Advantages of liquid silicone

1.Latest technical trends of LIMS

At present, not only is the transition from a simple mixing type with the above advantages to the LIMS method, but it is currently actively developing in the following two directions

(1) Fully automatic molding: no flash, no runner, automatic demoulding

With regard to the fully automated molding process, people have studied from various aspects such as injection machines, molds, materials and so on. It not only saves manpower in the process operation, but because it does not produce useless solidified materials, the cost of materials is reduced. From the perspective of environmental protection, this method has also attracted much attention. For the molding of miniature silicone products such as automotive skeleton oil seals, the molding cycle (from injection to the next injection) is required to be within 10s, so that it can be completed in a very short time.

(2) Composite molding: insert molding, binary molding

Because the form of the crosslinking reaction is addition curing, it can be molded at a relatively low temperature. Since no by-products such as peroxide decomposition residues are generated during the cross-linking reaction, it is not necessary to undergo secondary vulcanization in principle. Therefore, it can be integrally molded with the resin, and the dual molding of the sealing part and the skeleton part as a whole has also begun to spread by applying the primer material for insert molding.

Silicone rubber products have excellent properties (heat resistance, plug resistance, weather resistance, electrical insulation, flame resistance, etc.). Due to these properties, it is possible to make environmentally friendly molding based on fully automatic molding and integral molding with metal and organic resins.

2.Material for automatic molding without rubber edges / runners

In recent years, in terms of injection molding of liquid silicone rubber, a method known as no edging and no runner molding has become popular. This is a molding method that does not produce useless solidified materials and does not require secondary processing, that is, a molding method that has no injection port, no flow channel (if there is no curing), and no waste rubber edge. In order to implement this molding method, the structure of the model and the smoothness of the parting surface, the measurement and discharge accuracy of the injection machine must meet the requirements, and even in terms of materials, it must be a material that is difficult to generate waste rubber edges.

As shown, after the rubber material filled in the mold cavity fills the mold cavity, the rubber material flows into the parting surface due to too much rubber material or due to the thermal expansion of the silicone rubber, etc. After curing, it becomes a waste rubber edge. If the parting surface is designed to be narrow, it is difficult to generate waste rubber edges, but at the same time, the air is not easy to be removed, so it becomes the cause of air bubbles in the finished product.

Compared with the previously used materials, the curing curve of this material is a sharp turning state (the time from curing to curing is very short). By selecting the appropriate injection conditions for this type of material, that is, before the material fills the mold cavity, the curing has not yet begun, and the material has good fluidity, and when the material fills the mold cavity, the curing ends immediately, even if there is residual pressure, the material is not Will flow to the parting surface to prevent the formation of waste rubber edges.