Many mold silica gel manufacturers often encounter some problems when manufacturing liquid silicone gel molds or producing liquid silicone products. In general, the structure of liquid silicone gel molds is somewhat similar to that of thermoplastic plastic molds, but there are many significant differences.Liquid silicone products, for example, tend to have a lower viscosity and therefore a shorter filling time, even at low injection pressures.In order to avoid air retention in the mold, a good exhaust device must be designed in the liquid silica gel mold.

    In addition, liquid silica gel will not shrink in the mold like thermoplastic compounds. They are more inclined to expand under heat and will not shrink slightly as expected, so that their products will not stay on the convex surface of the mold as expected and difficult to release the mold.The following two points should be paid attention to in the production of liquid silicone mold:

    1. The shrinkage rate

    Although liquid silicone does not shrink during the molding process, it usually shrinks by 2.5 to 3 percent after release and cooling.The accuracy of shrinkage depends to some extent on the formulation of the material.However, from the mold's point of view, shrinkage may be affected by several factors, including the temperature of the mold, the temperature at which the material is demoulded, the pressure in the cavity, and so on.

    The location of the injection point is also worth considering because the contraction in the direction of the compound flow is usually greater than the contraction in the direction perpendicular to the compound.The size and shape of the product also have a certain effect on its shrinkage, thicker products generally have a smaller shrinkage rate.

    2. Moulding line

    The first step in the design of liquid injection mould of silica gel is to determine the position of the mold closing line.The exhaust design is mainly achieved through the groove on the parting surface, which must be located in the area where the liquid silica gel is injected into the final flow direction, so as to avoid the formation of bubbles in the molding process and reduce the strength loss of the bonding joint.

    Due to the low viscosity of liquid silica gel, it must be accurate in the design of the mold line to avoid the overflow of raw materials.Even so, you'll often see a mold line on the product (inevitably, liquid silicone is much thinner).Liquid silica gel mold will be affected by the geometrical size of the product and the parting surface position.A slightly chamfered liquid silicone product design helps ensure that the product has a consistent affinity with the other half of the desired mold cavity.

Pay attention to the above two points in the production of liquid silica gel products. I believe that the silica gel mold products you make can be qualified and meet the factory standards.