Why it's Difficult to Clean Cold Runner of Liquid Silicone Injection Molding?

What is Liquid Silicone Rubber?

Liquid Silicone Rubber also called as Liquid Silicone, LSR, Clear Silicone Rubber Liquid, LSR Silicone, which can be divided into Food Grade Liquid Silicone and Medical Grade Liquid Silicone. For common Liquid Silicone Rubber, that can achieve Food Grade, and if need to achieve complete 100% Medical Grade, will need second vulcanization.

 Liquid Silicone Rubber is safe can resistant bacteria growth and will not stain or corrode other materials.

To completely clean cold runner of liquid silicone Injection Molding need at least half a day.

As we can see  the structure of Liquid Silicone Injection Molding, it's complicated compared to compression molding. To clean a Liquid Injection Molding, need to clean feeding system, feeding nozzle, needle valves So that to make sure the hardness and color of the next product's precision.

One Production Case: My customer need 10 Shore A liquid silicone cannula samples, our factory did use 10 Shore A medical grade liquid silicone to produce. But when we got the samples, we found the hardness is more than 10 Shore A at least 20 ShoreA. So our production team tried to find out the reason. After double checking, the reason why the samples are 20 Shore A is because the worker didn't clean the feeding system completely. The former 30 Shore A material still stay in the feeding system, so the samples hardness is incorrect.

Liquid Silicone Injection Cleaning is much complicate and time consuming than Compression Mold. Compression molded parts is easier to change hardness and color, just need to adjust the material itself and do not need to clean the mold. In other word, this is an advantage of compression mold.

Although the cleaning process of liquid silicone injection molding is complicate, and cost of liquid silicone rubber parts is more experience than solid silicone parts, more and more customers still want to choose liquid silicone rubber as the material for their products. Because Liquid Silicone Rubber has superior advantages.

Liquid Silicone's Advantages

Liquid silicone rubber has very good compatibility with human tissue and body fluids, which is solid silicone can not achieve. So for many medical device related to human body, Liquid Silicone Rubber is the first/best choice.

Liquid Silicone Rubber parts have large temperature range ( –60°C to +180°C.), can withstand extreme high and low temperatures, so liquid silicone not only an ideal choice for medical device because of high safefy, but also a good choice for cars components that close to engines and need high temperature resistance.

Liquid silicone rubber injection molded parts are fire retardant and will not melt, which is a superior advantage compared to plastic injection molded parts.

Liquid Silicone Rubber can achieve the lowest hardness 5 ShoreA, for solid silicone can only be 20A, for many babycare products will LSR is a good option because it low hardness and softness. Liquid Silicone Rubber also has good elongation, high tear and tensile strength, and excellent flexibility.