Structural Foam Molding is the process through which thermoplastics such as high density polyethylene are processed in a low pressure environment. The process relies on the foaming action that is caused by an inert gas of the plastic material to facilitate flow. Similarly, foaming can also be caused by the decomposition of a chemical blowing agent added to the resin. All the aforementioned processes only require small amounts of pressure and not high ones, which are then used to force the molten polymer to fill up the cavity of the mold.
Usually, structural foam parts have thicker walls because their molding process lacks high pressures. In addition, they have a relatively high density reduction which at times extends to about 40 percent from the base material. Even though they have quality strength-to-weight ratio, acoustic insulation and improved qualities, the products still exhibit lower tensile strengths. Unlike injection molding, it uses cheaper and lighter molds of aluminum and can also be used to manufacture larger parts.
This method is preferred to the injection one for small-scale applications due to its cheaper initial cost. There are several sets of polymers that can be used for this type of molding. They include; high density polyethylene, polyethylene, styrene, polypropylene, and Acrylonitrile Botadiene Styrene. Both structural and injection techniques use the same designs, but the former process requires slightly thicker walls.
The foaming agent and the polymer melt are readily mixed and then the mixture injected into the mold, but in a slightly lesser volume. The purpose of this is to enable solidification. The next step involves filling the mold with a mix of the injection pressure and the expanding polymer at once. The contact between the melt and the cold surface of the mold forms a semi-solid skin. The expansion o the foaming gas, on the other hand, also forms a cellular particle in the inner core.
This process can be used to manufacture a lot of products of different types and sizes, while some of the products are also for molding. Generally, all thermoplastics can be used to mold since they have same qualities as the base resin. Other factors to consider include their physical qualities such as part shape, density reduction, general design and skin thickness.
Using the resins require proper selection depending on the actual properties of each of them. This also involves selective use of additives such as colorants, ultraviolet inhibitors and glass fibers. These are the commonly used additives because they can meet a wide range of application requirements.
The application requirements include; high temperatures, long-term weather exposure and rough handling. The method is still preferred to other materials. It has replaced a number of materials such as concrete, wood, metal, and solid plastics.
The common benefits of using structural foam molding includes; low weight, minimal cost of manufacturing, reduced corrosion, design flexibility, chemical resistance, clean ability, part stability and stiffness, as well as the mechanical properties. Other benefits are thermal and electrical insulation, sound absorption, less-stress concentration and minimal sink marks. This method can therefore be used to achieve a lot, depending with individual interests.
Usually, structural foam parts have thicker walls because their molding process lacks high pressures. In addition, they have a relatively high density reduction which at times extends to about 40 percent from the base material. Even though they have quality strength-to-weight ratio, acoustic insulation and improved qualities, the products still exhibit lower tensile strengths. Unlike injection molding, it uses cheaper and lighter molds of aluminum and can also be used to manufacture larger parts.
This method is preferred to the injection one for small-scale applications due to its cheaper initial cost. There are several sets of polymers that can be used for this type of molding. They include; high density polyethylene, polyethylene, styrene, polypropylene, and Acrylonitrile Botadiene Styrene. Both structural and injection techniques use the same designs, but the former process requires slightly thicker walls.
The foaming agent and the polymer melt are readily mixed and then the mixture injected into the mold, but in a slightly lesser volume. The purpose of this is to enable solidification. The next step involves filling the mold with a mix of the injection pressure and the expanding polymer at once. The contact between the melt and the cold surface of the mold forms a semi-solid skin. The expansion o the foaming gas, on the other hand, also forms a cellular particle in the inner core.
This process can be used to manufacture a lot of products of different types and sizes, while some of the products are also for molding. Generally, all thermoplastics can be used to mold since they have same qualities as the base resin. Other factors to consider include their physical qualities such as part shape, density reduction, general design and skin thickness.
Using the resins require proper selection depending on the actual properties of each of them. This also involves selective use of additives such as colorants, ultraviolet inhibitors and glass fibers. These are the commonly used additives because they can meet a wide range of application requirements.
The application requirements include; high temperatures, long-term weather exposure and rough handling. The method is still preferred to other materials. It has replaced a number of materials such as concrete, wood, metal, and solid plastics.
The common benefits of using structural foam molding includes; low weight, minimal cost of manufacturing, reduced corrosion, design flexibility, chemical resistance, clean ability, part stability and stiffness, as well as the mechanical properties. Other benefits are thermal and electrical insulation, sound absorption, less-stress concentration and minimal sink marks. This method can therefore be used to achieve a lot, depending with individual interests.
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