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Rubber Micro Molding: Everything You Need to Know

Hepako GmbH from Raisting am Ammersee, Germany, specializes in the production of micro parts made of rubber or silicone. This opens up unique possibilities for its customers in medical technology.

If you're in the manufacturing industry, you've probably heard about micro molding. But do you know what it actually means? Micro molding is the process of creating small parts with precise dimensions using high-precision molding techniques. Unlike traditional molding, micro molding is capable of producing parts with extremely tight tolerances and intricate geometries.

While plastic micro molding is the most common form of micro molding, there's another type of micro molding that's very important to many industries: rubber/silicone micro molding.

What is Rubber/Silicone Micro Molding?

Rubber and silicone micro molding are highly specialized manufacturing processes used for the production of very small parts with tight tolerances and intricate geometries. Micro molding involves the production of parts with tolerances of 5 microns or less and feature sizes that are typically less than 1 millimeter in size.

The process involves injecting a rubber or silicone material into a mold cavity, where it is allowed to cure and solidify into the desired shape.

The mold used in rubber/silicone micro molding is typically made from steel or aluminum and is designed to produce parts with complex geometries and tight tolerances. The mold is created using high-precision machining techniques, such as CNC milling or wire EDM, to ensure that it meets the required specifications.

Why Choose Rubber/Silicone Micro Molding?

Choosing rubber or silicone micro molding makes sense for a variety of reasons. Firstly, the process enables the production of very small, high-precision parts with tight tolerances that cannot be achieved through other manufacturing techniques. This allows for the creation of parts with complex geometries and intricate features that would not be possible with other processes.

Rubber micro molding also offers excellent part-to-part consistency, which is critical in applications where precision and consistency are key factors.

Furthermore, rubber/silicone micro molding offers a high versatility: Rubber/silicone micro molding can be used to produce a wide variety of small parts, including gaskets, seals, O-rings, and more. It allows designers to plan parts for areas that were previously not possible.

Overall, choosing rubber or silicone micro molding can provide a number of benefits for manufacturers looking to produce small, precise parts with tight tolerances and complex geometries. By leveraging the unique capabilities of rubber micro molding, manufacturers can create high-quality parts with enhanced functionality and improved performance.

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Applications of Rubber/Silicone Micro Molding

Rubber/silicone micro molding has a wide range of applications across various industries. Some of the most common applications of rubber/silicone micro molding include:

  1. Medical Devices: Rubber/silicone micro molding is frequently used to produce components for medical devices, such as catheters, surgical instruments, and implantable devices.
  2. Laboratories: Rubber and silicone micro molding are also commonly used in laboratory applications. The ability to produce small, precise parts with tight tolerances and complex geometries is essential for many laboratory applications, such as microfluidics and microelectromechanical systems (MEMS).
  3. Automotive Industry: Rubber/silicone micro molding is also used in the automotive industry to produce seals, gaskets, and other small parts.
  4. Aerospace Industry: The aerospace industry uses rubber/silicone micro molding to produce small parts for airplanes and other aircraft.
  5. Consumer Electronics: Rubber/silicone micro molding can also be used to produce small components for consumer electronics, such as cell phone cases and earbuds.

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How to Choose the Right Material for Rubber/Silicone Micro Molding

When it comes to rubber/silicone micro molding, choosing the right material is crucial. There are several factors to consider when selecting a material for rubber/silicone micro molding, including:

  1. Hardness: The hardness of the material will determine its durability and resistance to wear and tear.
  2. Temperature resistance: If the part will be exposed to high or cold temperatures, it's important to choose a material that can withstand the heat or cold.
  3. Chemical resistance: Some applications may require a material that is resistant to chemicals or other corrosive substances.

Biocompatibility: If the part will be used in medical devices or implants, it's important to choose a biocompatible material that won't cause an adverse reaction in the body. In this case, silicone rubber is the most commonly used material and is therefore in particularly high demand in medical technology.

