This manual, covering extruders and accessories, has been prepared for PTi customers.
Your plant personnel should use it as a guide for the installation, operation and
maintenance of your extruder.
Some parts of the manual are general and are applicable to older extruders, but the
manual refers specifically to the Trident Series of PTi extruders. A complete set of
assembly drawings listing all parts of the extruder is supplied with each new extruder and is
included in this manual (see Wiring and Assembly Drawings Section 6).
If needed, additional information is available from our Engineering Department upon
Equipment manufactured by PTi carries the standard machine tool guarantee of
freedom from defects in workmanship and material for one year from date of shipment.
Equipment manufactured by others, but furnished or installed by PTi, carries the original
TO INSURE THAT YOUR WARRANTY IS HELD IN EFFECT, PROPER OPERATION
PROCEDURES MUST BE OBSERVED.
NOTE: READ THE SAFETY PRECAUTIONS (see Safety Precautions Section 1 and
any safety precautions referred to in the specific accessories sections, if supplied)
BEFORE OPERATING THIS MACHINE.
Extruder Table of Contents
TABLE OF CONTENTS...............................................................................1
SYSTEM ESSENTIALS ...............................................................................2
Fluid Requirements ......................................................................................2.1
General Safety Notes ...................................................................................3.1
Extruder Safety Precautions & Warnings .....................................................3.2 & 3.3
SYSTEM DESCRIPTION .............................................................................4
INSTALLATION / SETUP ............................................................................5
PTi recommended spare parts list................................................................9.1
VENDOR MANUALS ...................................................................................10
Manufacturers’ Manuals List ........................................................................10.1
NOTE: The vendor supplied service material pages have not been numbered. The vendor service
material that relates to each of the sections listed above can be found in Section 8.
GENERAL SAFETY NOTES
Know your equipment
Carefully read the instruction manual.
Learn the use and limitations of the equipment.
Be sure you know the safe way to perform any given job.
If there is any doubt in your mind, ask the supervisor on duty.
Obey all posted signs and warning labels
DO NOT operate or use this equipment for any purpose other than its intended use.
DO NOT modify this equipment without written authorization.
DO NOT perform adjustments or maintenance while system is operating or energized.
DO NOT pass or alter safety features or procedures.
Keep guards in place
Never tamper with guards on the machine. If it is necessary to remove a guard for
any reason, first obtain permission from supervisor on duty. Then make sure that
the power is turned off and locked out before proceeding.
Be sure that all guards are in place and in good condition before operating.
”A clean house is a safe house.“
Keep working areas clean of all waste and rubbish.
EXTRUDER SAFETY PRECAUTIONS & WARNINGS
1. Install the extrusion equipment with regard to equipment specifications as stated in
this equipment manual.
2. The extruder, main control cabinet and all auxiliary
equipment must be ‘grounded’ in compliance
with NEC and all local codes. Failure to do so may
result in fatal injury to personnel and equipment
3. Proper rupture disc must be installed to prevent over pressure
Rupture Disk Installed
4. WARNING: Disconnect power before servicing the motor
control in cabinet.
5. WARNING: Disconnect power before removing barrel covers
or servicing heaters. Replace covers before reconnecting
power. Make no repair to equipment without shutting down
main circuit breaker and locking out the power.
6. Do not clean the equipment with flammable solvents.
7. Do not wash down the equipment with water. This could cause an electrical
8. For the operator’s safety, make sure all guards including coupling and gear pump
drive shaft, covers and filters are in place before starting the machine.
9. Make sure that the rupture disc and venting area is guarded. Hot materials and
gases may be vented and cause severe burns, etc.
10. Do not probe into extruder vent with the machine running. Never
use a metal probe in the vent area. The screw may shear the
probe, causing extensive damage to the barrel and screw. A
wooden probe is recommended.
11. Face shield, insulated gloves, etc. should be worn around the
extruder during operation. They must be worn when adjusting
the die, cleaning the screw, etc. The extruder temperatures and pressures are, by
nature, dangerous to personnel.
12. The feed hopper must be installed on the extruder feed section, slide gate, or
magnet drawer at all times.
13. Never put hands in the feed section or vent to remove material. SERIOUS
INJURY OR DEATH MAY OCCUR!
14. Avoid standing near the machine discharge or clamp end on startup or operation.
15. WARNING: Discharge all barrel pressure before removing the breaker plate,
screen changer or working at the discharge end of the extruder.
16. Be sure that machine is at operating temperature before starting the drive. Your
machine may be supplied with under-temperature alarms.
17. Purge compounds for cleaning extruders should not be used without prior approval
of PTi to prevent machine damage and possible unsafe conditions.
• Coupling guard, or barrel covers
• Clamp or discharge
• Feed section or throat
• Sharp blades / Slidegate
• Rotating or moving parts /
• Warning – High Voltage
• Service of electrical controls should be performed by a trained
• Ground equipment
• All terminals on die heaters, etc., must be guarded
High Temperature & Fire, Burns, Material Splatter, Etc.
• Insulated gloves and face shield
• Avoid vent
• Avoid die discharge
• Rupture disc
• Flammable solvents must not be used
• WARNING: Certain plastic materials being processed may
generate toxic gases when allowed to degrade or burn.
Proper gas protection must be provided.
• Proper ventilation must be provided. Exhaust fans and
hoods are recommended at the die area of the machine
Extruder System Description
SYSTEM DESCRIPTION: EXTRUDER
The following are engineering descriptions of the various components and elements in a
standard PTi Trident Extruder. To further define a standard extruder, in order to clarify
right and left hand, as well as direction of rotation of feed screw, input drive shaft, etc. A
standard Trident extruder is one that has the screw rotating counter-clockwise when
looking downstream. The motor is typically coupled to the transmission and located behind
the gearbox (Out the back, “Z” configuration) in most sizes. The transmission is a fixed
ratio (See Vendor Manuals, Section 10.) When a lower than standard centerline height of
an extruder is required, the transmission can be placed on its side.
The primary function of the base of any machine is to provide a level surface on which
various components can be securely anchored and held in alignment. The anchor bolt
locations, when foot mounted, are in multiple mounting pads welded to the base and are
standardized as to location to simplify customer mounting of anchor bolts prior to arrival of
the extruder in his plant. PTi can also incorporate casters and track into the base design
for rear expansion or easy access (optional).
Transmission & Lube System
A typical transmission uses a two step reduction to transfer motor RPM into screw RPM.
The housings are constructed of high strength close-grained cast iron in a rugged
design with heavy wall thickness. Typical reductions range from 10:1 to 20:1. The gear
ratio is determined by the requirements of the output of the extruder.
Gearing is from a high quality special grade steel and is precision machined. The
gearing is then case hardened for long life and maximum strength. The gears are used
to transmit constant torque to the screw.
A spherical roller (SKF style) or tapered roller bearing (T-type Timken) is used in the
thrust assembly for long life and reliability. The thrust bearing is mounted, in most
cases, on the backside of the low speed shaft for easy accessibility. However in some
cases the bearing is mounted in a bolt on thrust housing on the front side of the low
speed shaft which allows the ability to select the precise thrust bearing required for any
specific application. In either case the bearing is located between the transmission and
the screw shank to absorb the axial load.
The shafts are supported with amply rated anti-friction bearings. The high-speed shafts
are integral with the pinions and are made of the same material as all other gearing.
The low speed and intermediate shafts are made of forged carbon steel typically.
Extruder System Description
Most assemblies are of the universal design. This allows vertical and horizontal
mounting positions in a Tuck-under (“U”), wraparound (“U”), or out the rear (“Z”)
configuration along with left or right hand. In some cases only the horizontal mounting
position is available. This will only allow the wraparound (“U”) or out the rear (“Z”)
configuration along with left or right hand. In all, there are six (6) different assembly
positions which can be offered from the same gearbox. The breather and oil level gauge
are the only thing needed to be changed.
In most cases both gears and bearings are lubricated by
splash lubrication. Only in the larger size gearboxes are
some of the bearings forced lubricated. Thermal
considerations are addressed in smaller units (typically 3
inch extruders and below) by convection. In larger units
water is used for cooling circulated thru internal cooling coils
completely assembled with two external pipe connections.
