Molders work with our production staff to produce large, light weight, polyurethane plastic parts for a variety of industries and companies throughout the US and world. 

Position Requirements:

  • Work in non A/C warehouse
  • Building up and break-down production molds
  • Must work 40 hours; some overtime if necessary
  • Able to lift 25 lbs.
  • PPE Requirements: Long pants and safety-toe boots/shoes
  • Must be able stand for long hours while operating machines and presses
  • Must be fit tested for respirator; some use may be required
  • Forklift experience a plus

If interested, please send your contact information to

RIM Products & Parts: A Review of Projects

back of white rim molded products

Commercial Tractor Hood

32.5L x 21.5W x 22H     (7 lbs.)

The chemical reaction that distinguishes Reaction Injection Molding from typical injection molding makes all the difference in how your products perform. RIM Manufacturing uses low viscosity liquid polymers which expand and harden in the mold at much lower temperatures than those of plastic injection molding or thermoforming. Plus, your RIM designs can be much more intricate with a greater range of weight, strength, density, and hardness.

RIM is ideal for large parts that need to be lightweight, like the above tractor hood, which is only 7 pounds.

Medical Device Swivel Tray

18L x 18W x 5H     (2.5 lbs.)

RIM, and Structural Reaction Injection Molding, give you design options otherwise impossible. RIM is able to accommodate small to very large parts, impart structural integrity, tight tolerances, and greater ranges of wall thickness within the same part. Plus, several parts can be combined into one.

Consider the intricacy of the above design, with RIM, the medical device swivel tray doesn’t need as many post-production additions or assembly steps as other manufacturing options.

Laboratory Device Base

58L x 27W x 3.25H     (26 lbs.)

Since our RIM process requires lower temperatures and pressures than other manufacturing processes, RIM polymers can be injected into cost-efficient aluminum molds. These cost up to 70% less than steel molds and last longer. They may never need to be replaced and can be modified much less expensively.

For the laboratory device base above, the size, weight, and number of products needed, along with the intricacy of the design, made RIM an ideal process for the project.

Medical Device Cover

18L x 11W x 4H     (1.5 lbs.)

Whatever your specifications, we will work with you to check that RIM is the optimal process for your project. Depending on wall thickness and strength, ribs, draft, bosses, holes, grooves, and vent needs, we will help you select the right system and chemistry to achieve the correct process and end product.

RIM Manufacturing Will Help You Find the Best RIM Design for Your Project 

  • Elastomeric– for RIM parts with superior impact strength, durability, dimensional stability, and resistance to corrosion, abrasion, and wear.
  • Solid– produces RIM parts similar to those created with thermoforming or thermoplastic systems, but these allow variation in wall thickness throughout a part without visible sink marks. Typically, the minimum wall thickness is 1/8” to 1/2”.
  • Rigid Foam– a blowing agent creates a high-density skin around a low-density microcellular core. This skin gives the RIM part firmness and durability, while the low-density core reduces the part design’s weight. Wall thickness can vary from 1/4” to 11/2”.
  • Flexible Foam– this system’s blowing agents create self-skinning foams. The thickness of the skin and density of the foams can be adjusted to achieve the precise flexibility, firmness, and support characteristics your RIM part design requires.
  • Reinforced RIM (RRIM)– the Elastomeric system with glass or mineral fillers introduced to produce parts with greater rigidity.
  • Structural RIM (SRIM)– Solid or Foam chemistries can incorporate long-fiber reinforcements, like glass mats, to increase stiffness and impact resistance for your RIM design.

Contact RIM Manufacturing for a Quote

The RIM Manufacturing Process

RIM Manufacturing Process

RIM Manufacturing is well-known for helping our customers design molds, or “tools,” for the greatest efficiency, uniformity, and production productivity. During our RIM product design and manufacturing processes, we also consider including after-mixers and gating to maximize your part’s quality.

Planning & Communication

Our experience in the industry means we can help you achieve the ideal mold design by taking multiple 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, two mid-size, and two small machines.

