• Materials have varying specifications for rigidity and finishing options.
• Environmental stressors may necessitate reinforcing materials or other design elements to increase strength.
• Cost can be affected by the material and the complexity of your mold.

We recommend discussing your project with a RIM expert at Osborne Industries to ensure the material you choose meets your specifications. We can also provide customized guidance for your design.

Design Elements

The following best practices serve as general guidelines when designing for RIM. Talk through your project with one of our specialists for tailored advice.

Tolerances and Materials

Tolerances are broader in RIM than with traditional injection molding. RIM can produce large, complex parts with relatively low internal stress, but dimensions may shift because of shrinkage or curing variations. Critical features may require machining or inserts to achieve tight fits.

RIM supports a wide range of thermoset formulations. Parts can be rigid, semi-rigid, elastomeric, or foam-cored. Each material has different features, such as impact resistance, flexibility, or thermal stability, so material should be selected with the end-use environment in mind. Common RIM formulations are based on polyurethane and polydicyclopentadiene (pDCPD) materials.

General guidelines:

• Typical linear shrinkage: 0.004–0.006 inch per inch (0.1–0.15 mm per 25 mm) or 0.4%–0.6%.
• Dimensional tolerance: ±0.010 inch per inch (±0.25 mm per 25 mm).
• Machine or use inserts for features requiring precision fits.
• Select formulations based on application needs (e.g., rigid for housings, elastomeric for impact, foam for lightweight panels).

Wall Thickness

One of the most important aspects of any RIM design is maintaining uniform wall thickness, especially at corners. While some polyurethane designs can support varying wall thickness, consistency will result in more even cooling and reduce material degradation or warping.

Avoid designing walls that are too thick, as this can result in sink (indentions in the part on the finish side that naturally occur during cooling). Your chosen material will impact the allowable depth. You can increase part stiffness without increasing wall thickness by designing walls that are curved, chamfered, stepped, ribbed, or corrugated. Ribs (see below) can add strength and reduce the need for thick walls.

General guidelines:

• Ideal range: 0.125–0.250 inch (3–6 mm) for most RIM parts.
• RIM can handle thicker sections (up to ~1 inch or 25 mm) without sink.
• Uniform wall thickness is ideal for even curing and shrinkage.
• For areas needing extra strength, add ribs to avoid dramatically increasing wall thickness.

Parting Line and Draw Direction

In some designs, the location of the seam where the two sides of your mold meet will be easy to determine. Typically, the top of the part will have a cleaner finish, while the underside will be more complex. But the ideal parting line placement may not be obvious. The same holds true for draw direction when the part is removed from the mold.

Consider the final appearance and how the plastic will cool in the mold when determining where to put your parting line.

General guidelines:

• Parting lines: Place them in the least visible area of the part to reduce the need for additional finishing. Follow the natural geometry of the part by using edges, breaks, or feature transitions to help hide the parting line.
• Draw direction: If possible, design the part with one draw direction, so the part can be ejected with a single straight pull. Align features such as bosses, ribs, and recesses with the main draw direction whenever possible.

Drafting

To ensure the part can be removed from the mold with minimal resistance and no damage, you’ll want to taper or angle certain elements of the design. If possible, avoid 90-degree walls and use angled walls instead.

The deeper the ribs or cavities, the greater the draft required. Keep ribs and cavities as shallow as possible to minimize draft requirements.

More texture in a mold requires more drafting. So, offset any textures with proper angling.

General guidelines:

• Provide a draft of 1–3 degrees on vertical faces to make demolding easier.
• For textured surfaces, increase draft to 3–5 degrees to account for pattern depth.
• Keep the draft direction consistent to avoid complex mold actions.

Ribs

Ribs are an effective way to add strength, reduce the material required to make a part, and reduce cycle time. They can be a better option than designing thicker walls. Taller, thinner ribs are more effective than shorter, wider ribs, and are less prone to sink. Keep in mind that taller ribs require more drafting, so balance the elements accordingly.

Where possible, place ribs on the non-cosmetic/B-side of the part.

Rib joints at the wall tend to be slightly thicker. Because uniform wall thickness is important, design your ribs with a slight taper at the joint to minimize the impact on the wall depth.

General guidelines:

• Rib thickness should be 50%–70% of the adjacent wall to prevent sink marks.
• Space ribs apart by at least two times the wall thickness to avoid uneven flow.

Cores and Bosses

Cores are mold features that form holes/cavities in the part.

Placement of the parting line and adequate drafting are critical when incorporating cores in your design. For deep cavities, support the part walls around core features with ribs.

Bosses — protrusions often used for fasteners — shouldn’t be isolated. Always support them with gussets or attach them to a side wall.

General guidelines:

• Cores: Maintain at least 0.125-inch (3-mm) wall thickness between the core and the outer surface. For structural parts, keep thickness uniform around cores to minimize warpage.
• Bosses: Wall thickness should be 60%–70% of the surrounding wall. Provide a radius of 0.06–0.125 inch (1.5–3.2 mm) at the base.

Radii and Corners

Using rounded edges in your mold improves resin flow and reduces the chance of air pockets, or voids, forming. Avoid sharp 90-degree angles by using smooth radii.

General guidelines:

• Inside radii should be ≥ 0.06 inch (1.5 mm).
• Outside radii should be slightly larger to maintain uniform wall sections.

Hinges and Clips

RIM materials are not suitable for true living hinges. When designing hinges in RIM, use integrated hinge features such as bosses with through-holes and pin receivers or use metal inserts to create durable pivot points.

Clip fatigue life varies with material and geometry. Some clips may be designed for repeated flexing and must withstand hundreds or even thousands of interactions, while others are intended for single-use applications. In RIM, long-life clips require careful design and material selection to achieve durability.