When external heat exchangers are supplied they are used
in conjunction with a pump (motor driven), filter, strainer and
monitoring devices such as a pressure gauge, temperature
gauge and pressure switch. Lubrication is drawn from the
transmission reservoir and passes through a larger shut off
Extruder transmission valve. From there it is drawn through a y-strainer where
and lube system contaminants are removed and then into the pump. It is
then pumped past a pressure relief valve through a shut off
valve, past a pressure gage and into a duplex filter. Contaminants are once again
removed. A pressure gauge is supplied to let the operator determine if there is an
increase in pressure created by a dirty filter. There may also be pop-up indicators of
high pressure as well. Pressure upstream will increase as the filter clogs. A valve
allows the operator to switch the lubricant flow to a bypass filter circuit so that the dirty
filter may be changed.
The lubrication then passes through a heat exchanger where it is cooled by the heat
transferring action of the heat exchanger cooling tubes. From there the lubrication is
sent to the transmission housing where it is then splashed or channeled through orifices
to the gears and bearings.
A main drive interlock is incorporated to shut down the extruder when there is
insufficient oil flow to the gears or a high oil temperature. (See Vendor Manuals, Section
8 for your specific transmission specifications and information.) (Also see System
Essentials, Section 2 for oil volume requirements.)
The PTi principle of providing a modular or building block design permits the use of a
separate cast feed section. A prime requirement of a feed section is to provide adequate
cooling to prevent the thermoplastic material from absorbing sufficient heat that it becomes
Extruder System Description
tacky and impedes flow. Having properly placed inlet and outlet points and sufficient jacket
cooling capacity, the PTi feed section design is most efficient in this respect. The PTi
Trident series feed section is constructed of a ductile iron casting and can be supplied with
a hardened inner liner for long wear or a special grooved throat liner is available for
improved feeding action (optional) – used on some sizes. Another feature is large air gap
provisions to prevent the feed section from acting as a heat sink and incorporation of an
optional powder, low pressure gas (see Section 9.3 for removal and installation procedure
of standard seal assembly) or “hot melt” seal around shank of screw (see below for “hot
melt” seal installation and adjustment).
While the largest percentage of Trident extruders use barrels of the integral liner type, there
are different designs that can be supplied.
The most popular, the integral liner type, is fabricated of AISI 4140 steel with centrifugally
cast alloy liner. The nominal thickness of the alloy lining ranges from .050quot; to .080quot;.
Hardness is in the 55-60 range on the Rockwell ‘’Cquot; scale. Other liner types are available
The length of the barrel is usually given in some multiple of the diameter, such as 24:1
length to diameter ratio or L/D.
Barrel Support(s) are provided to support the weight of the barrel and also allow thermal
expansion of the barrel. The barrel supports are fabricated from cast iron and features jack
screws for ease of alignment adjustment.
Discharge End Features and Clamping
The PTi Trident extruders are available as a standard in a bolt-on or a threaded discharge
flange configuration to mate with down stream equipment being provided. This will be
specified at time of order. This flange can be supplied with its own heater and or control
T/C (optional) if required.
PTi can also supply (optional) an extra heavy clamp or heated clamp design. On extruder
sizes 3-1/2quot; and up, this clamp ring will typically be suspended and actuated for removal of
dies by a yoke and hand wheel lift arrangement. A heavy-duty 10,000 psi clamp design is a
In the clamp area is located the breaker plate (optional), which acts as a seal and register
between the barrel recess and the customer’s die adapter. The back face of the breaker
plate is recessed to allow for snap-in placement of various sizes of screen packs.
Recommended stainless steel mesh and wire sizes are tabulated. The general breaker
plate design incorporates round hole openings with each opening being countersunk to
provide minimal resistance to the flow of plastic material.
Extruder System Description
Also, in the clamp or discharge flange area is located a standard opening in the barrel. This
opening is equipped with a rupture disc to provide mechanical protection against over
pressure. More then one opening (optional) can be provided in this area, immediately
behind the breaker plate recess, for interchangeability of instrumentation probes (Melt T/C,
transducer, grease type pickup for pressure gauge, etc.) as specified by the customer.
Venting of the Barrel (Vent Stack, Diverter and Plug)
A vent port is optional on all extruders and is used to remove air, moisture, and volatiles
from the material being processed as it melts and moves along the barrel and feed screw.
The extruder may, for this reason, be equipped with a vent stack in the side (standard – left
side when looking from behind the gearbox downstream). When this is the case, a two-
stage feed screw is used so that the extruder pressure is relieved prior to entering the vent
area; thus preventing material leakage.
The vent stack and diverter are designed to give the optimum opening in the barrel bore
with relation to the movement of the screw flights. At start-up or shut down some of the
material may dump into the vent stack and must be cleaned out as soon as possible prior
to hardening, to insure proper venting. The vent stack is typically designed with a slightly
tapered bore and equipped with a mica band heater which is controlled by an adjustable
thermostat (factory set at approximately 80% power) and tied into the vent zone heater for
its power supply, to aid in this clean-out. (See Safety, section 3 prior to working at the vent
Some materials can run with the stack open to the atmosphere and, if the extruded product
is acceptable, this is the preferred way. An exhaust hood over this area is recommended.
Other materials require varying degrees of vacuum, typically up to a maximum of 27” HG,
to thoroughly exhaust gases and volatiles. A specially designed hinged cover is supplied at
the end of the vent stack. The lid and its mating surface are finished to a “flat” 16 polish
that forms a metal-to-metal seal and is held closed by the vacuum. The lid should not be
closed until material leakage stops and is cleaned out of the stack so the vent is performing
properly at atmospheric conditions. The lid also incorporates a specially designed vacuum
groove and suction port to prevent material leakage into the vacuum pump piping system;
it restricts the leakage to the vent stack area only.
Extruder System Description
Vacuum Pump System (Optional)
The extruder may be equipped with vacuum pump (See Vendor Section 10). That is
usually a water-sealed type (oil seal type, optional). It is designed to evacuate any air or
condensation of gases into the water stream that is used to generate the vacuum.
Evacuation of condensed gases can pollute an in-plant
water system, or clog the entry port to the vacuum
pump; therefore the vacuum system is equipped a
condensation trap. This directs the exhausted gases
around a water-chilled surface which causes
condensation. An easily removable drain plug or valve
is located in the bottom of the trap which is used to
periodically empty the collected liquid condensation.
This trap is located after the vent port and before the
Vacuum Pump vacuum pump inlet.
After the vacuum pump discharge is located, a water separator/cylinder which separates
the exhaust gases through a vent located in the top of the separator. This exhausts to the
atmosphere or through a scrubber depending on local regulations. The wastewater exits to
a drain or to a water treatment or cleaning system depending on local regulations.
The vacuum pump requires a water supply to form the vacuum seal and evacuate the
condensation. This supply can vary depending on the type and pump size (See Vendor
Manuals, section 10 and Drawings section 8).
Barrel Guard Assembly
The PTi Trident Series Extruder is provided with an insulated barrel guard assembly.
Hinge type doors provide easy access for
maintenance and inspection of the cast aluminum
heaters mounted onto the extruder barrel. Doors
are provided with two (2) lockable quarter turn
latches. Doors should remained closed locked,
during normal operation and be opened by
trained personnel only. One (1) latch is also
provided to hold the door open during
maintenance of the barrel heaters. Use care in
opening and closing the barrel guard doors.
Cutouts for vent stacks and side inlet ports are Barrel Guards Open
Extruder System Description
The standard PTi feed screw is made from heat treated AISI 4140 alloy steel, precision
turned, ground and polished with hard surfacing on flights and is chrome plated. Other
base materials such as stainless steel, Durametal, Hastalloy and tool steel are optional.
Since flight clearance is very critical to the screw’s performance, it should be checked at
least once every year. As a general rule, if the screw-barrel clearance is twice the original
screw-barrel dimension, consideration should be given to replacing or rebuilding the screw,
and possibly the barrel, to avoid such problems as surging and severe reductions in output.
The typical screw design has three sections. The first section is the feed section. There,
material is gravity fed from a hopper onto the deep channel of this section. The material
is then conveyed forward into the second section, called the transition section. Here, the
material is transformed from a solid to a molten state as the channel depth decreases
throughout this section. This would be considered a single stage screw since it has only
one compression section. The third section is the metering section, where the molten
material is pumped out of the extruder. Here, the channel depth is constant.