RIM parts are often light but can weigh as much as 100 pounds. The largest part RIM Manufacturing currently produces weighs approximately 50 pounds.

Mold Clamping Pressure

This is 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 (aluminum) can be as much as 70% less than injection molding (steel molds). Lower in-mold pressures allow molds to be created from lower-cost materials, and these lower pressures often lead to less wear and tear, allowing the mold to be used for longer, saving more in mold costs.

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

This is usually geared toward form, fit, and function, allowing molds to be built to absolute dimensions. Because this is more costly, designing parts for more practical dimensional tolerances generally saves money.

Quality & Dependability

RIM Manufacturing is known throughout the industry for producing parts that reduce cost without any reduction in dependability or quality. 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.

Our process goes a long way to ensure that we spend whatever time is necessary with customers assisting with and reviewing the final part design. Collaborative GoTo, WebEx, or in-person meetings are essential to designing parts that exceed everyone’s expectations.

After part drawings are finalized and the mold is designed and constructed, the Production Part Approval Process (PPAP) begins.

  1. First Article parts are produced, and our Quality Department inspects them for conforming to the part drawing. They measure all critical dimensions and callouts and review them for cosmetic conformance.
  2. Once approved, the polyurethane parts are sent to the customer for First Article Approval and sign-off.
  3. Once final approval has been obtained, our Quality Department produces Work Instructions for each relevant area of the part’s production – molding, secondary operations, painting, assembly, quality assurance, and packaging.

Our customers can count on us for quality and consistency, as evidenced by our ISO 9001:2015 and ISO 13485:2016 certifications. And we will continue to improve our processes, capabilities, equipment, facilities, and staff to sustain the highest level of customer satisfaction – that’s our guarantee.

Contact RIM Manufacturing for more information

Reaction Injection Molding Process VS. Other Processes

Reaction Injection Molding Process part

Reaction injection molding is cost-effective for the production of a few hundred to several thousand parts. Benefits include low-to-moderate tooling costs, short lead times, the ability to produce large and lightweight parts, parts with tight tolerances, enhanced design finishes, chemical resistance properties, 94V-0 and HB ratings, customized part properties, and wall thickness, as well as the ability to mold over metal, wood, glass, computer chips, and other parts.

RIM Advantages VS. Injection Molding

Reaction Injection Molding 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 Advantages VS. Thermoforming & Vacuum Forming

Reaction Injection Molding 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 Advantages VS. Sheet Metal

Reaction Injection Molding 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 Advantages VS. Cast Molding

Reaction Injection Molding 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 of 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

Contact RIM Manufacturing to Start Your Next Project

When You Consider All the RIM Advantages, We Know You’ll Have the Best Reaction. RIM Manufacturing is the Partner Uniquely Positioned to Accelerate Your Company’s Success!

RIM Manufacturing | Our Story & Experience

RIM Manufacturing work

RIM was founded in 1979, giving us over 40 years of experience in the reaction injection molding industry. We have grown over the last four decades to become one of the largest independently owned plants in the country specializing in custom Reaction Injection Molding.

We are ISO 9001:2015 and ISO 13485:2016 Certified for Reaction InejctionMolding and  Assembly. Additionally, RIM Manufacturing offers the widest range of chemistries to exactly meet your manufacturing needs. We are recognized as industry experts who have been optimizing our Reaction Injection Molding processes for decades in order to best serve our clients.

With over 40 years in the industry, we bring design expertise and experience to every project and with every client.

RIM Manufacturing | Our Team

Each member of RIM Manufacturing is dedicated to making our clients successful in every phase of their production process – from part and CAD design to mold design and manufacturing, part production, secondary processing, painting and silk screening, assembly, packaging, even shipping.

This makes us a top choice for reaction injection molding from start to finish, as we have the experience to help at every stage of your design, fabrication, and final product.

