Introduction
Silicone rubber and conventional rubber share a reputation for being flexible and durable, but which one is right for your project depends entirely on your performance requirements. Choosing the right elastomer is essential for achieving the desired durability, functionality, and cost efficiency in both prototyping and manufacturing.
In this guide, we’ll compare silicone rubber vs rubber, explore their key properties, manufacturing processes, and common use cases, while also looking at how elastomeric vacuum casting enables rapid production of high-quality silicone and rubber-like prototypes, and ARRK’s Silicone Rubber and PU Rubber options.
What is an Elastomer?
An elastomer is a type of polymer that can stretch under force and return to its original shape once the force is removed. This unique combination of flexibility and resilience makes elastomers ideal for seals, gaskets, vibration dampers, medical devices, automotive components, and countless industrial applications.
Silicone rubber, natural rubber, and synthetic rubber are all elastomers. However, while all rubbers are elastomers, not all elastomers are traditional rubbers. Silicone rubber belongs to a separate family of silicon-based elastomers, whereas conventional rubbers are carbon-based and derived from either natural latex or synthetic polymers.
What is Silicone?
Silicone is a synthetic polymer made primarily from silicon, oxygen, carbon, and hydrogen. Unlike conventional rubbers, which are carbon-based, silicone has a silicon-oxygen backbone that gives it excellent resistance to heat, UV radiation, ozone, moisture, and many chemicals.
Thanks to these properties, silicone is widely used across industries such as medical, electronics, automotive, aerospace, and food processing, where long-term performance in demanding environments is essential.
What is Rubber?
Rubber is a flexible elastomer valued for its elasticity, durability and ability to absorb impact and vibration. In prototyping, rubber-like materials can be used for components that need flexibility, resilience or a tactile feel similar to the intended production part.
For elastomeric vacuum casting, we offer PU Rubber and PU Rubber Clear, providing options for prototypes that require flexible and durable characteristics.
What is Silicone Rubber?
Silicone rubber (SIL) is a flexible elastomer known for its elasticity, durability, and resistance to heat, weathering, and many chemicals. These properties make silicone rubber suitable for prototype parts that need to replicate the flexibility and tactile characteristics of a final product.
In prototype manufacturing, silicone rubber can be used to produce flexible components such as keypads, buttons, seals, and O-rings. Through elastomeric vacuum casting, silicone rubber can be cast into moulds to create prototypes that closely replicate the functional and aesthetic characteristics of the intended production part.
We offer silicone rubber options in Shore A 40 and Shore A 60 hardness, allowing the material to be selected according to the flexibility and performance requirements of the prototype.
Key Differences Between Silicone Rubber and PU Rubber
When choosing an elastomer for a prototype, the right material depends on how the part needs to look, feel and perform. Silicone rubber and PU rubber offer different characteristics that can make each suitable for different prototyping requirements.
Silicone Rubber
Silicone rubber is known for its flexibility, temperature resistance and weather resistance. It can be a good choice for prototypes that need a soft, flexible feel or need to withstand more demanding environmental conditions.
ARRK offers Silicone Rubber Shore A 40 and Shore A 60 for elastomeric vacuum casting, providing different levels of hardness for prototypes such as flexible components, buttons, keypads and seals.
PU Rubber
PU rubber provides a combination of flexibility, durability and mechanical strength, making it suitable for functional prototypes where the part needs to replicate the feel or behaviour of a rubber component.
ARRK offers PU Rubber and PU Rubber Clear as part of its elastomeric vacuum casting materials, giving brands another option when developing flexible prototype parts.
Which Should You Choose?
Rather than choosing based on material specifications alone, consider how the prototype needs to look, feel and perform.
- Choose Silicone Rubber when flexibility, softness, temperature resistance or weather resistance are important.
- Choose PU Rubber when you need a durable, flexible prototype for functional testing or design validation.
The right choice ultimately depends on your prototype’s intended application, required flexibility and performance requirements.
Common Use Cases for Silicone Rubber
Silicone rubber is well suited to prototypes that require flexibility, a soft or tactile feel, and resistance to temperature and weathering. ARRK offers Silicone Rubber options for elastomeric vacuum casting, making it suitable for a range of flexible prototype applications.
- Keypads and buttons: Silicone rubber can replicate the soft, flexible feel required for buttons, keypads, and other tactile components.
- Seals and O-rings: Its flexibility makes silicone rubber suitable for prototypes of seals, O-rings, and other components designed to provide a close fit.