There are many variations to screw designs: an additional flight may be added to the
feed section to improve conveying of material; a two stage screw can be used for
vented extruders; a variable depth screw can be used to improve melting; a mixing
section can added to the screw to further homogenize the molten material. In addition,
feed screws can be made in a two-piece construction for long L/D’s, removable mixing
sections and replaceable high wear areas. This is accomplished with a left-hand
threaded male to female adaptation.
The most important design area is that pertaining to heating and cooling of the extruder
and the extrudate. The PTi Trident line is standardized on cast aluminum or ceramic
heaters. These heaters are designed by PTi and are available only through PTi.
A standard watt density of up to 30 watts per square inch has been decided upon to give
the closest approach to straight-line temperature control when used with”On/Off“or
proportioning type instruments.
These heaters are applied to the barrel and retained by special alloy bolts. Upon heating
up the extruder, the effect is one of increasing the tightness of the strap so that good
contact is maintained at all times.
On the PTi Trident line design, standard heaters are manufactured for operation on 460
volt 3 phase power or as required. On extruders with either water or air cooling, cast
aluminum heaters are typically designed as 460 volt 3 phase per half or as required.
Considerable thought has also been given to control thermocouple or RTD location to give
as near as possible straight-line temperature control during the extrusion operation.
Extruder System Description
Water Cooling General Description
In many areas of the country, the water contains excessive mineral deposits and/or
clogging agents. When this water is used for barrel temperature control, these solids
are distilled out of the water causing cooling tube clogging. The re-circulating cooling
system was designed specifically for use in these areas.
The PTi Trident extruder cooling system is by far the most effective cooling system being
offered today. Cooling of the barrel zones is accomplished by circulating water through cast
aluminum water-cooled heaters. Each barrel cooling zone is controlled by one manually
adjustable water valve and automatic solenoid valve thru a water-recirculating unit. Each
zone also incorporates a sight flow indicator for positive flow verification. Standard
systems are provided with a Stack Valve™ manifold/flow valve assembly, a removable
contaminant screen needs to be inspected periodically. Refer to Vendor Data Section
10 for disassembly of valve assembly.
The system is of the closed loop design, using
distilled or treated water as a cooling media.
The unit consists of a stainless steel tank, that is
the reservoir for the cooling media, motor driven
recirculating pump, large diameter heat
exchanger for reservoir cooling, cooling water
control valve, water level gauge, and water
strainer. The unit is designed to mount under the
barrel or on the side of the base.
If the unit is not pre-piped at the factory (optional)
the plumbing consists of connecting cooling tower
or chilled water to the tube side of a tube and
shell heat exchanger. A line from the
recirculating pump to the water manifold and
return lines from each of the individual zones is
Operation Top: Extruder Water Cooling System
Fill the unit with distilled or treated water until the Bottom: Water Cooling Barrel Heater
level is seen in the center of the sight glass. Jog
the unit to determine the pump rotation. If the
rotation is correct, the unit is ready to run.
Make sure all water supply valves are full open, they include the main supply and return
valves, transmission heat exchanger, barrel cooling water recirculating system heat
exchanger and the supply valve to the feed section. The manual valves that supply the
closed loop distilled water to the individual barrel cooling zones including the supply and
return header bypass or back pressure needle valve should be wide open. The individual
barrel cooling zone manual valves along with the feed section supply valve might need
Extruder System Description
adjusting after the extruder is in complete operation for at least one hour. The feed section
should be set to maintain a lukewarm external feel or from hot to cold depending on the
process. The manual zone cooling valves should be shut slowly only if that zone tends to
run below set point.
Cooling via air blowers is available as an option for extruders.
PTi has three (3) types of highly efficient barrel air cooling
designs. The first and most efficient zone cooling system
incorporates finned cast aluminum heaters with cast
aluminum shrouds that are close fit around the finned heaters.
This directs the flow of air around and thru the fins exposing
the maximum surface area for the most cooling exchange.
The air is supplied from properly sized and configured
The next system utilizes the same finned cast aluminum
heaters as the previous system but rely on the barrel guarding
and individual sheet metal zone dividers to direct the air flow
from properly sized and configured sheet metal blowers. This
system is utilized on extruders that are running polymers that
require less cooling such as PET or Nylon when used in a
fiber type application.
The last type of air system utilizes ceramic heaters in place of
the finned cast aluminum and is constructed similar to the
barrel guarding and divider system above. This is our fiber
line of barrel cooling and is used on extruders that are 5 inch
and smaller. Again this system is used on extruders that are
running polymers that require less cooling such as PET, Top: Air cooled (finned)
barrel heater without
Nylon 6, Nylon 66 or PP.
Middle: Cooling fans and
All of the above air cooling systems utilize barrel guards that shrouds in place
are insulated and vented on top. Bottom: Barrel vents on
top of guards
Extruder System Description
Positioned immediately downstream of the extruder barrel at the discharge end of the
machine, the polymer filter device an integral role in assuring the melt stream, is suitably
clean and void of contaminants. Melt stream contaminants consist of gels, paper, metals,
glass and degraded or carbonized material. In order to assure the melt stream is suitably
void of these contaminants a properly configured polymer filter must be used. There are
several types to consider, barrel clamp method, manual screen changer, ribbon style
screen changer, hydraulic slide plate screen changer, bolt type screen changer and rotary
style screen changer.
The gear pump features intermeshed counter rotating gears that when turning displace
small volumes of polymer for every rotation of the gear pump. It creates a buffer between
the upstream extruder and the downstream devices of the feedblock and/or sheet die
depending on whether the application calls for a mono-layer or multi-layer structure.
Pumps are sized according to the materials being processed and the output range desired
for the pump. Another benefit to using a gear pump is the pump can be used to establish
the discharge pressure of the extruder. Gear pumps feature pressure controllers that use
PID algorithms to control the speed of the extruder. The gear pump becomes the focal
point of control for an extruder/gear pump combination. The control logic slaves the
extruder control to the gear pump control such that the pressure set points raise and the
lower the extruder speeds accordingly in order to maintain the desired pressure. By setting
the suction pressure of the gear pump the extruder pressure can be increased or
decreased. This permits the operator to artificially reduce the head pressure the extruder
would otherwise create for a given application.
Static Mixer (if supplied)
The static mixer is located after the melt pump (if supplied) and before the die. It is a
series of non-rotating ribbon-like segments placed in a hollow manifold pipe. It is
available in various lengths depending on the degree of mixing required. It is primarily
used to completely eliminate temperature variations or “hot” and “cold” spots in the
polymer melt. The manifold is electrically heated and is usually one (1) temperature
See Section 8, Drawings, for location.
Feedblock (if supplied)
The feedblock combines layers of polymer through a rectangular entrance area that forms
a sandwich that is fed into the sheet die. The layers are then spread to the width of the
Extruder System Description
sheet die slot. The flow conditions within the feedblock and die must remain laminar at all
times such that layers remain discrete without mixing or developing turbulence.
Sheet Die (if supplied)
Extrusion dies are used in the production of flat, continuous webs of various materials.
Their most common applications are found in the extrusion of thermoplastics, either as
webs by themselves, or laminates to other materials. The main function of the die is to
spread the material being processed to the desired width and thickness in a controllable
and uniform manner.
The die can be supplied manually or automatically adjustable and have additional sets
of lips for alternate thickness ranges.
See Section 10, Vendor Manuals, and Section 8, Drawings, for all the required
information that pertains to the die.
Control System (if supplied by PTi)
The extruder control system consists of the following:
1. Temperature control
2. Drive control
3. Pressure monitoring/control
4. Device control
5. Melt temperature monitoring
PID loops are used to control the temperature of the extrusion process. The barrel
temperature zones have heat/cool control, where all downstream zones are heat-only.
All heating elements are resistive; The Barrel zones have three phase heaters at line
voltage, and all downstream heaters are single phase, 240 V. The barrel zones can be
either air cooled or water cooled. Air cooling uses individual three phase fans,
controlled by SCR contactors. Water cooling uses individual solenoid valves. Heating
and cooling is cycled by the PID controller using time-proportional digital outputs. Each
zone uses a type J thermocouple for temperature feedback.