Some of the most common materials used in rubber/silicone micro molding include:

  1. Silicone Rubber (HCR/HTV) or Liquid Silicone Rubber (LSR): Silicone rubber (& Liquid silicone rubber) is a popular choice for micro molding because it can produce parts with excellent mechanical properties, such as high tear and tensile strength, as well as biocompatibility. In addition, silicone rubber is characterized by the fact that it virtually retains its properties over a wide temperature range - both at cold and at heat.
  2. Ethylene Propylene Diene Monomer (EPDM): EPDM is a synthetic rubber that has excellent weathering and ozone resistance, making it ideal for use in outdoor applications. EPDM also has good mechanical properties and is therefore used, for example, as a material for diaphragms.
  3. Styrene-Butadiene Rubber (SBR): SBR is a synthetic rubber that has good abrasion resistance and can be used to produce parts with high resilience and flexibility.
  4. Nitrile Rubber (NBR): NBR is a synthetic rubber that is resistant to oil and fuel, making it ideal for use in automotive and industrial applications. NBR is also widely used as a sealing material in the dairy industry due to its resistance to grease.
  5. Chloroprene Rubber (CR): CR is a synthetic rubber that has good weathering and flame resistance, making it ideal for use in electrical applications.
  6. FKM (also known as fluoroelastomer or Viton®): FKM is commonly used in demanding applications where exposure to harsh chemicals, fuels, or extreme temperatures is a concern. Some examples of applications where FKM is commonly used include aerospace, automotive, and industrial applications.
    Choosing the right material for your rubber/silicone micro molding project will depend on the specific requirements of your application.

The Rubber/Silicone Micro Molding Process

The rubber or silicone micro molding process involves several steps, including:

  1. Mold Design: The first step in the process is to design the mold that will be used to create the part. The mold is typically created using high-precision machining techniques, such as CNC milling or wire EDM. The mold maker is a critical part of the micro molding process, as he is responsible for fabricating the molds that are used to produce the parts. The quality of the mold is directly tied to the quality of the final part, so it's important to work with an experienced and skilled mold maker to ensure the success of the micro molding process.
  2. Material Preparation: Material preparation is an important part of the micro molding process that involves carefully preparing the raw rubber or silicone material before it is molded into the desired part shape. This can include a variety of steps, such as measuring and mixing the materials, degassing the material to remove any air bubbles, and ensuring that the material is at the correct temperature and viscosity for the molding process. Proper material preparation is critical to ensuring the quality and consistency of the final parts, and requires careful attention to detail and adherence to established procedures.
  3. Molding process: The material is injected into the mold cavity using high pressure and temperature. The mold is heated to cure the material and solidify it into the desired shape. In some cases, compression molding can be a good choice to produce micro molded rubber parts.
  4. Part Removal: Once the material has cured, the part is removed from the mold using either by using ejection systems or manually.
  5. Post-Processing: Depending on the application, the part may undergo additional post-processing steps, such as trimming, inspection, or surface treatment, to achieve the desired final properties.

The micro molding process requires a high level of precision and control to ensure that the parts are produced with the required tolerances and surface finishes. The use of advanced molding machines, precise measurement equipment, and skilled operators is essential to achieving high-quality, consistent results in micro molding.


Rubber and silicone micro molding is a highly precise and efficient manufacturing technique that is ideal for producing small rubber or silicone parts with tight tolerances and intricate geometries. With its versatility, rubber and silicone micro molding has a wide range of applications across various industries, including medical devices, automotive, aerospace, and consumer electronics.

Choosing the right material and mold design is crucial to the success of any rubber/silicone micro molding project. By working with an experienced micro molding partner, you can ensure that your parts are produced to the highest quality standards and meet your specific requirements.

We hope this article has helped you understand the basics of rubber/silicone micro molding and its applications. If you have any further questions or would like to discuss your micro molding project, please don't hesitate to contact us.


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