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How to achieve clean ink jet auto start up and shut down

(auto start/stop)

How to achieve clean ink jet auto start up and shut down

• Symptoms of bad, dirty jet auto start up and shut down

• Why bad , dirty jet auto start up and shut down?

• Solutions to bad, dirty jet auto start up and shut down

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Symptoms of bad, dirty jet auto start up

• Gutter fault error after jet start up

• Auto modulation failure error

• EHT or charge fault error after auto start stop

• Missing drops from bottom of prints

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Why does bad jet auto start up happen?

Continuous Ink Jet (CIJ) nozzles get clogged either during operation or at jet start up or both.

1. Dirty jet auto shutdown • Insufficient solvent during auto clean shutdown • No solvent during auto clean shut down routine

2. Partially or completely blocked nozzle • Dried ink at the nozzle • Salt deposit at nozzle orifice

3. Incorrect auto start up & auto shut down software algorithm • Non-optimum sequencing of the ink system (solenoid valves opening and closing

order not optimum and not effective) • Non–optimum timings of the software auto start/stop algorithm (ineffective opening

and closing times of certain valves)

4. Non- optimum nozzle design for clean jet start/stop • Not the best nozzle orifice geometry, shape and form to allow smooth solvent

flow during jet auto shut down and start up (jet deviations) • Bad nozzle orifice surface finish leading to jet deviations during auto start /stop.

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How to solve dirty ink jet start/stop problems?

Bad auto jet starts/stops problems as a result of the first 3 reasons listed in the previous page are normally easily solved. To overcome these, it is normal practice for:

o The printer to automatically warn the operator if there is not enough solvent to do a clean shut down.

o The solution to bad start up as a result of partially or totally blocked nozzle, have been discussed in detail in another of our papers

o The ink jet printer manufacturers to carry out extended tests and several iterations to the auto start/stop software algorithm to ensure it is optimised to give clean auto jet start and stop

However, in the case of bad start/stop as a result of non optimum nozzle design, this cannot be solved by any of the above listed countermeasures. To solve this, nozzles design with correct geometry, shape, surface finish and material quality will be required.

Sellenis engineers have the expertise and the know how in this field. This ensures that Sellenis nozzles incorporate the best ink jet nozzle jewel design with the optimum geometry, shape and surface finish to give clean jet auto start/stop and overall high ink jet performance.

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