General guidelines:

• Hinges: Plan for hinge durability testing under real-use conditions, as hinge geometry, cycle frequency, and load can dramatically affect performance in RIM parts. This ensures the chosen design meets functional requirements before production.
• Clips: Add generous radii (≥0.06 inch or 1.5 mm) at the clip root to reduce stress. Use a tapered profile so force is distributed along the clip. Provide a defined flex zone with reduced thickness to control bending.

Inserts and Embedded Hardware

One of the advantages of RIM is the ability to mold directly over inserts or structural components. Embedding hardware such as threaded fasteners, metal frames, or reinforcing plates can reduce assembly steps and increase part strength. Proper planning is required to ensure good bonding and minimize cosmetic issues.

Inserts should be positioned so the liquid resin flows evenly around them, avoiding shadowed or unfilled areas. Always design smooth transitions between the insert and molded material for better resin flow and reduced stress points.

General guidelines:

• Use inserts for features that require tight tolerances or frequent fastening.
• Plan gating and venting to avoid trapped air near embedded hardware.
• During production, preheat larger inserts to improve bonding and reduce voids.

Surface Finish and Texture

Surfaces range from smooth/polished to coarse/grainy (SPI Surface Finish Classes A to D). The finer the surface, the more expensive and time-consuming production will be. Class A finishes require frequent mold polishing and are typically used only for highly cosmetic parts.

The finish on RIM products closely reflects the mold. While textures can be added after molding, the closer you can get to the final surface within the mold, the less finishing will be required.

General guidelines:

• RIM parts shrink less than injection-molded parts, so textures replicate cleanly.
• Tooling can be textured or polished, depending on the final appearance.
• Large, flat surfaces may show minor waviness. Use subtle curvature or ribs to break them up.

Additional Considerations

• Flow paths that are uniform in your design will reduce knit lines, voids, and uneven curing.
• Gates should be placed in low-visibility areas, as they can appear to be cosmetic defects. Use multiple gates only when necessary.
• Vent properly, ideally at the farthest flow ends, to avoid trapped air bubbles.
• Warpage may result from uneven part cooling, insert positioning, unfavorable geometry, or improper curing.

Ready for a Quote?

If you’re further along in the design phase and would like a quote for your project or review by an Osborne Engineer, fill out our Plastic Molding Project Quote Request form, and one of our knowledgeable representatives will reach out.

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Key Differences Between Thermoplastics and Thermosets

The differences extend beyond heat reactivity and are significant when determining the best material for your application.

Understanding the distinctive applications and properties of thermoplastics and thermosets, along with differences in how each is processed or manufactured, can help both manufacturers and product designers improve upon their products.

The following table provides an overview of the key differences between thermoplastics and thermosets.

How Thermoplastics and Thermosets React to Heat

Thermoplastics and thermosets are both polymers, but they behave differently when exposed to heat. Thermoplastics soften and melt when heated, while thermosets keep their form and remain solid when reheated after curing. The ability of thermoplastics to be remelted makes them ideal for applications that use recycled material, while products made from thermosets can withstand high temperatures without losing their shape, meaning they are more durable.

Thermoplastics Processing

When heated, thermoplastics soften and eventually become fluid. Processing thermoplastics involves no chemical bonding, which allows the material to be remolded and recycled without affecting its material properties. The properties of thermoplastic resins can vary significantly, but materials made from them tend to resist shrinking and offer considerable elasticity and strength. Thermoplastic resins are used for a wide range of applications, from industrial components in machinery to the plastic bags used in retail stores.

Advantages of thermoplastics include:

• Adhere well to metal
• Allow for high-quality finishes
• Capable of reshaping after reheating without much effect to material properties (recyclable)
• Chemical- and detergent-resistant
• Good electrical insulation properties
• Enhanced anti-slip properties
• Somewhat resistant to impact
• Offer options for both hardened crystalline and rubbery surfaces
• Resistant to chipping
• Resist corrosion well

Disadvantages of thermoplastics include:

• Ability to soften when heated makes them less suitable for some applications
• Often more expensive than thermosetting polymers

Examples of Thermoplastic Materials

Commonly used thermoplastic polymers include:

• Polyvinyl chloride (PVC or vinyl)
• Polypropylene (PP)
• Polystyrene (PS)
• Polyethylene (PE)
• Polycarbonate (PC)
• Polyethylene terephthalate (PET)
• Polyamide (nylon)

Thermoset Curing Process

Usually produced using the Reaction Injection Molding (RIM) or Resin Transfer Molding (RTM) processes, thermoset polymers combine to form permanent chemical bonds during the curing process. These bonds between monomer chains within the material keep them from returning to their original liquid state when reheated, meaning they are heat-resistant. This makes thermosets better for applications where heat is a factor, such as in housings for electronics or appliances and chemical-processing equipment. Thermosets also have greater structural integrity due to their chemical resistance. Thermosets also possess several improved mechanical properties, so products made from them are better at resisting deformation and impact.

Advantages of thermosetting polymers include:

• Allow for flexible product design
• Can be molded with different tolerances
• Capable of varying wall thickness to improve structural integrity
• Components usually cost less than those fabricated from metals — especially for large equipment body panels
• Excellent electrical insulation properties
• Greater resistance to high temperatures
• High dimensional stability
• Exceptional impact resistance
• Highly resistant to corrosion
• Low thermal conductivity
• Lower costs for setup and tooling compared to thermoplastics
• Offers high strength-to-weight ratio to improve product performance
• Water-resistant
• Wide choice of coloring and surface finishes

Disadvantages of thermosetting polymers include:

• Cannot be reshaped nor remolded
• Not recyclable

Examples of Thermoset Materials

Commonly used thermoset plastics include:

• Polyepoxides (epoxy resins)
• Phenol-formaldehyde (PF or phenolics)
• Polysiloxane (silicones)
• Polyester resins (unsaturated polyesters)
• Polyurethanes
• Polydicyclopentadiene (pDCPD)
• Structural foams

Surface Finish and Aesthetic Differences Between Thermoplastic and Thermosets

Though some may argue thermoplastics offer better aesthetics than thermosets, thermosets can offer better aesthetics than other alternatives like metals.

