occurrence numbers in Plastics Insight

By default, all surfaces and elements in the model are considered to have an occurrencenumber of 1. Using the Change Property functionality (Edit Assign Property), you can specify anoccurrence number other than 1, for example, for a model of a multi-cavity mold. All elementscontaining the same properties as the selected element will inherit the number, if the Apply to allentities option is selected.

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About runner dimension constraints

Runner dimension constraints are an optional prerequisite you can set for a runner balancinganalysis. These constraints allow you to determine the appropriate size for the runners in your modelto achieve balanced flow to all cavities. In order to ensure that each cavity fills at the same time andwith equal pressure for a multi-cavity part, you should perform a runner balance analysis. This topicprovides some guidelines for setting dimension constraints on your runners.

Runner Dimensions Constraint Guidelines

It is a common design principle that the minimum dimension of a runner section be 1.5mmgreater than the thickness of the part (in mm). This allows the cavity to pack evenly and produce aneven volumetric shrinkage. The choice of minimum dimensions may be affected by the material anddesign of the part. Runner dimensions may be dependent on material type - for example 1mm of styrene may snap, whilst 1mm of nylon may flex on ejection from the die, dependent on the ejectionsystem used. There can be no "reversed tapers" in the molding, which prevent the runner systemfrom being ejected. (A reversed taper is one where the runner section dimension is greatest in thefixed half of the mold).

Tip: It may be useful to run a runner balance analysis without runner constraints as a first pass, thenuse these new dimensions as the basis on which to set constraints. This helps to avoid the risk of over-constraining a part, and thus restricting the programs ability to provide a good balance for your runner system design.For models which have a combination of both hot and cold runners, only the cold runners will bebalanced using the auto-runner balancing algorithm. Models, which contain only hot runners, willautomatically be balanced using the runner-balancing algorithm. There are instances where you maynot want the program to alter the dimension of a particular runner section - for example when it isimpractical to reduce a runner's dimensions further. There may also be instances where you do not

wish the runner-balancing algorithm to alter the dimension of a particular runner section beyondcertain maximum and/or minimum limits. In the case of annular runners, a little more care is requiredwhen applying constraints. You must ensure that you do not make the minimum outer dimension lessthan the maximum inner dimension.

Supported Runner Types

The MPI runner-balancing algorithm will determine the correct runner dimensions for balancedflow in multiple cavities for the following runner types:

Circular runners Tapered circular runners Half-circular runners Half-circular tapered runners Trapezoidal runners Trapezoidal tapered runners U-shape runners U-shape tapered runners Rectangular runners Rectangular tapered runners Internally heated annular runners Customizable cross-section shape

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About ideal cavity/core side mold temperatures

If you have a molding scenario where certain areas of the mold are known to have higher or lower temperatures, you can simulate this using the Ideal cavity-side and ideal core-side moldtemperatures. For a flow analysis, this property should be used to simulate a mold that does not havea constant temperature .

Cavity-side vs Core-side

Creating an accurate model of not only the part, but the mold used to make the part is criticalto a successful flow simulation. Often, the mold used to make a plastic part consists not only of acavity hollowedfrom the mold plates, but also a core (the moving plate), which extends into the overall plane of a partto make a cylinder or depression. Inherently, the use of a core in a mold creates problems with the

cooling system. A core area is more difficult to penetrate with cooling channels, bubblers, baffles, andother cooling devices. Because the core is deep within the mold base, it is not only less accessible tothe cooling system, but it also has more difficulty in diffusing heat away from the part.

Unbalanced cooling, which is the result of temperature differences between the mold walls,can result in asymmetrical thermal-induced residual stress. This kind of unbalanced cooling results inan asymmetric tension-compression pattern across the part, and consequently a bending momentthat tends to cause warpage of the part.

MPI allows you to set your own cavity-side and core-side temperatures so that the flow simulationcan provide you with predictions of warpage..Using the simulation results, you can tailor your process

to minimize the temperature difference, and therefore a major cause of warpage, as much aspossible.

Generally speaking, only a small portion of a mold is designed to operate under differentcavity-side and core-side mold wall temperatures. MPI provides this feature so you can determine theoptimal core-side and cavity-side temperatures for minimum warpage. For all elements in which thecavity-side temperature equals the core-side temperature, you do not need to assign thetemperatures separately.

Tip: As a rule of thumb, the temperature difference for the cavity and core sides should not exceed20C (36F).

