In order to clarify undesirable phenomena in an injection molding such as residual stress or sink mark, it is very important to measure the melt pressure distribution in the injection mold cavity.
In this paper, we have proposed a new method for measuring the melt pressure distribution by using a mold with a pressure transmission pin array and a tactile sensor. The results obtained through the new measurement method are summarized below.
(1) After experimentally examining the output of the tactile sensor. We confirmed that the deflection of each sensing point is not more than 6%, and it is necessary to keep the temperature around the sensor under 35°C to increase the pressure measurement range.
(2) We proposed an effective calibration method using a quartz pressure sensor during the injection molding process.
(3) Based on the above measurement method, we measured the pressure distribution of low density polyethylene under various holding pressure period conditions, and the results detailed proved that this method is effective. For example, when the holding pressure period is longer than the gate sealing period, the decrease in the pressure starts around the end of the cavity. Conversely, when the holding pressure period is shorter than the gate sealing period, the decrease in the pressure starts around the gate.