Techniques such as gas-assisted molding produce plastic parts with smooth, good looking outer surfaces. This allows the manufacture of many products that previously required other more expensive processes.

Structural foam molding is mainly used to manufacture larger parts and components that are extremely strong and durable.

Traditional injection molding uses large amounts of machine pressure to fill a mold with melted plastic. Structural foam is similar; however, it uses lower machine pressures and a foaming agent to fill a similar mold.

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With the very large-sized molds often needed for structural foam molding, the cost savings or aluminum compared to steel molds is also significant.

High-pressure molding, typically referred to as injection molding, solely uses machine pressure to fill a mold. Low-pressure molding uses both machine pressure and a chemical blowing agent to fill and pack the mold into the desired product shape.

Other colors of resins are available and can be used. However, some colors, such as blue, can be affected by prolonged exposure to sunlight.

PP has very good overall property ratings. It scores slightly lower for impact resistance and compressive strength but is a very cost-effective material.

Plastic Structural foam molding is unique in the size, strength, and versatility it provides. The range of opportunities it brings designers and engineers is just as great.

Modern low-pressure structural foam molding machines are highly advanced. The presses feature technology and controls that allow the production of very large parts with superior strength and surface cosmetics that rival high-pressure injection molding.

These are the specifications of a few of the machines in their range. More press specs can be seen on our facilities page.

RIM molding is a chemical reaction where two different materials are combined to create a third material after molding. RIM is a very low pressure molding operation and the tools are much simpler than those used for structural foam molding. Structural foam is thermoplastic before, during and after the molding process.

Its high material ratings make it higher in cost compared to the other materials commonly used in structural foam molding.

The Gas Assist Injection Molding process uses nitrogen gas to create lightweight plastic products that have a superior surface appearance. Since the gas disperses evenly throughout the mold, the process can be used to create thin-walled parts that can be formed to a high standard of flatness without sacrificing strength and durability.Lomont Molding is a diverse company where people are the foundation. As a company, we reject discrimination. Anyone who knows our company, knows this. We value our customers, suppliers, employees, along with our communities where we are actively engaged.

Suggested nominal wall section is .250 inches. Parts can be made with thicker wall sections but this increases cycle time and adds to the cost.

When a product’s specifications call for a more attractive outer surface, techniques such as gas-assisted molding reduces and even eliminates swirling. These advanced techniques are outlined below.

Our most popular material is recycled high density polyethylene. Other popular materials are polypropylene, ABS, Styrene.

Over-Molding utilizes heat and pressure, which allows Lomont to mold two materials together. We offer Over Molding services that are utilized for a range of applications including electronic devices, medical devices, automotive components, appliances, and others. Over-Molding is available for various material types.

Since structural foam molding is injection molding much of the process, technology, terminology and design considerations are the same as with conventional injection molding.

The composition of the finished molded plastic makes is very strong, rigid, impact-resistant and impervious to extreme weather conditions.

It is a low-pressure plastic injection molding process used as an alternative to vacuum forming, rotational molding, sheet metal, & traditional injection molding to manufacture large, ridged, & element resistant parts

This is a fabrication process that is used to make decorative architectural pieces used in the home building industry. Expanded polystyrene (EPS) or molded urethane are often used to make items such as balusters,, columns, crown moldings and other architectural products.

HIPS is hard and rigid with highly rated tensile strength, stiffness and compressive strength. It does not rate as highly for impact resistance compared to other materials. This makes it better suited for products such as tanks and enclosures which don’t need to stand up to large amounts of impact.

Lomont Molding, LLC is a premier plastic molder offering complete in-house services including engineering, tooling, in-mold technologies and decorating, quality assurance, and assembly and secondary operations. We have been in business since 1982 and process various types of thermoplastic resins in our state-of-the-art manufacturing facility.

Yes, however the difference in thermal expansion between the insert and the structural foam plastic material can cause issues with the heating and cooling cycle.

The blowing agent aids the fill and pack of the tool cavity so a smaller tonnage machine is required. Smaller machines save on machine costs.

Structural foam molding allows for high-quality mass production of many products that used to require bulky materials and high amounts of hand assembly work.

Thermoforming involves shaping a plastic sheet by heating it to a high temperature and forming it over a mold. Vacuum forming, a subtype of thermoforming, employs a vacuum force to draw the heated plastic into the contours of the mold.

Impossible to answer without seeing your part design but suffice it to say that tools of this size and complexity are usually many 10s of thousands of dollars. Schedule a consultation with our team to get a quote!

Black resin is most commonly used for structural foam molding. One reason is that regrind resin material is often used when suitable. We molded over 40 million pounds of recycled material in 2019.

Low-pressure molding requires thicker wall sections in order to allow the foaming agent to expand. If the wall sections were too thin, the foaming agent wouldn’t have room to expand and the part would have solid wall sections like a high-pressure part. High-pressure molding uses thousands of pounds of pressure per square inch compared to low-pressure molding which only uses hundreds of pounds. The blowing agent works with the machine pressure to fill the mold.

Structural Foam Molding is used to create lightweight molded parts with dimensional stability and strength-to-weight performance. Structural Foam Molding can reduce molding costs and conserve raw materials and works for parts of all sizes but is ideal for large parts, particularly those that require thicker walls.