Both RIM and RTM techniques readily accept secondary painting but also allow in-mold painting or coating, which involves spraying coatings or gel coat directly into a mold before the thermoset polymers are injected into it. This process bonds the paint or coating to the surface, offering better adhesion to prevent chipping, cracking, or flaking even when exposed to harsh weather conditions.

This makes in-mold coatings of thermoset materials ideal for such applications as construction machinery or other components that need to withstand extreme conditions.

When to Choose Thermoplastics vs. Thermosets

Engineers and designers often select thermoplastics when they want a product that is recyclable, flexible, and can be manufactured at high volumes. Thermosets are typically chosen when components must withstand high temperatures, heavy loads, or corrosive environments. The choice depends on the performance requirements of the final product.

Factors to consider include the following.

• Heat resistance: Thermosets maintain structural integrity at higher temperatures, while thermoplastics can soften when heated.
• Strength and stiffness: Thermosets often provide greater rigidity and dimensional stability, while thermoplastics can offer more flexibility.
• Chemical and corrosion resistance: Some thermosets perform better in harsh chemical environments, making them suitable for industrial and agricultural applications.
• Manufacturing process and production volume: Thermoplastics are often preferred for high-volume production using processes like injection molding, while thermosets are commonly used for low to medium volumes in processes such as RIM or RTM.
• Sustainability considerations: Thermoplastics can typically be melted and reused, while thermosets cannot be remelted once cured.
• Part geometry and wall thickness: Thermosets can be well suited for large, thick, or complex parts that require high structural integrity.

Industries Using Thermoplastics and Thermosets

With the basic differences between thermoplastic and thermosetting plastics established, let’s look at what applications each type of polymer has within various industries.

Applications for Thermoplastic Polymers

Thermoplastics can be found in virtually any industry, with products ranging from milk jugs to piping systems. Because thermoplastics can withstand corrosive conditions, they work well as a substitute for metals but cannot withstand high temperatures as well as thermosets.

Industries utilizing thermoplastics include:

• Construction
• Electronics
• Medical and biomedical
• Food and beverage
• Chemical
• Automotive
• Plumbing
• And many more

Applications include:

• Fabricating ropes or belts
• Insulating electrical cabling
• Liquid storage tanks
• Protective covers for rigid equipment

Applications for Thermosetting Polymers

Offering an excellent combination of chemical resistance, structural robustness, and thermal stability, thermosetting polymers are widely used throughout a range of industries, as they offer an economical means to meet many production specifications. They are easily formed into complex geometric shapes that metal components cannot easily achieve, and components made via RIM and RTM techniques allow for considerable consistency in the fabrication process.

Sectors that use thermosetting polymers include:

• Adhesive and sealant
• Aerospace and defense
• Agriculture
• Appliance and electrical
• Automotive
• Energy
• Construction

Applications include:

• Equipment for generation of chlorine and other chemicals like piping, fittings, or cell covers
• Electrical or medical equipment housings and components
• Heavy construction or transportation equipment like doors, panels, or housings
• Livestock feeding troughs and other agricultural products
• Motor vehicle and tractor parts
• Military vehicle components

Contact Us

Understanding the difference between thermoplastics and thermosets is essential for both manufacturers and product designers alike. Osborne Industries specializes in thermoset manufacturing using RIM and RTM. To compare materials, use our online tool to help make the best selection for your project. To discuss our capabilities with thermosets and how they can offer added benefits to your products or parts currently made of metal or other materials, please contact us today.

Learn More About These Plastic Molding Processes

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Defense-ready products are often referred to as “military grade,” meaning they can be counted on to be of the highest quality and reliability. When products are competing at a global scale, precision, durability, and innovation are essential. The military relies on plastic molding with thermosets to:

• create equipment parts and casings
• safely store materials
• protect supplies and equipment

How Does Osborne Serve the Military Industry?

Osborne’s custom molding capabilities and ISO-certified quality control measures allow us to check all of those global competition boxes. With nearly 50 years of experience, we understand the minutiae of plastic molding materials and methods.

For each product we make, expert chemists develop the plastic formulation or composite that will provide the client’s desired level of hardness, flame resistance, corrosion resistance, impact resistance, and abrasion resistance. We have the capabilities to create two-piece, closed composite molds that provide better product quality than open molds. Our selection of molding processes — resin transfer molding (RTM), reaction injection molding (RIM), or RIM with polydicyclopentadiene (pDCPD) — offer the capacity to further customize the final product.

Military Industry Applications

The following are examples of two parts we supply to our armed forces:

Light-Armor Battery/Ballistics Cases

• Material: FRP composite, which provides high-strength glass reinforcement and flame-resistance.
• Process: RTM, which allows for the ability to build the cases to the military’s exact specifications.

Military Truck Fender

• Material: Hybrid polyurethane, which is custom formulated for all-weather impact resistance.
• Process: RIM, which creates a product that meets or exceeds all military requirements.
• Additional service: A five-axis CNC router is used to achieve a precise fit.

What Can We Do for You?

Do you have a complicated equipment need that requires a customized approach? Give us a call at 1-800-255-0316 or fill out our online form to discuss your project with a qualified Osborne specialist.

This is part of a series about thermoset plastic applications in various industries. Learn how custom plastic molding benefits the heavy machinery, agriculture and chemical manufacturing industries as well.

The post Custom Molding with Thermoset Plastics at Work: Military Industry Edition appeared first on Osborne Industries.

Why Choose Plastic Molding?

