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.
The low pressures are responsible for the thick formation of the structural foam walls. They also result to the high rates of density reduction, which can even reach a maximum of 40% of the base material. Structural foams boast a wide range of qualities such as proper insulation and good strength-to-weight ratio. However, they still have low levels of tensile strength. Contrary to the injection molding, the structural foam one uses aluminum instead of steel.
The initial cost of the process is cheaper, making it an ideal substitute for injection molding for small-scale applications. It is a flexible method, which uses a wide range of polymers. Besides the high density polyethylene, other polymers widely used in this method include; polypropylene, Acrylonitrile Botadiene Styrene, and polyethylene. Generally, the designs for both methods are similar, except that the structural foam one requires thicker walls.
The process requires that the foaming substance mixes with the molten polymer before being injected into the mold for solidification. After which the mold is filled with both injection pressure and the expanding polymer. An almost solid skin is formed the moment the melt comes into contact with the cold surface of mold. A cellular material of the inner core is also formed as a result of the expansion of the foaming gas.
The process greatly contributes towards production of a wide range items of different sizes and types, which can still be used for molding. Virtually, all thermoplastics can be used in this process because they have similar properties to base resin. Their physical characteristics are determined by skin thickness, general design, part shape, and density reduction attained.
Using resins involve proper selection with special attention to their individual characteristics. The process also requires use of additives such as colorants, glass fibers and ultraviolet inhibitors. These additives are widely used because they are applicable to different occasions. This also contributes low cost of production due to the flexibility of application.
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 benefits derived from structural foam molding include flexibility of designs, reduced cost of production, minimal corrosion, part stiffness and stability, high level mechanical properties, clean ability and chemical resistance. In addition, thermoplastics are good insulators of heat and electricity absorb sound, less stress concentration and have minimal sink marks. It is also worth noting that they are, generally, easy to maintain.
The low pressures are responsible for the thick formation of the structural foam walls. They also result to the high rates of density reduction, which can even reach a maximum of 40% of the base material. Structural foams boast a wide range of qualities such as proper insulation and good strength-to-weight ratio. However, they still have low levels of tensile strength. Contrary to the injection molding, the structural foam one uses aluminum instead of steel.
The initial cost of the process is cheaper, making it an ideal substitute for injection molding for small-scale applications. It is a flexible method, which uses a wide range of polymers. Besides the high density polyethylene, other polymers widely used in this method include; polypropylene, Acrylonitrile Botadiene Styrene, and polyethylene. Generally, the designs for both methods are similar, except that the structural foam one requires thicker walls.
The process requires that the foaming substance mixes with the molten polymer before being injected into the mold for solidification. After which the mold is filled with both injection pressure and the expanding polymer. An almost solid skin is formed the moment the melt comes into contact with the cold surface of mold. A cellular material of the inner core is also formed as a result of the expansion of the foaming gas.
The process greatly contributes towards production of a wide range items of different sizes and types, which can still be used for molding. Virtually, all thermoplastics can be used in this process because they have similar properties to base resin. Their physical characteristics are determined by skin thickness, general design, part shape, and density reduction attained.
Using resins involve proper selection with special attention to their individual characteristics. The process also requires use of additives such as colorants, glass fibers and ultraviolet inhibitors. These additives are widely used because they are applicable to different occasions. This also contributes low cost of production due to the flexibility of application.
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 benefits derived from structural foam molding include flexibility of designs, reduced cost of production, minimal corrosion, part stiffness and stability, high level mechanical properties, clean ability and chemical resistance. In addition, thermoplastics are good insulators of heat and electricity absorb sound, less stress concentration and have minimal sink marks. It is also worth noting that they are, generally, easy to maintain.
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