The main faults in the Machine may be of three types:
Electrical, Mechanical or Hydraulic. Electrical faults may be
due to loose contacts or malfunctioning of any of the instruments.
Hydraulic faults include damaged oil seals, non-development of
system pressure or non-working of solenoid valves. The general
faults and remedies are given below:
On every fault ensure whether the power supply is
reaching the concerned solenoid coil, if not, electrical fault
exists. Then you check the circuit and get the solution. If
supply is reaching, then either hydraulic, pneumatic or
mechanical fault is there. Please note that on each hydraulic
operation power should reach the unloading valve (wire no. 49)
and (wire no. 68) concerned solenoid coil.
while air blow is on. This will result in a weaker parting line of
article. The possible causes are:
Oil seal of the clamping cylinder is
leaking inside. To check this, set the cooling time to maximum
and turn off the system. Loosen the opening pipes from the cylinder
and press the "Close" push-button. If the seals are damaged, the oil
will leak from them. Hence, replace them.
Oil leakage in the pipeline of closing, in
between the manifold block and cylinder. Tighten the pipes if
3. Pilot operated check valve is leaking.
This will cause pressure drop in the closing system. The leakage
may be caused by small foreign particles in the spool of the check-valve. Clean the valve with kerosene.
Mould Does Not Close.
First check whether the supply is reaching the solenoid coil of
OPEN-CLOSE valve (wire no. 73). If power does not reach, check
Wire no. 73 is coming from the Limit
switches (LS-6&7) at the Stretching unit. Supply to these Limit
switches comes from the Closing Contactor through Opening
Contactor, Unloading Timer and AUTO MANUAL Selector switch (wire
nos. 27, 25, 38 & 71).
If the Closing contactor is not energising,
check the supply to the contactor coil (wire no. 33) from "Closing"
push-button. If the supply reaches, then check the coil and
replace if necessary.
If power supply is reaching the solenoid
coil and the valve is not energising, the solenoid coil should
If power is reaching and valve is
energising, check the hydraulic pressure. Hydraulic system
pressure should be developed with any of the hydraulic
For non-development of pressure, check
whether power is reaching the Unloading valve solenoid coil
(wire no. 49) & (wire no. 68). If not, trace the line as
discussed earlier. Note that the line for wire no. 49 and wire no. 68
are coming through wire no. 28 and Unloading Timer.
If supply reaches the unloading solenoid
and it doesn't energise, the solenoid coil should be replaced.
If unloading valve is energising and
pressure is not developing, then the unloading valve may be
faulty due to foreign particles inside. Clean the valve using
kerosene and re fit.
Mould Does Not Open.
If mould not opens while working in either AUTO or MANUAL modes,
check the electrical supply is reaching and valves are operating
Check whether power is reaching to the
Opening solenoid coil (wire no. 37). If not trace the line
coming through the wire no. 26 and Closing Contactor.
Check the opening contactor is energising
or not. If supply is not reaching trace the line to contactor
coil wire no. 31 and if supply is reaching check and replace the
If supply is reaching the Opening valve
solenoid coil, check and if necessary replace the solenoid coil.
If the opening valve is energising, check
the system pressure is developing or not. Trace the line for
unloading valve (wire no. 49), (wire no. 68) and check the
solenoid coil. If the valve energises and the pressure is not
developing, dismantle and clean the unloading valve and the main
If both the valves are working and
pressure is developing satisfactorily and still the mould does
open, check whether the check valve is OK. There is a small
pilot line in the manifold block which connects the opening line
to check-valve. It activates the check-valve during opening and
it should not be blocked.
System Pressure Not Developing
Check the power supply (wire no. 49) &
(wire no. 68) to the unloading valve & main valve with any of
the manual function. If it is not reaching trace it with the
hydraulic control circuit.
If the supply is reaching and solenoid
coil is not energising the coil is to be replaced with new one.
If the coil is energising and pressure is
not developing, the unloading valve is faulty. Dismantle and
Also check for leakage in any of the
pipelines. If there is a leakage pressure may not develop.