A closed loop water cooling system is included on all water-cooled extruders. The
system consists of a water pump, heat exchanger, reservoir with sight glass, metering
valves and solenoid valves. Adjustable metering valves limit the water flow in each
Barrel heating zones include AC ammeters to indicate current flow.
The melt temperature indicator displays the temperature of the molten plastic as it
enters the die.
The extruder screw and melt pump are individually driven by motors controlled with AC
vector drives. The gear pump (when supplied) establishes the product flow rate. The
Extruder System Description
extruder follows the gear pump by regulating the suction pressure (inlet pressure to the
melt pump). A pressure transducer converts pressure feedback into voltage or current
for the drive system to regulate. A proportional-integral loop trims the extruder speed to
maintain a constant suction pressure. Extruder head pressure and melt pump
discharge pressure are also monitored using similar transducers. High pressure in
either transducer will stop both drives.
The control panel is a sturdy, stand alone or machine mounted, self-contained unit
fabricated from heavy gauge sheet metal. All the electrical components and controls for
your extruder have been pre-wired to the maximum degree to eliminate high installation
Following is a list of some of the noteworthy features which have been engineered into the
control cabinet to help simplify your extrusion operation.
1. Safety disconnect switch shuts off the power when cabinet is opened.
2. Easy access to contactors, circuit breakers, fuse blocks and instruments.
3. All wires are numbered in accordance with a wiring diagram for easy identification.
4. Power lines and thermocouple or RTD leads are separated from each other in order
to prevent the stray currents of the power lines from disturbing instrument readings.
5. Each zone of the extruder die is individually controlled by a proportioning type
6. Operator control panel contains readings of screw rpm and motor amperage.
7. The panel typically comes mounted on the extruder base and pre-wired.
PTi RECOMMENDS THAT OUR FIELD SERVICE ENGINEERS ARE PRESENT FOR
START-UP TO INSURE THE PROPER EQUIPMENT INSTALLATION. PTi IS NOT
RESPONSIBLE FOR ANY DAMAGE THAT MAY RESULT FROM AN IMPROPER OR
To forestall voiding the warranty on your extruder, we suggest that the erection crew
installing your equipment follow the recommended procedures outlined below.
If required, PTi can supply supervisory personnel on a per diem basis to help in the
installation and to insure recommendations being followed. Proper installation will prevent
erratic operation, frequent maintenance, and poor product quality.
Your building construction should be adequate for a floor loading sufficient to hold heavy-
duty industrial machinery, and should be reasonably free from vibration. The ideal floor or
platform is of smooth level concrete.
The location selected should provide ample clearance according to the layout drawings of
the extruder for proper maintenance, including removal of the feed screw from the
discharge end of the barrel (see Maintenance, Section 7, for detailed instructions) and
removal of the screw cooling assembly from the transmission end of the extruder, if
applicable. Head room is required for access to the feed hopper and for any take-off
equipment necessary for the handling of the thermoplastic extrudate. The control cabinet,
in which terminals, instruments, and other auxiliary meters are mounted, should be so
arranged that it is close to the operator’s station and easily read from the die station.
Temperature and pressure gauges, plus other instrumentation, often give advance warning
and allow the operator to avoid damage to the equipment. Refer to PTi machine drawings
(see Drawings, Section 8) for necessary services required at the machine site.
An adequate supply of cooling tower or chilled water is required with as low a grain
hardness as is possible to obtain. Customer should provide a closed loop system for
cooling tower or chilled water.
• Equipment must be installed and operate within the ambient temperatures and
conditions for which it is designed.
• Maximum altitude 1000 meters (3300 feet).
• Ambient temperature 0 to 40 degrees C (32 to 104 degrees F).
• Line voltage source impedance and frequency must be within the equipment
specifications as described in the individual components manuals (see Vendor
Manuals, Section 10).
• Equipment must be located in an area provided with a flow of clean cool air, free of
dust, dirt, vapors, moisture or any abrasive elements. Provide fans and filters if
• Avoid mounting electrical control equipment on the body of rotating or vibrating
• Mount the equipment on a relatively high platform with good drainage to avoid
Care and Handling
The skids and/or crates (if supplied) used to protect PTi extruders during shipping are
designed and proportioned to give ample protection against the ordinary transportation
stresses. However, dropping the equipment, or sudden horizontal movement without
rollers, or even careless jacking, can cause damage. Standard domestic packaging
precludes the use of slings for lifting.
Under no circumstances should the extruder be lifted by the barrel or drive sections. Bars
placed through lifting holes or eyes provided on the base allow safe lifting of the extruder.
Unloading and Positioning
Unloading and positioning of the extruder is best done by experienced riggers under the
supervision of the customer’s Engineering Department. Extreme care should also be used
in handling the control cabinet.
Instruments, meters and contactors can be damaged by shock, and the careful testing and
adjustment originally completed in our factory can be changed by rough handling.
When skids and crates have been removed, you will note that numerous tags are fastened
to the extruder to call your attention to important considerations of installation and
operation. These tags should remain attached to the machine until the initial start-up
operations have been completed.
On some air-cooled units the discharge air plenum is removed for shipping purposes. If
this is the case the plenum should be carefully reinstalled using the screws which were
reinstalled in the taped holes on the top of the plenum support.
Some instrument and meter units have been separately shock-packaged and not installed
in cabinet support chassis. These must be installed and connected per wiring diagram.
Also check inside cabinet for special wire jumpers, braces, etc. which must be removed
before operating the machine.
The equipment must be stored in a dry, clean area and protected from corrosion, loss or
any weather damages. It is recommended to store the equipment in the original shipping
package or equal. If the storage area has a high level of moisture or temperature variation,
space heaters and climate control equipment are necessary.
The motor shafts need to be rotated manually about once every month; just a few turns.
All openings need to be screened to prevent rodents from entering the equipment.
If space heaters are used, keep the equipment openings uncovered to prevent moisture
from forming inside.
This equipment may have a specific shelf and operating life span, some
equipment/material replacement may be necessary if this period is exceeded. Consult PTi
engineering if extended storage, beyond 6 months is anticipated. Consult PTi for more
specific instructions if needed.
Leveling and Anchoring
Your PTi supplied extruder has been laser aligned at assembly and prior to delivery but
during the shipping process the machine may shift out of alignment. This is especially true
with extruders with a bore diameter of 3.5 inch and over. It is strongly recommended
however that during installation and prior to start-up the unit be realigned by laser or bore
scope to insure proper alignment of all critical components. If the barrel is not aligned prior
to start-up, SEVERE EQUIPMENT DAMAGE MAY RESULT!!!! PTi offers this as a field
service at additional cost or we can make recommendations for contacting an outside
organization to perform this service, possibly in your local area.
When the extruder has been moved to the proper location in the plant and with hold-down
bolts in place, BUT NOT TIGHTENED DOWN, the unit should be leveled from end to end
and side to side by means of jack screws and shims. This leveling device should be
adjusted so that the total weight is evenly distributed under each mounting pad. This device
should be provided on either side of each of the hold-down bolts so that, when tightened,
uniform pressure will be created on the supporting surfaces instead of creating a bending
strain in the machine base.
If the extruder is mounted on a concrete floor, an excellent and sanitary foundation is
provided by grouting the unit in place with a strong, rich concrete mix, grout. To insure a
firm grip between floor and grout, the concrete floor should be roughened and moistened
with water. For proper grouting, the shims or wedges should hold the extruder at least 1quot;
above the floor.
If the extruder is caster mounted, the tracks should be positioned and leveled by means of
jack screws and shims then anchored in place. The caster mounted extruder has a built-in
± 1-inch of wheel adjustment for centerline height and final leveling. Caster tracks should
be grouted as well.
(The following grouted tracks installation
procedure applies to a Co-Extrusion
Sheet Line. Similar procedures should be
followed for a single extruder sheet line.)