RIM Manufacturing | Our Growth

We are not only one of the most experienced leaders in the business, but our operating plant floor space exceeds 45,000 square feet and our three-acre site allows us to be flexible in our processes and nimble in our response to our client’s unique needs.

Our location near Dallas and Fort Worth, some of the world’s most significant air and land transportation hubs, helps us streamline our schedules and delivery, as well as cost – making our size and location some of the best benefits in our market.

When you consider all of the advantages you gain with RIM Manufacturing, it’s easy to see that we are your top partner every step of the way. Our unique position and experience are poised to accelerate your company’s success!

RIM Manufacturing | Our Designs & Advantages

With RIM Manufacturing, you can choose your parts’ precise characteristics:
  • Structural integrity and tolerances
  • Impact resistance, dimensional stability
  • Strength, wear- and corrosion-resistance
  • Thermal and electrical insulation
  • Sound absorption and natural adhesion
  • Solid, elastomeric, rigid- or flexible-foam
With RIM Manufacturing, you can create more than individual parts:
  • Combine several parts into one
  • Over-mold metal, wood, glass, and more
  • Encapsulate parts – cable, valves, circuits

RIM Manufacturing | Contact Us

Contact RIM Manufacturing today to learn more about our team, our personalized services, and our processes.

RIM Manufacturing, LLC

(817) 599-6521

Benefits of Reaction Injection Molding

orange polyurethane reaction injection molding part

RIM Molding is an excellent process for producing large, lightweight parts. The sweet spot for volumes ranges from a few hundred to several thousand parts per year.  And because of the wide variety of chemistries offered, parts produced can be structural foam, flexible foam, elastomeric, or solid RIM.  What’s more, the low temperatures and low pressures incorporated within the RIM process,  offer design opportunities that are superior to other processes such as injection molding, thermoforming, vacuum molding, and cast molding.

Additional Advantages of Reaction Injection Molding:

  • Variable wall thickness
  • Molded-in bosses, ribs, inserts, tabs, or undercuts
  • Flexible cosmetic surfaces or part design
  • Encapsulation (over-molding) capabilities
  • Dimensional stability
  • Chemical resistance
  • In-mold painting or post-paint
  • Low tooling cost

Technical Properties include:

  • Impact resistance
  • Dimensional stability and strength
  • Design tolerance
  • Wear- and corrosion-resistance
  • Thermal insulation
  • Electrical non-conduction
  • Sound absorption
  • Natural adhesion

Longer Cycle Times

To achieve creative and uniquely designed parts using RIM Molding, the production process requires longer cycle times.  The liquid chemicals used in RIM molding will more easily flow within complex tools to fully fill the cavity of the mold and, therefore, take longer to become a finished part.  A process like injection molding, which incorporates high temperatures and high pressures to quickly fill the mold cavity, has a much shorter cycle time. 

Contact RIM Manufacturing for Your Next Project and Experience the Difference!

RIM Manufacturing is known throughout the industry for its commitment to excellence and producing quality parts at a reasonable cost.  

Contact RIM Manufacturing to learn more about who we are and how the RIM process can deliver the parts you need.

Our Reaction Injection Molding (RIM) Process

Reaction Injection Molding part
Reaction injection molding and plastic injection molding have almost the same name, so even experienced engineers and designers may think they are the same. But the ‘reaction’ creates a big difference.

The Reaction Injection Molding Process: Pressure & Temperature

Step 1: Polymer Liquids

The RIM molding process begins with polymer liquids (polyol and isocyanate) stored in large storage tanks and dispensed by large, high-pressure industrial pumps. The polymers are recirculated from the storage tanks to a multi-stream mix-head on the machined aluminum mold and back to the storage tanks in a continuous loop.

Step 2: Mixing

When each part is made, a piston or plunger inside the mix-head retracts, breaking the continuous loop, and the polymers mix at a high velocity (approximately 1200 psi) to ensure the proper combination and mixture of the polymers. The resulting polyurethane enters the mold through the after-mixer, which maintains the mixture’s properties while reducing its velocity to 95-100 psi, a much lower pressure.

