Demystifying the LSR Injection Molding Process


In the realm of modern manufacturing, LSR (Liquid Silicone Rubber) injection molding has emerged as a cornerstone technology, offering unparalleled precision, versatility, and efficiency. This sophisticated process has revolutionized the production of intricate parts and components across diverse industries. In this comprehensive guide, we delve into the intricacies of the LSR injection molding process, unraveling its steps, equipment, and key considerations for successful implementation.

Understanding the LSR Injection Molding Process

LSR injection molding is a specialized manufacturing process that involves injecting liquid silicone rubber into a mold cavity to create high-quality, precision-engineered parts and components. Unlike traditional molding methods, LSR injection molding offers exceptional precision, consistency, and flexibility. The process begins with the meticulous preparation of the silicone material, typically a two-part liquid silicone compound. These compounds are carefully mixed and degassed to ensure uniformity and quality in the final product.

Once the silicone material is prepared, it is injected into the mold cavity under high pressure using a specialized injection molding machine. The mold is then closed, and the silicone material is allowed to cure and solidify within the mold cavity. Depending on the specific requirements of the application, you can accelerate this curing process by applying heat or other methods.

Key Steps in the LSR Injection Molding Process

The LSR injection molding process comprises several key steps, each essential for the successful production of high-quality parts and components:

1. Material Preparation: The first step in the process involves preparing the liquid silicone rubber material. This typically involves mixing the two-part silicone compound in precise proportions and degassing it to remove any air bubbles that may affect the quality of the final product.

2. Injection: Once the silicone material is prepared, it is injected into the mold cavity under high pressure using a specialized injection molding machine. To ensure uniform filling of the mold cavity and prevent defects like air entrapment or incomplete filling, we must carefully control the injection process.

3. Curing: After the mold cavity is filled with silicone material, the mold is closed, and the silicone is allowed to cure and solidify. Heat or other methods can speed up curing as per the application’s requirements. Proper curing is essential for achieving the desired mechanical properties and dimensional accuracy of the final product.

4. Mold Opening and Ejection: After the silicone cures, you can open the mold and eject the finished part from the mold cavity.During this step, it is important to take care to prevent any damage to the part and to ensure that it ejects smoothly from the mold.

5. Trimming and Finishing: Finally, the finished part may undergo trimming and finishing processes to remove any excess material and achieve the desired surface finish and dimensional accuracy. This may involve machining, grinding, or other post-processing techniques depending on the specific requirements of the part.

Equipment Used in LSR Injection Molding

LSR injection molding requires specialized equipment designed to handle the unique properties of liquid silicone rubber. Key components of the equipment include:

1. Injection Molding Machine: A specialized injection molding machine equipped with a high-precision injection unit and temperature-controlled mold is used to inject the liquid silicone rubber into the mold cavity.

2. Mold: Precision engineers create the mold, also known as the tool or die, according to the exact specifications of the desired part. When you close the two halves, the cavity and the core work together to produce the desired part geometry.

3. Temperature Control System: LSR injection molding requires precise temperature control throughout the process to ensure proper material flow and curing. Temperature control systems heat the silicone and cool the mold for curing.

4. Injection Unit: The injection unit is responsible for heating and injecting the liquid silicone rubber into the mold cavity under high pressure. It consists of a screw or plunger mechanism to meter and inject the material, along with heaters to melt and maintain the material at the desired temperature.

5. Curing System: To speed up the process based on application requirements, one can use curing systems. This may include heat, UV light, or other methods to initiate cross-linking and solidification of the silicone material.

Key Considerations for Successful LSR Injection Molding

Several key considerations are essential for successful implementation of the lsr injection molding process:

1. Material Selection: Choosing the right silicone material is crucial for achieving the desired properties and performance of the final product. Factors to consider include hardness, elasticity, thermal stability, chemical resistance, and biocompatibility.

2. Mold Design: Proper mold design is essential for achieving the desired part geometry, dimensional accuracy, and surface finish. Factors to consider include parting line design, gate location, venting, and cooling channels to optimize material flow and minimize defects.

3. Process Control: Tight process control is essential for achieving consistent results and minimizing variability in the final product. This includes monitoring and controlling key process parameters such as temperature, pressure, injection speed, and curing time.

4. Quality Assurance: Implementing robust quality assurance measures is essential for ensuring the quality and reliability of the final product. This may include in-process inspection, dimensional verification, and testing to ensure compliance with specifications and standards.

5. Post-Processing: It may be necessary to perform post-processing to achieve the desired properties of the part. This may include trimming, degating, surface treatment, and assembly operations as needed.


LSR injection molding offers precise and efficient production of high-quality parts. By understanding the intricacies of the process, selecting the right materials and equipment, and implementing robust quality assurance measures, manufacturers can unlock the full potential of LSR injection molding for a wide range of applications. LSR injection molding is a cornerstone technology in modern manufacturing for precision-engineered components, driving innovation.