Temperature, mold (transient from start-up) result

The Temperature, mold (transient from start-up) result shows the temperature of the mold as it changes during the injection cycle, from the initial start-up until the mold temperature stabilizes.

The temperature throughout the mold is determined using heat inputs from the cavity (melt), runners and cartridge heaters and heat outputs to the cooling circuits and outer mold boundaries. The calculation takes into account the Mold-melt Heat Transfer Coefficients (HTC) values, which you can set on the Mesh tab of the Solver parameters dialog, in the Advanced options of the Process Settings. The mold side of the part/mold interface will be slightly cooler than the part side of the interface.

Tip: The lower the HTC value, the greater the resistance to heat transfer between the polymer and the mold.

Using this result

Use this result to find localized hot or cold spots, and determine whether they will affect cycle time and part warpage. If there are hot or cool spots, you may need to adjust the cooling channels, or coolant temperature. Use a cutting plane to investigate hot or cold spots inside the part.

The minimum and maximum mold temperature should be within 10°C of the target temperature for amorphous materials and within 5ºC for semi-crystalline materials. This guideline may be difficult to achieve for most molds, but should be the target of the Cool analysis. The narrower the temperature variation over the mold face, the less likely the mold temperature variation will contribute to warpage or an extended cycle time. Cooling channel placement and the thermal conductivity of the mold will affect the temperature variations.

The Temperature, mold (transient from start-up) result will typically be between 10ºC and 30ºC above the coolant inlet temperature. If an automatic Injection + Packing + Cooling time is used, a coolant temperature too close to the target temperature will significantly extend the predicted cycle time.

Tip: You can create an XY plot of the transient mold temperature, on any given node to see how the temperature at that node varies with time. Click on Results in the Results pane of the Home tab, then click (New Plot > Plot) and scroll down to the result. Remember to change the Plot type to XY plot.

Things to look for

When viewing the Temperature, mold (transient from start-up) result, watch for the following.

• Localized hot spots.
• The cooling pattern. Is it evenly distributed?