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Mold Qualification Worksheets --
Once the machine is selected, the software provides input worksheets to develop in-mold rheological data, molding area diagrams, gate seal times and cooling time optimization.
The In-mold reheological curve helps the user to locate the Newtonian or the 'flat' area of the curve. This helps in deciding the injection speed to be used during the molding process. A injection speed in the flat region of the curves compensates for any variation in the material viscosity.
Viscosity
Having selected the injection speed, the next step is to determine if the cavities are balanced. A short shot with parts close to being full is molded and the different cavities are weighed. The part weights are plotted and the balance is determined.
Cavity Balance
Once the cavity balance is proved out to to acceptable, the optimum holding pressure is determined by generating a Molding Area Diagram also known as a Process Window. A larger process window assures that the molded parts are not sensitive to natural variations in the process.A large process window is key to a robust process.
Robust Process
The length of time that the screw is held forward during the pack and hold phase determines the freezing of the gate. Too little time will allow the plastic that has been forced under pressure to 'ooze' out causing underpacked parts. Underpacked parts have sink and exhibit a broad variation in dimensions. Optimum pack and hold time guarantees that the gate is frozen.
Gate Seal
The cooling time is the bulk of the heat exchange phase. Although heat exchange starts as soon as the melt hits the mold, the cooling time decides when the part can be ejected. Cooling time has the most effect on dimensions of the part only till a part reaches a certain temperature. A graph of dimensions versus time predicts the most optimum time.
Cooling
The software will also keep track of all the issues with the molds. There is an inbuilt (editable) Mold Qualification Report that will prompt the user to answer questions related to the molds. There is also an automatically generated Mold Progress Report that will track the number of iterations and status of the mold and issues through various mold trials.
Mold Qualification Report
These comments and action items can then be emailed to the respective person to fix the molds or could be simply used to give a status of the mold.
Mold Progress Report
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