Reaction Injection Molding (RIM) vs Other Processes

Comparison gives us a very positive reaction.

Reaction injection molding has many benefits: low tooling costs, short lead-times, large lightweight parts, high tolerances, enhanced design finish, desired chemical resistance properties, 94V-0 and HB ratings, customizing part properties, and molding over metal, wood, glass, computer chips and other parts.

Reaction injection molding is generally most cost-effective for the production of a few hundred to several thousand parts, but one RIM Manufacturing client has looked to us to produce more than 1,000,000 parts per year for 10 years.

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RIM Process VS. Injection Molding

RIM Process Advantages

  • Large, lightweight parts
  • Varying wall thickness with no sink
  • Deep draw
  • Can combine multiple designed parts into one part within a single mold
  • Low-to-moderate cost tooling – machined aluminum
  • Short lead-time
  • Tooling can be used for prototype and easily modified for production parts
  • Material flexibility – elastomers, solid RIM, structural foam, flexible foam, DCPD, etc.
  • Encapsulation of component materials including metals, electronics, plastic, valves, circuitry, etc.
  • Low-to-high production volume
  • Tight tolerances

Injection Molding

  • Small-to-mid size parts
  • Requires uniform wall thickness
  • Limited draw
  • Multiple mid-size parts generally require multiple molds
  • High-cost tooling – steel
  • Long lead-time
  • Prototypes require different tooling and tooling modifications are expensive
  • Limited material options
  • Limited encapsulation
  • Moderate-to-high production volume
  • Tight tolerances

RIM Process VS. Thermoforming & Vacuum Forming

RIM Process Advantages

  • Complex geometry and cosmetically appealing parts
  • Deep draw with structural integrity
  • Varied wall thickness throughout the part
  • Structural integrity molded into parts
  • Molded-in attachment points
  • Tight tolerances
  • Low-to-moderate cost tooling
  • Low-to-moderate production
  • Material flexibility – elastomers, solid RIM, structural foam, flexible foam, DCPD
  • Encapsulation of component materials including metals, electronics, plastic, valves, circuitry, etc.


Thermoforming & Vacuum Forming

  • Simple part design and geometry
  • Draw limited and requires post-molding structural features
  • Requires uniform wall thickness
  • Post-molding gluing of ribs
  • Glued attachment points
  • Low-to-moderate cost tooling
  • Limited material flexibility
  • No encapsulation capability

RIM Process VS. CAST Molding

RIM Process Advantages

  • Cosmetically appealing parts right out of the mold
  • Prototype tooling can be used for production parts
  • Tight consistent part tolerances
  • Variable wall thickness without sink
  • Tooling lasts the lifetime of the project
  • Short lead-time on tooling

Cast Molding

  • Cosmetic inconsistencies of parts off the mold
  • Prototype and production tooling are different
  • Part tolerance varies from part to part
  • Variable wall thickness generally includes sink
  • Short lead-time on tooling

RIM Process VS. Sheet Metal

RIM Process Advantages

  • Tremendous design flexibility
  • Large and light-weight parts
  • Structurally strong and durable
  • Molding in color an in-mold painting
  • Variable wall thickness within the same part
  • Affordable part cost
  • Capable of combining multiple parts into one integrated part
  • Provide sound and vibration insulation
  • Corrosion and rust-resistant
  • Part cost is more stable

Sheet Metal

  • Limited design flexibility
  • Parts are heavy
  • Post-painting required
  • High part cost
  • Varied wall thickness requires welding multiple parts
  • Multiple parts require labor and assembly costs
  • Structurally stronger parts
  • Part pricing is less stable due to the commodity’s market

RIM Process VS. Die Casting

RIM Process Advantages

  • Lower weight
  • Higher tolerances
  • Greater design freedom
  • No brittle parts
  • Net shape with no machining
  • Corrosion-resistance

Die Casting

  • Low tooling cost
  • Shorter lead-time