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CORPORATE TRAINING AND PLANNING
EXTRUSION
CORPORATE TRAINING AND PLANNING
Film Blowing, Mono- and Multi-layer and Double Bubble Film Blowing
3-layer 3 extruders3-layer 2 extruders 5-layer 3 extruders
5-layer 4 extruders 7-layer 4 extruders 7-layer 5 extruders
AXON manufacture machinery for both processes
There are two techniques of
making film. One is the cast film
process. The other is the blown film
process. The difference in qualities is
that the blown film is more christalline
than the cast film
FILM BLOWING
CORPORATE TRAINING AND PLANNING
Blown Film Co-Extrusion Barrier properties is the main reason to go for multi layer film
Three layer Co-Extrusion Five layer Co-Extrusion
CORPORATE TRAINING AND PLANNING
MULTILAYER BLOWN FILM
Please check below a number of layer-designs from 2 layer up to 7 layers. The glue-layers are of great importance where two different polymers are not compatible
3-Layer head for 2 extruders -Layer head for 3 Extruders
CORPORATE TRAINING AND PLANNING
CORPORATE TRAINING AND PLANNING
CORPORATE TRAINING AND PLANNING
Multilayer Film DiesMultilayer Film Dies
Two types of dies: 1.Feed Block 2.Multimanifold In Feed Block the melt streams are brought together and flow
out the die In Multimanifold the melt spreads independently and meet at
the die exit Two types of process Oscillating Platform Oscillating Haul-Off
CORPORATE TRAINING AND PLANNING
MULTI LAYER FLAT FILM DIES
Feed Block
Multimanifold three-layer flat-film die
CORPORATE TRAINING AND PLANNING
Advantages of Multi-layer FilmAdvantages of Multi-layer Film
Two to seven layers depending on the application. It possesses good barrier properties against gas and
moisture. High tensile,impact and tear strength. Good stiffness,optical,carrier and printing properties. e.g. LDPE/HDPE/LDPE,LLDPE/LDPE..etc.
CORPORATE TRAINING AND PLANNING
Sheet Extrusion
Sheet is produced by forcing molten thermoplastic through a long horizontal
slit die. The extruded hot web passes around metal cooling rolls and is then
cut up or rolled up.
Material used :
HIPS is the most important sheet material. HDPE, PVC, ABS are also used.
Sheet grades usually have high melt viscosity.
CORPORATE TRAINING AND PLANNING
Process Line
The sheet leaving from the slit die is picked up by vertical stack of three rolls.
The polishing rolls are usually chrome-plated and provided with temperature control by circulating oil. The polishing rolls imparts a good surface to the product without warpage. The temperature of the top rolls should be as high as possible without sticking, while the bottom roll should be just cool enough to prevent distortion.
From the polishing rolls the sheet passes along a conveyor, which consist of free running rollers.
The sheet is pulled by the pulling rolls are covered with elastomer. Their speed is adjusted to be slightly less than that of the polishing rolls to allow for shrinkage that takes place as the sheet cools.
The sheet is cut into desired dimensions by means of razor blades (thin sheets), shear cutting device (Standard sheets), or circular saws (thick sheets).
CORPORATE TRAINING AND PLANNING
Sheet Extrusion Line
CORPORATE TRAINING AND PLANNING
SHEET EXTRUSION ON 3-ROLLER CALANDERS
CORPORATE TRAINING AND PLANNING
Various Cross-Sections of Flat Sheeting Dies: Circular, Tear drop, Angular and Flat Teardrop
DiesDies used in sheet extrusion are similar to that of flat film dies. Various cross-section of a flat sheeting die is shown in fig
CORPORATE TRAINING AND PLANNING
Extrusion coating The plastic is coated over a substrate like paper, by extruding through a slot
die downward between two rolls.
Substrate is fed between the molten plastic and the roll and is joined with the plastic by pressure between rolls without the use of an adhesive.
Material used LDPE & PVC
PP, HDPE, Ionomer etc. are also used.
