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FLEXIBLE CAST EXTRUSION SYSTEMSIN MODULAR UNITS
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CAST Flex
. . . productivity, flexibility
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A cast line involves not only the assem-
bly of components, but also requiresimplementation of specific design skills,
technologies, electrical and mechani-
cal engineering expertise. Experience
needs to be fielded in collaboration
with qualified users.
Macchi possess the resources and the
experiences gained in over forty years
of activity, that allows to maximise in
any line production efficiency, energy
saving, ergonomics and ease of opera-tions. This, in short, is what Macchi
offers: its Know-how.
The production of cast film offers sev-
eral benefits over that of blown film:
the system offers a greater yield in
terms of the width and thickness of
the film
provides more versatility in the choice
of polymers great dimensional tolerance control
of the product
a film of outstanding optical proper-
ties
The materials normally transformed
on cast systems mainly belong to the
family of Polyolefins; the cast proc-
ess causes fast crystallization, exalting
their physical and chemical properties.
The primary materials used include:
polyethylenes especially linear
(Ziegler - Natta) and Metallocene
resins which are used in the produc-
tion of stretch film
polypropylenes Homopolymers,
Co-polymers and Terapolymers, gen-
erally used to make flexible packag-
ing in the food and technical sectors,
both directly and as components of
various films for lamination resins that are used for barrier and
packaging film that resist oxygen
transmission, control flavour for longer
product shelf life as well as various
cooking methods such as nylon (PA6,PA6-66) and ethylene vinyl alcohol
(EVOH)
resins with special sealing or struc-
tural properties Ionomer resins,
bonding resins, resins boasting par-
ticular thermal or mechanical resist-
ance, PET/PS
Macchi offers a range of cast film
products from small polyvalent, mono-
layer or co-extruded systems able tohandle film 1500/1600 mm in useful
width, through to typical systems for
co-extruded polypropylene films, also
in specific versions for high barrier film
up to 5 and 7 layers and 1600-2100
mm in width. Lastly, there are the large
systems for stretch film, with an output
of 1000/1200 kg/h at a width of 2000
mm, and more than 1800 kg/h at a
width of 3000 mm.
All Macchis systems are extremely
modular in design and we are particu-
larly proud of this achievement.
This means the systems are highly
rationalized, integrated and evenly dis-
tributed, allowing for ease of handling,
installation and maintenance. They are
also very user-friendly and easy to
service, ensuring a good level of safety
at the workplace.
Each unit is devised as a standalonemodule or can interface mechanically
or electrically with the machines other
modules.
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10 Trim suction and conveying11 Fluff de-dusting and conveying
12 Operator panel
13 Containerized electrical plant
14 Core feeding unit
15 Shaft handling and recoring
16 Reel handling system
17 Water chilling plant
18 Pumping and temperature control units
1 Main extruder2 Coextruders
3 Fluff re-feed extruder
4 Feed block
5 Flat die
6 Chill roll unit
7 Thickness scanner
8 Web gauge randomizer
9 Winder
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In the same vein as the blown systems,
the co-extrusion unit is mounted on asingle raised technical platform in such
a way that the melt can be transferred
via extremely short and rectilinear chan-
nels to the extrusion head.
At the top, a second service level
ensures safe and convenient access to
the resin inlet and outlet systems.
At the bottom of the structure sup-
porting the hot extrusion section isan insulated and conditioned container
representing the technical part of the
line; here, too, are installed all the
devices and electrical drives servicing
the various motors and utilities that
can therefore be inspected, connected
and tested quickly and easily by the
appointed staff.
Special care is taken over the selec-
tion of the electrical and mechanicalcomponents to ensure the ultimate in
reliability, safe operation and minimal
noise levels.
The layout of the casting unit, central
unit and winding unit has been devisedin such a way that it can be optimized
and customized according to specific
needs in terms of type of product and
available space.
At the end of the day, we aim to ensure
a machine that is ergonomic, user-
friendly and extremely secure, also with
regard to the required peripheral and
end-of-line accessories.
For example, the extrusion waste treat-ment and recovery unit and the large
cooling units required for this type of
system can be installed in a room other
than that in which is installed the extru-
sion line.
This makes it all much easier to clean
and ensures a higher technical output.
There is a main remote control so the
operator can control the unit at a safe
distance and at any time.
Film inlet winder
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The Plastex extruders come with:
extrusion cylinders with special wear-
resistant centrifugal bimetallic sur-
face
screws with special barrier proper-
ties polyvalent ones and custom-
ized ones. These too are made of
wear-resistant materials and those
intended for the treatment of particu-
larly aggressive materials are fully
chromed
multi-zone heating/cooling systemswith shielded ceramic heating ele-
ments for precise heat configuration
according to the selected resins
digitally-controlled maintenance-free
liquid-cooled AC motors
The hydraulic sliding-plate filter units
facilitate changeover and are extremely
compact to eliminate the risk of the
material stagnating. For specific appli-
cations there are also cartridge-typeelements with large filtering areas to
enable long production runs without
the need for downtime to change the
filters.
