SMEDA-JICA INDUSTRY SUPPORT PROGRAM
BEST PRACTICES MANUAL KNITTING SECTOR
Compiled by: Industry Support Cell
Small and Medium Enterprises Development Authority Ministry of Industries and Production Government of Pakistan
www.smeda.org.pk
SMEDA-JICA Industry Support Program
Best Practices Knitting Manual
ACKNOWLEDGEMENT This manual has been prepared under the SMEDA–JICA Industry Support Program. With the courtesy of Government of Japan and JICA (Japan International Co-operation Agency), this program has been started in Pakistan for the support of Textile Industry. The objective of this program is to provide expertise, knowledge transfer and skill up-gradation for the enhancement of productivity, efficiency and to give know how to local industry for better management practices.
Senior Japanese Knitting Expert Mr. Takao MIYAZAKI offered his services as Senior Volunteer for Knitting Sector of Pakistan for a period of two years. During this period Mr. Takao MIYAZAKI has provided guidance / consultancy to various industrial units.
This manual highlights the main areas where the guidance was provided in different industrial units. This includes key findings, process details, important recommendations / suggestions and recommended formats. It has been prepared by Mr. Muhammad Ayaz & Mr. Adil Nazir Malik of Industry Support Cell, SMEDA and reviewed and checked by Mr. Takao MIYAZAKI.
SMEDA-JICA Industry Support Program
Best Practices Knitting Manual
TABLE OF CONTENTS AREAS IDENTIFIED AND RECOMMENDATIONS……………………………...…………1 1 Production Control .......................................................................................................... 1 1.1 Production Targets for Feeders Machine .......................................................... 1 1.2 Actual Production for Auto Striper Machine..................................................... 3 1.3 Knitting Program Chart .................................................................................... 4 1.4 Data Chart for Knitting Condition .................................................................... 4 1.5 Knitting Machines Daily Efficiency ................................................................. 5 1.6 Production Analysis Graph............................................................................... 6 1.7 Setting of RPM ................................................................................................ 7 1.8 Humidity and Temperature............................................................................... 7 1.9 Traceability of data........................................................................................... 7 2
Quality Control................................................................................................................ 8 2.1 Yarn Knotting .................................................................................................. 8 2.2 Handling and Storage of Fabric Roll................................................................. 8 2.3 Graphical Representation of Defects................................................................. 8 2.4 One Feeder Tube Knitting Machine.................................................................. 8 2.5 Yarn Tension.................................................................................................... 9 2.6 Yarn Eye Guides .............................................................................................. 9 2.7 Creel Pipe Position ........................................................................................... 9 2.8 Yarn Passage.................................................................................................. 10 2.9 MPF Tension Washers ................................................................................... 10 2.10 Damaged Paper Cones.................................................................................... 10 2.11 Slub Catcher Gauge........................................................................................ 10 2.12 Bar (Patta) Line.............................................................................................. 11 2.13 Press off Problem ........................................................................................... 11 2.14 Methods to Control Winder Lines .................................................................. 12 2.15 Oil Stains ....................................................................................................... 13 2.16 Spot Marks on Fabric Surface ........................................................................ 13 2.17 Double Stitch Problem ................................................................................... 13 2.18 Air Circulation System................................................................................... 14 2.19 Separating & Covering the Knitting Machine ................................................. 14 2.20 Method of Checking Greige Fabric GSM ....................................................... 14 2.20.1 Guidelines for Checking of GSM .................................................................. 15 2.21 Stitch Length of Fabric Sample ...................................................................... 15 2.22 Calibration of Round Meter............................................................................ 15 2.23 Measuring Actual Stitch Length ..................................................................... 15 2.24 Fabric Inspection............................................................................................ 16 2.25 Analysis of Inspection Sheet Machine Wise ................................................... 17 2.26 Yarn Inspection .............................................................................................. 18 2.27 Use of Compact Yarn ..................................................................................... 18 2.28 Fabric Stability and Finished Width................................................................ 19
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Machine Maintenance.................................................................................................... 20 3.1 Machine Maintenance Schedule ..................................................................... 20 3.1.1 Daily Maintenance ......................................................................................... 20 3.1.2 Weekly Maintenance...................................................................................... 21 3.1.3 Monthly Maintenance..................................................................................... 21 3.1.4 Bi-Annual Maintenance.................................................................................. 22 3.1.5 Annual Maintenance ...................................................................................... 22 3.1.6 Machine Overhauling ..................................................................................... 22 3.2 Lubrication..................................................................................................... 22 3.3 Sinker Timing Gauge ..................................................................................... 23 3.4 RPM Meters and Counter Meters ................................................................... 23 3.5 Machine Cleaning .......................................................................................... 23 3.6 Needle Life .................................................................................................... 24 3.7 Needle Break Data ......................................................................................... 24 3.8 Operator Responsibilities ............................................................................... 24 3.9 Analysis of Machine Stoppages...................................................................... 25