Plastic molding allows a versatility that most metals just can’t provide, offering flexibility in size, shape, and performance characteristics. By choosing the ideal plastic material or composite, along with the molding process that best fits the project, clients can control the part’s corrosion resistance, stiffness, impact strength, and heat or flame resistance.

Plastic can also be an economical option. Switching sheet metal equipment components to thermoset plastics can reduce the number of parts for a product and simplify installation. Less labor results in savings, and the plastic’s longevity decreases replacement costs and lost productivity due to repairs.

Heavy Machinery Thermoset Plastic Applications

For more than 50 years, Osborne has helped companies in the heavy machinery industry meet their most complicated equipment needs with custom plastic products. Molding services at Osborne include resin transfer molding (RTM) and reaction injection molding (RIM), including RIM molding with highly engineered materials like polydicyclopentadiene (pDCPD). Osborne also offers value-added turnkey solutions with a variety of support services, which include CNC machining and metal fabrication..

Here are a few parts molded at Osborne that are used by the heavy machinery industry:

Aerial Lift Platforms (Aerial Lift Buckets)

Used by companies who manufacture equipment that elevates workers for electrical line maintenance, tree trimming, and more.

• Material: Fiberglass reinforced polymer (FRP) composite, which reduces a bucket’s weight by 30% and increases its strength by 200% (compared to steel alternatives).
• Process: RTM, which allows color customization of the buckets and a matching in-mold gel coat. Ribs and skids are also molded in for support.
• Additional service: Brackets are added, mounting holes are drilled and steps are structurally bonded to the buckets.

Portable Lighting Equipment Enclosures

Used by sports organizations, municipalities, emergency personnel, and others to supply temporary, supplemental lighting. Osborne has manufactured doors for the lighting equipment’s electronics housing.

• Material: Telene^® pDCPD instead of steel doors that are prone to rusting and denting, this plastic also provides impact and corrosion resistance, as well as thermal stability in hot or cold weather. Choosing pDCPD increases a door’s paint adhesion and reduces the number of parts it requires.
• Process: RIM, which provides more aesthetic benefits along with the ability to incorporate additives for specialized resin formulations.

Concrete Truck Fenders

Mounted over the wheels of concrete trucks and other heavy vehicles to provide housing for taillights and prevent the wheels from throwing water or debris.

• Material: Hybrid polyurethane and/or DCPD, determined to be the best option by extensive finite element analysis. Both materials are flexible yet strong, and better able to withstand the violent vibrations and impacts that made metal fenders break down.
• Process: RIM, which provides the ability to add conduit inside the molded fender for easy installation of tail light wiring.
• Additional service: Holes for taillights are drilled.

Every part molded at Osborne is subjected to intense quality-control inspection before, during, and after molding, per company policy. This careful oversight has not only earned Osborne ISO certification, but thousands of satisfied customers all over the world.

Wondering if a custom-molded plastic product might be right for your equipment? Give us a call at 1-800-255-0316 or fill out our online form to speak with a qualified Osborne specialist.

This is part of a series about thermoset plastic applications in various industries. Learn how custom plastic molding benefits the military, agriculture and chemical manufacturing industries as well.

The post Custom Molding with Thermoset Plastics at Work: Heavy Machinery Industry Edition appeared first on Osborne Industries.

The flexibility offered by custom-molded thermosets has allowed Osborne to assist ag equipment manufacturers with crafting innovative equipment parts that stand up to harsh conditions, boosting performance and durability. As residents of rural Kansas, we see firsthand how important these two qualities are to the agriculture and farming community, who counts on those parts.

Each ag equipment component produced at Osborne is created with its own unique combination of plastic materials or composites, using the molding process that best fits its purpose — resin transfer molding (RTM) or reaction injection molding (RIM) with innovative materials like polydicyclopentadiene (pDCPD). The result is a product made to exact specifications required for peak performance in the field — corrosion resistance, stiffness, color, impact strength, and heat or flame resistance — from a mold designed solely for the client and their part.

The benefits of thermoset plastic molding led John Deere^® to partner with Osborne for the production of two parts for their Model 9970 Cotton Picker. The two components required different plastics and were molded with different processes.

First, an industrial blower housing unit and cover was developed to contend with damp and abrasive cotton fields. Those conditions accelerated the corrosion process, which reduced the airflow that moves the cotton to the machine’s collection bin.

Industrial Blower Housing Unit

• Materials: Fiberglass reinforced polymer (FRP) composite with pre-molded reinforcing cores, pigmented to “John Deere^®” The composite was specially formulated to provide abrasion resistance.
• Process: RTM, which achieves the precise specifications required for the unit as well as enhanced airflow.

In the process of developing the blower housing, Osborne engineers were able to recommend another product that would simplify the manufacturing and installation of a louver for the engine compartment and hydro pump doors on the same machine.

Engine Louver

• Material: Polyurethane. Replacing the metal louver with one made of polyurethane reduced weight and component cost, improved airflow, and reduced inventory for John Deere^®.
• Process: RIM, which allowed for increased precision with John Deere^®’s specifications, adding strength and reliability.

These two high-quality products aced both in-house and worldwide field tests thanks to their design, material properties, and our ISO-certified quality control processes. Additionally, when molded products need additional supporting services, such as CNC machining or tool-and-die services, Osborne offers a convenient one-stop-shop experience.

Osborne Livestock Equipment

In addition to working with other equipment manufacturers, Osborne also manufactures hog feeders and other Osborne-branded livestock equipment. Utilizing similar materials and molding processes to the parts molded for John Deere^®, Osborne Big Wheel pig feeders provide outstanding performance in application.

• Material: FRP composite, chosen to produce a farm and animal-tough product.
• Process: RTM. Sharp precision allows parts to be used interchangeably across different models.

