1. Load mixer with powder and aluminium (or other) pigment.
2. Close lid.
3. Operator checks that dust extraction is in place and operational.
(This could be interlocked to sequence if required)
4. Start operational sequence.
· Nitrogen Flow Starts.
· Nitrogen Flow Switch indicates a flow.
· Operator Checks Flow Rate. (Pre-set at regulator?)
· Sequence Pauses.
· Operator Confirms Flow Rate and presses button to ‘continue’.
· Mixer Starts on Slow Speed.
· Nitrogen Flow continues for Pre-Set Time. (Tbc during commissioning)
· Mixer Speed Increases to Required Bonding Speed.
· Bonding Continues until End Point Reached. (Pre-determined by temperature?)
· Mixture Discharged to Cooler. (operator needs to manually check cooling water flow
· Nitrogen Flow Stops.
· End of Sequence.
As the cooler will hold more than one mixer load, then cooler discharge will be better
controlled manually rather than built into the PLC programme sequence.
Some care will be needed when loading the next batch as the mixer will still have some
nitrogen in it. As the mixer is emptied, air will be drawn in to replace the powder, so will
dilute the nitrogen. The residual nitrogen concentration should be checked during
commissioning using oxygen analysis.
The sequence would need to change slightly if it was decided to add aluminium after
the powder was hot via screw feeder.