Rubber Compound Development

Moving Die Rheometer (MDR)

Engineering Better Rubber Compounds from the Beginning

The performance of a molded rubber component throughout its lifecycle starts with the right formulation. At Rahco Rubber, we use rheometry as a critical material development tool to design and refine compounds before production begins.

The Moving Die Rheometer (MDR) evaluates how a rubber compound behaves and cures under heat and pressure, simulating the vulcanization process. By analyzing the cure curve, our engineers establish a material fingerprint for each formulation, helping determine optimal molding conditions and develop compounds that process efficiently while delivering the performance properties required for each application. This allows us to:

• Determine scorch time for safe processing
• Define optimum cure time (t90) to avoid under- or over-curing
• Evaluate cure kinetics and material behavior
• Measure viscoelastic properties such as storage and loss modulus

Testing is performed in accordance with ASTM D5289, providing reliable, repeatable data that enables Rahco to establish the proper cure cycle, minimize process variation, improve molding consistency, and reduce the risk of under- or over-curing conditions.

Optimizing Rubber Compounds for Manufacturing Success

The MDR is more than a testing instrument—it is an engineering tool that guides formulation decisions throughout the rubber compound development process. During formulation, rheometer data helps engineers make critical decisions, including:

• Selecting and balancing polymers, fillers, and reinforcing additives
• Balancing processing safety with production efficiency
• Adjusting cure systems (sulfur, peroxide, accelerator cure systems)
• Controlling viscosity and flow for complex mold geometries
• Reducing development time and minimizing trial-and-error

This data-driven approach allows Rahco to refine each formulation based on measurable performance characteristics rather than assumptions, helping ensure the compound not only meets specifications but also processes efficiently in production.

Designing for Real-World Performance

At Rahco, we don’t just create compounds—we engineer solutions. Our material science experts:

• Develop formulations to your specifications and application requirements
• Analyze compounds to support reliable, consistent performance
• Evaluate lifespan, durability, and shelf life
• Establish optimal processing parameters for efficient molding

Our objective is to ensure that each material meets its intended performance requirements, processes efficiently, and supports defect-free production.

Why It Matters to You

MDR testing plays an important role in maintaining manufacturing consistency. Using a rheometer throughout material formulation and development supports quality and process control by helping Rahco:

• Develop custom formulations engineered to meet specific performance requirements
• Support consistent part performance and long-term durability
• Develop efficient cure cycles with reduced trial-and-error
• Establish repeatable, efficient manufacturing processes
• Verify batch-to-batch material uniformity
• Support quality assurance requirements

Whether developing a new part or improving an existing design, Rahco works as an extension of your team to develop custom-engineered materials that meet demanding performance requirements. We do more than manufacture custom rubber parts; we formulate, mix, and mold the compounds that drive their performance, providing process transparency from formulation through final production.

For OEM customers and tier partners, this integrated approach provides greater confidence that each lot of molded components will deliver the expected performance, reliability, and quality.

When facing field failures, demanding specifications, or material performance challenges, Rahco provides the in-house expertise and material engineering support needed to solve complex challenges and develop components designed to perform.

Tensometer-Driven Material Development for Engineered Performance

Validating Mechanical Performance

At Rahco Rubber, custom formulations begin with your application’s performance requirements. After the cure cycle has been established and test specimens have been molded, our engineers use a Tensometer (Tensile Testing Machine) to verify the mechanical properties of the cured rubber compound. This testing helps us evaluate how the material will perform under real-world conditions and refine formulations to achieve the required strength, flexibility, and durability.

While the MDR determines how the compound processes, Tensometer testing confirms how the finished material performs. Together, these technologies provide a more complete understanding of the rubber compound before it advances into production.

Rahco performs tensile testing in accordance with recognized industry standards, including ASTM D412 for tensile properties and ASTM D624 for tear resistance.

Turning Data Into Better Formulations

During material development, Tensometer testing provides the empirical data needed to refine rubber formulations. It is an integral part of the compound development process rather than serving only as a final verification step. We use it to measure critical physical properties, including:

• Tear resistance
• Tensile strength for durability
• Elongation at break for flexibility
• Modulus for stiffness control
• Yield strength (where applicable)

These measurements help verify that each compound achieves the required balance of strength, flexibility, durability, and performance for its intended application. Performance data allows Rahco engineers to refine formulations by:

• Selecting the appropriate polymer system
• Balancing reinforcing fillers such as carbon black and silica
• Fine-tuning plasticizers and processing oils
• Controlling stiffness, flexibility, and elongation
• Improving durability while maintaining manufacturability

By measuring the impact of formulation changes, Rahco can make informed engineering decisions based on actual material performance rather than costly trial-and-error.