If you are interested in plastic molding for some of your organization’s equipment, tell us about your project! We’d love to answer your questions and provide you with a proposal to help solve your toughest material challenges.

This article is part of a series about thermoset plastic applications in various industries. Learn how custom plastic molding benefits the military, heavy machinery and chemical manufacturing industries as well.

The post Custom Molding with Thermoset Plastics at Work: Agriculture Industry Edition appeared first on Osborne Industries.

Each type of molding has its place within the plastics industry, with advantages and disadvantages for each.

Open Molding Process

Open molding is widely used in composite manufacturing, especially for fiberglass-reinforced plastic parts.

Advantages and Disadvantages of Open Molding

This process is generally less expensive since it doesn’t require the resin to be sealed off from the surrounding environment. Because tooling costs for open molds tend to be lower, open molding is more widely used for short production runs. It’s typically used for larger products for which automated processes are unsuited or products are made in very low volumes, where automation costs aren’t justifiable. As only one side of a finished part created in an open mold is smooth, the process is not appropriate for parts that require a smooth finish across all surfaces.

• Advantages: Low tooling costs, flexibility for large or custom parts, simple setup.
• Disadvantages: Slower cycle times, higher labor input, greater exposure to fumes, limited surface finish.

Types of Open Molding Processes

The three main types of open molding processes are:

• Hand lay-up molding is the least expensive and most common open molding method, with fiber reinforcement placed into a single mold cavity and resin applied via hand with rollers or brushes. It’s used for a variety of large and small products, including storage tanks, showers, tubs and boats.
• Spray-up molding is similar to the hand lay-up method, though it uses a chopper gun and other special equipment to cut reinforcing material into shorter fibers before adding it to the resin mixture on the mold’s surface. Because it involves some automation, this method tends to be used for producing on larger scales.
• Filament winding molding involves applying fiber strands that are saturated with resin to reinforce the material in a cylindrical mold that rotates. It’s less labor-intensive than other types of open molding methods and is used in the manufacture of items such as piping, stacks, chemical storage tanks, rocket motor casings, and other cylindrical composite structures.

Because tooling costs for open molds tend to be lower, open molding is more widely used for short production runs. It’s typically used for larger products for which automated processes are unsuited or products made in such low volumes that the cost of automating the process isn’t justifiable. As only one side of a finished part created in an open mold is smooth, the process is not appropriate for parts that require a smooth finish across all surfaces.

Closed Molding Process

Unlike open molding, closed molding takes place inside a sealed mold, producing parts with smoothsurfaces on all sides, more consistent quality, and less environmental exposure.

With closed molding methods, dry reinforcing material is placed into the mold, which is then closed. The plastic resin is then added into this enclosed cavity, using either a vacuum or pressure pump to infuse it with resin. Once the material cures, the mold is opened and the plastic part or product is removed. Closed molding via processes like Reaction Injection Molding (RIM) often do not utilize a reinforcing material, as the materials used are typically structurally sound without reinforcements.

Advantages and Disadvantages of Closed Molding

For most large scale plastic production, closed molding processes are more advantageous. When compared to open molding, closed molding techniques allow manufacturers to make better parts with less waste. Along with ensuring parts come out more consistently, they also look better cosmetically, thus requiring less work after the molding process.

Closed molding processes tend to be more expensive, however, as they require a greater capital investment. To counter the larger expenditure, closed molding systems produce significantly lower emissions, so they assist manufacturers in meeting emission requirements while reducing the need for protective equipment and lowering labor costs due to increased automation. Features such as in-house tooling or rapid prototyping can lower production costs for certain closed mold processes. For example, Osborne can reduce costs on RIM and RTM processes by producing in-house molds, providing the advantages of closed molding at a lower price point.

• Advantages: High-quality finish on all sides, repeatable parts, lower emissions, greater automation.
• Disadvantages: Higher capital investment, more complex setup, best for medium- to high-volume runs.

Types of Closed Molding Processes

The following are common types of closed molding processes:

• Centrifugal casting or rotational molding uses a rotating mold, where reinforcing material and/or resin solidify against the inside surface of the mold. The centrifuge holds the material in place as it hardens and cures, and the process is used to produce hollow cylindrical parts, such as pipes, tubes, and pressure vessels.
• Compression molding involves sandwiching composite materials between two matching molds, using heat and intense pressure until the part cures. Allowing for quick molding cycles and highly uniform parts, it’s used in the manufacturing of complex polymer components often reinforced with fiberglass.
• Continuous lamination combines resin and fibers in a highly automated process, sandwiching the two between two carrier films that are then steered along a conveyor. After forming rollers shape these into sheets, the resin is cured and used to make paneling and sheeting.
• Pultrusion allows for the formation of long, consistently shaped objects, using continuous strands that are moved through and soaked in resin baths. These elongated shapes are then pulled through heated steel molds and molded into lengths. The process can be easily automated and is used to manufacture solid or hollow bars, tubing, channels, pipes, rods, and structural reinforcements.
• Reaction injection molding heats and combines multiple liquid resins separately as they are injected into a closed mold. Composites made through this process feature lower labor hours, quicker cycling, lower scrap rates and low-pressure mold clamping. An almost identical process called reinforced reaction injection molding (RRIM) introduces reinforcing material into the composite mixture. This process allows fashioning of products that include body panels, vehicle bumpers and fenders, spoilers, roofing fascia and floor paneling.
• Resin transfer molding, also referred to as RTM, involves loading reinforcement materials, often fiberglass, into closed molds, which are then clamped before pumping resin under pressure into the cavity through injection ports. This procedure allows manufacturers to produce complex parts with smooth finishes and can be applied to either simple or highly automated processing. This process allows for limitless combinations and orientations to be used, including three-dimensional reinforcements. It’s used to make yacht hulls and decks, windmill rotor blades and for various purposes in the automotive, aerospace, military and defense, wind energy, and construction industries.
• Vacuum bag molding improves the laminate’s mechanical properties, by which liquid resin is applied to reinforcing fibers before a vacuum is used to force out excess resin and trapped air to compact the laminate. This process offers greater adhesion between sandwiched layers and helps eliminate excess resin buildup often found with the open molding hand lay-up technique. It’s typically used in manufacturing products across a wide array of industries, though its molds are similar to those used with standard open mold methods.
• Vacuum infusion processing uses vacuum pressure to infuse resin directly into laminate, using inexpensive and minimal equipment. Used for low-volume products, this technique typically is used when manufacturing very large structures, producing lightweight laminates while reducing emissions. It’s a more recently developed technique that is used to manufacture large objects such as wind turbine blades, boat hulls or structures in the aerospace industry.

