Tooling and mold design, featuring part fill analysis

Source: http://newsletters.hagerman.com/newsletters/ebul79-Mech.htm

With the recent release of Inventor 2010, there are so many new features to talk about. One of the key features added is the Tooling and Mold Design. Powered by Autodesk Moldflow plastic flow analysis tools, Inventor can help to optimize your design for moldability and minimize the number of mold iterations.

Even after rapid prototyping, there are so many things to consider before building the first mold. Things like part shrinkage, material flow rates, gate locations, runner locations, cooling and heating locations and process parameters. The product design cycle-tool and mold design creates a complex set of relating parameters. Change of a single mold variable can significantly alter the mold outcome which can sometimes cause a significant amount of lost time and money.

Usually, product quality and price depend upon a thorough understanding of the design parameters which are interrelated. For a new product, don't wait for the first shot at the molding machine to find molding shortcomings.

One way to find the shortcomings is to use the part fill analysis. This determines the following things:

• Will the injection molding process produce parts of acceptable quality?
• Which material should be used?
• What are the optimal process settings?
• How many gate locations are required and how will this affect mold filling?
• Where are the potential defects such as weld lines and air traps?

A fill analysis predicts the thermoplastic polymer flow inside the mold during the filling phase. The analysis calculates a flow front that grows through the part incrementally from the injection location, continuing until the velocity pressure switch-over point has been reached. The results of the fill analysis are calculated on four laminates through the thickness, and symmetrical cooling boundary conditions are assumed.

After determining the part, material and at least one gate, you are ready to do the fill analysis.

1. In the Core/Cavity tab, click Part Fill Analysis. The Part Fill Analysis dialog appears.

　

2. Click Start to begin the analysis. The Information dialog appears. Select "Don't show this again" to run the analysis in the background.

　

3. When the analysis is complete, a Results Summary dialog appears and the analysis results are added to the Results node.

　

Included in the Results node are great graphical analysis such as; the Fill time (Figure 1), Plastic flow, Confidence of fill (Figure 2), Quality prediction (Figure 3), Air traps (Figure 4) and Weld lines (Figure 5).

　

Figure 1

 

 Figure 2

Blue sections indicate the gate locations.

Figure 3

Figure 4

Figure 5