In order to attain a more stable mold temperature, mold preheat is a common technique that is used to heat the mold base before a molding cycle starts (as shown in the following picture). In injection molding, mold temperature is a critical processing parameter since it will affect the melt flow behavior and dominate the molded part quality. It takes a certain period of time to reach a steady mold temperature, thus, the prediction for the mold preheat time is a critical factor because it will affect the product quality.
Moldex3D R13’s mold preheat analysis and transient cooling analysis can help users estimate the preheat time and understand the history of the mold preheat stage. The operation steps for attaining a mold preheat analysis are explained below.
Step 1. Open a project with a cooling system (including a mold base, cooling pipes and heating rods). When setting the process parameters in the Process Wizard window, click Setting of mold preheat under the Cooling Settings tab.
Step 2. Select Preheat time and set up the preheat time (or select Cavity surface average temperature and set up the targeted temperature to preheat the mold). Input the cooling channel information such as temperature and flow rate, and then click OK.
Step 3. Under Analysis sequence setting, click Customize and add Mold preheat to the chosen analysis items.
Note: If the cooling analysis is run after the mold preheat analysis, be sure to choose Cooling (transient) instead of Cooling (cycle-average) in the same column.
Step 4. After the analysis is done, Mold preheat results will be shown in the analysis result list. The results of the temperature distribution and the history of the mold preheat stage are shown in the following pictures. As shown in the last figure below, the preheat time needed to make the mold to reach a steady temperature is estimated as 800 seconds (0.08×E4).
Note: If the mold preheat analysis is done before the transient cool analysis, the result of mold preheat will be the initial condition of the transient cool analysis.