LSR Injection Mold with Cold Runner System

LSR Injection Mold's Cold Runner system plays the same role as Hot Runner system for Plastic Injection Molding. According to mold runner system, LSR injection molding can be classified into two types, cold runner LSR mold and hot runner liquid silicone mold.

Cold runner system of Liquid Injection Mold keeps the liquid silicone cold until the Liquid Silicone Rubber inject into the hot cavities of the mold. So cold runner system can save a lot of material. Reduce waste.

In LSR injection mold, there are piston plate, manifold and insulation plaste where the cold runner system is located. Cooling water channel and piston needle valve consititute the cold runner system.  Both play important parts in LSR injection molding process. Cooling water keep running in the channel in order to prevent liquid silicone material from curing. And the piston needle valve controls accurate amount of raw material uniformly flowing to cavities and ensure a high quality LSR part. 

How Cold Runner System Works in LSR Injection Mold

Before silicone injection molding, the piston needle valve is close, so LSR raw material can not enter cavities. When the piston needle retract, it is time to inject liquid silicone rubber to mold cavity. During injection, needle valve is in a state of retraction. After cavity is filled with accurate amount of material, piston needle valve back and close.

High-precision piston needle valve is a crucial part to increase manufacturing productivity and eliminate product reject rate. Cold runner LSR injection mold is suitable for large volume part production and complicated silicone part with strict tolerance and appearance requirement. 

Hot Runner LSR Injection Mold

In hot runner liquid silicone injection mold, raw material is directly injected into cavity from mold nozzle. Precision of rubber part is not better than cold runner LSR molding, as raw material feeding control is not so uniformly and accurately. Besides, hot runner LSR mold generate much waste material in each curing cycle because the material channel is larger and more liquid silicone is required. It add more material cost to the unit price. 

LSR Injection Mold Cold Runner System Main Function

Save time and material within LSR project. As we known, production cycle time depends on the cure time of the runner and sprue. So to eliminate the runner system by gating directly into the cavities not only decrease cycle time, reduce material costs, but also simplifies mold automation.

Higher-quality liquid silicone part production. 

Although cold runner system is expensive, it is very helpful to produce high-precision silicone parts, complex design silicone part, and composite rubber part with plastic or metal inserts. Because liquid silicone material can evenly transfer to each cavity, product thickness will be very uniform. Cold runner LSR mold can also produce extreamly thin-thickness product.

LSR cold runner mold is beneficial to large volume production. Liquid injection mold with cold runner can accelerate production and its mold service time is longer.

LSR and LIM's Benefits

LSR is transparent, durable, and ultraviolet and stain resistant.

Compared with common rubber, LSR can withstand extreme high and low temperatures, can used in hot and cold environments.

LSR can be molded to varying wall thicknesses, within the same part, enabling ease of manufacturing for complex devices, ideal for intricate designs and close-tolerance parts.

LSR is liquid fluid, can molded to different thickness easily, can achieve strict tolerance. It’s a better choice for high precision and difficult structure products.

LSR Injection Mold's  designs are simplified, as liquid silicone rubber flows readily into very thin cross section. Liquid Injection Mold's surfaces do not have to be highly polished.

LSR Injection Mold's cure cycle is shot, as the silicone is fully cured, the product is finished with no or less flashing, which can improve efficiency.