In this study we are trying to establish mathematical formula to expressing the uniformity level for thermal bonded nonwovens fabric. Hoping this will be interesting and helpful.

1. By
Abhijit Biswas (QA)
& assist by
Pallabi Sinha Roy (Process)
28-08-2017

2. ▪ Uniformity- It is the identical characteristics of a substance in terms of Structure, Quality and Appearance.
▪ For Nonwovens, Web uniformity is the major controlling factor and it plays an important role in defining
performance and processability of the end product.
Uniformity
Fabric
Properties
Fibre Properties
1. Fibre Denier
Web Structure
1. Uniformity
Web Bonding
1. Mechanical Properties

3. ▪ The nonwovens industry uses the coefficient of basis weight variation as a standard quality index to
quantify the web uniformity.
Drawback observed at our end:
This method gives an idea about variation in Web Grammage, widthwise in different positions. But it is
showing variation in small percentages, which is not giving a very significant idea about the web uniformity.
A term needs to be defined to show a specific value, which directly indicates the uniformity, that can
be interpreted at the operator level also to judge the uniformity of a Web or a Nonwoven Fabric.
Conventional Method

4. Statistics – Basis Weight Histogram
22N : 116/117/117
22T1: 116/117/85
22T2: 116/90/90
Conventional Basis Weight Distribution
2
0
2
4
6
8
01
21
41
61
5.91 0.02 5.02 0.12 5.1
2
NveDtSnaeM
136803.056.02
136653.086.02
130704.023.0
D
ycneuqerF
ata
B
elbairaV
2T22-WB
1T22-WB
N22-W
H
lamroN
2T22-WB,1T22-WB,N22-WBfomargotsi

5. Statistics – Opacity & Air Permeability Histogram
Two more terms introduced which can provide better idea about Web Structure & Distribution
4
0
2
4
6
8
01
21
41
61
03 23 43 63 83 04 2
3
NveDtSnaeM
13817.150.73
13594.201.73
13184.257.5
D
ycneuqerF
ata
O
elbairaV
2T22-PO
1T22-PO
N22-P
H
lamroN
2T22-PO,1T22-PO,N22-POfomargotsi
3
0
2
4
6
8
01
21
41
0062 0082 0003 0023 004
3
NveDtSnaeM
1339.091382
132.5016892
130.321652
D
ycneuqerF
ata
A
elbairaV
2T22-PA
1T22-PA
N22-P
H
lamroN
2T22-PA,1T22-PA,N22-PAfomargotsi

6. ▪ Nonwoven Properties ,which can be used to determine the web uniformity are:
1. Basis Weight
2. Opacity
3. Air permeability
▪ Basis Weight: Information on Grammage or Mass Distribution.
▪ Opacity: Information on Web Structure - Opaque or Transparent
▪ Air Permeability: Information on Porosity or Web Structure – Open or Close
Properties influenced by Web Uniformity

7. Background of New Method of Calculation
Product Property
Calculations from
Population Data
Mean X
Minimum Y CV % (S / X) *100
Maximum Z Range % (R / X) *100
Standard Deviation S
Range R
Uniformity Concept
Uniformity = 100 %
Variation = 0 %
Range = 0 %
▪ Variability
▪ Spreadability

8. Uniformity Measurement
Web Uniformity
Concept Uniformity =100 %, i.e., Variation = 0% + Range = 0%
Parameters considered for
Uniformity Calculation
1. Basis Weight (BW)
2. Opacity (OP)
3. Air permeability (AP)
Nonwoven Uniformity Factor
(NWUf) [100−{(CVAP%+CVBW%+CVOP%)/3}+(RAP%+RBW%+ROP%)/3}] %
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Uniformity
Measures
Variability CVBW% CVOP% CVAP%
Spreadability RBW% ROP% RAP%
NWUf = Nonwoven Uniformity Factor

