maintenance of Heater and Thermocouple

Heater and Thermocouple Replacement

1. Remove hot half from mold
2. Remove Locating ring that clamps hot nozzle in place
3. Remove back plate of mold, if required, to give access to nozzle head
4. Using a small jimmy bar carefully remove the nozzle, ensure thermocouple and heater wires are not trapped
5. Remove cir-clip and heater cover
6. Grip body by the head and remove heater by turning the heater such that the heater coils loosen and at the same time pull the heater off the body
7. Remove thermocouple
8. Check the resistance of the thermocouple with a multi meter, the resistance should be 0.0 ohms (or less).
9. When replacing the thermocouple you need to bend the end as per figure below.To fit heater push heater as far as it will go onto the body, with bottom heater connection inline with slot on body.
11. Then turn ( “Unwind” ) the heater as you continue to push the heater towards the head of the nozzle.
12. Refit the heater cover, if the cover is tight check that the heater is not partially unwound
13. Refit the cir-clip
14. Recheck the thermocouple resistance as per 8 above
15. Refit nozzle into the nozzle cavity in the mold, taking care not to crush the heater or thermocouple wires

Tip Blockage

1. Very carefully try and remove the blockage with a small piece of wire, taking care
not to damage either the tip or the gate
2. If unsuccessful remove nozzle from tool.
3. Remove cir-clip and heater cover
4. Place body in three jaw chuck
5. Heat the nozzle up to the plastic’s processing temperature.
6. Unscrew nut
7. Remove plastic from bush and tip taking care not to scratch or damage either one
8. If the blockage is a foreign body, find cause and fix the problem. DO NOT reassemble nozzle and tool until the problem is identified, as more contamination coming through the hot runner system will only cause more blockages
9. Reassemble nozzle making sure to use the correct torque setting when tightening the bush nut
10. Reassemble mold