Moldflow

TUTORIAL [Reports]

 Introduction

You can use the Report Generator to create a report on a set of results. The report can include text, still graphics, and animations. The following tutorial shows you to how to use the report wizard. There are eight tasks to complete in this tutorial.

Task List

1.     Prepare the report

2.     Comment on the results

3.     The Report Wizard

4.     Select results

5.     Create the content

6.     Generate the report

7.     View the report

                                                                                       continue

Adviser requirements for STL files

Requirement 1

The STL file should be complete and incorrupt.

An ASCII .stl file must start with the lower case keyword solid and end with endsolid.

For example:

solid

...

facet normal 0.00 0.00 1.00

outer loop

vertex 2.00 2.00 0.00

vertex -1.00 1.00 0.00

vertex 0.00 -1.00 0.00

endloop

endfacet

...

endsolid

Requirement 2

The STL file can be in either ASCII or binary format. It is important to use the correct format with FTP. For example, if you have a binary STL file, you must set the FTP file type to "binary" before transferring.

Requirement 3

Only one solid should be present.

Requirement 4

The mesh triangles should be defined clockwise, with the normal indicating the "out" direction:

Requirement 5

The orientation of the triangle normals should be aligned.

Requirement 6

The triangles should share common corner node positions (the "vertex to vertex" rule), there should be no gaps or free edges in the mesh of triangles:

Requirement 7

There should be no intersections between the triangles' surfaces (naturally, edges should overlap).

Requirement 8

There should be no triangle overlaps.

Requirement 9

As a guide (not a requirement), there should be no more than 100,000 triangles in one model. If a model has more triangles than this, some fillets and other minor details are probably facetted too precisely.

If you can, use the STL settings in your CAD system to base the resolution of the tessellations on the chord height calculation below. You can thus reduce the number of triangles.

where:

·         c = chord height

·         p = part surface

·         t = tesselated surface

·         m = model size (the distance between opposite diagonals of the bounding box of the part)

·         q = part quality (recommended 0.3, limits 0.1 to 1.0)

Requirement 10

If your STL model has triangles with very high aspect ratio, the mesh will be distorted, and the analysis results will be less accurate.

For a mesh triangle, the aspect ratio is the ratio of the length of the longest side (a), to the height perpendicular to that side (b). As a general rule, this ratio should be less than 6:1.

The Adviser can accept some triangles with very high aspect ratios (hundreds or even thousands). However, try to keep the average aspect ratio below 6.

Acceptable model geometry

The Adviser works best when the model geometry is, on average, thin walled and composed of flat surfaces.

As a general rule, avoid models that are dominated by solid cones, solid cylinders, etc. However, there is no need to modify a model that contains such features, as long as they are not the majority of the model.

The Adviser is only accurate if the cavity walls are thin. The exact definition of thickness depends on the size and shape of the model. The following general rule gives satisfactory results:

1.     Consider the average of the length and width of a local region.

average of 15 & 25 = 20
thickness (3) < 1/4 of average (5)

2.     Ensure the thickness is less than one quarter of this average.

For real parts, it is time-consuming to apply the above rule to each wall. However, it is often possible to look at the entire part and decide whether or not it is suitable to be taken through the Adviser. For example, in the following diagram it should be obvious that the model on the left has an acceptable wall thicknesses, but the model on the right has not.

 Introduction to the Adviser

Cavity models

The Adviser allows you to create a model of your part in a CAD package, and then read the model in to the Adviser.

Preparations

For a Plastic Filling analysis, you need to select the polymer and the injection location. Other settings, such as material temperature and pressure, are automatically selected according to the material's properties, but you can alter them if you wish.

Additional analyses can also be performed in order to investigate other aspects of part design.

Results

After the Plastic Filling analysis has finished, you can look at the Confidence of Fill result, which is derived from the Fill Time, Injection Pressure, Pressure Drop and Flow Front Temperature results.

A green area has a high confidence rating, yellow indicates a medium confidence rating, while red shows a low confidence rating.

Read the Confidence of Fill advice for suggestions on improving a medium or low result. If the Confidence of Fill result indicates problems, look at the other results to find the reason for the low or medium confidence of fill.

If the Confidence of Fill result shows any molding problems, look at the pressure and temperature results to identify where the problem is coming from. After looking at the Confidence of Fill, you should study the air trap and weld line results to find other possible molding problems.

You can then review the inputs and try to resolve any problems. Areas on the part that show low or medium confidence of fill may need to be redesigned or a new material selected for the part to fill.

Once you are confident that the part will fill, you can check the Quality Prediction result, which estimates the expected quality of the part's appearance. To find out more information and possible solutions to any implied problems, use the same methods you used for investigating the Confidence of Fill result. You can also use other analyses available to investigate and solve design problems.

Further Analysis

If your model needs more detailed analysis, you can save it in .sdy format, which can be analyzed by products in Moldflow Plastics Insight, such as MPI/Flow or MPI/Cool. These analyses provide more detailed information about how the part fills.