Parison Not Dropping
1. Check whether the supply is coming to Accumulator
solenoid coil wire no. 44 or not. It comes from Accumulator
Contactor through wire no. 19 and Half-Close Timer.
If the power is not coming from the
Accumulator Contactor, check if the contactor is energising or not.
The power for coil comes through wire no. 35. Replace the
contactor coil if it is not energising even after the supply
If power reaches the Accumulator valve
solenoid coil, check whether the solenoid is energising with
power. If not replace the coil.
Check whether the pressure is developing.
If not check the wire no. 49, wire no. 68 and unloading valve.
If the pressure is developing and valve is
actuating check whether the Accumulator is filled with molten
material or not.
Check the heating in the Accumulator Head
and ensure sufficient heating is attained. If You are restarting
the Machine and not emptied the Accumulator when You shut off,
it will take double the normal time to attain heating.
Check the Flow Control Valve in the
Hydraulic circuit on the Accumulator B line. If it is closed
fully the Parison will not come out.
Parison Control Not Functioning
Check the Parison Control Time. It should
be less the Parison Length Time.
After completion of the Parison Control
Time the Parison control Cylinder actuates and the Core comes
down. The movement is controlled by the Parison Control Nut in
the top of the Parison Control Cylinder. If the nut is in fully
closed position, the Parison Control will not work.
Check the Flow Control Valve in the
Parison Control Circuit. If it is fully closed the Parison
Control will not work.
Check whether power reaches the Parison
Control valve coil. If not trace the supply (wire no. 45). It
comes from the Accumulator Contactor through wire no. 20 and
Parison Control Timer.
If the power reaches the valve and the coil
not energise, then the coil has to be replaced.
You can check the Parison Control only by
taking the Parison. This is due to the fact that the Parson Control
Cylinder actuates by the Parison push out pressure and not by
the Hydraulic. The Hydraulic pressure only holds the Cylinder in
the UP position and the pressure drops when the solenoid coil
Clamping Slow Down Not Functioning
Check whether power reaches the Slowdown
Valve Solenoid coil (wire no. 68). It comes from the Closing
Contactor through wire no. 43 and Slowdown Limit switch LS-2
If the power reaches the solenoid coil and
not energise then replace the coil.
If the valve actuates and the required slow
down is not achieved, check the Flow Control Valve in the Slow
Down Circuit. The slow down can be adjusted by setting the Flow
Blowing Does Not Take Place
Check whether the power reaches the
solenoid coil on the Blowing Valve. If not check the line (wire
no. 66). It comes through the Blowing Limit switch and Cooling
If power reaches, check the solenoid coil
is energising or not, if necessary replace it.
Check the pipeline for any damage.
Stretching Unit Not Functioning
Check for any mechanical misalignment or
loosening of the bolts and nuts.
Check the pipeline for any damage.
Check the air pressure.
Check whether power is reaching the
respective coil or not and trace the circuit if necessary.
If the solenoid coil is not energising
even after the supply is reaching the coil, replace it.
Check the exhaust port of the Pneumatic
valve, and ensure it is not blocked.
Noise in Hydraulic System.
If excessive noise is coming while hydraulic motor ON check the
Check the mounting bolts of Hydraulic
motor and pump. If necessary tighten them.
Check the SPIDER on the pump motor
coupling. If it is worn-out replace it.
Check the Hydraulic oil filter. If it is
blocked with foreign particles clean with kerosene and air
Check for the oil leakage in the system
Feeding Of Material Is Improper.
Check the temperature at the feeding zone,
i.e., first zone. Too high and too low temperature results in
feeding problem. Adjust it as per the requirement and quality of
Check the cooling water circulation
through the Barrel Cooling Jacket. If necessary, clean the
Remove the head from Barrel and clean the
Breaker Plate inside. If some foreign particles blocked the
small holes in the Breaker plate, the resin flow through it will
Note that if overheating caused the
feeding problem, reduce the heating and put some strips of
article, i.e., 2 or 3 cms wide and 2 or 3 mm thick, to the
feeding zone manually. It will clear off the overheated resin
from the feeding zone.