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.

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

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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.

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.

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.

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:

Post-industrialrecycled materials are the residual and discarded materials from the first production of a plastic items in companies. They are the most widely used materials in the plastic recycled sector because of their greater availability and facility of certification. At Maspi, each plastic material is carefully certified to be reused in a second production. This type of recyclate is the most used by Maspi for the Restylon Co-injection production.

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.

Post-industrialrecycled materials are the residual and discarded materials from the first production of a plastic items in companies. They are the most widely used materials in the plastic recycled sector because of their greater availability and facility of certification. At Maspi, each plastic material is carefully certified to be reused in a second production. This type of recyclate is the most used by Maspi for the Restylon Co-injection production.

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

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.

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.

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.

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.

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.

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.

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

Maspi aspires to be among the best plastic molding companies in the use of recycled plastic materials. Reuse of discarded waste elements is an unavoidable driver for the company, this in fact generates value not only from an economic point of view but also in terms of sustainability.

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.

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.

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!

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

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.

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.

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.

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.

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.

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

Post-consumer recycled plastics are items used and consumed by humans such as, plastic bottles, tetrapak, or food tubs. Even these can be reused for the production of new items as long as one is able to properly separate the different types of plastic. In the furniture industry, this type of recyclate has not yet been used frequently, so Maspi is engaging in the study and analysis of a new polymer from tetrapak recycling in order to create new more sustainable designs.

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.

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

Post-consumer recycled plastics are items used and consumed by humans such as, plastic bottles, tetrapak, or food tubs. Even these can be reused for the production of new items as long as one is able to properly separate the different types of plastic. In the furniture industry, this type of recyclate has not yet been used frequently, so Maspi is engaging in the study and analysis of a new polymer from tetrapak recycling in order to create new more sustainable designs.

Each recycled material in order to be properly reused must be carefully separated and identified exactly so that it can later be properly reprocessed.

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

Maspi aspires to be among the best plastic molding companies in the use of recycled plastic materials. Reuse of discarded waste elements is an unavoidable driver for the company, this in fact generates value not only from an economic point of view but also in terms of sustainability.  Maspi reuses in each of its products, thanks to Restylon co-injection technology, certified post-industrial recycled material that allows to drastically cut CO2 emissions by one-third and to avoid having to dispose of waste from the production area, which is instead stored and reinserted when needed.  Each recycled material in order to be properly reused must be carefully separated and identified exactly so that it can later be properly reprocessed.

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

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

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

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.

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

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.

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.

Maspi reuses in each of its products, thanks to Restylon co-injection technology, certified post-industrial recycled material that allows to drastically cut CO2 emissions by one-third and to avoid having to dispose of waste from the production area, which is instead stored and reinserted when needed.

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

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.

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

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.

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.

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.

Fill out a quote form or schedule a free call with our experts for smart solutions and American-made large structural foam and gas assist plastics

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.

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

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.

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.

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.

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

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

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.

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.

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.

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.

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.

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