Long-associated with plastics, injection moulding can also be used to produce complex parts from metal. It uses a powder mixture of metal and polymer, which is then melted and poured into a mould tool where it settles into the cavities and solidifies in the required shape. When the metal/polymer powder mixture (also known as 'feed stock') is heated, the metal does not actually melt - only the polymer. This makes it suitable for a whole range of metals, with some of the most popular being stainless steel, iron, copper alloys, titanium alloys and low-alloy steel.
After the injection moulding process is complete, the components then need to undergo a process called de-binding, where either a solvent or the application of heat is used to remove the polymer binding from the parts. Finally, the components must be sintered to ensure high density - this process involves placing the parts in a high-temperature furnace, where any empty space inside the parts is reduced as the components shrink under the heat.
Used to produce
Small, detailed, complex metal components.
Materials
As the metal itself is not melted during the metal injection moulding process, a wide range of metals can be used including stainless steel, iron, copper alloys, titanium alloys and low-alloy steel.
Advantages
Can be used to produce components in a wide range of materials.
Allows for a high degree of accuracy.
Faster production time than investment/lost wax casting.
Disadvantages
Can be very expensive due to the multiple post-production operations required.
Tooling costs can also be expensive, making it generally unsuitable for smaller production runs.
