Rubber is a foundational material in modern engineering—used across automotive, aerospace, infrastructure, energy, and beyond. Yet despite its widespread use, rubber remains one of the most misunderstood materials in product design. Unlike metals or thermoplastics, rubber introduces unique behaviors, performance variables, and formulation complexity that engineers must carefully navigate.
This guide breaks down the essentials of rubber—from how it functions and why it’s so effective to how engineers can make smarter decisions when selecting, specifying, or designing custom rubber products.
What Is Rubber in Engineering Terms?
Rubber refers to materials—natural or synthetic—that can stretch to at least twice their original length and return without permanent deformation. These flexible materials, known as elastomers, form the backbone of countless industrial rubber parts used in high-performance environments.
Whether you’re sealing fluid systems or absorbing vibration in heavy machinery, rubber provides the flexibility, resilience, and strength that few other materials can match.
For engineers developing custom molded rubber parts, understanding the fundamentals of elastomer behavior is critical to long-term performance and cost efficiency.
Why Rubber Excels in Transportation and Industrial Applications
One of the most recognizable rubber components is the tire, which demonstrates rubber’s ability to:
- Seal pressurized air for smoother rides
- Maintain flexibility and integrity across a wide range of temperatures
- Provide traction and enable steering, acceleration, and braking
But tires are just the beginning. Rubber is widely used across transportation systems and industrial rubber parts for:
- Bushings and isolators that reduce vibration and noise
- Seals and boots that keep out water, dirt, and debris
- Flexible mounts and couplings that protect equipment from misalignment and mechanical stress
This blend of flexibility, durability, and moldability makes rubber one of the most versatile engineering materials available—especially when developing custom rubber parts for specialized performance.
Six Key Functions of Rubber
Rubber stands apart because it can achieve multiple objectives in a single part. Its core functional roles include:
- Sealing fluids – O-rings, gaskets
- Conducting fluids – hoses, tubes
- Storing energy – bungee cords, tension bands
- Transmitting energy – belts, couplings
- Absorbing energy – vibration mounts, bumpers
- Providing structural flexibility – bridge bearings, expansion joints
Compared to metals or rigid plastics, custom rubber products often offer more elegant, lower-cost solutions in complex mechanical systems.
The Hidden Complexity of Rubber
1. Molecular Structure
Rubber polymers have the longest molecular chains of any commonly used material. These chains allow rubber to stretch, bend, and return to form—providing flexibility at the microscopic level.
2. Complex Formulations
A typical rubber compound includes 10–20 ingredients. These must be precisely balanced to achieve specific performance goals such as flexibility, strength, abrasion resistance, and chemical compatibility. Key ingredients include:
- Base polymer (e.g., EPDM, NBR, FKM)
- Fillers (carbon black, silica)
- Plasticizers and processing aids
- Curing agents (sulfur, peroxides)
- Accelerators, antidegradants, and more
Small formulation changes can result in major performance shifts—one reason custom molded rubber parts require such close attention to material selection and compound development.
3. Thermoset Behavior
Unlike thermoplastics, rubber is a thermoset material. Once it cures (vulcanizes), it cannot be re-melted or reshaped. This makes rubber both durable and reliable, but also harder to standardize—especially for engineers looking for off-the-shelf solutions. In most cases, custom rubber products must be formulated and tested for the exact application.
Selecting the Right Rubber for the Job
Rubber is never one-size-fits-all. Selecting the correct elastomer for an application requires understanding both functional goals and environmental conditions.
Functional Considerations:
- Sealing?
- Damping vibration?
- Withstanding pressure or movement?
Environmental Conditions:
- Extreme temperatures
- Chemical exposures (oils, fuels, solvents)
- Ozone, UV, or outdoor conditions
- Load cycles or dynamic stress
With clear definitions of these variables, engineers and their custom rubber parts manufacturer can develop targeted formulations that perform reliably without overengineering.
Designing for Dynamic Rubber Applications
Rubber excels in dynamic environments—but also faces the greatest risks there. Fatigue, stress relaxation, and thermal buildup must all be accounted for in applications involving:
- Cyclic loading
- Constant flexing or vibration
- High startup torque or load shifts
Key design inputs include:
- Frequency of movement
- Load profiles
- Amplitude of deflection
- Mounting configuration
By collaborating early with a custom rubber parts manufacturer, engineers can address performance challenges through smarter geometry, compound selection, and fatigue testing.
Testing and Validation: From Lab to Field
Designing effective industrial rubber parts often requires multiple test iterations, including:
- Tensile strength and elongation
- Abrasion and tear resistance
- Compression set and stress relaxation
- Chemical resistance and aging
- Dynamic fatigue and flex testing
At Robinson Rubber, we maintain comprehensive in-house testing facilities to simulate real-world conditions—ranging from chemical immersion to dynamic cycling. Field validation is also essential, particularly when lab conditions can’t replicate all environmental variables.
Rubber Is Not a Commodity Material
Unlike standard metals or plastics, rubber materials are typically non-standardized and proprietary. Even widely referenced specs like ASTM D2000 don’t guarantee performance in specialized environments.
To ensure reliability, engineers often need to:
- Use a proven proprietary formulation
- Partner with an experienced custom rubber parts manufacturer
- Integrate material testing early in the development cycle
Work With a Rubber Expert from the Start
Because rubber formulations are sensitive and highly application-specific, involving a knowledgeable partner early in the design process can save significant time, money, and risk.
At Robinson Rubber Products, we specialize in:
- Custom rubber products development
- Material selection and compound formulation
- Prototyping and performance testing
- Scaling production of custom molded rubber parts for critical applications
Whether you’re designing a seal, mount, or dynamic isolator, our team works closely with yours to align mechanical requirements with material capabilities.
Key Takeaways for Rubber Material Selection
- Rubber is versatile but complex, requiring expertise to specify and design correctly
- Custom formulations are the norm, not the exception—rubber is not a commodity
- Performance depends on the right match between material, environment, and load conditions
- Dynamic systems demand extra care in formulation, geometry, and testing
- Involve a custom rubber parts manufacturer early for best results in both performance and manufacturability
Get Expert Support on Your Rubber Application
Have a complex application or need help selecting the right rubber compound? Robinson Rubber is here to help you match performance demands with advanced elastomer solutions.
Get Started Today:
Email: sales@robinsonrubber.com
Website: www.robinsonrubber.com
Phone: 1-877-619-5825 or 763-535-6737
To learn more or request a quote