• STRUCTURAL FOAM MOLDS

Structural Foam Molding

WIT MOLD has expertise in plastic injection mold with medium to large complex designs, we have the ability to produce equipment and tools of almost any size. WIT MOLD not only provides custom injection mold. For many years, we have been providing high-quality injection molding parts . Our injection molded parts include plastic covers, handles, baffles, plastic panels and plastic enclosures for the medical, commercial, financial and laboratory markets.

WIT MOLD, a trusted mold manufacturer from southern China with over 10 years of experience, specializes in injection molds and offers a wide range of mold types, including BMC molds, collapse core molds, die casting tools, gas assist molds, high precision molds, and more. With 2,000+ molds successfully exported to various industries such as automotive, household appliances, medical, and telecommunication, WIT MOLD is committed to ensuring the success of every project. Backed by a well-trained team, we provide efficient support from RFQ to shipment, making us your reliable partner in mold making.

WIT MOLD provides many injection molding services to meet your standards for molding large plastic parts. No matter what your requirements are, we can provide suitable injection molding process and equipment to make your products stand out from the competition. Services range from engineering and design to final assembly, decoration and transportation. WIT MOLD is your single source for your entire project and complex components. Our internal service portfolio can help simplify your supply chain, reduce costs and shorten delivery times. Contact us now to discuss your injection molding needs.

Stuctural Foam Molding

Stuctural Foam Molding

WIT MOLD To ensure that all mold or injection molded products always meet your expectations, our highly skilled team is trained to use the most modern quality assurance methods:

ISO 9001:2015
Statistical process control
Team-oriented problem solving
Gage R&R Research
Continuous improvement
Three-dimensional layout
Gage measuring system
Advanced Quality Plan (AQP)
Color measurement system

Structural foam molding is an injection molding derived process that either adds a gas to the polymer to reduce its density or introduces blowing agents to achieve the same result. When the gas or blowing agent is added the plastic foams, hence the name. The end result is a lighter product that requires fewer post-production processes and less assembly.

Types of Structural Foam Molding

There are two main types of structural foam molding. The first type is known as the low-pressure process. During this process, a gas is added to the melted plastic before it enters the mould. Once the plastic is injected into the mould the gas causes it to foam.
The second type of foam molding uses ordinary injection molding machines but includes a blowing agent in the material mix. These blowing agents are dry chemicals that are added to the plastic granules before they enter the machine. When the plastic is melted by the machine’s heating elements the heat causes the blowing agent to react, turning into a gas and foaming the plastic.
The texture of the plastic these processes produce is often described as a sponge or honeycomb because of the small pockets of air that are created. The honeycomb centre is surrounded by a dense outer layer to ensure stability.
In some cases, the finish of a product created using structural foam molding is not acceptable as it creates a streaky surface. This can be remedied with extra filling or painting.

Structural Foam Molding Uses

Structural foam molding is a commonly used process that can create many useful products. The low-pressure version of structural foam molding is a more controlled process than standard injection molding. This allows larger pieces to be produced.
In addition, structural foam products have a high stiffness ratio that can be beneficial in many settings. What’s more, since structural foam products are coated with a strong outer skin, they remain strong, as well as flexible and lightweight.
Some common uses of structural foam are in the making of machine housings for businesses, components for point-of-sale displays, container pallets, and machine chassis components.

Structural Foam Molding Materials

Many different types of plastic can be used in the structural foam molding process. Each offers its own unique properties and characteristics. Commonly used plastics include the following:
Acrylonitrile-Butadiene-Styrene ABS
Polystyrene PS
Polycarbonate PC
Polypropylene PP
For more information about the types of plastics used in structural foam molding processes and injection molding see here.

Foam injection molding is a specialized process that produces lightweight and durable parts, often used in various industries. One common method is structural foam molding, where structural foam is injected into molds to create components with a strong yet lightweight core. Structural foam injection molding combines the benefits of traditional molding with the advantages of foam materials, making it ideal for producing large and complex parts. The structural foam molding process involves the use of structural foam materials that expand within the mold, resulting in a product with excellent strength-to-weight ratios.

Many foam injection molding companies specialize in this technique, offering expertise in the foam molding process to create durable, high-quality products. If you’re wondering what is structural foam, it refers to a type of plastic that is injected with a gas to form a cellular core, which is then surrounded by a solid outer layer. Injection foam molding and structural foam molders are crucial in industries requiring robust and lightweight components. The use of foam molds allows for precise shaping and intricate designs in the final product.

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What is Structural Foam Molding?

Structural foam is a composite material that is produced when a polymer (usually thermoset (but also thermoplastic)) is mixed with an inert physical gas (such as nitrogen) or a chemical blowing agent during the molding process. The result is not a solid material, but a combination of a low-density microporous “core” and a high-density external “skin”. The core reduces the overall weight of the material, while the strong skin keeps it strong and impact resistant.

Why use Structural Foam Molding?

