Advantages and applications
ICM
Injection compression moulding (ICM) aside
from reduced material shear and less orientation,
offers numerous qualitative advantages for
injection-moulding parts. ICM also permits a
re duction in injection pressure, clamping force,
and cycle time. Added to this is often an improved
hold pressure effect, which minimises sink
marks and warpage.
Advantages of injection compression
moulding for the process
• Compensates shrinkage by compressing the
melt through the clamping movement
• Distributed, uniformly acting holding pressure
• Reduces holding pressure time, shortens cycle
times
• Permits overpacking of cavity
• Reduces clamping force requirements
• Less orientation and molecule alignment
during injection
• Easier and faster mould fi lling through
improved venting
• Less material shear
Advantages of injection compression
moulding for moulded part properties
• Eliminates sink marks with thicker wall
sections and at the end of the fl ow path
• Reduces to warpage susceptibility improves
long-time dimensional stability
• Reduces stresses in mats or fi lms in direct
back injection for decorative parts
• Reduces fi bre degradation in parts made of
long-fi bre-reinforced thermoplastics (LFTs)
and, consequently, improved mechanical part
properties
• Improves optical properties in the case of
transparent parts
There is a trade-off between the numerous advantages
and the extra expense for the machine
and mould as well as restrictions in terms of
part geometry:
• In addiction the IM machine requires an injection
compression control system whose extra
price, however, is frequently exaggerated
• The physical design of the mould must be
adapted to injection compression moulding
in order to prevent the melt from penetrating
into the parting line. There are a number of
technical solutions to overcome this problem
• Undercuts or penetrations across the compression
direction are problematic
• Only components that are of very great depth
in the injection direction are very diffi cult to
produce by injection compression moulding