The channels that transfer the polymer
from the filter-changers to the feed-
blocks or extrusion head are the hall-
marks of quality design. They feature
sturdy metal sections guaranteeing
excellent thermal stability and the inter-nal channels are carefully designed to
ensure optimal melt flow.
Our specialized polymer flow design
engineers now have a well-established
method for designing feed-blocks and
flat extrusion heads, to optimize poly-
mer distribution and production effi-
ciency for a wide variety of materials
and structure configuration.
The feed block has the task of receiving
and superimposing the layers of two or
more materials which, during lamina-
tion, are conveyed to the extrusion
head where this multi-layer sandwich
is stretched and thinned before being
placed on the surface of the chill roll.
All the heads have a flexible upper lip
for the actuators to automatically con-
trol the output gap and therefore the
final thickness of the film.
The restriction to the width of the
extruded film one of the few disad-
vantages of the cast technology has
now been easily eliminated by using
systems for internal limitation of the
melt flow channel.
Called Internal Deckling Systems, fixed
Drawing of flat die with encapsulation
Detail ofInternal Deckling System (IDS)
photoC
loeren
photoCloeren
View of automatic flat die and chill roll from operator side Group of extruders with screenchangers
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1
2 3 4
5 6
Layout of chill roll for the production of polypropylene
that can tend to form and solidify during
the extrusion process.
To obtain production of exceptional
quality at the high speeds involved in
the cast process, the products stability
has to be ensured during the criticalphase between it leaving the extrusion
lip and the melt being deposited on the
surface of the chill roll.
A suction chamber extracts the fumes
that are developed during the proc-
ess and ensures the counter-pressure
required to control correct exhaust
evacuation during the quenching proc-
or with sliding inserts, these optimize
output by minimizing the width of wasteat the sides and therefore the amount
of product to be fed back into the line or
discarded, as in the case of co-extrud-
ed films where there may be chemical-
physical incompatibility between the
costly resins used.
This device is especially useful in the
production of PP film, which is extreme-
ly sensitive to the amount of re-used
material put back into circulation, usu-ally featuring the formation of gels
which cannot be tolerated in the final
product.
The chill roll systems come in different
geometrical shapes that vary according
to the type of film to be made, and their
size depends on the systems width
and production capacity.
The main chill roll, with cutting edgegearless/torque motor, can have an
external diameter of 800, 1000 or 1400
mm to offer cooling capacity and sur-
faces suited to the required output.
A secondary chill roll, also has dif-
ferent diameter requirements based
on processing requirements as well
as variable positioning for optimized
film cooling and stabilization process,
which is particularly important in the
production of thick film or film madewith resins (e.g. PP) that cannot with-
stand overly vigorous cooling phases.
Macchi design engineers have paid
special attention to the cooling fluid
circulation system and its associated
heat regulation and pumping circuit.
Both are essential to obtain accurate
and constant regularity of the surface
temperature and therefore even cool-
ing which affects the optical character-istics and thickness tolerances of the
finished product.
A cleaning cylinder removes any traces
of wax from the surface of the chill rolls
View of chill roll for the production of stretch
1 Chill roll - main
2 Chill roll - secondary
3 Suction knife (vacuum box)
4 Air knife (optional)
5 Cleaning cylinder
6 Chill roll height adjustment
device
ess. A fully adjustable outlet vent cre-
ates the flow of air required to obtain a
point of contact between the melt and
the chill roll that is perfectly parallel with
the axis of the roll.
There are also electrostatic loadersat the edges that control the viscous-
elastic contraction of the melt at outlet,
the so-called neck-in.
The movement and positioning of the
air vents and their respective air capac-
ity settings are automated and control-
led by means of recipes memorized on
the machines supervision PC.
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The typical output of a cast line
demands a winding technology that isbest suited to the required production.
This involves not only the typical phys-
ical-mechanical properties for forming
a well-produced reel that can then be
successfully used for processing the
film, but also important economic con-
siderations also associated with prod-
uct distribution.
Macchi has devised its line of cast wind-
ers using three winding systems, con-tact, centre and centre-peripheral that
can also be used in tandem according
winding quality for all products made
directly into commercial reels
There are three machine versions, all
specifically for cast film -so are espe-
cially stable and sturdy- and featuring
the latest generation of motors and
electronic controls:
BoPlus Axial winding machine with
reel on swing arms generally intend-
ed for polyvalent lines where the
needs for winding thin adhesive andstretch films are combined with the
need to wind delicate, strong or slip-
pery films. The option for pure gap-
winding makes the machine ideal for
barrier cast film configurations or for
lamination
BoPlus HS winding machine with
flat-bed generally used for the pro-
duction of stretch film and intended
for in-line production of large jumboreels for conversion, as well as reels
for direct use on automatic palletiza-
tion units
BoPlus HS Fast Matic the latest
in Macchis range and the first in the
world, with indexing turret four spin-
dles and extremely fast changeover
permitting the creation of all stretch
products in their various commercial
forms. From jumbo reels to reelsfor automatic applications, and reels
for manual applications produced on
both standard 3 spindles and light 2
ones
With reel changeover time in less than
30 seconds, automatic control of the
spindles, winding devices and reels
produced becomes essential. Macchi
proposes different versions determined
by the winder model, each featuringdifferent approaches to the varying
product requirements.