Also, please reference the installation
instructions from the PTi Operation &
Maintenance Manual and the included
grout specification sheets for high
precision, non-shrink, natural aggregate
grout. (Refer to the Masterflow 713 Grout
Specification in the Vendor Manuals,
Section 10, for mixing and application
PTi strongly recommends that all
extruder bases and tracks be properly
grouted. This will help with vibration and
leveling issues. PTi recommends at
least 1.00 inch of grout under all the
PTi recommends that the contractor
responsible for the installation of the Roll
Stand tracks use a laser or sight to assure that the tracks are level. The tracks should
be level to +/- .015 inches when sighted down the length of a track assembly or from
track to track. Machine tracks are to be installed to within .015 inches straight when
sighted down the length of one track assembly and to within .015 inches parallel from
track assembly to track assembly. Grouting pads should be positioned below all jack
screw taps in the tracks. Consult PTi engineering for the number and size of grouting
pads recommended. Shim stock should be used on top of the grouting pads to properly
level the tracks. Thickness and quantity of shim stock will vary depending on the
levelness of a floor.
PTi recommends at least 1.00 inch of grout under all equipment…
1. Using proper surveying techniques, strike a centerline down the bay of your plant for
the Main Extruder, Roll Stand and Winder (if applicable). Using the floor plan
provided, locate tracks for all machinery. The tracks for the main extruder and roll
stand, once properly located and leveled, can be anchored permanently. Proper
anchoring bolts designed for use with heavy equipment should be used. Do not
permanently anchor the co-extruder tracks yet, since it’s alignment with adapters
needs to be verified first. Use anchors at corners of track at this point only, just in
case tracks need slight position adjustment. Also do not permanently anchor the
accumulator and winder until the extrusion plant and roll stand are permanently in
place, if applicable. Please note, if bolt and nut style anchor bolts are used, ensure
that the bolts are cut down enough so that they will not interfere with the caster
2. After allowing proper time for curing of the grout, locate the extruders and roll stand
onto their respective tracks, using proper rigging technique. Please note that the
caster assemblies for the Co-extruder have side to side play. When positioning the
co-extruder on the tracks, center the caster in its bracket.
2.1. Level the Main Extruder to the proper centerline height, as indicated on the
installation drawings. When leveling a PTi extruder, a precision machine level
should be placed on the top surface of the feed section where the magnet
drawer or hopper would be mounted. Both cross machine (side to side) and
machine direction (length ways) should be checked and leveled using this
2.2. Repeat this process for the co-extruder as well.
2.3. The screen changer can be assembled to the barrel at this point, if it is a slide
plate type. When the extruder has a dual bolt type or similar, the screen
changer can not be assembled to the extruder prior to laser alignment. The
laser target and eventually the screw need to pass through the screen changer
to be installed. This is possible with a slide plate screen changer by removing
the downstream bushing.
2.4. The extruder should now be laser bore aligned. PTi recommends that each
extruder be laser aligned by a PTi Technician once the extruders have been
set in their final locations as suggested in the following instructions.
2.5. Install the Main Extruder Feed Screw into the machine. It is recommended that a
PTi Technician be present to assist in this operation.
2.6. The Main extruder is now located, leveled, and aligned.
2.7. Build the equipment downstream from the Main Extruder. This includes the feed
pipes, gear pump, static mixer, feed block and die assembly.
3. Verify parallelism between the sheet die lip and fixed middle roll of roll stand. The
position of the main rolls in the roll stand section, relative to the sheet die is a critical
reference point in the installation of the line. For a pivoting extruder base adjust the
angular position of the main extruder as required to assure parallelism. Reference
the PTi installation drawing that is provided. Adjustable stops are provided to hold
position of the pivoting extruder.
4. The co-extruder should have the screen changer mounted to the barrel. The feed
pipes of the co-extruder from the screen changer to the feed block can now be
assembled, leveled and preliminarily installed. Ensure that the adapters are properly
supported during this process. Adjust the position of the co-extruder as required to
line up with the adapters. Adjusting position of co-extruder by use of play in caster
should be sufficient. In some cases it may be necessary to re-position the extruder
tracks. Once the feed pipes have been bolted to the extruders, use a precision
machine level as described in Step 2.1 to level the extruders.
5. Disassemble all feed pipes and adapters leaving the screen changers in place, if it is
a slide plate type.
6. The co-extruders should now be laser bore aligned as was the main extruder. PTi
recommends that each extruder be laser aligned by a PTi Technician once the
extruders have been set in their final locations.
7. Install the co-extruder Feed Screws, after the co-extruder has been aligned. It is
recommended that a PTi Technician be present to assist in this operation.
8. Reassemble and mount the feed pipes to all the extruders. During the process of
laser bore aligning the machines, the alignment of the extruder to the adapters may
have changed slightly. Use the following steps to compensate for this condition.
8.1. For slight side to side adjustment of the caster mounted extruders. Casters for
Co-extruders have side to side play (adjustment) to allow for minor
8.2. If the center line height of the extruder needs to be raised or lowered to meet up
to the feed pipes, raise or lower the extruder using the caster adjustments, so
that the machine remains level. To do this, use a precision machine level on
the top surface of the feed section as described in Step 2.1. Note:
readjusting the extruder’s position should be minimal as to not cause mis-
alignment to the extruder.
8.3. Once the feed pipes are re-mounted to the extruders, the co-extruder can be
grouted in place. Use the Masterflow 713 Plus specification (Vendor Manuals,
Section 10) on high precision, nonshrink, natural aggregate grout as a guide.
The PTi extruder design incorporates the motor base as an integral part of the extruder
base and would automatically be secured to the floor during the alignment, leveling and
NOTE: On direct-coupled machines the coupling should be rechecked for alignment
before starting drive. On belt driven machines, alignment and belt tightness should also be
Alignment instructions by the coupling manufacturer are included (see Vendor Manuals,
If the motor is found to be out of alignment, the factory-installed tapered pins should be
removed and the motor realigned. After final alignment of drive, dowels should be
reinstalled to prevent any further shifting during operation.
Electrical Control Cabinet Installation
If the electrical cabinet does not come mounted on the extruder base and pre-wired,
position it adjacent to the extruder for ease of operator access and follow these steps:
1. Run conduit between control cabinet, the extruder junction box, the main motor,
the drive panel if it is supplied in its own panel, etc. as required by the supplied
cable groups list (see Drawings, section 8).
2. Ground equipment per NEC and all local codes.
3. Use only type J thermocouple wire for all thermocouple connections unless
expressly stated by manufacturer. Note: Polarity of thermocouples is critical for
correct operation. The white lead is considered positive. Also, all thermocouple
wires must be routed in a separate conduit away from and not parallel to high
voltage wires (for example 460, 380, 230 or 120 VAC).
4. Route all encoder and signal wires in separate conduit(s) and terminate shield
at only one end (preferably drive control end).
5. Install isolation transformer, if provided, with sufficient open area (not less than
two feet) around the transformer for cooling.
6. After cable installation it will be necessary to verify all connections per
7. Motor cabling must be shielded per manufacturer’s recommendation.
Water and Compressed Air (If Required) Hook-Up
If the unit does not come pre-piped from the factory (optional), make all connections to
feed section, heat exchangers, vacuum pump solenoid and to the stuffer ram pneumatic
solenoids (if supplied).
Verify that there is sufficient water or oil to cover the pump seals before rotating the lube
pump, the water pump and the vacuum pump.
Verify that there is sufficient air supply to the solenoids on the stuffer ram (if supplied)
Feed Screw Checkout
Feed screws are shipped separate from the extruder in a wooden crate, but with a
protective coating. It is therefore necessary to clean the screw prior to running plastic.
CAUTION: PTi has various feed screw key configurations, single or dual keys may be
provided depending on the transmission used. It should also be noted that, depending on
the feed screw shank diameter, the key or keys might have to be removed and installed,
through the air spacer behind the feed section and in front of the transmission, immediately
after or before the screw shank leaves or enters the quill (see Drawings, section 8 to see if
this applies to your machine).
Screw extractors are available as an accessory and enable screw removal to be
accomplished without damage to the feed screw shank. No circumstances will warrant
sledge hammers and drive bar for screw removal. Machine warranties are voided by such
After the screw has been removed, the drive key or keys located in the shank of the screw
should be checked to make certain that it is firmly seated in the key slot without burrs and
that the retaining screw, if supplied, in the drive key is tight.
