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| |
| The choice of the
moulding and forming technology will often be determined by the shape,
cost and number of parts to be produced. |
| |
| compression
moulding |
| The simplest process
is compression moulding where the compound is placed into a mould and the
product shape is formed under heat and pressure in a press. Typical
moulding times depend on the thickness, geometry and materials and may
vary from 5 minutes to 20 minutes
Small amounts of scrap material are produced, typically
as flash along the mould join.
|
 |
| |
| injection
moulding |
| Injection
moulding is used to rapidly reproduce large numbers of components
accurately and repeatedly. Compound is injected into the mould
through gates.
Whilst a good process for large volumes of cheap (and
often relatively small) components, injection moulding can produce a large
amount of scrap material, sometimes as much as is used for the component
itself. |
 |
| |
| extrusion |
| Extrusion
Any changes to the line, including during start-up and
run-out, can generate large amounts of scrap material and off-spec
product. |
| |
|
| overview |
|
number of parts |
tooling cost |
cure time |
labour cost |
part cost |
scrap volume |
| Compression
Moulding |
low |
low |
long |
high |
higher |
low |
| Injection
Moulding |
high |
high |
short |
low |
low |
high |
| Extrusion
Moulding |
high / continuous |
low |
low |
low |
low |
low |
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