Understand Application Requirements
The first step to choosing the right material for a rubber molded part is understanding the unique requirements of its intended application. This includes:
- The product’s performance expectations, such as repeat flexing, fluid transfer, or vibration absorption.
- The product’s service environment. Variables to consider include extreme temperatures, humidity, fluid exposure, and others.
- Quality and regulatory requirements. Most rubber molded parts are required to adhere to some type of specification, such as an industry standard or OEM spec.
Knowing these requirements is key to selecting a material that can adhere to all of them.
Evaluate Common Materials and their Properties 
Many different types of rubber are compatible with rubber molding processes, each with its own combination of benefits and drawbacks.
It’s worth noting that properties of many rubber materials can be modified with the addition of certain ingredients, such as antioxidants or fillers, during the compounding process.
Natural Rubber
Natural rubber is strong, tough, and flexible, making it a popular material choice for heavy-duty applications and rubber molded parts. It is also resistant to water and many chemicals. However, compared to other types of rubber, natural rubber does not hold up well against grease, UV rays, or extreme heat.
Ethylene Propylene Diene Monomer (EPDM)
EPDM is a durable type of rubber that offers excellent weather resistance and performs well outdoors. The primary drawback of EPDM is its poor resistance to flames and many types of oil.
Silicone Rubber
Silicone rubber offers excellent resistance to high temperatures and low chemical reactivity. It also reacts well to many different sterilization methods, which is beneficial for medical and food applications. However, silicone has poor tear strength, and its relatively high price tag can be cost-prohibitive.
Nitrile
Nitrile has a strong resistance to oils and fuels, mainly hydrocarbon oils and fuels.
Neoprene
Neoprene offers some oil resistance, though not as much as Nitrile. It is the catch all polymer, but it is expensive.
Polyisoprene
Polyisoprene is a synthetic, molecularly identical polymer to Natural Rubber. As such, it has the same physical properties.
Consider the Manufacturing Process 
A rubber molding manufacturer can advise which materials are most compatible with different rubber molding methods.
Rubber Injection Molding
For high-volume runs of tiny, complex, or precise shapes, rubber injection molding is a fantastic option. Rubber injection molding allows for tight tolerances and automation.
Rubber Transfer Molding
Rubber transfer molding generates very little waste compared to other rubber molding methods. This method is highly flexible and well-suited for products that will undergo a secondary process, such as packaging, assembly, or the addition of any adhesives or fasteners.
Rubber Compression Molding
Rubber compression molding uses less machinery and simpler tooling compared to other rubber molding methods, making it an economical option. Rubber compression molding is great for simple shapes, such as seals and o-rings.
Factor in Cost and Availability
Product requirements and manufacturing aren’t the only variables to consider when choosing the right rubber material for a project. Cost is another important factor. Some rubber materials are more costly than others, and manufacturers must make strategic decisions to balance performance expectations and budget.
Depending on the rubber material in question, availability may be a concern as well. Natural disasters, geopolitical unrest, and other supply chain disruptions can affect supply and demand, especially for natural rubber, forcing manufacturers to choose different suppliers or different materials altogether.
Consult with the Experts at Universal Polymer & Rubber
At Universal Polymer & Rubber, we understand the many variables that must be considered when manufacturing rubber parts, from rubber material choice to rubber molding methods. With our many years of experience in rubber parts manufacturing, we can help you make strategic, confident decisions that align with your goals, priorities, and resources.
UP&R offers 10 different rubber materials for rubber molded parts and a full suite of rubber molding capabilities to meet your needs, from simple to complex. Whether you’re starting a new project, tweaking an existing design, or simply continuing production for a tried-and-true product, you can count on us for reliable timelines, expert guidance, and excellent service.
To learn more about our rubber material selection, talk to a member of the UP&R team.