After the screw has been cleaned and the barrel swabbed out, reinstallation should be
done immediately. Just prior to reinstalling the feed screw, a protective coating of light oil
and graphite should be wiped on the screw shank to prevent corrosion and subsequent
difficult removal of the feed screw. A light coating of silicone based grease may be applied
to flights to avoid metal to metal contact while inserting screw into the barrel. NOTE:
Always support the weight of the screw, as it is installed using a hoist or rolling table to
INSTALLATION CHECK LIST
a. The transmission is tagged with a warning that the unit has been shipped without oil
in the reservoir. Therefore, the right type and quantity of oil must be supplied before
operation of the extruder. This data is on the nameplate attached to the
transmission. The exact level is determined by a level bull’s-eye on transmission
body. (see System Essentials, section 2 for approximate amounts required or read
the transmission manufacturer’s nameplate located on the unit.)
b. The thrust bearing obtains its lubrication by a gravity feed and return system built
integrally with the transmission.
c. The coupling needs to be lubricated as specified in the coupling manufacturer's
service bulletin which is located in the vendor data section. If the motor and
coupling have been mounted by PTi, then it is pre-lubricated.
d. Lubricate rotary union (if supplied) as specified in the rotary union manufacturer's
lubrication schedule which is located in the vendor data section.
e. The throat seal (if supplied) will need to be lubricated with a high temperature
silicone type grease before start-up.
f. If casters are supplied lubricate bearings with a good multi-purpose grease. Cutout
is supplied for this access.
g. If supplied verify that the closed loop barrel water cooling tank is filled to the sight
glass with distilled or treated water. An appropriate corrosion inhibitor should be
used with process water.
a. Verify motor wiring. Refer to drive manual for proper connection of motor leads
to ensure proper rotation of screw.
b. Re-check motor rotation by jog starting the motor. A visual check through the feed
hopper opening will show if motor rotation is proper as the flight lands of the screw
should be visibly moving forward during operation. (Counter Clockwise when viewed
from the non-discharge end.)
a. Check water lines connected to the base to be certain that shut-off valves have been
provided. (Customer to supply).
b. Check return/drain lines to be certain that no obstruction exists throughout the
c. With power locked out check all termination’s with a screwdriver to ensure tight
d. Using a Multi-meter, measure heater and motor wiring impedance to ground.
Verify all heater and motor terminations are not grounded. If any termination
reads continuity to ground consult PTi Engineering.
e. Be certain that all fused connections have proper fuses installed. DO NOT
ASSUME ANYTHING. Fuse sizes for control panel are listed on wiring diagrams.
f. Visually check all temperature controllers or control screens to see that the process
valve is reading room temperature. Each thermocouple should be removed from its
thermocouple well on the barrel/adapter and then heated with a lighted match or
heat gun briefly. The process temperature on the controller should increase quickly.
g. Check all disconnects to be certain of proper functioning and recheck all power
connections to be certain that the applied voltage is within tolerance.
h. Lift or remove barrel covers and visually check all wiring connections to be certain
that no contaminates have accumulated in the open sections between heaters or
around heater terminals. Pipe fittings can also be checked for tightness.
i. With a Multi-meter set on AC volts (1000 VAC scale) verify the line side of the
main circuit breaker to be within equipment tolerance as stated in equipment
specifications. If voltage is not within tolerance turn power off and consult your
electrician. If voltage is correct then check load side of breaker. The voltage
across the three phases should match the line side of the breaker. If not, consult
the equipment manufacturer.
j. With the above complete, the circuit breaker may be switched 'on'. Note: The
lube pump and the main motor blower will turn on with main power applied. This
is to ensure that the gears are covered with oil prior to running.
k. Verify operation of the entire emergency stop circuit.
l. With correct voltage to control cabinet, jog the water pump (if supplied). Check
m. Jog barrel air cooling blowers (if supplied). Check rotation.
n. Jog vacuum pump (if supplied). Check rotation.
o. Jog screen changer hydraulic pump motor (if supplied). Check rotation.
p. Check rotation of transmission lube oil pump motor (if supplied). Verify flow at
q. Check rotation of main drive motor and variable frequency drive cooling blower.
Airflow should be present at exit end of motor.
r. Heaters should be turned on and allowed to heat up to approximately 300°F (150
deg C). Heater bands or bolts should now be tightened to assure good heater
contact to barrel surface. Consult heater installation section of manual for higher
temperature applications (PET, Nylon, etc.).
s. Start main motor per drive manual. Check rotation of screw (should be counter-
clockwise as seen from shank end of screw). Change rotation, if necessary, per
t. The extruder is now ready to run.
a. Prior to turning the installation over to production people, the installation personnel
should check out the complete operation of the machine with all utilities connected
and all power lines quot;hot“.
b. On the initial start, the start-stop buttons should be handled to provide a jogging
start condition with close attention to the motor ammeter to be certain that no
overloading or shorting conditions exist.
c. If the barrel and screw have been properly cleaned in accordance with earlier
instructions, the unit is now ready for production operations.
PTi RECOMMENDS THAT OUR FIELD SERVICE ENGINEERS ARE PRESENT FOR
START-UP TO INSURE THE PROPER EQUIPMENT INSTALLATION. PTi IS NOT
RESPONSIBLE FOR ANY DAMAGE THAT MAY RESULT FROM AN IMPROPER OR
INCOMPLETE INSTALLATION! IT IS ALSO STRONGLY RECOMMENDED THAT
PRIOR TO START-UP ALL 3.5 INCH AND LARGER UNIT BE REALIGNED BY LASER
OR BORE SCOPE TO INSURE PROPER ALIGNMENT OF ALL CRITICAL
READ SAFETY PRECAUTIONS BEFORE OPERATING MACHINE (See Safety, Section
The fundamental extrusion process consists of feeding granules of plastic onto a
rotating screw which then conveys the material through a heated barrel and then forces
it out of a die. The primary process element is the screw. With it the material is not only
carried through the barrel but is also subjected to heating, mixing, shearing and
A key process element is the die. The die is connected to an adapter which is in turn
connected to the barrel or to a screen changer which is connected to the barrel. It
configures the output form of the extrudate. Typical forms include fiber, strand, profile
and sheet. The design of the die centers around material specifications, flow rate,
output form desired and operating conditions.
Various components support the extrusion process. A DC or AC motor drives the screw
through a transmission. The transmission converts motor RPM into screw RPM and
supplies the torque required to turn the screw fully loaded with plastic. A vacuum
system, utilized on vented extruders, carries away fumes and moisture from the molten
plastic after it has been compressed by the screw. A screen changer, mounted to the
end of the barrel, filters or strains out impurities in the melt flow and allows the operator
to change out screens without system shutdown. A temperature control system
maintains precise temperature control along the length of the barrel, as well as on the
screen changer, adapters and die.
The extrusion process can easily be monitored and controlled on line and therefore
proper instrumentation is a requirement. This would include: PLC control systems or
PID temperature controllers, melt temp indicator, barrel head pressure indicator, screw
RPM meter, DC ammeter for motor load indication and AC ammeters for heater load
indication. Ancillary instrumentation could include: an annunciator for troubleshooting,
a chart recorder to monitor process variables over time and a discharge pressure gauge
to monitor differential pressure at the screen changer.
a. Make sure all water supply valves are full open they include the main supply and
return valves, transmission heat exchanger, barrel cooling water recirculating
system (see System Description, section 4 for more detail), heat exchanger and the
supply valve to the feed section. The manual valves that supply the closed loop
distilled water to the individual barrel cooling zones including the supply and return
header bypass valve should be wide open. The individual barrel cooling zone
manual valves along with the feed section supply valve might need adjusting after
the extruder is in complete operation for at least one hour. The feed section should
be set to maintain a lukewarm external feel or from hot to cold depending on the
process. The manual zone cooling valves should be shut slowly only if that zone
tends to run below set point.
b. Start the barrel water cooling system pump (if supplied).
c. Turn on all heaters. Establish profile for the material to be run.
d. Allow all zones to reach set-point before starting the main drive system.
