Post by Aug 7, 2022 11:06:31 AM · 3 min read

What Products Are Made from Reaction Injection Molding (RIM)?

Reaction injection molding (RIM) is a low volume manufacturing process used to produce high-quality polyurethane (PUR) plastic parts for a wide range of products in many industries.  Often confused with injection molding, RIM is a low pressure, low temperature liquid injected molding method that creates strong, lightweight, durable, large and or highly detailed parts in a cost-effective manner.  

The RIM molding process starts with two liquid polymers (isocyanate and polyol) contained in separate storage tanks, they are continuously circulated in a continuous loop until a shot is called for at the tool mix head.  When a shot is called for the polymers are gravity fed into the mold.  Once filled, an exothermic reaction takes place between the two liquids (polyol and isocyanate), and the heated tool surface.  Once fully cured in the mold, the resulting polyurethane parts are light, strong, and have either very complicated geometries or are very large parts depending on design and the RIM material selected (compact or a structural PUR). 

With so many advantages of RIM, it’s easy to see why industries are taking advantage of this process.

Popular RIM Products and Industries

In the last few decades, reaction injection products have grown in popularity, with businesses across a variety of industries switching to the RIM molding process in order to create high-quality, strong, lightweight, and durable products.

Here are some examples of industries and products that commonly take advantage of RIM.

Medical and Healthcare Industry

The medical industry takes advantage of the RIM process to design and build many different medical devices. RIM can be used to make complete device enclosures like CT scanners, MRI’s, dialysis machines, surgical robots, mammogram machines and medical carts.  Other parts such as doors, panels, trays, and various other device coverings can be made.  Many of these can be large in size such as 8’ x 8’ x 2’ (in a single RIM shot) or smaller with very detailed and complicated geometries.  Typical parts made with RIM are used heavily in lab, scientific, diagnostic and assorted components for surgical devices.

Electronic Housings and Enclosures

A major application of RIM is creating housings and enclosures for a variety of electronic devices. The versatile and highly customizable nature of the RIM process—as well as the low temperature and pressure requirements—makes it easier to manufacture the small, intricate products required by the electronics industry. Electronic and glass encapsulation is also possible due to the low temperatures used in the RIM process.  Molding in components and over molding batteries, circuit boards, transmitters, and various RF components is also possible.  Another major plus of many of the RIM materials molded, they are compliant to UL 94 V0.

Automotive Industry

Since it was first developed, the RIM process has been used in the automotive industry. A majority of car and truck manufacturers use RIM to create large parts for vehicles, including but not limited to the following:

  • Bumpers
  • Wheel arch liners
  • Steering wheels
  • Dashboard consoles
  • Instrument gauges
  • Decorative trims
  • Quarter panels
  • Armrests
  • Body frames

RIM products are durable and can be molded using a flexible PUR elastomeric system which provides vehicle parts with shock resistance and extensive tensile strength. They are also easy to paint, allowing for a matching finish with the rest of the vehicle.  In addition, they can weigh less than products made from other materials, making vehicles more fuel efficient.

Heavy Equipment

Heavy equipment manufacturing uses the RIM process to create equipment consoles, cabs, exterior panels and intricate parts for complex equipment like generators, heaters, excavators, earth moving equipment and various farm vehicles. Since the polyurethane plastic parts developed through RIM are more resistant to wear and tear, they are more durable and easier to maintain than other alternatives.

The RIM process can also create lightweight products, so heavy equipment will be easier to lift, manage, and use.

Construction Industry

RIM applications for the construction industry include windows, doors, cab roofing, access panels, instrument panels, trim and sheathing. The wet conditions of construction mean that materials need to be strong and durable in harsh conditions, and polyurethane has the ability to retain its shape and shine for years after exposure to the elements.

Large and Small Appliances

Commercial and some home appliances, both large and small, often have components produced by RIM processes. The insulation in refrigerators and parts of heating/cooling units, for example, can benefit from the thermal properties of RIM.

Panels, Doors and Architectural Molding

Panels, doors, structural and architectural moldings and other stiff parts can easily be created through RIM manufacturing processes. Flexible and lightweight plastic doors and panels are a common application of RIM.

Sport and Recreation Industry

RIM is often used in the sport and recreation industry. It can be used to create elastic, flexible products developed for outdoor activities and sports such a ski’s, wakeboards and even snow shoes. Additionally, with the lightweight properties of RIM, it is a great choice for recreational vehicles like scooters, dirt bike parts, golf carts and ATV’s. 

Structural Parts

With its ability to create complex, lightweight products with variable wall thicknesses, the RIM process is an ideal option for making structural parts. Small plastic parts for any product or industry can benefit from RIM.

Contact the RIM Process Experts at Thieme

For more than 50 years, Thieme has offered custom reaction injection molding for a wide range of devices and industries. With our RIM technology expertise, responsive service, and exceptional program management, we are proud to serve as a trusted supplier of large format molding for our local, regional, national, and global customer base.

Our experienced full-service team is ready to help at every stage of your RIM project, from conception and planning to production and fulfillment. Contact us today to request a consultation and discover how you can benefit from our RIM services.

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