Bonded Piston Seals for Modern Engines

Piston Seals | DuPont TM Vamac®

Bonded piston seals, shaft seals, oil seals and shaft boots made with DuPontVamac® are a proven part of the performance envelope for modern vehicle drivetrains.

Many of today’s vehicle drive train systems are designed as a sealed tight system for reduced maintenance/zero maintenance for the life of the vehicle warranty.

Bonded piston seals, shaft seals, oil seals, shaft boots and other elastomeric components parts must provide the fluid resistance and grease resistance to retain physical properties for long-term performance at both high and low temperatures for the life expectancy of the vehicle.

The ability of Vamac® to form a lasting bond with plastic or steel provides additional lifetime value and criteria to meet the longer requirements.

Other related automotive applications that use Vamac® are:

  • Engine seals such as rocker cover gaskets
  • Oil pan gaskets
  • Transmission oil cooler hose
  • Turbocharger hose
  • Turbocharger molded air ducts

Properties Made For Piston Seals

The Vamac® product line has four grades and families that include standard grades (G, GLS, GXF and DP) and the Ultra family with improved performance designed for precision applications in blow molding, compression molding, and extrusion, while also providing excellent, bonding to metal and plastics. , The product family also includes specialty performance grades for low oil swell, high green strength, and/or no-post-cure.

Downsized engines require incorporation of power-boosting  technologies, such as turbocharging and exhaust gas recirculation (EGR), to improve fuel economy without sacrificing performance. Vamac® provides the flexibility of rubber with resistance to the high heat and harsh chemicals that these technologies entail. OEM’s and drivetrain designers along with component suppliers are constantly working to reduce weight increase fuel efficiency while obtaining more power from smaller turbocharged engines.  

That puts a premium on consistent quality and application-specific performance, and makes DuPontVamac® ethylene acrylic elastomer (AEM) a material of choice. It is specified for bonded seals, shaft seals, boots, and other vital parts by large OEM suppliers and by many OEM’s.

Key properties that are a good match for bonded piston seal applications include:

  • Excellent bonding to metal, which can be enhanced with certain primers.
  • Retention of shape under extreme pressure and flex, even in high temperatures.
  • Low flex cut propagation.
  • Cost-effective quality
  • A proven record in automotive applications, with tested applications, including piston seals, transmission oil cooler hoses, dampers, gaskets and turbo charger hoses.

Key overall Vamac® properties include:

  • Temperature range -40°C (-40°F) to 175°C (347°F).
  • Excellent toughness and abrasion resistance.
  • Good processability for accurate seal dimensions and fit.
  • Outstanding oil and fluid resistance, especially to engine oils. Outstanding ozone and weather resistance.
  • Very good performance in compressive set and compressive stress relaxation (CSR) rating.
  • Vibration-damping consistency.
  • Non-halogen, low-smoke emissions.

Vamac® is a versatile family of ethylene acrylic elastomers (AEM), material, that delivers consistent, rubber-like flexibility over wide temperature ranges, and with exposure to oil and greases.

Support and Quality Worldwide

DuPont is a global automotive materials supplier, working locally with parts and vehicle makers in every region. DuPont is committed to the highest standards of quality and global supply, supported by regionally based innovation centers, technical support and manufacturing. 

Vamac® application experts provide knowledgeable technical support, from material selection to end-use testing, across four continents.  For global manufacturers, there’s also peace of mind in knowing that seals evaluated and tested in one region can be commercialized in another region.

*The Viton® fluoroelastomer business is now part of The Chemours Company.  Visit for more information.

*For information on Neoprene, contact