Equipment compresses of
Pre treatment unit
Coating unit
Take off & winding
Sketch of Paper Coating for Extrusion Process
CORPORATE TRAINING AND PLANNING
Dies
Coat hanger die
‘T’ type die
Coat-Hanger Die : (a) Die Body, (b) Manifold, (c) Fixed Jaw, (d) Movable Jaw, (e) Choker Bar, (f) Clamping Screw and (g)
Jaw Adjusting Screw
Manifold T-die : (a) Die Body, (b) Manifold, (c) Adjustable Lip and (d) Clamping Screw
CORPORATE TRAINING AND PLANNING
Wire Coating/Cable CoveringUnit comprises of
Un wind unit (For conductor)
Pre treatment unit
Wire coating unit
Steps Involved
Wire/conductor is unwound & straightened by Tension
Control Unit.
Pre treated to promote adhesion of molten plastic
Then passed through the Cross head die of the coating unit
Coated wire is then cooled by passing through cooling trough
Wound on the winder
Cooling Trough Take off/ wind up.
CORPORATE TRAINING AND PLANNING
Wire Coating Extrusion Line
Diagram of a production line for the coating of wire or cable with plastic. The conductor to be covered unwinds at the left, is preheated, passes into the crosshead die (center). The extruder is behind the die, and feeds it with molten plastic, which coats the conductor. The finished product is cooled, tested and wound up at the right.
CORPORATE TRAINING AND PLANNING
Die used
Tubing die
USED MAINLY FOR SECONDARY INSULATION
USED MAINLY FOR PRIMARY INSULATION
Pressure die
CORPORATE TRAINING AND PLANNING
Dies
T-TYPE
DIE
COAT HANGER
TYPE DIE ( Widely Used)
Coat Hanger type of Die is much more stream lined than T-type Die
CORPORATE TRAINING AND PLANNING
Tube/Pipe Extrusion
Wall thickness & flexibility/Rigidity differentiates between tube/pipe
Pipes are produced by horizontally extruding molten polymer through an annuler opening into several sizing, cooling devices that stabilizes the final dimension.
Comprises of
Extruder
Die
Sizing device
Cooling bath
Cater puller
Cutter or winder
CORPORATE TRAINING AND PLANNING
DIES USED
STRAIGHT THROUGH
OFF SET DIE
CORPORATE TRAINING AND PLANNING
Sizing Equipment - MethodsVacuum Trough
Widely used
With the help of vacuum, Pipe is stabilized and sized to retain the shape
Sizing Sleeve
Methods fixes the outside pipe diameter as it hardens by contact with a water cooled metal sleeve.
FLOATING PLUG SYSTEMS- USED FOR RIGID PIPES OF MEDIUM AND LARGE SIZES
TO PREVENT LOSS OF AIR PRESSURE FLOATING PLUG SYSTEM IS USED
CORPORATE TRAINING AND PLANNING
Extended Mandrel
Method uses a water cooled extended mandrel
Provides additional internal cooling and internal support
Sizing plate
Method involves pulling the pipe through a series of brass plates
Mainly for small dia pipes/tubes.
CORPORATE TRAINING AND PLANNING
Extrusion of Mono filaments
Mono filaments are wise like polymer strands of dia 0.09 to 1.52 mm. Usually they have circular cross-section.
The polymer melt from extruder is pumped out through a multi-hole die, quenched, stretched/oriented and annealed to get the filament of enhanced properties.
The production process comprises of Extrusion Filament forming Stretching (orientation) Annealing Winding
CORPORATE TRAINING AND PLANNING
A
B
C
D Liquid-bath method
Orientation Systems
Air - Oven method
Heated Point method
Cold Drawing
CORPORATE TRAINING AND PLANNING
Extrusion -- Box- Strappings
The process sketch is similar to Monofilament line except the die – A slotted die is used in place of multi-hole monofilament die
Plastic Strappings, made of PP/HDPE replace iron because of their flexibility.
Process outline
Plasticated melt from an extruder is pumped out through a slot die
Quenched in water bath
Bath temperature - 800C for PP
- 900C for PA-6
Passed through a orientation system and stretched to about 8 times in order to improve tensile properties.
Annealed in an annealing chamber to relieve the stresses
Wound on winder.
