Liquid silicone rubber (LSR) injection molding is a method for making supple, long-lasting components in large quantities. Learn more about the key characteristics, benefits, and uses of liquid silicone rubber injection molding by reading this article.
What is Liquid Silicone Rubber (LSR) Injection Molding?
The most popular production technique, liquid injection molding, is used in liquid silicone rubber (LSR) molding to create a broad variety of products from raw LSR components. With pressured impingement mixing, the injection molding process is different from the norm. Mechanical mixing techniques are used in liquid injection molding, which is mostly used for elastomers like liquid silicone rubber (LSR) and related liquid rubbers.
The earliest method of creating silicone rubber components, high consistency rubber (HCR) injection molding, is still widely used today. However, for many producers of rubber products, liquid injection molding is the best option. due to its exceptional product performance, including its tensile strength, flexibility, precision, and longevity. The capacity to produce continuously and with high levels of automation is another benefit of liquid injection molding.
Liquid Silicone Rubber Injection Molding Process
The next part provides a step-by-step walkthrough of the entire liquid silicone rubber molding process:
- Uncured liquid silicone is stored in two buckets or supply drums. The base-forming substance is kept in one of those containers. The alternative has a catalyst.
- A metering device is present. The two materials should be automatically released in a proportion that is both equal and constant. The metering devices also release any colouring additives that may be present.
- The operator may personalize and configure the silicone rubber molding machine to make it automated. To ensure a uniform shot size for each item, the injection is tailored.
- Prior to sealing the mold, the platens and pistons are aligned. Depending on the parameters, the alignment has multiple settings for the applied pressure, temperature, cycle duration, and injection rate.
- The molding machine heats up and the mold temperature increases after the operator sets all the variables. The clamp on the mold is subjected to the right amount of clamping force.
- The silicone rubber is forced into the mold cavity with the aid of an injection mechanism after the mold is closed and the pump and injector are ready.
- At the proper pressure and temperature, the liquid silicone rubbers are cured until solidification takes place.
- The user can physically remove the silicone rubber product once it has solidified. It is also possible to employ an automated ejection mechanism with gippers. However, since silicone rubber is so flexible, ejector pins are not necessary for removal.
Also take note of the post-molding procedures including cleaning, inspection, and packing. These procedures are equally important for ensuring the quality of your silicone rubber goods.
Liquid Injection Molding Machine
In a kit, liquid silicone rubber material typically comes in two parts, A and B. The following are the essential elements of the two-part LSR injection molding process:
- Supply drum: The pumping system is connected to these silicone liquid jugs or plungers. A third pigment container is typically included in two-container configurations.
- Metering units: To maintain a constant contemporaneous release, this metering device pumps two liquid silicone materials (A and B) at specified ratios.
- Mixer: The liquid silicone components from the metering unit are combined in this static mixer before being pressured and injected into the mold.
- Injectors: Using pressured force, this device moves LSR forming material into the pumping mechanism.
- Nozzles: The nozzles allow the liquid forming chemicals to enter the mold.
LSR Molding Design
Liquid injection molding (LIM) can be used to manufacture liquid silicone rubber (LSR). A cold-runner system uses a 1:1 mixture of the liquid raw material from the two distinct components to inject it into a heated mold. The benefit of quick cycling and quick manufacturing is provided by the short time it takes to cure.
What is material used for make silicone rubber?
Polysiloxane, sometimes referred to as silicone rubber in science, is an elastomer consisting of silicon, carbon, hydrogen, and oxygen. It is safe to use for infant bottle teats and tough enough to withstand the rigors of jet engines. High-performance polymer made from silicon metal and silica powder is known as silicone rubber.