The mold transparency method is an intuitive and efficient technique for adjusting injection molding machines. Its core principle involves creating a simulated mold using transparent materials (such as acrylic or transparent resin sheets), or modifying key areas of an existing mold to be transparent. This allows operators to observe the melt flow, filling process, pressure distribution, and cooling status within the mold in real time. This method breaks the limitations of traditional machine adjustment based on experience and guesswork, providing a visual basis for precise adjustment of process parameters. For example, when producing complex plastic parts, a transparent mold can clearly indicate whether the melt is experiencing stagnation, jetting, or air entrapment, helping operators quickly locate and identify defects and their causes, allowing for targeted adjustments to parameters such as injection speed, pressure, and temperature.
When using the mold transparency method for machine adjustment, it is first necessary to create a suitable transparent simulation mold based on the structural characteristics of the plastic part and the mold design parameters. The transparent mold’s cavity structure, gate location, runner dimensions, and other features should be consistent with the actual production mold to ensure accurate observation results. During the production process, attention must be paid to the transparent material’s high-temperature resistance and mechanical properties to avoid mold deformation or damage caused by the high pressure and high temperature during the injection molding process. Furthermore, to enhance observation, high-speed cameras and temperature sensors can be installed on the outside of the transparent mold to record the dynamic process of melt flow and temperature changes in real time, providing detailed raw data for subsequent parameter analysis and adjustment.
During actual machine adjustment, the mold transparency method can be used to focus on observing the melt filling stage. When the melt enters the cavity from the gate, the flow pattern at its front can be clearly seen through the transparent mold: if the melt advances in a smooth laminar state, it indicates that the current injection speed and pressure settings are relatively reasonable; if the melt front is turbulent, diverted, or backflows, it may be caused by excessive injection speed or improper gate design. It is necessary to promptly reduce the injection speed or optimize the gate size. In addition, the transparent mold can also intuitively display the location of trapped air – when the melt is filled to the end of the cavity, if bubbles are retained and cannot be discharged, a clear bubble shadow will appear on the transparent mold. At this time, the problem can be solved by adding venting grooves, adjusting the filling sequence, or reducing the melt viscosity.
The mold transparency method also plays an important role in optimizing the holding and cooling parameters. The holding stage is a key step in ensuring the dimensional accuracy and density of plastic parts. The transparent mold can be used to observe the shrinkage of the melt during the holding process: if obvious shrinkage marks appear in the corners of the cavity or the wall thickness, it means that the holding pressure is insufficient or the holding time is too short, and the holding pressure needs to be appropriately increased and the holding time needs to be extended; if the melt overflows during the holding stage, it means that the holding pressure is too high or the clamping force is insufficient, and the relevant parameters should be adjusted in time. In the cooling stage, the transparent mold can help observe the solidification process of the plastic part. By observing the solidification rate and cooling uniformity of the melt, the temperature, flow rate and cooling time of the cooling water channel can be reasonably set to avoid defects such as warping and deformation of the plastic part due to uneven cooling.
It is worth noting that although the mold transparency method has many advantages, it also needs to be used reasonably in combination with actual production conditions during its application. The production cost of transparent molds is relatively high and their service life is limited. Therefore, they are more suitable for new product development, process debugging or production optimization of complex plastic parts, rather than large-scale batch production. In addition, the optical properties of transparent materials may have a certain impact on the observation results, such as visual errors caused by light refraction. Operators need to make a comprehensive judgment based on experience and data. With the development of science and technology, the combination of transparent molds and computer simulation technology has become a trend. By comparing and analyzing the actual data observed in transparent molds with the predicted results of simulation software, the accuracy and efficiency of machine adjustment can be further improved, providing strong support for the high quality and high efficiency of injection molding production.