When compared to open molding, closed molding techniques allow manufacturers to make better parts with less waste. Along with ensuring parts come out more consistently, they also look better cosmetically, requiring less work after the molding process.

Closed molding processes tend to be more expensive, however, as they require a greater capital investment. To counter the larger expenditure, closed molding systems produce significantly less emissions, so they assist manufacturers in meeting emission requirements while reducing the need for protective equipment and lowering labor costs due to increased automation.

RTM & RIM Closed Molding Processes at Osborne

Two types of closed molding processes in which Osborne specializes are resin transfer molding (RTM) and reaction injection molding (RIM). Using proprietary and custom techniques, Osborne provides manufacturers with economical composite molding and is capable of producing extended runs through unique in-house molding processes.

Having the ability to produce composite RTM tooling in house, Osborne offers much greater cost-effectiveness when compared to compression equipment. The company’s RTM molds provide customers a better return on investment than simpler open molds, and Osborne can easily match production capacity, even on larger-scale projects.

Durable and inexpensive, Osborne’s RIM molds allow greater flexibility in earlier stages of production while allowing conversion to high-speed metal tooling for high-volume production. Osborne’s RIM molding process allows manufacturers to test new designs, tie investment to market demand and increase production as demand increases.

Learn how Osborne’s custom molding support services can add value to your project or try our web tools to compare and select the best material and process for your needs.

Contact the Closed Molding Experts at Osborne

Osborne offers composite molding that produces high-quality components quickly and efficiently, outperforming other tooling and processes used by competitors. Have more questions? Ready to get started? For more information about our plastic molding capabilities for your next project, contact the experts at Osborne Industries today

The post Differences Between Closed Molding vs Open Molding appeared first on Osborne Industries.

One plastic manufacturing process — reaction injection molding (RIM) — is gaining popularity because it can deliver a strong yet lightweight part, often at a lower cost than alternative processes.. Learn more about the RIM manufacturing process in this beginner’s guide to see if it might be right for your next project.

What is RIM?

The basics of RIM are simple: It combines liquid resins into closed molds to produce plastic parts.

The resins are stored in separate tanks. When the manufacturing process begins, the resins are pumped into a mixing chamber. The pressure and speed at which they’re combined starts a chemical reaction that bonds molecules from the two resins. The resulting mixture is immediately injected into a closed mold, where the chemical reaction continues, and the newly formed material — a thermoset plastic — cures, or hardens, into the desired shape. (Thermoset plastic refers to plastic that cures through heating.)

The entire process can take as little as a few seconds or a few minutes, depending on the size of the part.

Benefits of RIM

In addition to forming strong yet lightweight parts, RIM molds can be complex, meaning the designs can have more complicated shapes or geometries. Not all manufacturing processes can support the same level of detail.

Because the RIM process doesn’t take a long time, you can quickly create prototypes and manufacture parts.

RIM is a great option if you don’t have a large production run. Because the initial tooling investment is fairly low, RIM is ideal for medium-sized quantities.

Lastly, RIM is versatile. It can produce rigid or flexible parts, depending on the materials used.

Materials Used in RIM

Polyurethane is one of the most common types of plastics found in RIM, but other thermoset plastic options include dicyclopentadiene (DCPD) and polyimides. These materials are very durable. They’re resistant to corrosion and impact, and they can withstand high temperatures and other harsh conditions. Osborne specializes in thermoset plastic molding, and many of the products we make are for original equipment manufacturer (OEM) parts, which often call for the strength these plastics can provide in the field.

Applications of RIM

Thanks to the versatility and durability found with RIM products, it’s used in a variety of industries.

• Automotive, agriculture, military, and construction: Fenders, bumpers, dashboards, and other heavy-duty equipment panels
• Medical: Enclosures for equipment such as MRI machines
• Industrial: Machinery housing
• Furniture: Custom parts, such as for gaming chairs
• Consumer: Housings for appliances such as refrigerators and air purifiers

How RIM Compares to Other Molding Processes

RIM can support complex designs, results in strong parts, and can accommodate low or medium production volumes. See how these features stack up against other manufacturing methods.

• Standard injection molding is when plastic pellets — thermoplastics — are melted and injected into a mold under high pressure. This can also produce strong parts but is better suited to larger production runs than RIM. RIM requires a lower tooling investment, making it a cost-effective option, especially for lower volume production.
• Blow molding is used for manufacturing hollow products. In this process, thermoplastics are heated, then air forces the pliable plastic into the sides of the mold. These designs are typically less complex, and the products are not as strong as those made using RIM.
• Rotational molding, also called centrifugal casting, is when plastic in powder form is placed inside a mold. Then the mold is heated and rotated, so the plastic sticks to the sides. This process is also used to make hollow items. Like RIM, this process supports lower production volume, but the parts are not as strong.
• Compression molding uses thermoset resins, which are heated and compressed in a mold. This process is better suited to making simpler forms, while RIM allows for more design freedom.
• Thermoforming is when a plastic sheet is heated then formed onto a mold using positive (gauge) or negative (vacuum) pressure. These parts are simpler in design and not as strong as those produced using RIM.

