Comparison Between Injection Moulding And Extrusion Moulding
Injection moulding and extrusion moulding
Injection moulding and extrusion moulding are popular plastic manufacturing processes. At an initial glance, it may appear to be similar. Both injection moulding and extrusion have their own purpose and advantages.
Injection moulding is similar to die casting. Here plastic pellet is first melted and injected to mould cavities of the required shape with some types of injectors. Then it is allowed to solidify in the die. The final product is then ejected from die ejectors. Example chair, basket, casing, toys
Extrusion is the process of making continuous linear or two-dimensional shapes. In the extrusion process, the material is first melted and then forced through a metal plate (die cavity), having shaped cut and creating a continuous form. Then it is cooled to set. This continuous shape can be cut to length into parts once it is set as per demand. Example: rails, pipes, tubes.
Difference between injection moulding and extrusion moulding
|
Injection
moulding |
Extrusion
moulding |
|
Higher initial design cost |
The initial cost is low |
|
Making a three-dimensional shape. Its
cross-section does not need to remain in a parallel line. |
Continuous one or two-dimensional
product |
|
Molten material pushed to desired mould
cavity then allow solidifies there. |
Molten material forced out through
die having desired cross-section profile. |
|
It is a cyclic process |
It is a continuous process |
|
The product is in the final
dimension. |
It is ideal when a different length
of the same profile shape is required. It is cut to length as per demand. |
|
Parts with excellent tolerance can
be produced. |
The surface of extruded material
is so smooth. Do not require post-production surface finishing. |
|
It offers good strength to the product |
Comparatively weaker product. |
|
Expansion of material is
constrained. |
Free expansion is possible. |