PET Preform
Injection Moulding Machines
Minimized costs through maximized output —
that is the declared aim of every manufacturer
of PET preforms.
Minimized costs through maximized
output – that is the
declared aim of every manufacturer
of PET preforms.
The new range of machines
have now been extended to include
a completely new field of application:
to produce PET preforms for
the stretch blow moulding of PET
bottles.
Service-proved a Hundred
Times Over
The nucleus of every high-performance
preform injection moulding system is a
toggleclamp machine rated for fast-cycling
applications. Equipped on the injection
side with a special holding pressure
unit the range available comprises
of varied sizes of machine with clamping
forces of up to 5,000 kN and specially
tailored for use with moulds with
12, 16, 24, 32, 48, 64, 72 or 96 cavities.
A five-point double-toggle clamp
operating in conjunction with an additional
hydraulic accumulator ensures
not only rapid opening and closing of
the mould but also extreme rigidity of
the clamping system and gentle treatment
of the mould: lock-to-lock time,
i.e. the mould opening and closing time
including the removal of all parts, is a
maximum of 2.8 seconds in the case of
the 96-cavity mould. Economical operation
of the machine is made possible
by an energy-saving hydraulic
system comprising of servo-controlled
variable delivery pumps for all screw
movements. Specific energy consumption
is reduced to a very minimum.
Gentle Plasticizing
The injection unit is of short, spacesaving
design and equipped as
standard with a barrier screw (L/D
ratio between 22:1 and 24:1 depending
on screw diameter) which ensures
gentle treatment of the melt
despite its very high plasticizing
capacity. If the melt is to be pigmented,
screws are available with
integrated mixing elements for optimum
homogeneity. If a consistently
low concentration of acetaldehyde
across all the cavities of the
mould is a specified quality requirement,
a static mixing element is installed
in the space in front of the
screw (the standard concentration
is max. 3 ppm, measured either in
the preform or in the blow moulded
bottle). Acetaldehyde results from
the inevitable mechanical and thermal
stress on the melt during the
plasticizing process.
The economic efficiency of a
PET preform production line depends
not least on the de-moulding
system. In order to make the cycle
times as short as possible, the pre-
forms are cooled partially inside and
partially outside the mould. The linear
robots used in these machines
are thus equipped with special demoulding
devices with integrated
cooling systems. A rotating quadruple
takeover device ensures that
the preforms are post-cooled for the
duration of four injection cycles
prior to being stacked.
Simple to Use
The injection moulding machine,
the de-moulding robot and the peripherals
share the same control
panel. The robot control is integrated
in the machine control system
as standard anyway, a feature
which not only facilitates operation
but also keeps the necessary time
for data exchange to a minimum and,
by the same token, makes for very
short cycle times. The machine control
system is similarly compatible
with the other component modules,
such as the cooling system for the
mould and the robot, the upstream
drying and conveying system for
the PET granules and the dry air
curtain surrounding the mould, all
of which are integrated into the system
in keeping with the customer’s
need for a complete, fully equipped
preform production cell supplied on
a turnkey basis.
....contd.
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