BLOW MOULDING
Aim: To prepare a bottle of 200ml using blow moulding machine.
Equipment: Blow moulding machine
Material Required: Low grade poly ethylene
Operating instructions:
a) Install the machine on a leveled strong flooring near the compressor (within 2 meters).
For letter rigidity foundation bolt is recommended & anti vibration rubber mounting can be used.
b) The machine must be placed in a position where all parts are accessible readily.
c) Check for loose any loose electrical connection with the help of certified electrician and with the electrical circuit enclosed.
d) Fill the lubricator with SAE 20 grade oil to the level indicated. The lubrication has been set to allow one drop of oil for every 5 strokes of air cylinder (oil) drop is factory set, no need to adjust)
e) Connect the air filter to the compressor by rubber/nylon hose (Min inside dia 10mm), pressure with standing capacity 20kg/cm2.
f) Set the pressure switch in the compressor as per the compressor manual to switch on 7 kg/cm2 pressure & switch off at 10kg/cm2 (NOTE: The air pressure should not exceed 10cm2)
g) Set the air pressure in machine by adjusting the injection & release regulator (18).
h) Set release pressure 2kg/cm2 by adjusting release regulator.
i) Operate the hand lever valve (13) and check for smooth functioning of plunger.
j) Set the blow pressure in regulator (15) and operate the hand lever valve (14) to check flow of air throw blow nozzle.
k) Electrical connection should be given as indicated on the main plug phase, neutral and earth.
l) Proper earthing should be done.
m) Check the incoming voltage (230VAC, 50Hz) Now the machine is ready for operation.
Working Principle: The process is applied to only thermo plastics, which are used for producing hollow objects such as bottle, and flow table objects by applying air pressure to the sheet material when it is in heated and in soft pliable condition. Blow moulding can be accomplished in two manners; one is direct blow moulding and other indirect blow moulding. In the former case, a measured amount of material in the form of tube is either injected or extruded in a split cavity die. The split mould is closed around the tube, sealing off the lower end. The air under pressure is blown into the tube, which causes the tube to expand to the walls of cavity. In the latter case, a uniformly softened sheet material by heat is clamped at the edges between the die and cover, which causes the sheet to attain a hemispherical shape or the configuration of mould whatever
it may be parts obtained by indirect blow moulding have excellent appearance but they are more costly as only to percent of the sheet stock is utilized and also there is a tendency for excessive thinning of sheet at the deepest point.
Procedure:
1) Set the die in position. Adjust the guide rod nuts to suit die height. Align the tapered face of the die for sealing the parison while blowing also checks for the face opening and closing of the die.
2) Ensure minimum die height is 80mm. provide spacing plates if necessary.
3) Set the injection, release and blow pressure by rotating (clockwise) the regulator knob to suit the requirement of moulding the container.
4) Feed correct quantity & quality of plastic material and switch on the power supply.
5) Switch on the heater.
6) Set the required timings controller to control the bottom heater.
7) Allow sufficient time to stabilizer.
8) When temperature reached, operate the hand lever valve.
9) Extrude the parison (Tubular form) to the required length and close the two die halves. Release the injection cylinder.
10) Operate the hand lever valve and blow the air so that the parison to form the shape of the container as designed in the die.
11) Allow the component to cool.
12) Open the die & take the product out of the die.
13) Now the machine is ready for nest cycle.