10. Uniformity Measurement by New Method
22 GSM SSS HI – Normal
(116/117/117)
22 GSM SSS HI – Trial 1
(116/117/85)
22 GSM SSS HI – Trial 2
(116/90/90)
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Mean 20.33 36.07 3255.81 20.70 36.96 2974.41 20.67 37.47 2824.24
Min. 19.20 29.70 2970.00 19.90 30.20 2760.00 20.10 32.80 2610.00
Max. 21.00 41.00 3510.00 21.50 42.60 3150.00 21.30 42.10 3000.00
SD 0.40 2.62 123.04 0.38 2.68 107.65 0.32 2.13 96.08
Range 1.80 11.30 540.00 1.60 12.40 390.00 1.20 9.30 390.00
CV% 2.0% 7.3% 3.8% 1.8% 7.2% 3.6% 1.5% 5.7% 3.4%
Range% 8.9% 31.3% 16.6% 7.7% 33.5% 13.1% 5.8% 24.8% 13.8%
Average CV% 4.3% 4.2% 3.5%
Average R% 18.9% 18.1% 14.8%
Uniformity % 76.8 % 77.7% 81.7%

11. Visual Inspection & Analysis
22 GSM SSS HI – Normal
(116/117/117)
Uniformity 76.7 %
Denier 2.06
22 GSM SSS HI – Trial 1
(116/117/85)
Uniformity 77.6 %
Denier 1.58/2.02
22 GSM SSS HI – Trial 2
(116/90/90)
Uniformity 81.7 %
Denier 1.63/1.92
Visual Inspection Survey Results for Uniformity
Product Percentage Rating out of Maximum Possible Rating
22 GSM SSS HI – Normal 51%
22 GSM SSS HI – Trial 1 61%
22 GSM SSS HI – Trial 2 85%

12. Statistics for Distribution
3
0
2
4
6
8
01
21
41
0062 0082 0003 0023 004
3
NveDtSnaeM
1339.091382
132.5016892
130.321652
D
ycneuqerF
ata
A
elbairaV
2T22-PA
1T22-PA
N22-P
N
2T22-PA,1T22-PA,N22-PAfonoitubirtsiD
lamro
4
0
2
4
6
8
01
21
41
61
03 23 43 63 83 04 2
3
NveDtSnaeM
13817.150.73
13594.201.73
13184.257.5
D
ycneuqerF
ata
O
elbairaV
2T22-PO
1T22-PO
N22-P
N
2T22-PO,1T22-PO,N22-POfonoitubirtsiD
lamro
2
0
2
4
6
8
01
5.91 0.02 5.02 0.12 5.1
2
NveDtSnaeM
136803.056.02
136653.086.02
130704.023.0
D
ycneuqerF
ata
B
elbairaV
2T22-WB
1T22-WB
N22-W
N
2T22-WB,1T22-WB,N22-WBfonoitubirtsiD
lamro

14. Uniformity Measurement by New Method
13 SSS HI 13 SSMMS HO
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Mean 12.28 16.88 5111.21 12.57 27.31 1473.00
Min. 11.60 11.50 4740.00 12.30 26.50 1360.00
Max. 12.90 20.40 5680.00 13.17 28.60 1570.00
SD 0.36 2.06 231.03 0.26 0.78 71.34
Range 1.30 8.90 940.00 0.87 2.10 210.00
CV% 2.9% 12.2% 4.5% 2.9% 2.1% 4.8%
Range% 10.6% 52.7% 18.4% 6.9% 7.7% 14.3%
Average CV% 6.5% 3.3%
Average R% 27.2% 9.6%
Uniformity % 66.3% 87.1%

15. Visual Inspection & Analysis
13 GSM SSS HI
Uniformity 66.2 %
Denier 1.8
13 GSM SSMMS HO
Uniformity 87.1 %
Denier 1.56

16. Statistics for Distribution
5
0
01
02
03
04
05
06
0001 0002 0003 0004 000
1
NveDtSnaeM
012.5813105
0143.17374
D
ycneuqerF
ata
1
elbairaV
PA-SSS31
PA-SMS3
N
PA-SSS31,PA-SMS31fonoitubirtsiD
lamro
3
0
5
01
51
02
52
01 51 02 52 0
2
NveDtSnaeM
01502.276.51
018387.013.7
D
ycneuqerF
ata
1
elbairaV
PO-SSS31
PO-SMS3
N
PO-SSS31,PO-SMS31fonoitubirtsiD
lamro
1
0
1
2
3
4
57.11 00.21 52.21 05.21 57.21 00.31 52.3
1
NveDtSnaeM
017233.084.21
016362.075.2
D
ycneuqerF
ata
1
elbairaV
WB-SSS31
WB-SMS3
N
WB-SSS31,WB-SMS31fonoitubirtsiD
lamro

