About liquid silica gel injection molding process, I believe that many customers are not very clear, its important content includes the characteristics of the material and the molding process, the following by liquid silica gel products factory to share for you:

One, liquid silica gel introduction

Liquid silica gel is a kind of flexible thermosetting material with non-toxic, high temperature resistance and high resilience. Its rheological behavior is mainly manifested in low viscosity, rapid curing, shear thinning and high coefficient of thermal expansion. Its product performance for better thermal stability and cold resistance, excellent electrical insulation performance and combustion will not produce toxic substances; Therefore, liquid silica gel has become an irreplaceable material in the production and design of health products, automobiles, silica gel baby bottles, medical supplies, diving supplies, silica gel kitchenware and other products.

Two, the forming process

Liquid silica gel is divided into two groups of liquid material, which is divided into A material and B material. The work of the mixer will fully mix A material and B material in an accurate 1:1 ratio. Because most liquid silica gel products are colored, the machine is equipped with color pump set and color measurement part. A+B material, curing agent, color paste, etc. are fully mixed into the plasticizing system. This plasticizing screw has the function of homogenization and mixing at the same time. Through the screw, the mixture is injected into the mold. At the mold temperature of about 180℃, the curing reaction of silica gel occurs. When using a cold runner system, it is important to note that the runner should be sufficiently cold. In order to avoid glue leakage in the production process, the needle valve will be installed on the surface of the mold parts, and when the injection is finished, the needle valve will immediately close the injection hole.

Due to the high coefficient of expansion of liquid silica gel, there will be a large expansion when heated, but only a small contraction when cooled, so the parts can not maintain accurate side distance in the mold. So we can use cold flow channel processing, liquid silica gel should keep a low temperature and maintain liquidity, cold flow channel is a closed system, in the injection cycle, the closed system in each flow channel using "sealing needle" or "needle valve" to control the accurate measurement of liquid silica gel material. Because of the low viscosity of liquid silica gel material, in the process of processing to consider the material reflux and leakage of these two problems, so the sealing of the screw is a necessary condition; Because liquid silica gel has significant thermal expansion characteristics, the shrinkage rate is about 3 percent (vulcanization temperature is 150℃), and silica gel has the characteristics of compression deformation.

Four, the design of liquid silica gel mold should pay attention to the following aspects

1. In order to avoid turbulence and jet, please use a small injection nozzle.

2. Please use needle-shaped or wing-shaped glue injection orifice.

3, with T type guide bolt instead of column guide bolt, demoulding using injection air gun, add insulation layer/plate.

4, do not use anti-rust oil containing polymer inhibitor, generally available toluene, xylene and so on instead.

The above common knowledge about liquid silica gel injection molding process, liquid silica gel manufacturers today to share here for you, I hope the knowledge described above can make you better understand liquid silica gel products and its processing process.