The foam injection molding process can be used for parts of many different sizes to produce lighter, high-strength molded parts. Many large parts require wall thicknesses that can be efficiently produced by standard injection molding. Structural foam can achieve faster processing and cycle times on thicker parts. This low-cost molding process produces parts with reasonable structure, almost stress-free, and minimal warpage. WIT MOLD’s structural molded parts are thicker and stronger than those made by other processes.

Structural Foam Molding features

The structure of this material is like a sandwich, the low-density core is completely surrounded by the high-density skin. The texture of the core is often described as resembling a “sponge” or “honeycomb”. Due to its unique core texture, structural foams are generally 20% to 40% lighter than solid polymers, aluminum, steel, sheet molding compounds, or other commonly used materials.

Due to its less robust nature, the base material used to make structural foams is usually a thermoplastic polymer rather than a thermoset polymer. Commonly used thermoplastics include, but are not limited to: polyurethane, polycarbonate, polyphenylene ether (Noryl), polybutylene terephthalate (Valox), and acrylonitrile butadiene styrene.

Structural Foam Molding process

Structural foam molding is a low-pressure injection molding process that can produce very large structural parts. The molten plastic is mixed with the foaming agent and injected into the mold to “foam” the plastic. The structural foam injection molding process is very suitable for large plastic parts, because the foam bubbles in the resin matrix squeeze out the resin and reduce the incidence of plastic parts showing side sinking. Structural foam molded parts are usually very thick, with wall thicknesses close to 0.250 inches, making them ideal for making invisible plastic structural elements. Visible parts require sanding, painting and finishing.

The process of forming structural foam parts is very similar to the traditional reaction injection molding method. The two components, such as polyol and isocyanate (which combine to form polyurethane) are stored in liquid form in separate containers. They are mixed together to form a resin, which is injected into a pre-prepared mold and cured by a chemical reaction.

In addition to polyols and isocyanates, inert gases or chemical blowing agents are added to the mixture during the injection process. This changes the nature of the chemical reaction that ultimately occurs.

Compared with standard solid polyurethane reaction injection molding, fewer polyols and isocyanates are used, so the resin will not completely fill the mold. Instead, the gas or blowing agent is activated by the reaction between the two components. It expands and fills the empty space of the mold with foam. This creates the “honeycomb” texture known as the inner core of the structural foam. The surface cells collapse when in contact with the mold wall, forming a solid surface layer around the outside of the material.

Structural Foam Molding material

Polycarbonate
Polyphenylene ether-PPO (Noryl)
Polybutylene terephthalate-PBT (Valox)
Acrylonitrile Butadiene Styrene – ABS

Benefits of Structural Foam Molding

The use of structural foam as a manufacturing material has many advantages. Of course, structural foam was initially known for its ability to produce components of unparalleled size, such as vehicle roofs or body panels. However, it was soon discovered that structural foam brought many additional benefits.

Structural foam components are very light. With typical weights ranging from 55 pounds per cubic foot to only 2 pounds per cubic foot. In addition to weight reduction, structural foam is strong, durable, and very rigid—in fact, it is eight times harder than similar materials such as solid polymers. The modulus of the material increases as its density increases, reaching an astonishing 250,000 psi. In addition, this foam material is a good heat and sound insulation material.

Structural foam is also highly plastic, and it can produce different wall thicknesses on a single part. In some cases, structural foam can even produce wall thicknesses greater than the previous largest 1/2 inch (13 mm). It also allows the use of thicker ribs and bosses and reduces the risk of “sinking” on ribs or large sections due to the low viscosity of the mixture. Structural foam products bear less overall stress during the molding process and have strong resistance to warping or deformation.

Structural Foam Molding retains the common impact resistance, impact resistance and temperature resistance of thermoplastic and thermoset polymers. It has almost no thermal expansion, so it is very suitable for products used in various climates or temperatures. The acoustic and sound-damping properties of structural foam are also superior to standard solid polymers.

Structural Foam Molding is also a very cost-effective process. Lower pressure and clamping force are required during injection and curing, allowing tools and molds to be made of lower cost materials such as aluminum. The cycle time is competitive with injection molding and reaction injection molding, which makes it a time-saving and cost-saving process.

The risk of damage to Structural Foam Molding products in the mold or during removal is below average, making it an efficient and easily repeatable method. In addition, structural foam does not produce potentially harmful styrene fumes, reducing the health risks of workers involved in the molding process.

Finally, Structural Foam Molding also has a highly paintable and beautiful surface. All Structural Foam Molding products can be sprayed in the mold (IMP), which further saves time and money. It is also possible to apply multiple colors to a single part in the mold. The surface is easy to clean and can be sawed, screwed, stapled or bound without any problems.

If you need to manufacture large parts without sacrificing quality, Structural Foam Molding is your best choice.

Suggestions for Structural Foam Molding

Use low pressure injection molding (LPIM) machines to inject large Structural Foam Molding products, such as material handling bulk boxes, pallets, tool boxes, construction products, pool panels and ladders, fences, retail display stands, suitcases, storage sheds, shelves, cargo systems , Ground fences, leisure slides and toys, outdoor furniture, water storage tanks and drainage systems, tombs, garden trellis, dog houses, dock systems, cleaning and restaurant products, and industrial carts.

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