Step 3: Molding

Since these liquid polymers require less pressure and lower temperatures than typical ingredients, they can be injected into cost-efficient aluminum molds, lowering tooling costs. The molds are then moderately heated (~190°), but the resulting exothermic reaction quickly brings the materials to (~325°) and promptly cures the part inside the mold.

Step 4: Curing & Cooling

Cure times vary from less than a minute to several minutes, depending on the part’s size, geometry, function, and thickness. Polymers and RIM processes can be chosen to produce solid, elastomeric, rigid-foam, or flexible-foam finished polyurethane parts.

Differences Between Reaction Injection Molding & Plastic Injection Molding

Unlike plastic injection molding, reaction injection molding (or RIM molding techniques) utilizes low-viscosity liquid polymers in thermoset – not thermoplastic or thermoforming – processes.

Through a variety of chemical reactions, these polymers expand, thicken, and harden only after they’re injected into a heated mold, accommodating much more intricate designs than ordinary plastic injection molding.

Raw materials and polyurethane reaction techniques can be selected and even customized to precisely deliver desired weight, strength, density, and hardness characteristics. The result is large polyurethane parts with a much lighter weight than those created by more commonplace processes.

Learn the Advantages of the Reaction Injection Molding Process from RIM Manufacturing

Reaction injection molding not only offers certain advantages over injection molding, but also vacuum-forming, pressure-forming, and cast molding.

The admittedly longer production time of reaction injection molding is more than offset by its benefits to design, flexibility, and cost-efficiency, not to mention the wide ranges of part size, design uniqueness, and colors.

Contact RIM Manufacturing to Learn More!

What are the Benefits of Reaction Injection Molding?

new green reaction injection molding part
“Reaction Injection Molding “RIM” is a Thermoset process where low-viscosity liquid polymers and isocyanates are mixed at high-pressure (2000 psi) and injected into temperature-controlled molds at low-pressure (150 psi). An exothermic reaction occurs as the temperature of the liquids reaches 350 degrees Fahrenheit before cooling to become a solid polyurethane part.”

When Should You Use RIM Molding?

RIM Molding is good for low volume and large, lightweight parts. The RIM process may be a better solution in certain situations because of the chemistries offered, or because of the low temperatures and low pressures used in RIM versus other injection molding processes.

RIM Molding for Over-Molding

RIM Molding uses lower temperatures and lower pressures, which make it the most effective process for over-molding production parts.  Over-molding materials like sheet metal, steel, and other substrates allow the combining of multiple parts into a single part.  RIM Molding is also perfect for over-molding sensitive materials, like circuitry or valves, that would otherwise be destroyed by the high operating temperatures and pressures of injection molding.   

RIM Molding for Varying Thickness

The RIM Molding process provides greater design flexibility because it allows varying wall thickness within the same part and without sink or deformities.  Wall thickness throughout an injection molded part must be uniform, otherwise, the part will deform as it cools.

RIM Molding for Various Sizes

Injection molded parts are typically small in size. To produce one large part generally requires producing several smaller parts and then assembling to create the larger part. Tooling costs will be significantly higher than building one large RIM tool. And the single RIM molded part eliminates assembly costs associated with combining the smaller injection molded parts into one larger part.

Reaction Injection Molding for Colors

Large RIM molded parts can be molded in color, which is cosmetically appealing, and can be shipped to the customers immediately upon demolding with some minor trimming of flashing – or excess material. Whereas large injection molded parts often have significant, visible, and unappealing ‘flow lines’, which require painting for cosmetic acceptance.

RIM Molding Tooling Materials & Costs

Reaction injection molding uses aluminum tools instead of steel tools, which translates to lower tooling costs per mold.  Unlike injection molding tools, which are made of steel to sustain the high operating pressures and temperatures, RIM molding uses machined aluminum tools because of the low operating pressures and temperatures.  Therefore, the capital requirement for RIM tools is significantly less than injection molding, by as much as 2 to 3 times!

