Many designers directly copy the design logic of thermoplastic molds to develop liquid silicone rubber molds, which is the most common core misconception. The difference in material properties between the two can directly lead to a large number of molding defects. The viscosity of liquid silicone rubber is extremely low, and the filling speed is much faster than that of ordinary thermoplastic rubber materials. If the large gate and deep exhaust groove design of thermoplastic molds are used, serious overflow is almost inevitable. However, blindly copying the shrinkage rate calculation logic of thermoplastic molds will completely ignore the special law of "in mold expansion and cooling shrinkage after demolding" of liquid silicone rubber, ultimately leading to a significant deviation in product size from design requirements.

The misconception in the shrinkage design process is very common, and many designs directly apply fixed shrinkage values of 2.5% -3%, completely ignoring the variable effects of rubber formula, product thickness, and secondary vulcanization process. In fact, the fluctuation range of shrinkage rate of liquid silicone rubber with different hardness and filling systems can reach 1.5% -3.5%. The shrinkage rate of thick walled products will be significantly lower than that of thin-walled products. Secondary vulcanization will also cause an additional 0.5% -0.7% shrinkage in the products. Directly applying fixed values can easily lead to batch size deviations.

The common misconception in the design of parting lines is to set the parting surface at the end area of the rubber material flow, or to choose the non contour turning position of the product. The former will directly block the core channel of the exhaust, causing the air inside the mold cavity to be unable to be discharged smoothly, while the latter will allow low viscosity liquid silicone rubber to overflow along the small fitting gaps of the parting surface, forming difficult to clean flying edges. Many designs also neglect the control of contact pressure on the parting surface, relying solely on ordinary flat surfaces to lock the mold without reserving sufficient rigid support. Slight deformation of the template during the production process can cause large-scale adhesive overflow.

The misconceptions in exhaust system design often manifest in two extremes: either simply copying the deep exhaust groove design of thermoplastic molds, with a depth far exceeding the safety upper limit of 0.005mm, directly causing continuous overflow of glue; Either the exhaust groove is set in the wrong position, not arranged in the dead corner area where the rubber material is filled at the end, and only set up exhaust near the rubber inlet, which cannot completely exhaust the trapped air deep in the mold cavity. There are also many designs that completely omit the sealing gasket of the parting surface, do not set up a vacuum structure for the mold cavity, and rely only on natural exhaust. For products with slightly more complex structures, it is almost inevitable that white edges, bubbles, and even local adhesive defects will form on the surface.

A common misconception in the design of cold runner systems is the lack of an effective temperature isolation structure between the hot mold cavity and the cold runner. Either the runner is not cooled enough, causing the rubber material to sulfurize and block the runner before injection, or the runner is cooled too much, absorbing too much heat from the high-temperature mold cavity, resulting in incomplete solidification of the rubber material at the gate position. There are also many designs that ignore the flow balance of the channels, resulting in significant differences in the length of each channel in multi cavity molds, and the inability of the rubber material to simultaneously fill all mold cavities, ultimately leading to the contradiction of partial cavity under injection and partial cavity overflow.