You are here

Home / Processes / Formsprutning / Chemical foamed injection molding

Chemical foamed injection molding

Forming process where a chemical substance is added to create a porous detail.

Beskrivning
Illustration of Chemical foamed injection molding

The process

Plastic pellets mixed with a gas generating chemical agent is fed through a container [1] into a rotating screw [2] whose spiral shape moves the pellet forward through a heated chamber [3]. The mixture is heated gradually blending into a homogeneous plastic melt. The chemical process starts and microscopic bubbles begin to emerge.

The mixed mass is then forced into a mold [4] as the entire screw is pushed forward by an applied pressing force. The small gas bubbles grows larger during cooling and thus creates a porous interior while the surface is solid. The mold is opened and finally the part is removed by means of ejectors [5].

Chemical foamed injection molding
Advantages and disadvantages
In comparison with alternative methods
Ideal for larger wall thicknesses
No capital investment
Economic foam method for low production volumes
less tension in the product
Improved dimensional accuracy
Reduced distortion
Less material consumption, lower density
Less predictable heterogeneous material structure
About 50% of the CFA is broken down into gas, while the rest of the additives remaining in the polymer
The resulting surface is very rough