The collaboration between Parmel Gomma and Valplast aimed to develop a rubber gasket for the one-way valve used in PVC drainage systems. The application imposed strict functional requirements, both in terms of sealing and long-term reliability, under operating conditions characterized by wet environments, repeated opening–closing cycles, and pressure variations.
The project was approached as a co-development process, in which product design and manufacturing process design were addressed simultaneously.
Definition of Functional Requirements and Application Constraints
The one-way valve is a critical element in drainage systems, serving to prevent backflow and ensure unidirectional flow operation. The gasket associated with this assembly must simultaneously meet several requirements:
- reliable sealing at low and medium pressures;
- rapid elastic recovery capability after deformation;
- resistance to wet environments, wastewater, and common chemical agents in drainage systems;
- dimensional stability throughout the product’s service life.
In addition, the integration of the gasket into a PVC body imposed strict geometric tolerances and high repeatability of the manufacturing process.
Material Selection and Compound Formulation
In the initial phase of the project, several elastomer variants were analyzed, with emphasis on chemical compatibility and cyclic deformation behavior. The final solution consisted of an elastomeric compound specially formulated for this application, optimized for:
- controlled elasticity, to ensure valve closure without delays;
- resistance to aging in wet environments;
- long-term hardness stability.
The formulation was validated through internal laboratory tests, followed by functional tests in actual assemblies provided by Valplast.
Design and Manufacturing of the Rubber Injection Mold
The gasket is manufactured by rubber injection, a process chosen to ensure dimensional precision and consistent productivity. The mold design was carried out in close collaboration with the Valplast technical team, taking into account the valve geometry and assembly method.
Critical aspects addressed in mold design included:
- positioning of injection points to avoid areas with internal stresses;
- material flow control to eliminate the risk of critical weld lines;
- optimization of the air evacuation system to prevent surface defects.
After mold completion, the process adjustment phase allowed fine-tuning of injection and vulcanization parameters, so that each cycle produces conforming parts.
Industrial Validation and Series Optimization
Gasket validation was not limited to laboratory tests. Assembly and operation tests were performed under actual operating conditions in simulated drainage systems. The feedback obtained was used for minor adjustments to geometry and process parameters.
The result was a functionally stable product, with a low rejection rate and easy integration into the Valplast valve assembly line.
Collaboration Results
The Parmel Gomma – Valplast collaboration demonstrated the effectiveness of an approach based on technical co-development. The resulting gasket meets the functional requirements of the application and is produced in a robust, repeatable process adapted to series production.
The project strengthened the relationship between the two companies and created a solid technical foundation for future developments in the field of rubber components for water and drainage infrastructure systems.
Conclusion
The development of the gasket for the PVC check valve highlights the importance of close collaboration between the rubber component manufacturer and the final assembly manufacturer. When functional requirements, materials, and manufacturing process are addressed in an integrated manner, the result is a reliable product, industrially validated and adapted to the actual requirements of the application.