RIM Design & Quality
Get A Better Reaction To Your Design
In general, reaction injection molding (RIM) allows for superior design in polyurethane parts – over plastic injection molding, thermoforming, and cast molding – when you require:
- Low cost tooling
- Large parts
- Variable part wall thickness
- Molded in bosses, ribs, inserts, tabs or undercuts
- Flexible cosmetic surface and part design
- Encapsulation capabilities
- Dimensional stability
- Chemical resistance
- In-mold painting and post-paint
RIM Manufacturing Will Match the Best System for Your RIM Design
Structural Foam RIM (94V-0)
A closed-cell polyurethane two-part chemical system that uses a chemical blowing agent to create a cellular structure within the material. Provides unique properties, including high strength-to-weight ratios, thermal insulation, and sound deadening.
Shore Hardness: 66D – 81D
Tensile Strength: 3,100 – 4,800
Flex Modulus: 160,000 – 240,000
Min. Wall Thickness: .250”
Flexible Foam RIM
Integral skin foam forms a dense outer layer (or skin) during the foaming process. The skin provides a durable, non-porous, and aesthetically pleasing finish
Shore Hardness: 18 – 45A
Solid (“Rigid”) RIM (94V-0)
Rigid RIM produces high-quality, lightweight, and strong plastic parts with complex geometries with high strength-to-weight ratios, durability, and precision.
Shore Hardness: 75D
Tensile Strength: 7,000
Flex Modulus: 290,000
Min. Wall Thickness: .125”
Elastomeric RIM
Elastomeric systems produce plastic parts with excellent mechanical properties, including high elasticity, strength, flexibility, durability, and high impact resistance.
Shore Hardness: 65D – 71D
Tensile Strength: 3,700 – 7,000
Flex Modulus: 50,000 – 200,000
Min. Wall Thickness: .125”
DCPD
Though DCPD is NOT polyurethane, the material is processed using the same RIM process to produce parts that can replace materials from steel to composites. The system balances strength and toughness with excellent resistance to harsh chemicals and hot, wet environments.
Shore Hardness: 82D
Tensile Strength: 6,700
Flex Modulus: 274,000
Min. Wall Thickness: .250”
RIM Design Factors to Consider
RIM Manufacturing will work with you to maximize your RIM part’s design by making the ideal choice from the wide array of manufacturing chemistries and systems we offer.
Together we’ll consider:
- Your part’s purpose
- Structural, impact, and load requirements
- Unique environmental conditions the part will be subjected to
- Chemicals the part will be exposed to
- Special design requirements to be considered
- Aesthetic requirements
- Weight requirements
- Particular finish, color or paint requirements
- Cost-reduction opportunities
Then We’ll Work with You to Enhance Your RIM Design Specifications
Wall Thickness & Strength
We will help you select the right system and chemistry to achieve the optimal cross section for cycle time, output, and cost.
Ribs
Usually running the length of a part, ribs can also be bidirectional to allow for thinner walls, greater strength, warp reduction, and lower cost when faster cooling reduces cycle time
Draft
Considered in every surface parallel to the direction of the draw, draft angle increases with part height. This is an especially important consideration for the core side of the mold since the part shrinks onto the cavity as it cools. With RIM Manufacturing, drafts can be as slight as 1°
Bosses
Frequently incorporated to accommodate threaded inserts, their primary benefit is allowing air to escape during molding and optimizing cycle time. This is generally most successful with bosses in side walls or gussets added to isolated gussets
Holes, Grooves, & Vents
These features, oriented in the direction of the chemical flow, can enhance injection into the mold by reducing stress concentration, air entrapment and knit lines, especially rounded or chamfered grooves. Usually created by hand-loaded inserts or hydraulic inserts, the incorporation of holes and grooves is sometimes more cost-effective when they are drilled
Our Experience Means We Can Help You Achieve the Ideal Mold Design by Taking these Factors into Consideration
The Right RIM System
Part size is the primary factor for determining the size of the dispensing machine used to inject the polyurethane into the mold. RIM Manufacturing offers a wide range of capability with three of the largest machines made, three mid-size and two small machines. RIM parts can weigh as much as 100 pounds, though the largest part RIM Manufacturing currently produces weighs approximately 50 pounds.
Mold Clamping Pressure
Determined by the amount of chemical and the type of RIM system injected into the mold. Generally, clamping pressure can range upwards of 200 tons, but typical molding pressure is less than 100 psi.
Mold Cost
RIM molds can be as much as 70% less than injecton molding. Lower in-mold pressures allow molds to be created from lower-cost materials, usually machined aluminum.
Part Shrinkage
All plastics, including RIM materials, shrink during molding. The amount of shrinkage characteristic of the particular RIM system is factored into the tool’s design.
Dimensional Tolerances
Usually geared toward form, fit, and function, molds can be built to absolute dimensions. Because this is more costly, designing parts for more practical dimensional tolerances generally saves money.
Our Quality Gets the Best Reaction
RIM Manufacturing is known throughout the industry for producing parts that reduce cost without any reduction in dependability. For decades, our customers have relied on us because they need parts to be defect-free while they strictly conform to form, fit, and function requirements.