- Flexible covers and components: Silicone rubber can be used for prototype parts that require flexibility and a soft-touch surface.
- Functional prototypes: Silicone rubber is useful for validating the fit, feel, flexibility, and overall design of elastomeric components before production.
- Product design and development: Different hardness options allow prototypes to be developed with characteristics closer to the intended production part.
Common Use Cases for PU Rubber
PU Rubber is suitable for prototypes that require flexibility, durability and a rubber-like feel. It can be used for functional prototypes where the look, feel and performance of the intended production part need to be evaluated.
- Keypads and buttons: PU rubber can be used to create prototypes of flexible components that require a tactile or rubber-like feel.
- Seals and O-rings: Its flexibility makes PU rubber suitable for prototyping seals, O-rings, and other components that require a close fit.
- Flexible covers and components: PU rubber can be used for prototype parts that need flexibility combined with durability.
- Functional prototypes: PU rubber is suitable for validating the fit, feel, flexibility, and function of rubber-like components before production.
- Product design and development: PU rubber provides an alternative to silicone rubber when developing prototypes that need to replicate the characteristics of a flexible production part.
How Are Silicone Rubber and Rubber Prototypes Made?
For product development projects, elastomeric vacuum casting can be used to produce flexible prototypes in materials such as PU Rubber and Silicone Rubber. ARRK offers elastomeric material options across different Shore A hardnesses, with applications including keypads, buttons and O-rings.
The process typically follows these steps:
- Create a master pattern: A master model is produced using CNC machining or 3D printing.
- Make the silicone mould: Liquid silicone is poured around the master pattern and cured to form a flexible mould.2
- Cast the prototype: Liquid silicone rubber or rubber is poured into the mould under vacuum conditions to eliminate air bubbles and accurately replicate the part.
- Cure and finish: Once cured, the prototype is removed from the mould and trimmed to achieve the desired finish.
- Evaluate the part: The prototype is inspected and tested for fit, form, and function before further design refinement or low-volume production.
Compared with traditional manufacturing methods, elastomeric vacuum casting offers faster lead times, lower tooling costs, and greater design flexibility, making it an efficient way to validate silicone rubber and rubber components before mass production.
Conclusion
Silicone rubber and conventional rubber often get lumped together, but they behave quite differently in real-world conditions. Choosing the right material early helps ensure the best balance of performance, manufacturability, and cost.
For businesses developing silicone rubber or rubber components, early prototyping helps validate designs and reduce development risks before mass manufacturing. As a prototyping company, ARRK Asia supports every stage of product development, from material selection to prototype manufacturing. Contact us today to discuss the best solution for your project.
Frequently Asked Questions
1. Is silicone a rubber or plastic?
Silicone is a synthetic polymer in the elastomer family. When cured into a flexible material, it becomes silicone rubber, which is known for its flexibility, durability and resistance to heat and weathering.
2. Is silicone rubber the same as rubber?
No. Silicone rubber and other rubber-like materials have different characteristics. For prototyping, the right choice depends on the flexibility, feel and performance required for the part.
3. Is silicone rubber better than rubber?
Neither material is universally better. Silicone rubber can be a good choice when flexibility, softness, temperature or weather resistance are important, while PU Rubber can be suitable for durable, flexible prototypes intended for functional testing and design validation.
4. Is silicone rubber stronger than rubber?
Not necessarily. Silicone Rubber and PU Rubber offer different characteristics, so the more suitable option depends on the prototype’s intended use, flexibility requirements and expected performance.
5. What are the disadvantages of silicone rubber?
Silicone rubber may not be the most suitable choice for every prototype. Depending on the application, another rubber-like material may provide characteristics better suited to the required durability, flexibility or functional testing requirements.
6. Can silicone rubber replace natural rubber?
For prototyping, the choice depends on the characteristics required from the part. Silicone Rubber and PU Rubber can both be used for flexible prototypes, with the appropriate option depending on the intended application and performance requirements.
7. Which material is better for prototyping?
It depends on the prototype. Silicone Rubber can be suitable when flexibility, softness, temperature or weather resistance are important, while PU Rubber can be a good option for durable, flexible prototypes used for functional testing or design validation.
8. Which material is better for manufacturing?
The most suitable material depends on the product’s requirements and manufacturing process. For prototype development, ARRK offers Silicone Rubber and PU Rubber options for elastomeric vacuum casting, allowing different material characteristics to be evaluated before moving forward with production.