About RIM Manufacturing

We are industry experts offering a wide range of chemistries and process capabilities designed to meet the needs of our customer’s projects.

Every member of RIM Manufacturing is dedicated to making your project successful at every phase of our production process!

Contact RIM Manufacturing today!

Combining Multiple Parts into One: A Key Advantage of RIM

Metal part from injection molding (RIM)

Advantage of Reaction Injection Molding

Reaction Injection Molding or RIM is a process used to produce a wide variety of polyurethane parts, including: structural foam, solid RIM, elastomeric, flexible foam, and composite parts. These are used in multiple different industries, ranging from automotive to medical.

RIM involves using polymer liquids – polyol and isocyanate. These liquid polymers are dispensed through high-pressure pumps at low pressure into aluminum molds, which are temperature controlled. injected into heated molds. Inside the mold, the combined chemicals produce an exothermic reaction transforming the liquids into a molded part. This process allows you to easily create products that are customizable according to your desired tolerance, density, weight, thickness, and hardness.

Because the RIM process is perfect for larger, lightweight parts, designing several parts into one part can reduce the need for multiple molds and the labor required for assembling multiple parts. Additionally, over-molding sheet metal or steel can eliminate the need for hinges or attachment points creating additional cost savings.

Contact Us for Your Next RIM Manufactured Part

RIM (Reaction Injection Molding) vs. Plastic Injection Molding: What Are the Differences?

Trilogy Accelerator Machine from reaction injection molding

Product manufacturers may look to injection molding when they need to produce custom parts. However, there are several processes available for producing plastic parts. Depending on the size of the part, the geometric design, the functionality, the quantity required, and the capital expenditure budget, RIM (Reaction Injection Molding) may be a better option.

Though these two molding processes are similar, they are also very different – here are a few of the key differentiations.

The Processes 

The Reaction Injection Molding (RIM) process uses a sophisticated closed circuit dispensing machine to mix two-component non-viscous liquid polyurethane materials (a polyol and isocyanate) at high-pressure within the mix-heads mixing chamber. This combined material is then injected into machined aluminum tooling at low pressure and low temperature.

The Plastic Injection Molding (PIM) process uses an injection machine to melt plastic resin pellets into a viscous molten material which is then injected, at high pressure and high temperature, into steel tooling.

Design Benefits 

Reaction Injection Molding (RIM) is perfect for large, light weight parts with varied wall thickness and unique geometric design. Additionally, RIM’s molding functionality allows for the combining of several parts into one part and easily accommodates over-molding materials like sheet metal, steel, circuitry, valves, etc.

Injection Molding is perfect for small parts and high volumes. The more simplistic the design, the better the efficiency for production.

Cost Benefits 

There are several cost benefits to using the RIM process:

  1. RIM uses machined aluminum tools that can easily be modified for subsequent design changes. The cost of aluminum tooling is significantly less than steel tooling, used in injection molding, and there is little to no maintenance.
  2. Aluminum is easier to machine than steel allowing the RIM process to bring a product to market much faster than injection molding.
  3. The RIM process uses non-viscous liquids which allow for several smaller parts to be molded into one larger part thereby reducing the costs associated with inventory management and assembly.
  4. Unique design features, including over-molding increase the functionality and eliminate potential assembly labor.

However, because the RIM process is better suited for larger parts, the per part cost will be higher than injection molding.

Injection Molding requires steel tools in order to accommodate the process of high pressures, high temperatures and highly viscous material. While the capital expenditures and lead-times are significantly higher and longer than RIM Molding, the rugged steel tools allow for faster processing of parts resulting in a significantly lower part cost than RIM.

Experience the Advantages of RIM Processes

For more than four decades, RIM has been optimizing Reaction Injection Molding for various industries.

We produce high-quality plastic components to help our customers achieve their business goals and objectives.

Get in touch with us for more information about our RIM services.