CORPORATE TRAINING AND PLANNING
CORRUGATED PIPES The characteristics of corrugated plastic pipes depend on profile and
material.
Corrugated pipes have either parallel ring grooves or a continuous helical groove.
The pipes design can be single walled or twin walled.
Most common thermoplastics are PVC, PE,PP, PA and fluoropolymers.
The most important advantages are
Considerable raw material savings
High pressure resistance with good flexibility.
High impact strength
Good hydraulic characteristics
CORPORATE TRAINING AND PLANNING
Essentially IIIr to extrusion of pipes except that the die and the calibration units are specially designed to produce corrugation on the pipes.
The cylindrical part of the pipe die head extends into the closed area of a revolving mould block chain. The plastic tube is pressed against the profiled, revolving mould block halves by internal air pressure or by vacuum calibration.
As it passes through the forming machine, it is cooled by contact with the mould blocks, and by that time it reaches the end of the chain, the tube must be sufficiently cooled to leave the rotating mould blocks in a stable form.
Process
CORPORATE TRAINING AND PLANNING
a--Pipe die head with Insert
b--Compressed air inlet
c-- Shaping die
d -- Sealing stopper
e -- Vacuum connection
CORPORATE TRAINING AND PLANNING
In order to let the pressure or vacuum sizing become effective,
the molten tube must be brought over a special extended outer die ring
as close as possible to the moulding chain –inlet. Otherwise the tube
would be blown off in pressure sizing and fail in vacuum sizing.The
extended position of the outer die ring cannot be heated separately. So
that it must be made of a material of high thermal conductivity.
CORPORATE TRAINING AND PLANNING
Double walled corrugated pipe production:
The manufacturing process is the same as with
standard corrugated pipes, but when the first tube has been
formed, the second tube is laid smoothly on the inner
surface of the still plastic corrugation and welded to the first
with the aid of a sizing mandrel.
CORPORATE TRAINING AND PLANNING
Double Walled Corrugated Pipe Productiona -- Die for coextrusionb --Through flow guidec --Mandrel extrusion for inner layerd -- Shaping die
CORPORATE TRAINING AND PLANNING
Applications of Corrugated pipes are:
Conduits for cable protection, TV,Telephone, Glass fibre, power, control and computer lines, automobiles, machines and planes, protective pipes and conveyor pipes.
Drain pipes for fields, streets, squares and houses.
Pipes for vacuum cleaners, washing machines, dish washers, medical application – drip irrigation, hoses for fields, hot houses and plantations.
Protection pipes for district heating, domestic connection lines, structural and civil engineering.
Large size pipes for sewage, waste water, control shafts and conveyor pipes.
Corrugated pipes are produced with diameters form 3\5 to 2000mm.
CORPORATE TRAINING AND PLANNING
POST EXTRUSION FORMING
Inline postforming with extruder : Embossing one or both sides with shallow or deep patterns
CORPORATE TRAINING AND PLANNING
INLINE FIXED / ROTATING RINGS USED TO TWIST EXTRUDATE
CORPORATE TRAINING AND PLANNING
INLINE VACUUM/PRESSURE FORMER FOR PLASTIC SHEEET WITH MATCHED, WATER COOLED
FORMING MOULDS ON CONTINOUS CONVEYOR SYSTEM
AN INLINE COIL FORMER CAN PRODUCE TELEPHONE CORDS, SPRINGS, ETC., USING EXTRUDED ROUND, SQUARE, HEXAGONAL, AND OTHER SHAPES
CORPORATE TRAINING AND PLANNING
PROBLEM CAUSES (S) SOLUTION(S)
General Considerations
Surging
Resin bridging in hopper Eliminate bridging
Incorrect melt temperature Correct melt temperature
Improper screw design Check design
Rear barrel temperature too low or too high
Increase or decrease rear temperature
Low back pressure Increase screen pack
Improper metering length Use proper screw design
Gels(Contaminants that look like small specks or bubbles)
Melt temperature too high Lower melt temperature
Not enough progression in screw use new screw
Bad resin Check resin quality
Melt fracture (Rough surface finish)
Melt temperature too low Increase melt temperature
Die gaps too narrow Heat die lips
