Custom-Molded Elastomers

Elastomers are highly customizable materials that offer a unique combination of elasticity, abrasion resistance, impermeability, and resistance to temperature fluctuations. Using compression molding and other plastic fabrication techniques, these materials can be formed into various shapes to create everything from leak-tight mechanical seals to durable vehicle adhesives.

As a custom elastomer manufacturer, APM Hexseal uses tailored molding processes to fabricate custom-molded elastomeric products for a range of sensitive and mission-critical sealing applications. Our versatile elastomer options allow us to create safe, reliable solutions that are carefully optimized for their intended environment.

What is an Elastomer?

Elastomers are loosely crosslinked synthetic or natural polymers with viscous and elastic properties. The softness and flexibility of these polymers make them easy to mold and extrude into high-performance parts with simple and complex geometries. Used in a range of sensitive or extreme operating environments, molded elastomeric parts feature excellent dimensional stability, load-bearing performance, and resistance to high temperatures and harsh chemicals.

Available in several types, elastomeric polymers each have distinct compositional and structural properties that influence their performance and longevity in various environments. A few of the most commonly used elastomers are:

  • Silicone
  • Natural rubber
  • Synthetic rubber
  • Isoprene rubber
  • Ethylene propylene diene monomer (EPDM)
  • Styrene butadiene rubber (SBR)

How are Custom Elastomers Molded?

Elastomers can be molded using several techniques, each of which offers specific advantages and limitations depending on the polymer being molded and the desired outcome. The most suitable technique for a given project depends on several factors, including:

  • Cost considerations
  • Precision and speed requirements
  • Elastomer compatibility
  • Part size and shape

Four commonly used techniques for elastomer molding include:

  • Compression molding: Compression molding is one of the most popular approaches for elastomer molding due to its relatively low tooling costs and quick lead times. During the process, the raw elastomer material is placed into a preheated mold and heated until softened. Once soft, applied compression forces the elastomer to conform to the shape of the mold. Pressure is maintained until the elastomeric part is cooled or vulcanized.
  • Transfer molding: With transfer molding, the elastomer is heat-softened to a liquefied state. A plunger forces the elastomer into an enclosed mold. Once the mold cavity is full, the elastomer is left to cool and solidify. The transfer molding process applies more pressure than other molding techniques, making it ideal for creating parts with tight tolerances or intricate designs.
  • Cast molding: Cast molding is an economical and versatile molding approach with relatively simple tooling requirements. First, the heat-softened liquid elastomer is poured into a heated mold. The mold is then placed in an oven to cure, and the elastomer part is removed once solidified. Some elastomeric materials, such as rubber, must be cured twice.
  • Injection molding: Elastomer injection molding offers excellent speed, precision, and repeatability, making it ideal for mass production molding applications. The first step of the process involves melting the elastomer and placing it into an injection unit. The molten material can then be injected into the mold and left to cool into the desired shape.

Advantages of our Custom-Molded Elastomers

At APM Hexseal, we specialize in creating custom-molded elastomer sealing solutions that fit a range of budget requirements, technical specifications, and industry regulations. Benefits of our products include:

  • Consistent quality: As demonstrated by our exceptional quality production track record, we are committed to consistently providing safe, reliable products that meet or exceed customer expectations and industry requirements.
  • Unparalleled design customization: Working closely with each customer, our engineers provide key design and material recommendations as well as 3D CAD models and functional prototypes for client approval. We work hard to ensure that each custom product is fully optimized for its application before beginning the manufacturing process.
  • Environmental compatibility: From military-grade fluorosilicone to ASTM D200-certified neoprene, we work with several high-performance elastomers that are engineered to provide optimal performance and longevity in a range of harsh or abrasive environments.

Custom Molded Elastomers from APM Hexseal

Using precision transfer and compression molding techniques, APM Hexseal creates high-quality custom-molded elastomers for a range of applications and environments. We also offer several off-the-shelf, self-sealing hardware solutions as well as sealing boots and bushings. To learn more about our custom elastomer design capabilities and how we can assist with your next project, please request a quote, visit our homepage, or reach out to us by phone (201.569.5700) or email (

Standard Elastomer Options and Typical Properties for APM Hexseal®Sealing Boots, Bushings, Seelnuts® & Seeloc® Washers

Material Name Relevant Specifications Service
Temperature in °F
Temperature in °C
Tensile PSI Elongation % Abrasion
Compression Set
2701 Silicone A-A-59588, Class 3A,
GR50, Grey †
-103° to +400° -75° to +204° 500-1800 100-800 Recommended Recommended
2615 FluoroSilicone MIL-DTL-25988 (B),
Type 2, Class 1, GR60
-70° to +392° -57° to +200° 600-1400 100-700 Sufficient Recommended
4601 Buna N
ASTM D2000
60 Durometer
-22° to +212° -30° to +100° 1500-3000 400-600 Recommended Fair
3601 Neoprene ASTM D2000
60 Durometer
-40° to +257° -40° to +121° 1500-4000 100-700 Fair Sufficient
7601 EPDM
(Ethylene Propylene)
ASTM D2000
70 Durometer
-60° to +300° -51° to +149° 1400-1600 500-600 Fair Recommended

† Various durometer and color options available. Please contact us for more information.