ASH Industries Manufacturing Groups

Solutions for Manufacturing, Here in the USA

Liquid Injection Molding (LIM)

What is Silicone Liquid Injection Molding?

Silicone liquid injection molding, or LIM, is a manufacturing process commonly used to make silicone parts (considered a subset of rubber or thermoset) that need to withstand extreme conditions, regardless of the industry. The process is an injection molding process at heart, meaning that materials are injected into a pre-made mold, where heat accelerates part curing. Then, the process repeats itself until the part run is complete.

While Silicone LIM is best used for short and long run part production, it can also be utilized in the final stages of the prototyping process as well, as the process permits engineers to experiment with different material configurations to fine tune the product before it is green-lit for production. Plus, since a mold needs to be created for the process to take effect, product developers can save time and money by using Silicone LIM for both final prototyping and production processes.



ASH Injection Molding Benefits

  • State-of-the-art Equipment
  • Experts in the LIM process
  • Strict Quality Checks & Control
  • Customer Focused Staff
  • Made in America

Why Use ASH Industries for  Molding & Manufacturing?

ASH has been in the manufacturing & engineering business for over 30 years, which gives us tremendous depth, experience & knowledge about molding. In our time helping clients with creating products and parts we've seen and done it all. Experience & expertise is important when it comes to manufacturing products - ASH can offer you deep insights into the best way to utilize the liquid injection molding process for your product to save you time, money and achieve success.

New Technologies & Capabilities: ASH is constantly updating and evolving our manufacturing processes, developing new techniques for thermoplastic injection molding, medical injection molding, rotational molding, silicone liquid injection molding that save you time and money bringing your product to market. 

Made in America: ASH® is proud to do all our injection molding manufacturing in America, no outsourcing. Every point of our process is done right here in the USA, at our product manufacturing facility in Louisiana. We work with clients all over the United States and can ship products nationally and globally. 

Experienced Engineers & Project Managers: Our injection molding engineers have vast experience in manufacturing and helping customers bring their idea or product to fruition. We work hand in hand with you and ask all the right questions to give you the tools your product needs to succeed and do the job you designed it for in targeted environments.


Liquid Silicone Manufacturing Process

pic-limThere are two main types of LIM processes - injection molding of silicone rubber, or LSR, and injection molding of fluoro liquid silicone rubber, or F-LSR. The former is the most common method that product developers take in producing rubber parts while the latter type is used to craft more high performance parts in industries ranging from automotive to aerospace.


Silicone LIM (Liquid Injection Molding) is a complex manufacturing process which relies on a lot of different variables for part runs to be successful. For instance, important components of liquid injection molding machines include:

  • Injectors: These devices pressurize the liquid material and maintain the two components at a homogenous temperature.
  • Metering Units: In order for LIM to be successful, there's needs to be a catalyst and a base forming silicone material. Metering units help ensure that these two materials maintain a constant ratio while they're in the process of being released.
  • Supply Drums: These components, which are also commonly referred to as "plungers," are the mixing containers.
  • Mixers: These combine the materials before they're injected into the designated mold.
  • Nozzle: Paired specifically to a mold, these enhance injection. 
  • Mold Clamp: This is what secures the mold during the production process, as well as what opens the mold back up when the process is completed

Below is a further look at the ASH™ Silicone LIM process, it's pros and cons, design considerations and other information you can use to determine if this manufacturing process is the right one for your next product run.


Advantages of Silicone Liquid Injection Molding

Silicone LIM is ideal for creating thermoset (rubber) parts or parts that need to withstand elevated temperatures and which must remain inert to various chemicals or bodily fluids. Seals, o-rings, isolators, electronic components and other parts in the aerospace and automotive industries are common applications. Here are some of the advantages of using the Silicone LIM process for your product run:

  • Durable: LIM parts are able to hold up to elevated temperatures, which make them ideal for parts under the hood of cars or near engines on airplanes. LIM parts are also often fire retardant and won't melt away or warp like those that are created via similar injection molding processes, such as plastic injection molding.
  • Tensile Strength: To piggyback off of the above advantage, Silicone LIM parts are strong which makes them applicable for a variety of industries.
  • Flexibility: Silicone LIM parts can exhibit elongation up to six times length before breakage.
  • Accuracy: Another big advantage is the high level of accuracy in production Silicone LIM parts.
  • Automation: LIM is a process that can run around the clock with minimal supervision.


Limitations of Silicone Liquid Injection Molding

Like any production process, LIM isn't without its disadvantages as well. For instance, LIM is a process that takes a high level of expertise to carry out, as there are numerous points during the fabrication process where things can go wrong, potentially dramatically impacting the quality of the part run. Perhaps the biggest concern that must be taken into consideration is the molds for Silicone LIM must be exacting with carefully tuned vents in the mold to allow air to escape while aloowing minimal flash. To help combat this, ASH™ uses mold fabrication techniques designed to make the best parts possible.


LIM isn't an ideal process for every part application. While ASH’s SuperMold process makes it possible to minimize capital outlay for molds, there is an upfront cost that can be substantial.  Silicone LIM can take several tests in order to find the ideal surface finishes and additives to get the parts desired before green-lighting production.  Additionally, some medical varieties of Silicone LIM can cost thousands of dollars per quart.  Speak to your ASH Production Engineer to help decide the best course of action for your project.


Silicone LIM Design Considerations

liquid injection molding partsGenerally speaking, design considerations for LIM are about the same as design considerations for plastic injection molding. However, there are a few points to note.

Liquid silicone rubber, while it doesn't shrink inside the mold as substantially as thermoplastic parts, it can shrink up to 3% after it's ejected from the mold and is left to finish curing. Venting is a crucial part of mold design in the LIM process. That's because it's important to avoid air entrapments, which can lead to flawed parts. Also hot tearing can be an issue when the silicone part is ejected from the mold. Depending on the part this may make automation difficult, but ASH™ will work with you on your project to address any concerns up-front.


Materials Used in Silicone Liquid Injection Molding

The most common material used in the Silicone LIM process is a high-purity platinum core silicone that's able to create the highly durable parts that are utilized in so many industries. For example, liquid silicone rubber is especially cherished in the medical industry, as tools and instruments made from the material are biocompatible, well made and reduce the risk of contamination. Fluoro liquid silicone rubber is another material that is making headway via the LIM process, especially when it comes to automotive parts, smaller parts or parts that require extreme precision.


Trust ASH™ for Injection Molding Made in America

ASH® is a production manufacturing company that is focused 100% on your success. It doesn't matter if you are a Fortune 500 company that needs to mass produce a part for your new medical device or an entrepreneur looking for help with producing & developing your prototype product, ASH can help you achieve success. One of ASH's core tenants is hiring the best people in our industry, right here in America. We hire people who truly love what they do, listen to the customer and are passionate about creating the best product possible.

Engineers at ASH Industries™ understand the complexities of beginning a new LIM project and want to help you to bring your project to fruition. You can trust the experts at ASH to take your product from concept to completion.

For more information on ASH™ liquid injection molding and if it would be the right method for your part run, contact one of our manufacturing & engineering experts now.



About ASH Industries

ASH® Industries offers a wide range of product manufacturing solutions.

Our engineering knowledge, patience, technical expertise, and desire to please clients has led to consistent innovation. 

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1330 W. Willow St.
Lafayette, LA 70506 
Ph: (800) 598-5274 
Fax (337) 235-0971

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