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Reaction Injection Molding

A reliable source for Reaction Injection Molding information and leading Reaction Injection Molding Companies & Suppliers.

Reaction injection molding (RIM) is a polymer part manufacturing technique that involves direct polymerization in the mold via a mixing-activated reaction. Impingement is used to combine two reactive monomeric liquids, which are then injected into the mold. Read More…

Reaction Injection Molding Reaction injection molding (RIM) is a plastic molding process commonly used for larger (parts up to 8' x 8'), geometrically-complex parts, rigid foam parts and parts that have lower annual production runs (100-20,000).
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Leading Manufacturers

Denver, CO  |  303-592-9548

For 50 years, LTM Plastics has been a leading manufacturer of injection molded plastics. When working with LTM Plastics, our customers can be assured that they are getting high quality products at a competitive price. We pride ourselves on our team’s communication and collaboration with our customers to meet their needs.

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LTM Plastics $$$

Imlay, MI  |  248-275-1978

If you are in need of injection molded plastic parts that are of consistent quality, look no further than MSI Mold! We have over 30 years of experience in design, production, and tooling of custom plastic parts.

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MSI Mold $$$

Cleveland, OH  |  440-238-3009

You won’t find better quality injection molded plastics anywhere else in the industry. We have built ourselves up from a small manufacturing company to a large company with decades of experience.

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GSH Industries, Inc. $$$

Stuart, FL  |  772-286-9278

We may have started small, but today, we offer our products and services to companies around the world. We are dedicated to our customers, and our goal is to offer better service and pricing to any customer no matter the size.

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Britech Industries $$$

Riverside, CA  |  951-354-0258

At R.M.Tool, we provide custom CNC Machining to help our customers solve some of their toughest machining needs. Our state-of-the-art CNC machining department is equipped with Milling, Turning and Wire EDM Machining Centers. We can process materials such as Steel, Stainless, Aluminum, and other Exotic Materials. We strive to always please our customers by always delivering quality products. From design to finished product, R.M.Tool is your one stop shop for all of your CNC machining needs.

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Hi-Rel Plastics & Molding $$$

Tempe, AZ  |  951-509-6918

Call Molded Devices for a fast, competitive quote on plastic molding, plastic injection molding, and medical injection molding services. A wide range of standard & proprietary caps, covers & containers plus custom components for all your needs. We are your one-stop for design consult, quick prototyping, custom formulations & secondary operations!

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Molded Devices, Inc. $$$
placeholder image LTM Plastics MSI Mold GSH Industries, Inc. Britech Industries Hi-Rel Plastics & Molding Molded Devices, Inc.

What is Reaction Injection Molding?

Reaction injection molding (RIM) is a polymer part manufacturing technique that involves direct polymerization in the mold via a mixing-activated reaction. Impingement is used to combine two reactive monomeric liquids, which are then injected into the mold.

Polymerization and phase separation normally occur in the mold, after which the portion solidifies and is expelled. Automotive parts, commercial machine housings, and furnishings are among the most common applications for RIM goods.

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Reaction Injection Molding Process

The chemical reaction that occurs within the plastic throughout the injection, curing, and cooling phases is known as reaction injection molding. At a mixhead, two liquid components – a polyol and an isocyanate component – collide and are subsequently injected (mainly by gravity) into a heated aluminum mold.

These liquids react chemically (thus the term "reaction" injection molding) before hardening into the shape of the mold cavity. As a result of the chemical reaction, a foaming activity occurs between the two components, forming a cell structure that then fills the mold cavity.

The physical qualities of the final foam material and the type of polyurethane part generated are determined by the chemistry and mix rations of the polyol and isocyanate. The foam structure may be soft and flexible, like a seat cushion, or it could be designed to react and form with little foaming action.

The reaction then produces a hard (solid), thin-walled foam that mimics the physical qualities of injection molded plastic, like a computer casing. In addition, the chemistries could be tweaked to increase impact resistance while allowing for flexibility. Another benefit of RIM is its adaptability; there is no limit to the number of goods that may be made using the process.

Because of the cure time, the size of the pieces, and the slower cycle durations involved in the process, reaction injection molds are more cost-effective and allow for greater design flexibility. Still, they have a lower production rate than normal injection molding.

Reaction Injection Molding

Advantages of Reaction Injection Molding

These parts are tough, resilient, and resistant to aging and weathering. The reaction molding method is frequently used to manufacture molded plastic parts that must endure impact and abuse, such as radar antennae, telephone system shields, and automotive bumpers.

Due to low labor costs, little material waste, the utilization of low-cost aluminum equipment, and a variety of material alternatives, reaction injection molding is a cost-effective option for producing these parts.

RIM's other advantages over other low-volume production methods are cost reductions, part repeatability and consistency, weight savings, design freedom, and overall part quality. RIM offers high cost, weight, and quality benefits for organizations that already use FRP (fiberglass layup) as a production method.

RIM will always create a better fit and complete assembly than other methods because of the control over wall thickness and dimensional/assembly features it allows. RIM also allows large draws and varied wall sections to be created without sinking or deformation.

RIM engineers can design for both the aesthetic (side A) and functional (side B) aspects of a part and employ various DFMA principles.

Applications of Reaction Injection Molding

Due to its low processing temperatures and decreased injection pressures, RIM is well-suited for molding big components with variable wall thickness and smooth surface finishes.

Manufacturers can also take advantage of its relatively rapid turnover rate, allowing them to easily handle low- to mid-volume projects. RIM parts also have high tensile strength, are heat resistant, and are resistant to corrosive chemicals and solvents.

Long-term exposure to sunlight, on the other hand, can destroy polymer-based parts, and tooling and machining costs for polymer-based goods are quite high. RIM's steering wheels, side panels, instrument gauges, dashboard consoles, armrests, body frames, and bumpers are used by many automakers.

Some RIM components' elastomeric qualities make them ideal for use in domestic appliances, heating and cooling systems, and recreational equipment like water skis.

Parts consolidation is possible using reaction molding, which can speed up the manufacturing process and eliminate the requirement for supplementary tooling. Some manufacturers have used this advantage to create in-metal components like frames and hinges.

Reaction injection molding, on the other hand, is not suited for high-volume projects involving smaller, mass-produced components. Metal molds are costly and prone to wear throughout long production runs.

Furthermore, even minor pressure calibration mistakes in the mixing head can result in considerable variations in the amount of material injected into the mold and product cracks after curing.

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