Liquid injection molding (LIM), an industrial fabrication process, molds materials into a variety of components and products. It varies from the standard reaction injection molding process in that it doesn’t rely on a pressurized impingement mixing. Instead, liquid injection molding uses a mechanical-mixing process that concentrates mostly on liquid silicone rubber (LSR) and similar elastomeric materials.
This has become the preferred process among many manufacturers of rubber parts, including Si-Tech, due to its superior end-of-product performance. This process offers:
- Durability
- Tensile strength
- Flexibility
- Accuracy
- Chemical resistance
- Biocompatibility
- Temperature resistance
- Transparency and pigmentation
On top of all that, the liquid injection molding process allows for higher levels of automation and 24/7 production.
Keys to Flexibility
One of the most important benefits that speaks to the flexibility of liquid injection molding? The one-of-a-kind properties of liquid silicone materials. This material has high heat and flame resistance characteristics, and can withstand temperatures of more than 250°C, and as low as -90°C. Silicone also offers unmatched formability qualities, allowing for the transparency or coloring of the finished product.
Just about every industry can benefit from the liquid injection molding process, including:
- Automotive
- Aerospace
- Medical
- Defense
- Electronics
- Appliances
- Textile
- Food
How it Works
The materials commonly used in this process include silicones and acrylics, requiring the use of a spring-loaded pin nozzle to prevent the machine hardware from clogging. One plunger holds the base forming plastic, made stronger by additives and fibers, while the other plunger contains the catalyst. Each is put into a static mixer to trigger the mixing reaction.
The liquid mixture will then be injected into a mold and heated at temperatures between 355 and 390 F. While it begins as a fluid, it is heated within the mold to start the curing process. Then, once hard, the molding machine will eject the nearly finished part.
The materials are heated to their melting point and then must cool off while in the mold. Many manufacturers use computer-aided design (CAD) tools to ensure a more efficient process. This allows operators to figure out the most cost-efficient and effective process and conditions, then be better able to evaluate results.
Thermal imaging technology can also be used to determine potential costly production mistakes, such as design irregularities and molding defects.
In a nutshell, the liquid injection molding (LIM) manufacturing process molds silicone rubber into a wide array of parts and products. While the oft-used standard reaction injection molding (RIM) process uses a pressurized impingement mixing process, Liquid Injection Molding uses a mechanical mixing method that combines a two-component compound together within a mold.
Contact Si-Tech
LIM is the process used by the experts here at Si-Tech. To learn more about the process and how your business can benefit, contact us at 757-887-8488.