The classic Easy Load manipulators,
equipped with their respective Module
to the type of winder required by the
product processed on the line.
This production and associated work
conditions pose several problems,
however:
film tension control upon arrival from
the line and at the reel that needs
to be carefully monitored during the
production of film such as PP that is
particularly slippery and can shrink
back
winding stability during the produc-tion of stretch film at speeds over 500
metres per minute
View of turret type winder
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C automation, allow Macchi to provide
industrial logistic solutions for manag-ing the finished product ranging from
the palletization of the finished reels
to more complete product collection
and boxing systems, all controlled by
a dedicated PC to optimize the associ-
ated functions.
Mandrel extraction unitMandrel extraction clamp
Winder inlet cutting knives and automatic trim recovery system
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As previously noted, the electrical equi-
pment is installed in a specially desi-gned controls container that serves
to optimize the space required for the
control devices, as well as provide a
controlled environment temperature for
the control systems.
The control system is based on the
same approach to the distributed elec-
tronics, with serial communication
centralized on the supervision system
within the controls container whichgreatly reduces the risk of downtime
due to complicated cabling and inter-
connections between the electrical and
electronic boards and machine units.
Macchi prides itself on the control of
the machines functions and qualitative
control of the end product.
Operators can often be intimidated by
Line management and thickness control panel
computerized systems not best sui-
ted to industrial environments; Macchihowever provides two man-machine
interfaces with touch-screens that are
both simple and easy to understand.
There is the screen for the EASY
CONTROL Plus system that displays
and controls all the machine functions
from gravimetric feed to heat regulation
and recipes. There is also the monitor
that interfaces with the thickness sen-
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sor, dedicated to the products profile
and management of the extrusion lip.
A heavy emphasis is also, of course,
put on the electronics and associated
dedicated software for controlling the
production transition, from the lines
acceleration and deceleration ramping
to maintaining product quality control in
the process, to management of potential
faults or emergency situations.
Gravimetric dosing system and loaders
Thickness meter screen page Screen pages of EASY CONTROLplus system menu
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Ilcontenuto
diquestocatalogoservesoloatitoloinformativo.
Lespecifichetecnicheeproduttivegarantitedipendonoesclusivamentedagliaccordicontrattuali.
Rev.0
03-03/09
The cast film must inevitably be trimmed to
remove those edges affected by neck-in proc-
ess as well as the bleed trim process in some
applications. Quantity-wise, the trim represents
a considerable percentage of production and
must be recovered in line by means of a closed
loop circuit that will not cause contamination and
allow the trim scrap material to be recovered
and recycled back into the production process
as soon as possible. Trim is always recovered
in line, except in certain cases involving the pro-duction of film comprising 5 and 7 layer barrier
film, when the incompatibility of some materials
does not permit in-line scrap recovery. Although
there are alternative methods available, such
as barrier layer encapsulation which can allow
for some in line scrap recovery.
The fluff is processed by a mill and then
conveyed via a special pneumatic system for
removal of any dust and separation of finer
dust particles a potential source of gels inthe finished product and then on to recovery.
The system comprises a side extrusion/injec-
tion device that compacts the fluff and puts it in
the plasticizer screw for extruding (normally the
central screw in the case of co-extruders). The
re-feed position is selected in such a way as
to minimize the risk of overheating the reclaim
materials and designed to provide consistent
re-feed rate to avoid output variations in the
primary extruders production capacity, so the
melt temperature and pressure, and therefore
the quality of the finished product, remain unaf-
fected. Trim recovery systems are available in
certain cases and on request.
2
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Soundproof box for trims suction and grinding
TECHNICAL SHEET
Exruder diameter range from diameter 55mm to 160mm L/D1/30
Feed Blocks and die from 1 to 7 layer automatic and tith IDS
Production capacity range from 200 to 1800 Kg/h
Film gauge range from 10 to 300 micron
winding speed maximum 200 Mt/min for PP 500 Mt/min for stretch
1 Main extruder section
2 Extruder/injector fluff screw
3 Antistatic hopper for fluff
4 Barrel cooling device
5 Screw cooling device
Schematic of fluff extruder/injector
www.bo
nobodesign.i
t
Macchi S.p.A. - 21040 Venegono Inferiore (VA) Italy - via Papa Paolo VI, 5 - Tel. +39 0331 827.717 - Fax. +39 0331 827.750
Service Hotline +39 0331 866.427 - email: macchi@macchi.it - www.macchi.it
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