In this section we have pointed out the proper operating procedures to assure
profitable production. THE MOST IMPORTANT POINT IN THE ENTIRE
OPERATION OF THIS EXTRUDER IS TO BE CERTAIN THAT SUFFICIENT TIME
IS ALLOWED FOR PROPER HEAT-UP OF THE EXTRUDER AND THE PLASTIC
MELTS IN THE EXTRUDER PRIOR TO TURNING ON POWER TO THE FEED
SCREW. A good conservative rule would be to allow 30 minutes per inch of
diameter of extruder screw.
Number 1 zone is the first zone forward of the feed section. Zones #2, #3, #4, etc.
follow in order down to the discharge point of the extruder barrel.
On extruders designed for devolatilizing, specific reference is given to the vent zone
control and may be marked as such on the control panel.
The general profile of temperature settings for any material, when fed in cold
powder or pellet form, is an increasing temperature level from Number 1 through to
the next to last zone; and either a leveling or reduction of temperature in the last
zone prior to the die. Consult your resin supplier for the best temperature profile for
Once a temperature profile has been set up and the machine has been allowed
sufficient time to heat up, it is now ready for start-up.
With the completion of the installation and check-out, you are now ready to extrude
Recheck to see that the lubrication system is properly filled and the oil pump (if
supplied) is working. Now, with the machine up to heat and the breaker plate (if
supplied) and die removed, plastic can be fed into the hopper. Start the screw
rotating slowly (5 to 10 rpm) and gradually increase the speed after the plastic
emerges from the barrel discharge end. If the motor load and general machine
operation seems OK, stop feeding material and run the screw until it is empty and
The extrusion die and other equipment downstream from the barrel can now be
installed and the heat up procedure repeated for these parts.
e. Start main motor and turn screw slowly.
f. Feed material into hopper and allow it to coat screw.
NOTE: If the machine is a dual-diameter and is equipped with a hopper agitator,
it should be started prior to feeding the material. It is generally run at a speed
similar to that of the screw RPM, but if a higher output is obtained by running the
agitator slower or faster, this speed should be maintained.
g. Watch pressure gauge. As material begins to fill the screw notice the head
pressure gauge start to fluctuate.
h. Turn screw speed slowly up and continue to add material. DO NOT start the
screw at high speed, pressure will built rapidly and may cause serious damage
to the equipment or injures to personnel. DO NOT leave the extruder unattended
while ramping up speed.
i. Run machine at flow rate desired and continue to monitor both temperatures and
head pressure. Adjust temperatures and/or speed to obtain optimum extruder
operation. Refer to material specifications as provided by your material supplier.
Note: Excessive pressure will cause the rupture disc to blow (shoot material out onto
the floor). The extruder rupture discs are designed to safely and effectively
relieve built up pressure for the safety of personnel and equipment, but even
when they are for safety, care should be taken to prevent front blown them up to
reduce down time and lost in production while replaced for a new one.
Stand clear of rupture disc at all times during operation of extruder. Be sure melt
valve or other restrictive devices (such as die choker bar) are wide open. The melt
pressure should not exceed 5000 psi in most cases, and usually is the first
indication of something wrong.
If the operator is inexperienced in extrusion, it is recommended that PTi’s Service
Department be contacted for start-up assistance to avoid any start-up problems.
The procedure for shutdown will vary with the type of resin being extruded, the reason for
the shutdown, and the length of down time.
Heat sensitive materials such as vinyls, acetates and nylons, will degrade when exposed to
the residual heat in the barrel. This is especially true when some air is entrapped in the
plastic melt and oxygen is present to accelerate the degradation. With these heat sensitive
materials, it is best to extrude continuously with the supply hopper shut off until no further
flow of material can be observed at the die orifice.
WARNING: DO NOT OPEN HEAD UNTIL HEAD PRESSURE READS “0” ON GAUGE.
The head can then be opened by removing the clamp and the breaker plate (if supplied).
While the die and cylinder flanges are still hot, and prior to the polymer freezing, mating
surfaces should be thoroughly cleaned with brass tools. A purging compound can then be
put through the machine, and it will be ready for start-up the next day.
When temporary shut-downs are needed for screen changes or die changes, but not
polymer changes, reduce temperature settings on the barrel and stop the extruder while
the barrel is still full of polymer.
In the event a new die is installed that is cold, start-up will have to be delayed until the die
has reached proper operating temperature. Such changes should be accomplished rapidly
to prevent start of degradation in the barrel.
Operator skill will reach a point where, generally speaking, there is little danger of polymer
Upon resumption of the operation at normal operating speeds, some degradation in the
form of carbonized particles may be observed but should clear up rapidly as the process
continues. If, and this depends upon the polymer, the situation does not clear rapidly, then
a complete purge would be indicated. Awareness of melting points of various thermoplastic
materials should be a part of the operator’s knowledge.
On an overnight or weekend shutdown, full cooling can be applied to the barrel if the
polymer is not run out and, in so doing, the material can be set or frozen quickly to prevent
residual heat degradation. An indication of temperature can be observed on the
temperature control instrument. When it is indicating below 200 it is generally safe to turn
off the cooling to all components and cut the power to both the motor and control cabinet.
On long shut-downs, where it is felt advisable to check feed screw condition, a feed screw
ejector should be attached to the rear of the extruder; and while the machine is still up to
temperature, the feed screw can be pushed through the opened discharge end and onto a
support stand. If this is done in steps, 12quot; at a time, the feed screw can be wiped clean
while removing. After removal of the screw, a swab should be run through the barrel, back
to the feed section opening.
CAUTION: NEVER USE A FLAMMABLE SOLVENT
An inspection of the liner surface and screw flights can be made at this time to determine
whether or not an abnormal wear is being encountered. In some instances, nylon can be
removed from the feed screws and die parts by submerging them in heat transfer salts that
become molten at 800 F.
Resumption of operations will follow the pattern outlined at the beginning of this section.
Maintenance of the extruder can be divided into two main areas: Electrical and
The main electrical component is the drive system and regular maintenance on a 6 month
schedule is sufficient preventative maintenance. In most cases, the drive manufacturer is
best suited to do the inspection and the charge is minimal.
The heat control system which consists normally of power contactors, control instruments,
thermocouples and the heaters should be given a routine inspection by an
experienced electrician every 2 to 3 weeks. A thorough inspection of the temperature
control instruments should be made every 6 months by an instrument serviceman. This
serviceman can be obtained direct from the instrument supplier or through the PTi Service
The main items are the transmission and the thrust assembly. These should be thoroughly
inspected every 6 months. A good flushing every 12 months of both with a light oil and
replacement of the used oil with the type recommended in the Appendix Sections 9.6, 9.7
& 9.8. This will assure proper lubrication and result in long life of all bearings and gears.
The extruder screw and barrel should be inspected every year for wear and a record kept
to anticipate when they will have to be replaced. The dimensions given in the Appendix
can be used as a general rule for determining when parts should be replaced. During this
inspection, any deep score marks should be honed out of the barrel and sanded off the
screw to assure that the best possible performance is achieved.
NOTE: See also Maintenance Chart (page 7.2).
A recommended spare parts list is supplied with this manual (See Spare Parts List Section
9) and is adequate for most extrusion applications. If preferred, a list can be prepared by
customer’s maintenance department utilizing the list of components shown on the
assembly drawings (See Wiring and Assembly Drawings Section 8) also supplied with this
EXTRUDER MAINTENANCE CHART
Week Month Quarter Year
Transmission oil level (if applicable), * x
* oil pressure, and oil filter
Change oil in the transmission x
Drain force feed lube system (if applicable) x
Alignment and check tightness of drive * x
belts (if applicable)
Lubricate drive coupling (if applicable) * x
Check motor coupling alignment (if applicable) * x
Check motor brushes (if applicable) x
Lubricate all motor bearings * x
Check motor cooling blower filter (if applicable) x
Check water level in water recirculating unit (if *x
Check for water flow to each zone control flow * x
indicator (if applicable)
Check Stack Valve™ manifold/flow valve * x
assembly contaminant screen (if applicable)
Check for water flow to feed section * x
Check for water flow to all heat exchangers (if * x
Clean all heat exchangers (if applicable) x
Check inlet and outlet to air cooling blower (if * x
Continued on next page . . .