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Chapter 7

Analysis Process

To set the molding process

When using MPI to analyze the design of a plastic part, the first thing that you need to do is set an

appropriate molding process. The molding process you set must represent the real-case scenariothat you are simulating. Once a molding process is selected, MPI automatically updates with thesupported analyses sequences.

1. Click Analysis Set Molding Process.2. Select the molding process that you want to simulate.

The Study Tasks pane is updated with the molding process type.3. Next, set the analysis sequence to be run within the selected molding process.

To set an analysis sequenceAn analysis sequence is a pre-defined series of MPI analyses. MPI allows you to set analysis

sequences for a model at the beginning of the pre-processing stage, provided that you know all of theanalyses that are required. Before you can select the analysis sequence, however, you must firstselect the molding process that you want to simulate.

Note: Selecting a new analysis sequence after already performing an analysis sequence invalidatesany existing results. Selecting Create Copy from the prompt allows you to retain the results andcreate a duplicate study.

1. Ensure that you have set the required molding process.2. Click Analysis Set Analysis Sequence.

This menu option contains a list of all possible analysis sequences that exist for the selected

molding process.3. Select the required analysis sequence for your study. The new analysis sequence is updatedin the Study Tasks and Project View panes.

To select a material for analysis

In order to run a Moldflow analysis, you must select a material to be analyzed. The properties of the material are used to simulate conditions inside the mold, indicating any potential problems if youused this material in a real-life molding situation. You can select a thermoplastic material for a flowanalysis, a thermoset material for a reactive molding analysis, and encapsulant molding compoundswhen running either a microchip encapsulation or underfill encapsulation analyses.

1. Click (Analysis Select Material), or double-click the material icon in the Study Tasks window.The Select Material dialog opens on screen.

2. Click on the Manufacturer drop-down list and select the manufacturer of the material that youwish to use.

3. Click on the Trade Name drop-down list and select the name that the required material istraded under.Tip: Click Details to view the properties of the selected material.

4. Click OK.The material is updated in the Study Tasks window, which provides the default settings for theProcess Settings.

Tip: The Select Material dialog also allows you to search for materials. If you click Search , you canenter a property to search for in the Moldflow Material database.

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To select the process conditions

Before an analysis, you must specify the processing conditions that you want to simulateduring the analysis. The Process Settings wizard is used to enter process conditions for the selectedmolding process and analysis sequence therefore, it is configured differently depending on theanalysis sequence set.Note: The Process Settings wizard updates with default settings after you select a material.

1. Ensure that you have already set the molding process, then set the analysis sequence, to berun, and also selected a material do not have to have set an injection location at this stage.

2. Click (Analysis Process Settings), or double-click the Process Settings icon in the Study Taskspane.

3. Complete all of the required fields within the Process Settings wizard.This wizard allows you to specify the conditions for the selected molding process.

4. Click Finish.

To set ideal cavity/core side mold temperatures

In the injection molding process, there are areas of the mold that may have higher or lower temperatures due to part/mold design. If there are mold regions that will have fluctuating surfacetemperatures, you can set an ideal cavity, or ideal core side mold temperature. The ideal cavity-sidemold temperature is the temperature that you set for the cavity-side mold wall; in other words, it is themold temperature that you want to use on the cavity-side of the mold. The ideal core-side moldtemperature is the temperature that you set for the core-side mold wall.

1. Ensure that you have set the Thermoplastic Injection Molding process.2. Click (Analysis Process Settings), or double-click the Process Settings icon in the Study Tasks

window.3. Click Detailed and select a process controller. If one is already selected, click Edit.

4. Click the Temperature Control tab.Set mold and ambient temperatures for the injection molding process.5. In the Mold temperature control drop-down list, select Cavity differs from core and click Set.6. Enter the ideal cavity-side and Ideal core-side mold temperatures.7. Click OK to remove all dialogs from screen and save the mold temperature settings.

Options for running the analysis

Once you have provided all of the relevant details required to run the analysis you have four optionsrelating to running the analysis.

You can run the analysis immediately. This will send the analysis to the Job Manager and place it onthe priority queue. If there are no other jobs currently in the queue it will run immediately. If there areother jobs that were submitted before it to the priority queue then it will be run once all of these jobshave finished. Any job in the priority queue will run before the jobs in the batch queue.

The analysis can be sent to the batch queue. The Jobs can then be run at any time by selecting theJob tab, right clicking on the batch queue node and selecting run batch queue. The batch queue willrun in the order that the jobs were submitted. Any jobs in the priority queue will run before the batchqueue is run.

You can submit the job later. This will create a p

mpi 6.0 materials

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