4
Cost Control .................................................................................................................. 26 4.1 Yarn Waste .................................................................................................... 26 4.2 Oil Leakage.................................................................................................... 26 4.3 One Operator for at least Two Machines ........................................................ 27 4.4 GSM Measurement ........................................................................................ 27 4.5 Individual Work Order Closing Report........................................................... 27
5
Fabric Development ...................................................................................................... 28 5.1 Stitch Length of Fabric Sample ...................................................................... 28 5.2 Determination of Count/ Denier of Given Yarn .............................................. 28 5.3 Actual consumption of yarn............................................................................ 29 5.4 Ratio of Cotton to Lycra Feed ........................................................................ 32 5.4.1 Finding the Percentage of Lycra ..................................................................... 32 5.5 Determination of Finish Fabric Gauge............................................................ 34 5.6 Setting of GSM in Greige Fabric .................................................................... 36 5.7 Knitting process ............................................................................................. 36 5.7.1 Analyze the Sample........................................................................................ 36 5.7.2 Development of Knitting Specification........................................................... 37 5.8 Knitting Construction and Layout Graph ........................................................ 37 5.9 Use of 1/1000 Gm Graduation Scale............................................................... 37 5.10 Knitting of 100 % Polyester or 100 % Lycra .................................................. 38
6
Useful Calculations........................................................................................................ 39 6.1 Calculating GSM of Swatch ........................................................................... 39 6.2 Calculating Length from Fabric Weight.......................................................... 40 6.3 Conversion Formulas for Cotton Count and Polyester Denier ......................... 40 6.4 Formula for Finding Gauge of the Yarn Count ............................................... 41 6.5 Calculations for Finding GSM........................................................................ 42
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5 S (A Japanese Management Technique) ...................................................................... 44 7.1 How to Practice 5S......................................................................................... 45 7.1.1 Seiri ............................................................................................................... 45 7.1.2 Seiton............................................................................................................. 46 7.1.3 Seiso .............................................................................................................. 47 7.1.4 Seiketsu.......................................................................................................... 47 7.1.5 Shitsuke ......................................................................................................... 48
8
Fish Bone Theory .......................................................................................................... 49 8.1 Identify the Problem....................................................................................... 49 8.2 Work out the major factors involved............................................................... 49 8.3 Identify Possible Causes................................................................................. 50 8.4 Analysis your diagram.................................................................................... 50
9
Employee Participation & Training................................................................................ 51 9.1 Employee Training .................................................................................................... 51
ANNEXURE Annex-I: Knitting Program Chart54 Annex-II: Data Chart for Knitting Conditions Annex-III: Machine Counter Status Annex-IV: Production Analysis Graph Annex-V: Machine Wise Inspection Report Annex-VI: Machine Maintenance Schedule Annex-VII: Lubrication Annex- VIII: Knitting Construction Graph Annex-IX: Fish Bone Chart
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Best Practices Knitting Manual
AREAS IDENTIFIED AND RECOMMENDATIONS 1
Production Control 1.1
Production Targets for Feeders Machine
Daily production targets should be defined on the basis of production capacity of the machine. There is a 20 round method to measure the actual production capacity of the knitting machines. In this method, the weight of the fabric produced for 20 rounds is taken and the production is calculated in a kilogram which is based at 100 percent efficiency by using the calculations explained below. On the basis of this value, the actual efficiency of the machine and corresponding production target may be defined. The following is the procedure of the experiment that needs to be conducted on the knitting machine:
Run the machine for 20 rounds and produce the fabric
Cut the 20 round fabric from the roll. If possible, a colored yarn can be used to identify the fabric produced in 20 rounds
When cutting this fabric from the roll, handle it carefully
Now immediately place this fabric on the table in relaxed state and measure the length and width of the fabric
Weigh the fabric
Using this data, calculates the production target as follows: Fabric Width
= =
(cm) /100 (m)
=
(1) × 2
=
/100 (m)
……. (2)
the 20 rounds (cm)
=
/100 (m)
……..(3)
Weight of Fabric produced in 20 rounds
=
Fabric Double Width
……. (1)
(cm)
Length of Fabric produced in
-1-
(gm)
...….. (4)
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Weight of One Round Length (4) / No. of rounds
=
...…... (5)
Meter Weight (4) / (3) (gram / meter )
=
...........(6)
GSM (6) / (2)
=
gram / meter 2
...........(7)
Production Calculation (on 8 Hours basis): Production for 100% Efficiency =
Machine R.P.M × 8 hours × 60 minutes x (5)
=
(Fabric Weight in Grams)
=
(Fabric Weight in Grams) / 1000
=
(Fabric Weight in Kilo Grams)
……. (8)
This will be the weight of fabric produced at 100% efficiency at that particular machine in 08 hrs. Similarly, the 100% production in 12 hrs or 24 hrs can be found.
