What is the machine shutdown procedure?
The plastic injection moulding process features a correct method of turning injection moulding machines on and off that should be followed to ensure efficiency and safety.
Injection moulding machines contain large cylinders of molten plastic. The machines get very hot: machines at Essentra will go from 150 – 320°C, depending on the type of material being processed. Obviously, the machine presents a considerable hazard when it is hot.
Wearing the correct PPE
Operators turning off an injection moulding machine must ensure they are wearing the correct PPE. That includes safety goggles and heat resistant gloves, or gauntlets. In a mould shop, operators will also wear steel toe-capped safety shoes and ear defenders.
The correct procedure at Essentra is always followed for turning an injection moulding machine off.
Follow the correct procedure
This procedure runs as follows:
- Stop the machine. The machine goes ‘into hand’ – so the operator has full manual control. The injection unit is retracted.
- Pull the hopper across and get rid of any existing material from the barrel by purging the machine.
- All engineered or volatile materials must be purged with polypropylene or LDPE. With an engineering grade – such as a nylon material – the material will be more volatile. A high-density polyethylene or polypropylene must be used to purge the barrel clear. This is used as a purging agent. It is not good practice to leave engineered grades of materials in screw barrels.
- Remove the purge – use a piece of cardboard to minimise any risk of contact.
- Ensure the screw tip is left fully forward. This tells other personnel that the machine is empty.
- Ask the setter to lower the machine temperature to 100°C.
Following this plastic injection moulding procedure correctly makes the injection moulding machine safe, and ready for restarting.
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