All these methods use closed molds. (Thermoforming can use closed and open molds.) Because closed molds completely encase the plastic, the final products don’t have a rough surface that requires finishing. Products made with closed molds are more consistent right off the production line and result in less waste.

As you continue to research the RIM process, you’ll want to dive deeper into details. Osborne Industries provides specs for the machines and presses we use for our RIM clients.

Partnering with a Manufacturer

When you’re ready to get started, look for a manufacturer who will consult with you on your project. Osborne has been manufacturing plastics for over 50 years. Our experts can provide guidance and offer innovative solutions.

To discuss your project with a specialist, fill out our contact form, and we’ll get in touch to understand your needs and determine next steps. If you’re ready to start your project, request a quote for manufacture at Osborne.

The post Understanding Reaction Injection Molding (RIM): A Beginner’s Guide appeared first on Osborne Industries.

Today, the top producer of plastics is China. While the Chinese produced approximately 33 percent of plastic products in 2023, North American countries – Canada, Mexico and the USA – accounted for 17 percent. This isn’t surprising, as China has largely become the “world’s factory,” producing an outsized portion of goods globally. Yet the American plastic industry is one of the strongest, and USA molding continues to lead the world in technological advancements.

Made in the USA: Molding Advantages for Product Manufacturers

The world is connected globally, and even when tensions run high, trade is still a vital part of international relationships. As such, manufacturers can source products and services from anywhere in the world, including plastics produced by various methods like injection molding, resin transfer molding (RTM), and reaction injection molding (RIM). Benefits the USA offers many benefits over competing countries, with the following seven reasons being just the tip of the iceberg.

Advantages of working with USA injection molding companies include:

1. Control & Ownership of Molds

In the USA, plastic molds and molding forms typically don’t belong to the company tasked with producing them. Though a handful of American toolmakers deal with prototypes, and low output production runs retain ownership of the molds they produce, ownership almost exclusively belongs to the end-product manufacturer. As long as they remain in good standing, product manufacturers shouldn’t have any problem moving their molding processes to another facility, regardless of whether they’re American or foreign plastic manufacturers.

2. Quality & Consistency

Excellent mold makers exist worldwide, but there’s a reason that the plastics industry (unlike many others) has continued to grow in the USA. Plastic molding by American companies is generally more consistent and of better quality, especially with processes like injection molding and reaction injection molding (RIM). The American-based Plastics Industry Association (PLASTICS) has set high molding standards for the industry to ensure superior workmanship, a crucial element in many products made from plastic. Products made with American plastics also often undergo more stringent inspection and must meet higher standards than those made abroad.

3. Shrinking Price Differential

Many product manufacturers who chose offshore production did so because of lower costs, particularly regarding labor. Yet in places like China, where much plastic production moved during the 20th century, rising wages offset these benefits. An increasing number of companies are also finding that the costs of things like raw materials, shipping, complex regulations, and even corruption, add to their expenses. These factors have prompted moves back to the USA, where composite molding is becoming increasingly economical.

4. Supply Chain Issues

The Coronavirus pandemic made a mess of the supply chain worldwide, and most industries are still feeling its effects. Injection molding customers that depended upon Chinese companies and other foreign sources for plastic components found themselves unable to continue production due to logistical difficulties. Add container shortages, factory fires, and a container ship blocking the Suez Canal, and logistics quickly turned into a nightmare. Disruptions in production point toward the need for manufacturers to source injection and other plastic molding companies closer to their production facilities.

5. Strategic Advantages

The oil and gas sector largely fuels the American plastics industry, as several common plastics require the use of ethylene, which is made from natural gas. As natural gas is a plentiful resource in the USA, injection molding in the country benefits from easy access to petrochemicals. Plentiful American shale oil and gas reserves give the country an advantage in plastic production, which will be increasingly important for oil companies as transportation-related demand for petroleum decreases.

6. Innovation

American innovation hasn’t faded in the plastics industry, even after more than a century. Processing methods for plastics and materials that were developed in the USA, like injection molding itself, have continued to be used by manufacturers globally. Advancements in automation and 3D printing have shown how American ingenuity continues to drive technological advancement, along with the development of new types of plastics. In 2020, chemists from the Massachusetts Institute of Technology (MIT) produced a new, degradable polydicyclopentadiene (pDCPD) thermoset plastic, possessing a superior combination of corrosion and chemical resistance, durability, strength, and resistance to heat as compared to typical materials used in traditional injection molding, but offering the recyclable benefits of thermoplastics.

7. Tariffs & Trade Wars

Domestic production doesn’t incur import taxes. In 2018, such duties were imposed on Canada, the European Union and Mexico regarding steel and aluminum imports. This affected the American plastics industry, which depends on such imports to support its manufacturing. That same year saw a trade war develop that affected many industries in both China and the USA. In total, approximately $200 billion in Chinese plastic products saw new import taxes, including molds, plastic machinery and components, pipes, hoses, flexible tubing, furniture, building products, luggage, and more.

In 2025, tariffs ranging from 10% to 145% were imposed on China. China retaliated with their own tariff announcements. This ever-evolving trade war has pushed many businesses into uncertainty, with the price of supplies fluctuating often. Relying on American producers removes this worry altogether and makes business projections easier to determine.

USA Injection Molding by Osborne Industries

Osborne Industries specializes in thermoset plastics, particularly liquid molding using reaction injection molding (RIM) and resin transfer molding (RTM) methods. Our company has over 50 years of practical experience in composite production, which makes us the ideal partner for manufacturers who need to resolve challenging issues regarding plastics being produced abroad. Our experienced team works with a range of materials and can formulate custom materials to meet the most demanding of applications. To learn more about our capabilities, please contact us today.

