castflex eng

5/26/2018 Castflex Eng

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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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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

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Lespecifichetecnicheeproduttivegarantitedipendonoesclusivamentedagliaccordicontrattuali.

Rev.0

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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.

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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

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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: [email protected] - www.macchi.it

castflex eng

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