crescentformer general process. tissue machine voith

Crescentformer Forming Presentation

Agenda

•1/ Fabric Design: – Warp Bound Triple Layer (Enterprise)

•2/ Key Operating Variables – Sheet Trim Method / Fabric Width Considerations

– Operating Tension

– Jet Impingement

•3/ Showering: – Showering Best Practices

FABRIC DESIGN

Crescentformer Forming Fabric Design Criteria

Drainage: • fabric must be open enough to handle high dewatering loads

• speed, formation, tensile ratio

Fiber Support • fabric must be fine enough to retain fiber, build sheet

• retention, pin holes, tensile

Stability / Durability • width stability critical on Crescentformers

• wear potential for life

Conventional Triple Layer

Reported as Open Area

Blocked by Weft Binders

Paper Making Surface

• Enterprise at 450cfm WILL OUT DRAIN other products at +550cfm

• in conventional weft bound fabrics, considerable amount of

reported Open Area actually blocked by binder

• no extra binder yarn in Enterprise

• open structure for ease fast dewatering, ease of cleaning

MD

Conventional Triple Layer

Binder Wear

Weft Binding

• delamination with conventional WEFT bound fabrics limits life

• warp bound Enterprise will not delaminate

• longer life potential

Warp Binding

CDL-4 DAR (Marking)

CDL-4 SAR (Non-Marking)

CDL-4 WEAVE COMPARISON• take existing bottom MD warp yarn to bind

Warp Binding

Patented Enterprise Design: • More Open than conventional Triple Layer and Double Layer designs.

• Faster drainage

• Dryer sheet off the former / machine speed

• Sheet formation (flocs)

• Higher Fiber Support than other designs:

• Fiber retention

• Sheet tensile

• Pin holes / formation

• Better Life potential than other designs:

• No delamination with warp binding

• Excellent wear potential

• Improved width stability with use of comparable weft diameters

Comparison of Specifications P621 / T521 Enterprise 2184 - Fine Enterprise 2184 - CoarseWEFT Binding WARP Binding WARP Binding

Mesh - Total (/inch) 188 x 120 184 x 165 184 x 141

Mesh - Top (/inch) 94 x 80 92 x 110 92 x 94

Mesh - Bottom (/inch) 94 x 40 92 x 55 92 x 47

Warps (MD) 0.125mm 0.127mm 0.127mm

Wefts (CMD) 0.15mm 0.11mm 0.13mm

0.11mm

0.25mm 0.21mm 0.25mm

Caliper 0.027" 0.024" 0.026"

Permeability 490 cfm 450 cfm 480 cfm

Open Area 30.0% 36.7% 36.3%

Drainage Index 39.2 DI 49.5 DI 45.1 DI

Frame A (MD x CMD) 0.178 x 0.686mm 0.121 x 0.437mm 0.140 x 0.437mm

Frame B (MD x CMD) 0.178 x 0.145mm 0.121 x 0.155mm 0.140 x 0.155mm

MD Frame Length 0.178mm 0.121mm 0.140mm

Fiber Support Index 138.1 FSI 187.0 FSI 165.6 FSI

Support Points (/inch2) 3760 6600 5640

Conventional

Triple Layer

Stability Benefits - Enterprise

0

100

200

300

400

500

600

700

800

900

Gemini

Plus

2184-Fine Polaris 2184-

Coarse

mN

mNm

Tissue References - The AmericasMachine # Former Width Grades BW Furnish Speed Fabric(Outer)

