ids presentations

© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.

Ink Delivery System (IDS) issues overview

Gengrinovich Semion

IDS group


Content

2

• What it is IDS?

• Pressure

• Temperature

• Maintenance

• Numerical Simulation


IDS – what is this?

3

IDS – system that responsible supply ink whenever PH’s need

ink ink inkink

Load Cell

Ink

Atmosphere

10L Supply Tank

Ink ID

Air Purge valve

Pressure 0.9bar

T2 (Optional)

Pum

p

Radiator

Filter 1m

ic

3Way Valve

ffl

ffl fflffl

Recycling Bath

fflffl

ST1 ST2

Filte

r 1m

ic

Feeding main Tank /

Recycling pump

3Way Valve

Ink Ink Rec Ink

Ink

Ink

Ink

Ink Rec

Air valve 2Air valve 1

Ink Circ

Air for ST’s valves

Air relief for Valves

Pressure/Atmosphere

Atm

Heater

Water IN

T1

fflCritical

fflFeelingffl

OverflowPressure Transducer

3Way

Val

ve

Feeding Secondary tanks Pump

Ink Ink

OverflowFeeding

LowCritical INK line

INK RecyclingINK CirculatedWater lineAir Valve reliefAtmosphere/Purge

Manual Valve

Waste Tank

Ink ID

Manual Valve

Separator

Waste pump

Vacuum knife

Waste lineSimplified IDS

Actually IDS


IDS – what is this?

4

Pressure issues in PH’sMachine serge

-140

-120

-100

-80

-60

-40

-20

0

20

40

1550 1600 1650 1700 1750 1800

Time (50samples per sec)

Pres

sure

(mm

H2O

)

Machine serge

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-120

-100

-80

-60

-40

-20

0

20

-3 -2 -1 0 1 2 3 4

Time(sec)

Pres

sure

(bar

)

theoretical calculation Machine phenomena

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-120

-100

-80

-60

-40

-20

0

20

-3 -2 -1 0 1 2 3 4

Time(sec)

Pres

sure

(mm

H2O

)

Theoretical calculation Surge with flexible tubes

1!]


Pressure issues in PH’s

5

HP Confidential

-100-90-80-70-60-50-40-30-20-10

0

0 5 10 15 20 25 30 35 40

Pres

sure

(mmH

2O)

Time (sec)

Valves 400 in nominal condition (pressure in Inlet of PH 16)

Valve 400 – opens dH=40mm

H=50mm

-150

-100

-50

0

107 112 117 122 127 132 137

Valves 400 - closed during the printing)

After 4 copies in print mode 480 BB 100% 3.2 meter - Failure appear

H=80mm

-110

-60

-10

110 115 120 125 130 135 140 145

Siphon installed - valves 400 in nominal conditions

H=30mm

Valve 400 – opens

• After 20 copies in print mode 480 BB 100% 3.2 meter –Stable (Failure not appear) butnot repeatable in all colors

• After 20 copies in print mode 480 BB 100% 3.2 meter –Stable for all colors


Pressure issues in PH’sSolved the “starvation” – tested on one machine – 6 colors

6

• After 4 copies in print mode 480 BB 100% 3.2 meter - Failure appear in all colors

• After 20 copies in print mode 480 BB 100% 3.2 meter – Stable for all colors

© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.7

18 October

Particles with a size of 20 m or larger should be prevented from reaching thenozzle. Inside the printhead, this can be achieved through filters. But dustparticles from outside also form a threat. Printing in a clean environment shouldprevent particles from reaching the nozzle. Unfortunately, for printers in anindustrial environment it is often impossible to control the cleanness of theambient air.

Air entrapment triggered by particles in the ink, disrupting the droplet formation

J. Acoust. Soc. Am., Vol. 120, No. 3, September 2006 de Jong et al.: Air entrapment in piezo-driven inkjet printheads

© Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.8

Air entrapment caused by an ink layer on top of the nozzle plate

The ink layer on the nozzle plate should stay below a thickness of 30 m. This

may be accomplished by a special design of the nozzle plates.

J. Acoust. Soc. Am., Vol. 120, No. 3, September 2006 de Jong et al.: Air entrapment in piezo-driven inkjet printheads


White ink sedimentation

After Week End of 60Hr (2.5 days) and post weekend maintenance of purge 2sec * 3times @ 2bar in machine #40, was discovered a lot of missing nozzles in the middle of the beam. After additional full cycle maintenance, problem disappear.


White phenomena solution – through RCD

10

Missing Nozzles in the middle of the beam requires twice the “Purge”

process to “wake up”

During circulation More fresh ink is available at the mid ink bushing for

sediments

Sedimentation rate of pigment at the middle of the beam is higher

Stagnation point of bushing creates more sediments in the

mid beam area

High ink waste – 66% at xx usage

Sedimentation rate of pigment at the middle of the beam during

circulation is higher

And/Or

And/Or

Change in flow direction separates the pigments from the carrier

during the flow

First DOE iteration point us to that

Root Cause

Well, Why the middle is dramatically different from

others? Lets work on circulation sequence.

Ok, This one can be easy to check, by removing

the insert from the middle

This one not easy to implement for proving, and can affect on

whole white system


Decap/Open time No First drops jetting due to changing of ink

properties

Ink polymer separation in nozzles

Under investigation

Proven false hypothesis. This is not a cause of the problem

Proven true hypothesis

NOT Under investigation

Last Update: 22/03/2012Updated by: Semion Gengrinovich

Locally in nozzles Ink properties changed to

viscoelasty

Cross talk pressure wave during the

printing

Temperature gradient between nozzles and

plenum

Cheek depth geometry differences

Temperature gradient between PH’s in the

beam

Ink Volume above the PH’s

Short decap / open time

Spontaneous curing of ink at nozzle level

Sedimentation of ink at nozzle level

Ambient temperature

Higher ink Evaporation at nozzles level

Stray lights

And/Or

Nozzle plate protruding

No circulation/mixing/vibrations during the

idle time

Degassing level of ink

Ambient Air flow above nozzle plate

And/Or

Initial Conditions After 10min with air flow

After 20min with air flow

After 40min with air flow

RCD:

60 min idle, “micro purge” 0.01bar, 10 sec, no dripping observed


Thermal issues


Solution to dissipate the heat

Temperature during the printing @30kHz with Heat Sink

37394143454749515355

1400 1450 1500 1550 1600 1650 1700 1750Time (sec)

Tem

pera

ture

(C)

Ink temperature inside the PH chamber Electronic part of PH

Condition with water cooler. The effect of water cooler is clearly observed (The temperature almost identical on the all area of PH – around 41.5C).Temperature at PHs ink chamber– 37C

•Max hot spot temp(Initial to max)=44-40.5 = 3.5 [°C]•Reservoir printing max Ink temp (Initial to max) = 38.5-40.5 = 2 [°C]


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