Production @ 85% Efficiency In order to set the production target for the knitting machine, multiply the 100% production value with the desirable efficiency (in our case we took it 85 %) =
(8) x 0.85
=
Kilo Grams
……… (9)
This (9) will be the production target based on the actual conditions.
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Actual Production for Auto Striper Machine
The actual production of Auto Striper machines is calculated in kilograms at 100 percent efficiency by using the calculations explained as below. A
=
No. of Courses
B
=
No. of Courses
C
=
No. of Courses
D
=
No. of Courses
E
=
No. of Courses
Rounds of X Pattern Repeat =
(A+ B+C+D+E+……) × No. of Repeat No. of Feeders
Fabric Width (cm)
=
(m)
……… (1)
Fabric Double Width (cm)
=
(m)
……… (2)
Length before cutting of X Pattern Repeats
=
(m)
……… (3)
Weight after cutting of X Pattern Repeats
=
(g)
……… (4)
Weight of One Round Length
= (4) /Rounds of X Pattern Repeat … (5)
Meter Weight (4) / (3) (gram / meter)
=
……… (6)
Production Calculation (on 8 Hours basis): Production for 100% Efficiency =
Machine R.P.M × 8 hours × 60 minutes x (5)
=
(Fabric Weight in Grams)
=
(Fabric Weight in Grams) / 1000
=
(Fabric Weight in Kilo Grams)
Production for 80% Efficiency =
(8) x 0.80
=
Kilo Grams
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……… (8)
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Best Practices Knitting Manual
Knitting Program Chart
A knitting program chart should be attached on each machine. This will help to provide complete view of the existing work order running on the machine (Format is attached in the annexure-I). The knitting program chart should include the following points:
Machine No.
Work Order No.
Machine Type
Machine Gauge /Dia
Machine RPM
Yarn Brand
Yarn Count
Fabric Type
Slitting Line Y/N
Stitch Length
GSM
1.4
Data Chart for Knitting Condition
Whenever, starting the new article it is appropriate to make a data chart (attached in the annexure-II). This chart will help to have complete information about that article and will be used for future reference. The implementation of this process will reduce the wastage of time whenever a repeat order is requested. This will also make the working easier and any problem that encountered during the production of a repeat order can easily be solved. Following information should be included in the said data sheet:
Machine Number
Design
Yarn Count
Stitch Length
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Round Meter
Tension
Sinker Timing / Needle Timing
Feeder Position.
IRO Tape.
Number of teeth of MPF tape
Greige GSM
Finish GSM
Problems encountered during production of the article
Possible solutions of problems
Swatch of the Fabric
Knitting Machines Daily Efficiency
For calculating the actual efficiency of machines and operators (shift wise & on daily basis), a counter status check method is suggested (Format is attached in the annexure-III). This counter status check is used to determine the actual production shift wise. The following example illustrates the method to calculate the actual efficiency: For example: I. M/C No.
=
1
=
1685
III. RPM (Round Per Minute)
=
20
IV. Total No. of Hours of One Shift
=
8
=
1900
=
3
=
105
=
1100
=
1000
II. Work Order No.
V. Counters Required to Knit One Roll VI. No. of Rolls Produced in One Shift VII. Total No. of Kilograms Produced in One Shift VIII. Counters Received from the Previous Shift IX. Counters Forwarded to the Next Shift
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So, the Total actual rounds (counters) in the shift will be: =
(VI × V) + IX – VIII
=
(3 × 1900) + 1000 – 1100 = 5600 Rounds
But as per the speed (rpm) 100% rounds should have been
=
IV ×60 × 20
=
9600 Rounds
The Machine Efficiency can be found as follows:
= 100 x Actual Rounds /100% Rounds =
100 × 5600 / 9600
=
58.33%
Following is the Format to calculate the efficiency of machine M/C #
W/O #
RPM
Weight
Counters
Rolls
C. Rec
C. Lft
Ttl
1 Shift
%
1
1685
20
105
1900
3
1100
1000
5600
9600
58.33
1.6
Production Analysis Graph
Graphical representation of the data is very useful to analyze and monitor the trend. Therefore, production data should be represented graphically to analyze the production trends. It indicates the low production values and helps to take immediate actions for production improvement. (Graph is attached in the annexureIV). This graphical representation of production data will help to effectively control the production activities and to achieve the desired production targets.