Extruder Maintenance Chart - continued
Week Month Quarter Year
Check heater terminal connections * x
Check heater retaining bolts or straps. Check * x
torque on bolt-on heaters, set torque at 60
Check thermocouple on RTD seating * x
Re-calibrate instruments - * x
A. Temperature controls
D. Melt temperature indicators
Inspect contactor or starter points (if x
Check control cabinet air inlet filter (if x
Check all E-stops and safety interlocks * x
Lubricate rotary union (if applicable) *x
Lubricate feed section seal (if applicable) *x
Check barrel alignment - * x
A. At feed screw
B. At support(s)
Check barrel clamp or discharge flange * x
Inspect breaker plate (if applicable) x
Clean and re-coat the feed screw shank * BEFORE EACH INSTALLATION
Inspect feed screw flights and
root diameter and barrel bore WHENEVER SCREW IS REMOVED.
* - Indicates initial maintenance
x -Indicates frequency felt desirable
Rupture Disk Replacement
1. Lock-out and tag-out all control cabinets for the
2. There may be residual pressure behind the rupture
disk, so wear protective gear during removal.
3. If there is protective tubing around the rupture disk, remove this
to gain access to the rupture disk.
4. Use proper sized wrench to unscrew the rupture disk from the
barrel or adapter.
5. Barrel or adapter hole must be cleaned out prior to installing
new rupture disk.
6. Replace rupture disk with one of equal pressure and
temperature rating as originally supplied with machine. (refer
to PTi recommended spare parts list for rupture disk part
7. Apply ‘never-seize’ to threads of rupture disk
8. Insert new rupture disk into barrel or adapter hole, screw in
9. Re-install protective tubing around rupture disk (if applicable)
Motor Cooling Blower Filter
The motor cooling blower filter should be inspected monthly or more
frequently to assure proper air flow. The dirty filter should be removed and
cleaned from the inside out with a blast of compressed air.
To remove air filter,
loosen retaining wing
nuts and slide filter out.
Extruder Feed Section Rear Seal
The extruder feed section rear seal should be inspected and lubricated
Feed section rear seal
grease port. Lubricate
weekly with grease gun.
Feed Section Seal Replacement
Removal (Split Seal*):
1. Remove seal retainer extension
2. Remove seal with putty knife or
1. Locate split of seal at top
2. Locate retainer split horizontally
and grease fitting at top
3. Notch seal at top to allow passage
of grease into seal
4. Grease fitting extension should
extend just past top guard; notch
guard as necessary
*Note: For non-split seals, remove all downstream equipment to allow extruder screw enough forward
movement to slip seal over shank of screw. Instructions on screw removal can be found in section .
Extruder Screw Removal
1. Follow proper machine shutdown
procedures (see section --)
2. If removing screw from a cold state,
preheat machine to 300 degrees F.
Having the extruder warm will make
the screw easier to remove. Machine
temperature should be 300 deg F.
3. Lock-out and tag-out all control
cabinets for the extrusion line.
4. Remove all downstream equipment Extruder Pivoting Base
(die, adapters, gear pump, screen
changer (if other than a slide plate
5. Remove feed section seal (see Feed
section seal removal section)
6. Remove screw cooling (if applicable).
Turn off cooling water utilities prior to
7. If a slide plate screen changer,
remove the downstream bushing
using tapped holes on bushing.
8. If not already done, pivot the extruder
far enough to allow removal of the
screw out the front of the barrel.
9. The screw needs to be pushed out of
the barrel. Attach the screw pusher
adapter to upstream side of gearbox
(PIC) using correct hardware. Use of
PTi screw pusher adapter highly
10. Thread screw pusher into screw
pusher adapter until in contact with
upstream end of extruder screw.
11. Use a large wrench to turn the screw
pusher clockwise (looking
downstream) to slowly push extrusion
screw out of the barrel.
Extruder Screw Removal, Cont’d.
12. Using proper rigging techniques,
support the end of the screw (once
exposed). Continue to push forward
and adjust straps as necessary to
sufficiently support the screw.
13. Once the screw pusher reaches the
end of its length, the screw can be
‘pulled’ out of the barrel using proper
14. If the screw has been in the extruder
for many years, it may be necessary
to use a hydraulic ram to assist in
screw removal process.
15. If difficulty is encountered pushing the
screw forward, consult PTi
For non pivoting base systems, extruder
must be moved back or the roll stand
must be moved forward so that there is
adequate clearance to remove the
screw. Otherwise all pivoting base
Static Mixer Removal/Installation.
1. Follow proper machine shutdown
procedures (see Operation, section 6)
2. If removing static mixer from a cold
state, preheat machine to 300 degrees
F. Having the extruder warm will
make the removal easier.
3. Lock-out and tag-out all control
cabinets for the extrusion line.
4. Remove adapter or component
downstream of static mixer adapter
5. Pull static mixer from the static mixer
adapter without twisting, pull straight Cross section of
static mixer inside
out, there is a pin that could shear if adapter
6. With the adapter still warm, clean out
static mixer adapter bore of any
1. Make sure main bore and counter bore
2. Insert static mixer into static mixer
adapter making sure to alignment pin
on the base of the static mixer wit the
drilled hole on the static mixer adapter
3. Reassemble downstream adapter
Barrel Heater Installation
Cast Aluminum Heater Band Installation
(Bolt-on or Strap-on Connection)
1. Correctly align the heater half along
the length of the barrel.
2. Press the heater over the barrel.
3. Tap the heater lightly with a rubber
mallet to seat it tight against the
4. Align the opposite half with the half
already on the barrel.
5. Repeat the seating process. Barrel heater (water cooled)
6. Install and tighten down the straps or
bolts, nuts and washers depending
on the heater style. If bolt-on style,
torque the bolts to according to bolt
size. .50” : 65 ft-lbs .625”: 126 ft-lbs
.75”: 200 ft-lbs
7. Connect the electrical leads and the
cooling lines (if required)
8. For bolt-on type heaters, run the
heaters to 1/2 the operating
temperature and re-torque to 125 ft.
lbs. For strap type heaters, run the Barrel heater (air cooled) with
heaters to operating temperature and
re-tighten as required.
For higher temperature applications
(PET, Nylon), refer to extruder heater
layout (in Extruder Drawings) for
Barrel Cooling System for Water Cooled Extruders
Barrel Cooling Tank. The barrel cooling tank supplies cooling water to the
individual barrel zones of water cooled extruders. The cooling tank must be
filled with distilled or treated water prior to operation of the extruder.
Use filler/breather cap to fill tank
with distilled or treated water.
Monitor temperature and water
level gauge for proper operational
ranges (normal temperature range
Barrel Cooling Tank approximately 100-130°F) add
water as needed.
valve. Used to stop
water flow when
Plant chill water
shutoff to heat
Barrel Cooling System Pump. Check
pump label for servicing instructions, if
Barrel Cooling Solenoid Valve System
The barrel cooling solenoid valves control the water flow to each barrel zone of
the extruder. Red (no flow) and green (flow) LED’s indicate whether the valves
are open or closed. Each valve features a flow turbine to visually indicate flow
activity. The valve system is pre-configured at the factory and requires little
overall maintenance with the exception of checking and cleaning the
contaminant screens (annually).
Remove to access
Barrel Cooling Solenoid Valves
Note: Reduced flow indicates
possible filter cleaning necessary.
Barrel Cooling Zone (Inspect periodically Inspect and clean filters annually.
Rebuilding Barrel Cooling Solenoid Valves
Remove valve Replace
cap, solenoid housing cap
Insert new Restore
Fit solenoid to
Changing extruder transmission oil filters. It is recommended that the
transmission oil filters be inspected on a quarterly basis. Filters can be
changed while the extruder is operating.
Filter selection handle allows
the operator to switch between
filters. In this position, oil is
flowing through the right filter
only, allowing the left filter to
Red indicator pops up when
filter needs replacement.
To remove filter cartridge,
unscrew 4 bolts and remove
cap. Replace with new filter.
Extruder Transmission, Cont’d
The transmission oil
should be changed
annually using the oil
type and quantity
specified by the
Transmission oil drain valve Transmission oil flow sight
transmission oil flow,
pressure should be
monitored on a regular
Transmission thermocouple Transmission oil temperature
(180°F shutdown) gauge
Transmission oil pressure Transmission oil pump with
gauge pressure sensor