Increase die gaps
Use processing aids
TROUBLE SHOOTING
CORPORATE TRAINING AND PLANNING
Bad colour
Colour concentrate incompatible with resinEnsure melt index of concentrate base
Bubbles
Wet material Dry thoroughly
OverheatingDecrease temperature; check thermocouples
Shallow metering sectionUse proper compression-ratio
screw
Overheating
Improper screw design Use lower-compression screw
Restriction to flow Check die for restrictions
Barrel temperature too low Increase temperature
Die lines
Scratched die Refinish die surface
Contamination Clean head and die
Cold polymer Check for dead spots in head;
adjust barrel and head temperature to prevent freezing
Flow lines
Overheated material Decrease temperature
Poor mixing Use correct screw design
Contamination Clean system
Improper temperature profile Adjust profile
CORPORATE TRAINING AND PLANNING
Blown FilmWrinkles Dirty collapsing frame Clean frame
Too much web tension Adjust tension
Improperly designed air ring Use new air ring
Gauge variations See gauge variations
Insufficient cooling Use refrigerated air
Increase flow of Air
Reduces output
Misalignment between nip rolls and die Check alignment
Fold, creases Excessive stretching between nip and roller Reduce winding speed
Nip assembly drive not constant Adjust or replace drive
Blocking Inadequate cooling Use better cooling method
Excessive winding tension Adjust tension
Excessive pressure on nip rolls Adjust pressure
Bad resin Check resin
Port lines Melt temperature too low Increase melt temperature
Die too cold or too hot in relation to melt temperature Adjust die temperature
Splitting Excessive orientation in machine direction Increase Blow-up ratio
Degraded resin Reduce melt temperature
Poor resin choice Ensure resin is suitable
CORPORATE TRAINING AND PLANNING
Die lines Nick on die lip Chande die
Dirty die Clean die
Inadequate purgingIncrese purging time between resin changes
Gauge variations (machine direction)
Surging
Check temperature
Check hopper for bridging
Inconsistent take-up speed Check take-up speeds
Gauge variations(transverse direction)
Non-uniform die gap
Adjust gap
Centre air ring on gap
Printing problems Insufficient treatment Use properly treated film
Additives interfering with inkUse resins with no interfering additives
Erratic treatmentReduce slip levels to about 600 ppm for water-based inks
CORPORATE TRAINING AND PLANNING
Sheet
Poor gauge uniformity Melt flow is not stable Use gear pump to stabilise flow
Viscosity not stable Poor mixing Use static mixer
Streaks Contaminated System
Clean hopper
Check screw and die;
Clean if necessary
Total discoloration Excessive regrind Check amount of regrind used
Discontinuous lines Too much moisture Increase resin drying
Use hot regrind
CORPORATE TRAINING AND PLANNING
Pipe and Tubing
Poor output Improper die or screw designEnsure die and screw are designed for desired output
ID blisters
Insufficient vacuum Increase vacuum
Excessive moistureMaintain normal percentage of moisture in compound.
Gases entrapped Reduce temperature
Water inside pipe Stop water access
ID burn streaksMandrel heat too high Check mandrel heat
Stock temperature too high Reduce temperature slowly
ID grooves Mandrel is coated with material Clean mandrel
ID wavy surfaceScrew clearance set improperly Adjust clearance
Puller drive slipping Adjust or replace puller drive
CORPORATE TRAINING AND PLANNING
OD burn streaksMaterial hung up on die Clean die
Temperature too high Reduce temperatures slowly
OD uneven circumference
Too much air pressure on puller Reduce air pressure
Insufficient air pressureCheck air pressure and all connections
OD discoloured Stabiliser level too low Check stabiliser level
OD pock marks
Air bubbles adhering to pipe in flotation tank
Install wiper in tank
Improper adjustment of spray rings that surround water tank.
Readjust spray rings
OD oversized
Air supply too high Adjust air supply
Insufficient water supply Increase water supply
Pipe hot when measuredAllow pipe to cool before measuring
Wall too thick
Mis-adjusted die bushingAdjust die bushing to achieve uniform thickness
Wrong die set-up Use correct set-up