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Best Practices Knitting Manual
Setting of RPM
Every knitting entrepreneur wants to know the ideal speed of the knitting machine. But it is very difficult to determine an ideal speed (rpm) even for particular design and machine itself. It differs with the yarn quality as well as the machine condition. Therefore the optimum speed of machine may be set after experiments.
1.8
Humidity and Temperature
The humidity and temperature in knitting department should be 60± 5 % and 25± 5 °C. However during dry season when the outside humidity level falls, humidification in the department needs to be controlled more efficiently. Maintaining required humidity level improves the performance of knitting machine without affecting the metallurgy of the machines.
1.9
Traceability of data
If reports and filing system are not managed properly, it creates difficulty to monitor the trends. Therefore it is necessary that the reports and filing system should be managed properly.
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Best Practices Knitting Manual
Quality Control 2.1
Yarn Knotting
Whenever yarn breaks or finished, it should be knotted instead of twisting as this is normal practice used in industry. Because, in case of twisting it is likely that it may open and may cause cut in the fabric. It is also one of the ways to reduce the cut in the fabric. During yarn knotting, the operator should use scissor / clippers for cutting the extra knot edges. The extra knot edges should not be more than 5 mm in lengths.
2.2
Handling and Storage of Fabric Roll
Fabric roll should not be placed on the floor as it causes oil marks on the fabric. A clean plastic sheet may be used to place the fabric roll on the floor. Also place plastic sheet over the stored rolls to avoid accumulation of fluff on the fabric.
2.3
Graphical Representation of Defects
Graphical representation of fabric defects is very useful to analyze the quality. Fabric defects should be represented graphically to easily monitor the quality and take necessary corrective actions for each machine. Data recording in tabular form is not easy to analyze whereas, graphical representation makes easier to view the trend. Also, it is useful to find out the most recurrent faults.
2.4
One Feeder Tube Knitting Machine
The quality of incoming yarn can be easily monitored using one feeder tube knitting machine. Another model of this machine is available with a creel for testing more then one yarn cones automatically.
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Best Practices Knitting Manual
Yarn Tension
Yarn Tension plays an important role in the knitting. It should be set properly at start of each order and monitored as well. Yarn tension meter should be used to set the yarn tension. The tension calculating formula for all type of yarns is: Grams = 5315 / S (Count) × 20 This provides the starting guidelines for tension setting which can further be adjusted by experimenting. Variation in tension of yarn occurs due to improper winding. The following should be taken care of:
2.6
MPF washer spring adjustment
Slow vibration of stopper
Presence of yarn eye guides (feeder, pipe, creel) on all machines
Replacement of damaged pipes
Even yarn wrapping on MPF (Main Pully Feeder)
Yarn Eye Guides
All yarn eye guides (feeder, pipe and creel) play an important roll in knitting process. Missing yarn eye guides cause variation in yarn tension and high friction hence affecting smooth flow of yarn. This also results in yarn breakage, knitting holes and more fluff in the department. Therefore, missing eye guides must be checked at regular intervals and replaced accordingly.
2.7
Creel Pipe Position
An improper position of creel pipe affects the yarn tension and thereby affecting machine efficiency and increase fabric faults. Therefore, the creel pipe position should be properly adjusted for smooth flow of yarn and damaged pipes should be replaced with new ones. Also position of ring guides on creel should be at the centre of paper cone tip.
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Best Practices Knitting Manual
Yarn Passage
Yarn passage should be as smooth as possible. It should not touch any part of the machine other than guides. Similarly, the correct passage of yarn should be followed. If yarn touches any part of knitting machine other than guides, it will increase the hairiness in yarn due to rubbings. It will also affect the yarn tension and affects the machine efficiency and increase fabric faults (Knitting holes). To overcome this problem, appropriate adjustment in the position of MPF should be made.
2.9
MPF Tension Washers
MPF tension washers play an important role. As the name shows, MPF tension washers control the yarn tension. If MPF tension washer is out of order or missing, it will cause variation in yarn tension and high friction hence effecting smooth flow of yarn. This also results in yarn breakage and fabric fault especially in fine yarn count. Therefore, missing MPF tension washers must be checked at regular intervals and replaced accordingly.
2.10 Damaged Paper Cones If paper cones on the creels are damaged, it causes yarn breakage during unwinding from these cones. It happened if the yarn suppliers is using paper cones of poor quality and/or also care is not being taken during transportation and material handling. The mill management must complaint the supplier if damaged cones are received. Also, handling of yarn should be improved while loading / unloading as well as placing on the knitting machine.