1 3 CrescentFormer 110 Tissue 9.5-12 Waste 5600 Gemini Plus

2 3 CrescentFormer 254 Tissue/Towel 9.5-27 Kraft 4600 Enterprise

3 3 CrescentFormer 110 Tissue/Towel 9.5-12 Waste 5500 Enterprise

4 9 CrescentFormer 202 Tissue 9.5-11 Waste 5500 Enterprise

5 20 CrescentFormer 280 Tissue/Towel 9.5-15 Waste 5500 Polaris

6 5 CrescentFormer 310 Tissue 9.5-11 Kraft 5600 Polaris

7 1 CrescentFormer 130 Tissue 9.5 Kraft 5500 Enterprise



10 18 CrescentFormer 200 Tissue/Towel 9.5-13 Waste/Kraft 5700 Enterprise




14 1 CrescentFormer 172 Tissue 9.5-11 Kraft 5500 Enterprise


16 1 CrescentFormer 132 Tissue 9.5-11 Waste/Kraft 4500 Enterprise

17 2 CrescentFormer 132 Tissue 9.5-11 Waste/Kraft 4500 Enterprise


19 1 CrescentFormer 209 Tissue 9.5-11 Kraft/Waste 5700 Enterprise



22 11 CrescentFormer 200 Tissue 9.5-12 Waste 6000 Polaris/Enterprise



25 1L CrescentFormer 171 Tissue 9.5-11 Waste/Kraft 3500 Polaris

26 11 CrescentFormer 110 Tissue 9.5-13 Waste 5000 Polaris

Mill: Midwestern US

Machine: 202” Crescentformer

Grades: 9.5 - 13# (15 - 20 gsm)

Furnish: 100% Waste Furnish (high ash content)

Speeds: 5800 ft/min (1765 m/min)

Fabrics: Enterprise 2184 preferred product

Improved retention and formation

Excellent drainage and wear potential

Improved sheet CMD profile

Trim Beads

Case Study #1

Mill: Mexican Mill


Grades: 9.5 - 13# (15 - 20 gsm)

Furnish: Waste / Kraft Furnish



Excellent formation / tensile

Improved sheet properties over other deigns

Trim Beads

Case Study #2

Mill: Eastern US Mill


Grades: 9.5 - 13# (15 - 20 gsm)

Furnish: 100% Waste Furnish (Low quality, dirty)



Improved drainage / formation

Runs cleaner than other designs

Trim Beads

Case Study #3

Defining Sheet

Edges

Defining Sheet Edges

Not possible to locate Trim Squirt on Forming Fabric, as is common practice on other Former types:

– Locate Trim Squirt on felt:

• poor sheet edge

• felt filling

– Trim Sheet Using Plastic Fabric Edges

– Trim Beads

Extruded Edges

•1cm and 1” widths common

• provides a straight inner edge for sheet trim

• protective shield recommended

Headbox

Fabric Extruded Edges

Fabric Edges

inside Headbox

Sheet Trim – Trim Beads

–at Yankee, Creping Blades see a temperature step change where sheet ends – Crepe blade wears at this point.

• if in sheet, edge tears and breaks. • if in Shaving, reduced sheet breaks and blade changes

- No sheet Trim to Yankee

- temperature step change at sheet edge

- sheet trim to Yankee

- Temperature step change in Shaving

Sheet on Yankee Yankee

Crepe Blade

Trim Beads

Plastic beads extruded inside fabric edges:

locate 1.5 – 4cm inside fabric edges.

generates sheet Trim / Shaving

durable Polyurethane withstands Chemical attack.

5mmmmmmmmmm

Protective Shield

HP Shower Boom

Protective Pan

Fabric (Blue Edge Glue)

OPERATING

VARIABLES

Crescentformer Adjustments

BR - FR Gap -25 – 30mm common

- uniform front/back

Separation Angle

(3 – 70 common)

• Jet / Wire Ratio

• Jet Impingement

Fabric Tension

Headbox Considerations

• Consistency: Low = Best Formation (0.1 - 0.3% common)

– Low HB consistencies = higher drainage load on fabric

– No different from other Former configurations

• Jet / Wire Ratio: rushing the jet can “pick” the felt surface

– Limitations on using jet/wire to control tensile

– Increases the benefits of fast draining fabric design

• Jet Impingement Angle: angling too much into felt can result

in “picking.” – Again, limitations here increase importance of fabric design

– Must be fast dewatering

– At same time, must have high FSI to optimize retention / pin holes

Jet Impingement Angle

Forming Roll

Breast Roll

Breast Roll

Forming Roll

Excessive

Impingement

Angle

Correct

Impingement

Angle

Jet Impingement Measurement

Fabric Tension

• Dewatering a function of Fabric Tension:

D = T / R D = Drainage T = Fabric Tension R = Radius of Forming Roll

• Use as much tension as is needed to get desired dewatering rate:

– sheet formation – CD Tensile (MD/CD Tensile Ratio)

• Typical Tensions 35 - 55 PLI

WIRE TENSIONING

• Operating Tension:

– single Layer Fabrics - 30 - 40 PLI

– multi-layer Fabrics - 35 - 55 PLI

• Tension Measurement: – Huyck Tensometer still industry standard.

