Silicone Molding Rapid Prototyping: What Are the Options? (UPDATED 2025)

Speed, cost, and approximation to the final part design (including material properties and dimensions) are key criteria when selecting a fabrication method for making a silicone prototype. For silicone parts, there are actually more options than there are for thermoplastics, which makes the product development process for silicone products a little more challenging. Available processes for making silicone prototypes include: RTV (room temperature vulcanization) molding, selective laser sintering (SLA) and fused deposition modeling (FDM), transfer press molding using high consistency rubber (HCR) materials, and injection molding solutions. As we discuss these options, please keep in mind the vastmajority of new silicone products are manufactured from LSR (liquid silicone rubber), injection molded in a durometer range of 30-70 Shore A.

 

A Review of 4 Methods

RTV Molding – Industrial RTV silicone formulations are widely available—some can even be found at the corner hardware store. Making parts out of these materials requires a mold, which can be made of almost any metal or plastic material. Although by definition RTVs will cure at ambient temperatures, albeit over hours, ovens are often used to accelerate the curing of the material.

• Pros: The use of RTV is attractive because of the low capital equipment requirements and the availability of raw materials. RTVs can be a very close approximation to their LSR relatives. It is common that well-equipped R&D labs have the ability to manufacture tools from plastic and/or soft metal materials in-house. Once the mold is made, making parts is a simple fill-and-wait process. A skilled technician can make the first part within a day.
• Cons: RTV molding is a slow process with cure times extending from 20 minutes to hours. Production rates and cost per piece are both largely determined by the processing time.

 

HCR – Transfer molding is used to make parts out of HCR, and is a simple manufacturing process an HCR (“gum stock”) material into a heated cavity to cure and form a part. HCR is a natural fit for transfer molding since gum stock is much more viscous than LSR.

• Pros: Simple tools.  Little or no process development.
• Cons: Complex geometries may not be possible. Longer cycle times than LSR.

LSR – Production equivalent injection molding press and production grade materials are molded in soft metal tooling.

• Pros: Tooling can be made quickly and the production of parts is fast. The resulting prototypes are very close approximations of production parts.
• Cons: Can result in a higher cost per part for small runs of parts, since the initial tool cost can’t be amortized over a large number of parts.

 

3D Silicone Printing

• There are a variety of 3D printed materials available, but silicone is inherently more difficult to print because of its heat cured nature.  As a result, this technology lags many years behind thermoplastic 3D printing.
• 3D parts of silicone are generally a poor approximation of production parts.

 

Silicone Rapid Prototyping Comparison

 

FAQs

 

1)  What Types of Silicone Rapid Prototyping Services Does ProMed Offer?

ProMed offers a comprehensive suite of silicone rapid prototyping services to support various stages of product development, from early concept evaluation to final design validation. 

These services include RTV (Room Temperature Vulcanization) molding, HCR (High Consistency Rubber) transfer molding, and LSR (Liquid Silicone Rubber) injection molding. 

RTV molding is well-suited for quick-turn, low-volume prototypes and involves creating a mold from soft materials such as plastic or aluminum, allowing for cost-effective, small-batch part production. 

HCR transfer molding uses gum stock silicone and is ideal for functional testing when greater material fidelity is required. 

For high-fidelity prototypes that closely resemble production parts, ProMed uses LSR injection molding with soft aluminum tooling. This method is often employed for regulatory testing and clinical trials. 

Additionally, ProMed supports hybrid approaches, such as using 3D-printed molds for RTV or overmolding prototypes onto rigid substrates, offering clients the flexibility to move from prototype to production with minimal disruption.

 

2)  How Does ProMed Determine Which Prototyping Method is Best for My Project?

ProMed collaborates closely with each client to recommend the most appropriate prototyping method based on several critical factors, including timeline, budget, part geometry, and material performance requirements. 

If the goal is to quickly evaluate the form or basic fit of a component, RTV molding is often the best choice due to its rapid turnaround and minimal tooling costs. When a prototype needs to undergo mechanical or functional testing and the final design is still evolving, HCR transfer molding offers a good balance of speed and material accuracy. 

For more advanced stages of development—such as design validation, regulatory submission, or clinical trial preparation—ProMed typically recommends LSR injection molding. This process uses production-grade materials and tooling, making it ideal for creating prototypes that are virtually indistinguishable from final production parts. 

Because of ProMed’s deep expertise in medical-grade silicone manufacturing, their recommendations always take into account not just technical feasibility but also regulatory and commercial considerations.

 

3)  What are the Typical Lead Times for ProMed’s Silicone Prototyping Services?

Lead times for ProMed’s prototyping services vary depending on the method selected and the complexity of the part. 

For RTV molding, tooling can typically be completed in 2 to 5 business days, with parts available within a day or two thereafter. This makes RTV a great choice for fast-turnaround projects. 

HCR transfer molding, which involves more robust tooling, generally requires 3 to 7 business days for tooling and an additional 1 to 2 days to produce the first parts. 

LSR injection molding, which offers the highest fidelity to production, takes slightly longer—usually 5 to 10 business days to complete tooling, with initial parts available shortly after. 

These timelines reflect ProMed’s ability to rapidly iterate while maintaining a high standard of quality. For urgent projects, expedited services and parallel tooling development are also available.

 

4)  How Does ProMed Ensure Quality in Silicone Prototypes, Especially for Medical Applications?

Quality is a core pillar of ProMed’s prototyping services, particularly when serving customers in the medical device industry. 

As an ISO 13485:2016-certified manufacturer, ProMed implements rigorous quality control measures even during early prototyping stages. These include incoming material verification, dimensional inspection, durometer testing, and documentation of all molding processes. 

When required, prototyping can also be performed in a cleanroom environment to ensure compliance with regulatory cleanliness standards. 

Additionally, ProMed offers Design for Manufacturability (DFM) reviews to identify potential issues early, reducing the risk of costly changes later in the development cycle. These quality assurance protocols not only ensure functional and dimensional accuracy but also align with the stringent regulatory requirements of medical device development.