Molded Rubber Parts

Molded Rubber Products

Genesis Rubber excels in the design and supply of custom molded rubber products. We work in collaboration with your engineering, design and purchasing staff to develop personalized products using drawings, samples, or reverse engineering. Genesis Rubber can build a molded product for you that will meet your sealing and specification needs. The combinations of materials, formulations and processes are virtually limitless. Whatever your molded rubber requirements may be, at Genesis Rubber Solutions Begin Here™

Rubber Molding Process

An uncured elastomer preform is placed into a heated mold. The rubber is compressed between top and bottom plates (generally 2 plates but may contain 3 or more depending on part complexity and configuration) and the rubber part is vulcanized (cured) with heat and pressure (from compression).
An uncured elastomer is placed in a “transfer pot” located above the mold and the cavity. A piston transfers the uncured rubber into a pre-heated mold through a sprue, runner and gate system. The rubber part is vulcanized through heat and pressure..
The preheated mold is closed by a press which applies pressure to keep the mold closed during the injection and curing cycles. An uncured elastomer is injected into a heated mold by a large ram or screw. The elastomer is forced into the mold and its cavities through a runner, sprue and gate system.
Custom Molded Rubber Products

Reverse Engineered Molded Products

Genesis reverse engineers your existing rubber products and incorporates enhancements for an optimized final product and life-cycle.


Custom Molded Rubber Parts

Custom molded rubber parts that are tailor-made for your application and supplied in high quality materials, that best function in your products environment.

Molded Rubber to metal

Rapid Rubber Prototyping

Mitigate the risks of guess work and reduce costs. Genesis provides a functional part in a material suitable for end use tests; fit, form and function.

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Allow one of our technicians to guide you with your molded rubber product development.

Our rubber specialists can guide you through product concept and give you the power you need to create.
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  • Silicone

  • EPDM
  • Nitrile (NBR)
  • Neoprene
  • Viton® (Fluoroelastomer)
  • Natural Rubber
  • SBR


  • RoHS
  • ASTM
  • USP Class VI
  • UL
  • MIL Specs
  • SMP800C

Molding Capabilities

Factors Affecting Molded Tolerances


Including: Metals, plastics, fabrics etc...

The factors affecting inserts in a molded part:

  • How the insert fits in the mold
  • Location of inserts
  • Correct spacing to match inserts with mold pins
  • Insert Alignment

Trim and Finish

Finishing operations to remove excess rubber material
Trimming removes excess rubber not part of the finished part. Almost always completed successfully without issue. However, occasionally material can be removed from critical areas through the tumbling de-flashing process.


Can occur when demolding the finished product
Distortion can occur when the rubber part is removed from a mold and stretched over a core. Distortion can cause issues in measurement and final inspection. This can be minimized by allowing parts to rest for a period of 24 hours before shipping.


There are several factors affecting shrinkage
Shrinkage is the dimensional difference between the rubber mold and finished product after curing. All rubber parts experience shrinkage. The rates vary depending on temperature, compound selection, cure time, pressure, and post-curing

Dimensional Terminology

Closure Dimensions VS. Fixed Dimensions

Fixed dimensions: Best described as being parallel to the mold parting line. They are not affected by flash thickness variables
Closure dimensions: These are vertical to the mold parting line and are affected by flash thickness.

Our molded rubber products are tested and inspected to strict RMA guidelines. This allows us to assure conformance to dimensional, flash and finish specifications, thus assuring the parts we deliver are of the highest quality.