Balancing Performance Tradeoffs

Rubber formulation requires carefully balancing competing properties. Tensometer data enables us to quantify these tradeoffs and understand how formulation changes affect material performance:

Higher filler content → Increases strength and stiffness while impacting elongation
More plasticizer → Increases flexibility while impacting strength

While the Tensometer provides essential data, experience and judgment are equally important in making the right formulation decisions. Rahco’s subject matter experts combine test results with practical experience to evaluate these tradeoffs and determine the appropriate balance for each application.

By directly measuring these effects, our engineers can fine-tune formulations to meet precise application requirements—achieving the right balance of performance, manufacturability, and specification compliance.

Matching Materials to Application Requirements

Different applications require different mechanical profiles. Tensometer testing allows us to tailor materials accordingly:

• Dynamic seals and components: High elongation with controlled strength and durability
• Vibration mounts and isolators: Controlled modulus and flexibility
• Couplings and bellows: Robustness and pliability

We use real test data to help ensure the final compound performs as required in its intended application.

Validating Performance Over Time

Tensometer testing also supports long-term performance validation by:

• Comparing new and existing formulations
• Evaluating the effects of temperature, chemical, UV, and environmental exposure
• Evaluating whether properties remain stable over time

Why It Matters to You

Material selection is critical to the success of any rubber component. Developing the right compound requires understanding both how the material processes during manufacturing and how it performs after curing in its intended application.

Every component must withstand a unique combination of mechanical, chemical, thermal, and environmental conditions. Testing helps Rahco develop formulations tailored to each application’s specific performance requirements by:

• Matching material properties to specific application demands
• Balancing strength, flexibility, and durability
• Evaluating performance under mechanical stress
• Comparing new formulations with proven materials
• Validating performance after exposure to heat, oils, chemicals, weathering, and other environmental conditions

The result is a rubber compound engineered to deliver consistent, reliable performance throughout its expected service life.

From Formulation to In-House Mixing

Once the formulation has been developed and validated, the process moves naturally from material engineering into controlled production.

Rather than developing a rubber recipe and transferring it to an outside mixer, Rahco mixes its rubber compounds in-house. This keeps formulation, material preparation, testing, process development, and molding within the same manufacturing environment.

The developed formulation is transitioned through Rahco’s scale-up process, allowing the material and manufacturing process to be evaluated as production quantities increase. Once the required formulation and processing parameters have been established, the recipe and process controls are locked in to support consistent production.

This integration helps ensure that the compound developed during the engineering process is consistently reproduced for manufacturing.

Maintaining Batch-to-Batch Consistency

A successful rubber formulation must be repeatable. Rahco uses controlled manufacturing and material-handling procedures to maintain consistency as compounds move into ongoing production.

These controls include:

• Raw-material barcoding
• Controlled material weigh-up practices
• Inventory controls
• Defined mixing procedures
• Material testing
• Batch traceability
• Established processing parameters

MDR testing can also be used to compare material characteristics from batch to batch against the established material fingerprint, supporting quality assurance and manufacturing consistency.

Together, these controls help maintain homogeneous, repeatable compounds and provide traceability throughout the material and manufacturing process.

From Formulation to Function

Rahco’s compound development process brings formulation, testing, in-house mixing, scale-up, and manufacturing together. Moving Die Rheometer (MDR) analysis evaluates how a compound processes and cures, while Tensometer testing evaluates the mechanical properties of the cured material. Combined with controlled in-house mixing and production processes, these capabilities enable Rahco to develop and manufacture compounds engineered for both processing and end-use performance.

This integrated process provides:

• Materials engineered for specific end-use conditions
• Reduced development risk through real performance data
• Reduced development time and trial-and-error
• Verified mechanical performance before production
• Improved molding consistency and product quality
• Batch-to-batch material consistency and traceability
• Improved durability and reliability in the field
• Confidence that materials meet demanding specifications

Whether developing a new product, replacing an existing material, or solving a challenging performance or processing issue, Rahco provides the engineering expertise, testing capabilities, and in-house compounding resources needed to develop the right rubber compound.

Developing the Right Rubber Compound Together

Choosing the right rubber compound is one of the most critical decisions affecting the performance, manufacturability, reliability, and service life of your product.

Rahco combines advanced material testing, in-house rubber compounding, and decades of manufacturing experience to work with you in developing compounds that process efficiently, perform consistently, and meet the specific demands of your application.

We don’t just develop compounds—we formulate, test, mix, and mold materials engineered to perform.

Whether you are developing a new application, improving an existing compound, or addressing a material performance challenge, contact Rahco today to discuss your requirements.