– different curves for different fabric styles.

– curves for all fabric designs converge above

about 40 PLI.

Tensiometer Curve Voith Fabrics - Tension vs Huyck Reading

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

Hu

yck R

ead

ing

2184 Avg.

2164 Avg

852 Avg

2152 Avg

Prod. Graph

2184 Avg. 28.857 56.429 75 83.714 90.857 96.75 102.5 107.5 107

2164 Avg 40.359 59.897 75.436 84.872 93.04 98.877 103.13 107.49 111.76 113.86 117.17

852 Avg 0 41.233 61.567 76.367 85.9 94.172 100.05 108.13 111.88 115.67

2152 Avg 57.167 73.833 81.333 88.667 93 99.5 107 110 110 108 112

Prod. Graph 72.5 83 92.5 100 107 111 115.5 120 123 126

PLI 5 10 15 20 25 30 35 40 45 50 55 60

Saturn

Gemini Plus

2164

2184

Average

SHOWERING

Typical Showering

• Inside HP Fan (150 – 250 psi)

• HP Needle (350 - 500 psi) – Face Side preferred

•Flooded Nip Shower (Volume)

• Edge Showers

• Barrier Chemical Shower

– Application Rate (ml / min) – Need for Caustic Stripping

Showering – Best Practice

Flooded Nip HP Needle Shower

HP Fan

Chemical

Shower

Needle Showering Inside or Outside ?

Typical Stickie - paper side of fabric

- forms at yarn cross-overs

- blind to Inside HPS

- inside HPS even less

effective with multilayer

fabrics

Needle Showers Effective Against Stickies

Typical Stickie

- need HP Needle

Needle Showers Distance from Fabric

0-4” 4-8” Beyond 8”

Effective

Cleaning

Distance

Needle Showers Location to Rolls

2 - 5” Common

Locate close to Roll - support fabric

- wasted shower pressure

- fabric damage

Needle Showers Angle to Fabric

10 – 20o

Angle into Fabric Run Direction

- OUTSIDE HPS

- maximize impact energy

- “chisel” contaminants”

Needle Showers Damage to Fabrics

Excessive Pressure

Poor Oscillation

Needle Showers Damage to Fabrics

Macro view of High-Pressure damage to fabric surface

Flooded Nip Shower Fiber Contamination

Typical Fiber Carryback

- High Pressure Fan

- Flooded Nip

Flooded Nip Showering Volume Calculation

RVV = C x W x S x V

C = fabric caliper (inches)

W = fabric width (inches)

S = fabric speed (ft/min.)

V = fabric percent void (use 0.6)

* 100% of RVV not needed, depending on speed of machine.

At +5000 ft/min, as little as 70% of RVV can be effective.

Chemical Showering

Rate of Application:

• can not add faster than chemicals being worn off by HPS

• uniform application (shower nozzle conditions)

apply cleaning chemicals:

Solvents

Caustic wash-ups

• effect on fabric monofilament

• effect on extruded edges / Trim Beads

Fabric Life

Considerations

FORMING FABRIC LIFE

• Normal Failure Points – Wear

• Roll Side or Sheet Side

• Caliper Loss Measurements

• Seam Issues (single layer designs)

• Typical Life

– Single Layer: 45 - 75 days

• stability issue / seam issues

– Multi-layer Designs:+75 days

• Damage most common limitation

Wear Profiles

AMERICAN TISSUE ST. HELENS, OREGON

.0150

.0160

.0170

.0180

.0190

.0200

.0210

.0220

.0230

.0240

0

18

36

54

72

90

108

126

144

162

180

198

216

234

252

WIDTH (INCHES)

CA

LIP

ER

(IN

CH

ES

)

ORIGINAL

USED

SAFE WEAR

MACHINE #3-CRESCENT FORMER

FRONT

#15531

Hour-Glassing

Drag Wear

MD

Wear Burrs on trailing edge of CMD knuckles

Roll Wear

Wear Burrs on all sides of CMD knuckles

Roll corrugation probable

crescentformer general process. tissue machine voith

Engineering