The post 7 Advantages of Working With a USA Injection Molding Company appeared first on Osborne Industries.

At Osborne, we create plastic products custom-molded for your specific equipment needs. One of the first steps in creating a custom-molded plastic part is considering how the product will be used so that the right material and molding process can be selected. Factors like heat resistance, strength, stiffness, and impact resistance can be tailed to the part’s specific use so that your product remains durable over time and maintains a long lifespan.

If you have ever considered custom plastics, but aren’t sure where to begin or what your options are, our material selection tool and process comparison tool can help you get started.

Material Selection Tool

When selecting the right material for your part, there are a handful of factors to consider. With our new material selection tool, a step-by-step series of considerations are presented that can help you determine the right material and process for your new project.

First, what kind of temperatures will your part or product be exposed to over its lifetime? This could range from extreme cold (minus 40 degrees Fahrenheit) to extreme heat (320 degrees Fahrenheit). For this question, we want you to choose the most extreme temperature that the product could experience. This helps us know if the material needs to be resistant to cold or heat.

For the second question, we dive into size. More specifically, the largest dimension for the part. If the measurement is approximately 20 feet by 10 feet by 5 feet, you’ll need to select “20 feet” in the dropdown menu.

Next, how many production parts will you need annually? For this dropdown, select the option that best fits your volume needs, which can range from fewer than 99 to more than 100,000 pieces.

Question four deals with part flexibility. All materials fail after a certain amount of pressure is applied, but some are much stronger than others. Options range from extremely flexible like a seat cushion or a rubber sole to more rigid like hardwood flooring or porcelain.

Lastly, how important is it that your part is lightweight? For this question, we want you to consider the importance of its weight to the other four factors involved: temperature, size, volume and stiffness. If the other factors are far more important than how light it is, then select “not important.” If weight trumps the other requirements, select “very important.” If all characteristics are about the same level of importance, you can select “somewhat important.”

Once you’ve made your selections and clicked “show results,” the tool displays which material is most suitable for your requirements from 0 to 100 percent compatibility levels.

Process Comparison Tool

Another tool now available to aid in determining the right process for your molding project is our process comparison tool. This tool compares two molding processes, outlining various features, capabilities, requirements and more.

Process options with the new comparison tool include:

• Reaction injection molding with DCPD
• Reaction injection molding with polyurethane
• Long fiber injection
• Resin transfer molding
• Vacuum infusion
• Pultrusion
• Compression molding
• Injection molding
• Blow molding
• Rotational molding
• Hand lay-up
• Spray-up
• 3D printing

Selecting processes from the dropdown menu will allow you to compare composition, process capabilities, material capabilities, tooling requirements, and advantages and disadvantages.

Let’s say, for example, you want a custom-molded plastic part made but you can’t decide between reaction injection molding (RIM) and thermoplastic injection molding. Using the tool, you can see that while injection molding is better suited for high volumes, its mold cost compared to RIM is higher, and it isn’t suitable for very large parts. Important advantages and disadvantages for both are also displayed that can help you consider which process is best.

You can make unlimited process comparisons using the tool, so don’t be afraid to continue evaluating until you fully understand your options. We created these tools to give you a better idea of the material options and processes available to you, whether that be from us or another manufacturer.

If you’re still on the fence after diving into the tools, let us help you decide if a custom-molded plastic product is right for you. Contact us today.

The post Comparing Plastic Materials and Molding Processes for Your Next Project appeared first on Osborne Industries.

As a leader in custom plastics manufacturing and molding, Osborne Industries has decades of experience helping our customers understand the different reinforcement materials available for their products. We’ve collaborated with clients to produce custom composites that support everything from aerial lift platforms and agricultural equipment to parts for the medical and construction industries.

Choosing the right reinforcement material is critical to developing a reliable and long-lasting product. Fiberglass, aramid, and carbon fiber all have pros and cons to consider when planning your project.

Fiberglass

Fiberglass is strong yet lightweight. It’s made of thin, intertwined glass strands, which are impregnated with polyester resin during the Resin Transfer Molding (RTM) process. Fiberglass is considered the most common reinforcement for composites.

As the name implies, fiberglass has characteristics of glass. It does not rust or absorb moisture and is a relatively affordable material to use in manufacturing. It’s versatility allows for use in components and parts like boats, pools, pipes, tanks, and much more.

Using fiberglass will result in a cost-effective, structurally strong product. Fiberglass has the lowest price tag of the three materials.

Aramid

Aramid is a lightweight, synthetic fiber famous for its strength and resistance to impact and heat. These properties make it ideal for use in parts requiring ballistic protection.

Despite aramid’s impressive heat-resistant characteristics, it’s sensitive to sunlight and can change colors. Without UV protection, parts can even begin to degrade with too much UV exposure.

Using aramid will result in a lightweight but strong and durable product. Aramid is usually more expensive than fiberglass but less expensive than carbon fiber.

Carbon Fiber

Carbon fiber, composed of thin carbon filaments, has the highest material strength and strength-to-weight ratio of the three materials. It’s also the most rigid. Carbon fiber is frequently used in the manufacture of electronic, aerospace, automotive, sport, and drone components.

The impressive features of carbon fiber, however, come at a cost: carbon fiber is typically the most expensive of the three materials. In addition, carbon fiber’s stiffness can cause it to break easily if excessive pressure or impact is applied.

Choosing the Best Material for Your Project

Deciding whether to use fiberglass, aramid, or carbon fiber comes down to your project’s unique requirements. If strength-to-weight ratio is most important and budget allows, carbon fiber is a great choice. Aramid works great in a scenario requiring high performance and impact resistance. For a product dependent on versatility and cost-effectiveness, consider fiberglass.

If you have questions about which reinforcement materials to use in your next custom molding project, contact us today!

The post Three Common Reinforcing Materials for Plastics appeared first on Osborne Industries.