18. Uniformity Measurement by New Method
15 SSS HI 15 SSMMS HO
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Mean 14.51 19.27 4146.06 14.45 28.19 1221.00
Min. 14.00 15.70 3930.00 14.20 27.10 1160.00
Max. 15.40 23.10 4400.00 14.87 29.40 1310.00
SD 0.33 1.61 104.61 0.21 0.69 47.25
Range 1.40 7.40 470.00 0.67 2.30 150.00
CV% 2.3% 8.4% 2.5% 1.5% 2.4% 3.9%
Range% 9.6% 38.4% 11.3% 4.6% 8.2% 12.3%
Average CV% 4.4% 2.6%
Average R% 19.8% 8.4%
Uniformity % 75.8% 89.0%

19. Visual Inspection & Analysis
15 GSM SSS HI
Uniformity 75.8 %
Denier 1.76
15 GSM SSMMS HO
Uniformity 89.0 %
Denier 1.74
▪ Here, Denier for both SSS & SSMMS is same but Uniformity % is high for SSMMS Fabric because of Coverage
Factor due to Meltblown Content.

20. Statistics for Distribution

22. Visual Inspection & Analysis
8 GSM SSS HO
Uniformity 72.5%
Denier 1.45
8 SSS HO
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Mean 7.42 11.86 7006.00
Min. 7.13 9.50 6770.00
Max. 7.63 14.90 7540.00
SD 0.18 1.57 258.98
Range 0.50 5.40 770.00
CV% 2.4% 13.2% 3.7%
Range% 6.7% 45.5% 11.0%
Average CV% 6.4%
Average R% 21.1%
Uniformity % 72.5%

24. Visual Inspection & Analysis
80 SSS HO
Properties
Basis Weight
(BW)
Opacity (OP)
Air permeability
(AP)
Mean 79.98 62.50 380.40
Min. 78.10 61.10 365.00
Max. 81.53 64.00 394.00
SD 1.07 1.01 11.36
Range 3.43 2.90 29.00
CV% 1.3% 1.6% 3.0%
Range% 4.3% 4.6% 7.6%
Average CV% 2.0%
Average R% 5.5%
Uniformity % 92.5%
80 GSM SSS HO
Uniformity 92.5%
Denier 1.53

25. ▪ Uniformity % is dependent upon two factors: Basis weight & Fiber denier for Spun bond fabric
(For Spunmelt Fabric, Meltblown Content also needs to be taken into consideration for Uniformity & Structure Evaluation)
Structure Matrix
Low High
Open Close
Low High
Close Open
Basis Weight Denier
Web Structure Web Structure

26. Uniformity
15 GSM: 75.8%
22 GSM: 76.7%
Structure Matrix: 15 & 22 GSM SSS HI
15 22
Open Close
1.76 2.00
Close Open
Basis Weight Denier
Web Structure Web Structure

27. Uniformity
8 GSM: 72.5%
13 GSM: 66.2%
Structure Matrix: 8 GSM SSS HO & 13 GSM SSS HI
8 13
Open Close
1.45 1.80
Close Open
Basis Weight Denier
Web Structure Web Structure

28. Uniformity
8 GSM: 72.5%
13 GSM: 85.9 %
Structure Matrix: 8 GSM SSS HO & 13 GSM SSS HI (UC)
8 13
Open Close
1.45 1.5
Close Open
Basis Weight Denier
Web Structure Web Structure

29. ▪ Uniformity can be measure using the below stated formula:
NWUf = [100−{(CV%AP+CV%BW+CV%OP)/3}+(R%AP+R%BW+R%OP)/3}] %
Advantages of this New Method:
1. Easy to calculate & interpret, even at the operator level.
2. Uniformity Calculation & Comparison across all the basis weight.
3. Web structure and Coverage Factor can also be identified with this Method of Measurement.
Summary