The Liquid Injection Molding Process

Liquid injection molding uses liquid silicone rubber (LSR) and similar elastomeric materials to produce a wide range of durable, pliable products such as seals and sealing membranes, electric connectors, medical applications, kitchen goods, and infant products. Due to LSR’s unique properties, liquid injection molding relies on a mechanical mixing process to churn out parts rather than the pressurized impingement mixing found in standard injection molding.

Liquid injection molding can be used to quickly manufacture a wide range of products and parts in various industries. Well-suited to a variety of applications, it’s among the most versatile and cost-effective manufacturing methods available today. 

An Overview of the Process 

The liquid injection molding process uses a set of plungers to mix and dispense LSR or similar plastic-based material. A base-forming plastic that can be reinforced with additives and fibers is contained in one plunger; the catalyst that will activate the mixing reaction is located in the other. 

Using either a static or dynamic mixer, the materials are combined into a compound. A metering unit ensures that the materials are pumped in equal proportions. The compound is then injected directly into a sealed mold. The nozzle that feeds the mixture automatically shuts off once it detects that the mold is already filled. 

A clamp holds the mold in place after the actual injection. The same clamp is opened once the process is complete, and the molding machine ejects the finished component.

Liquid Injection Molding Process 

The ETI Approach to Liquid Injection Molding 

Traditionally, the most common materials used in the liquid injection molding process are silicones and acrylics. At ETI, we prefer to use LSR because of its ability to keep its physical properties even in extreme temperatures, as well as its flexibility and durability.

Aside from LSR, we also use high consistency rubber (HCR) for silicone molding applications. Our facility features cold deck systems with an efficient material delivery configuration that enables us to minimize waste during parts production. For risk-sensitive products, we offer ISO Class 8 clean room molding. We also have the ability to co-mold two materials to create a fully integrated part in a single operation.

Easy setup is characteristic of our energy-efficient, 50- and 100-ton injection molding presses. Backed by precision built tooling that offers us tight control over shot sizes, we’re able to achieve outstanding accuracy and repeatability on parts with complex geometries and varying wall thicknesses. This gives us the flexibility to handle a wide range of jobs, from small projects with a 1,000-unit production requirement to large production runs of a million units or more. 

Working with ETI 

With more than 30 years of experience, ETI is the perfect partner of manufacturers looking to maximize the efficiencies of liquid injection molding. Using your requirements as its baseline, our proprietary Project Forecaster analysis tool reviews every aspect of your company’s operations and develop the ideal solution for your manufacturing needs. 

If you’re searching for a simpler approach to manufacturing complex plastics, ETI can provide you with a perfect solution. For more information on what we can offer your company, contact us.