Structural foam molding is the cousin of injection molding. The major difference is how the molds are filled. Structural foam uses inert gas pressure to fill the tools while injection molding uses hydraulic or electric machine pressure.

Gas assist uses gas channels while structural foam molding uses a gas blowing agent. We sometimes will use both processes in the same part.

Our high pressure plastic injection molding  process is ISO 9001 Certified and is suitable for molding a wide range of materials. Injection molding is a low-waste, low-cost process that is suitable for production runs of any size, and the final product typically requires little to no finishing.

Structural foam is used for many outdoor and garden products. Green or brown materials are commonly used for these types of products.

Other than the size and physical properties of the parts produced, here are a few of the notable differences between structural foam and conventional injection molding:

In its most basic form, single-nozzle structural foam molded parts will have a visible swirl on the outer surface. This swirling is also known as silvering or streaking. Swirling is usually not an issue for parts that do not require a high cosmetic finish, for example on reservoir or tank units that will be buried underground.

Regrind refers to recycled plastic material – recovered from post-consumer or post-industrial sources – with potentially variable properties. Regrind is generally the most cost-effective option, great for applications where consistency and finish are a lesser priority.

Blow Molding involves inflating hot thermoplastic inside a closed mold, and is used to produce hollow plastic parts. Our Blow Molding capabilities include stretch blow molding, injection blow molding, and extrusion blow molding. We utilize a wide range of thermoplastic raw materials for the molding process.

With proper care aluminum tools can last much longer than steel molds used for traditional injection molding. Molds have been known to last 25 years or longer.

ABS is an opaque thermoplastic and amorphous polymer. It performs very well across the board including tensile strength, stiffness, impact resistance, compressive strength and combustibility.

Lomont’s Manufacturing Services are focused on delivering quality products and development utilizing the latest technologies in CAD software. We can assist with all stages of product and tooling development and offer services to help you reduce tooling costs and lead times.

Critical considerations when designing a part and tool for any plastic injection molding and special factors for structural foam include the following:

We will request quotes from several highly qualified tool makers. From those bids we select the best candidate to build your tools. The price of the tools are not marked up. We send them as a straight pass through.

Lomont provides secondary operations and assembly services to prepare your product for distribution including: painting, shielding, balancing, date coding, labeling, post-production bending, part assembly and packaging.

In similar fashion as typical thermoplastics, structural foam parts made out of the correct materials can be glued together.

Virgin prime material is newly produced, high quality plastic resin created with strict quality control measures for use in applications where quality and consistency are crucial (medical or food packaging). Virgin prime material is typically more expensive than other resins.

Typical part sizes range from around 12”x12”x12”, about the size of a kitchen toaster, to a maximum size of 6’x6’x3’ or larger depending on the part geometry. Flat panel-like parts can be molded as large as 13”x6’ or larger in dimensions.

Along with the Frequently Asked Questions about low-pressure plastic injection molding below, we’ve created a Low-Pressure Structural Foam Molding Design Guide to help you get the most out of this valuable process.

Painted finishes can also be applied to structural foam parts when a very high level of finish is desired. However, the cosmetic finish produced with the latest structural foam molding technology means that painting is not needed for many parts even those that are visible on the exterior of a finished product.

Extrusion is used to create plastic products with a continuous cross-section such as pipes and decorative molding. Plastic extrusion uses raw thermoplastic beads that can be enhanced with custom colors and UV inhibitors, and is a versatile molding process that is inexpensive and can be used for a wide range of applications.

The biggest difference between the two processes is the pressure at which the molten plastic is injected into the mold cavity. Low-pressure structural foam injection molding is different from traditional injection molding because it is used to produce larger, less dense parts with a thick wall section on smaller tonnage machines.

HDPE is a lower cost material. However, it rates highly for impact resistance, weather resistance, mold and mildew resistance which makes it a good choice for many types of structural foam molded products such as outdoor consumer products.

Multi-nozzle molding is a beneficial technology that is often used with structural foam molding. Multiple gates and the ideal gate location need to be included in the tool design.

Wide spec virgin is newly produced plastic that doesn’t meet the strict requirements of prime material, exhibiting minor variations in color or melt index. Wide spec costs less than virgin prime but is still new resin suitable for applications with less stringent appearance standards.

Low-pressure molding is also less stressful on the tool itself compared to high-pressure molding. This extends the lifetime of the tool and saves money.

NOTE, structural foam molding can be and is used to manufacture architectural pieces such as crown moldings. Structural foam would be used when a much more robust product and/or larger quantities needed.

Other than generally being much larger in size, there are other differences between structural foam and conventional injection molding tools that must be designed and built into the tool.

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Just as with high-pressure molding, a top-quality tool-maker will serve the manufacturing company well when designing, building and testing your molds.

This is a foam material fabrication process that uses 3-D CNC Cutting, Die-Cutting, Heat Thermoforming and other techniques used to manufacture seat cushions, foam packaging inserts, safety foam materials and other items made of soft foam.

Polypropylene is commonly used for structural foam molded crates and boxes. It also holds up well against cleaning agents which makes it a good option for medical equipment. It is also used for products that require a higher flammability rating.

The low pressures used in structural foam molding mean that aluminum tools can often be used. This saves money on tooling costs.

With ‘structural’ and ‘foam’ in its name, it is not surprising that other manufacturing processes are sometimes confused with structural foam molding.