2.11 Slub Catcher Gauge The following slub catchers are recommended to use:
0.4 mm slub catcher for 59/s and above count
0.6 mm slub catcher for 24/s to 39/s
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2.12 Bar (Patta) Line Bar line is a major fault on the knitting machine. Bar line is basically appears due to yarn tension variation or due to yarn quality. These are following steps for analysis of bar line:
Take a piece of fabric from the defected portion
Marked length of 60 centimeters on both sides of fabric for analysis
Take out some yarns and find out the average length of yarns
If yarn which is creating bar line have same length as compare to other yarns. This shows that the bar line may be appearing due to mixing yarn lot or using different yarn count
If the stitch length of all yarns is not same then it will be the fault of yarn tension
To control Patta in knitted fabric due to yarn tension variations, detect the feeders where the Patta is visible and find out the respective feeders. Then keep on changing the position of the cones on the creel till no such effect is visible.
2.13 Press off Problem Press off is another problem being faced in knitting department. Press off problem is basically a yarn breakage and it results due to the bad quality of yarn. During knitting of fabric yarn break from feeder appears in the fabric as press off because it broke after sensor. To control the press off problem, the better quality yarn should be used and yarn tension variation should be controlled on the knitting machine. The following points will help to reduce the press off problem:
It should be ensured that passage of yarn is proper. It should pass from all yarn eye guides and also should not touch with any other part on the knitting machine
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All missing yarn eye guides should be checked at regular intervals and replaced accordingly. Otherwise, yarns tension variations will result in press off
The tension of all yarns should be set equal
The professional style of knotting should be adopted and operators should use scissor for cutting extra knot edges
Fluff should be removed from machine and especially from feeders. Fluff in feeders creates tension variation in yarn and increase the possibility of yarn breakage
2.14 Methods to Control Winder Lines Winder line is another problem of knitting. Following are the guidelines to control the winder line:
Fastening woven fabric on the both ends of nip roller.
Ensuring minimum possible tension pressure on the fabric during winding.
Plaiting in a box.
Edge of the fabric from both sides should be made free by creating groove on the nip roller
Slightly lower down the frame of fabric on knitting machine.
Changing the design of frame with Cadaratex frame (Fukuhara).
Slightly moving the winder line at inspection machine during inspection
The storage time of fabric should be as minimum as possible specially in case of lycra fabric
Also, in dyeing department the fabric should not be stored for longer period of time
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2.15 Oil Stains Oil stains is the serious problem that affect the quality of fabric. One possible reason is the use of excess oil than the actual requirement of the machine. This excess oil spreads on the machine causing high accumulation of fluff at cylinder, this fluff than goes under the needles and sinkers which creates oil stains in the fabric. To control this problem, an appropriate amount of oil should be used. Another possible reason is the frequent machine stoppages. When machine stops frequently, the absorption of oil becomes high at the needles and sinker as compared to the running condition of machine and that causes oil stains in the fabric.
2.16 Spot Marks on Fabric Surface Spot marks (Lycra, Polyester, Inlay yarn) on fabric surface are due to improper adjustment of sinker timing. Proper setting of sinker timing with adjusting feeder setting controls this problem. Yarn tension is also another reason and it should be checked by tension meter and adjusted one by one on all feeders and if required tuck tension should be increased.
2.17 Double Stitch Problem The following are the precautions to avoid the double stitch problem in a particular fabric:
Yarn passage must be smooth. Missing eye guides or improper yarn passage causes yarn to vibrate
Control of yarn Tension. Tension meter should be used to control
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2.18 Air Circulation System The overall cleaning condition on production floor affects fabric quality. To get good quality fabric, floor cleaning and fluff suction system should be adequate. To improve fluff suction system, increase the capacity of suction system or install air conditioning system to maintain relative humidity of department as well as proper suction of fluff. At least industrial vacuum cleaner should be used for fluff control.
2.19 Separating & Covering the Knitting Machine The striper machines should be covered with polypropylene sheets to avoid fluff accumulation from one machine to another. This will improve the fabric quality. Similarly, the machines which are not in operation should be covered with polypropylene sheets from top to bottom for avoiding the accumulation of fluff on it. Due to less accumulation of fluff on the machine, the maintenance of machine will be decreased and it will increase the machine life.
2.20 Method of Checking Greige Fabric GSM It is general industry practice to check the greige GSM with GSM cutter. As in this case, sample size taken is too small, therefore, GSM measured with GSM cutter shows more variation. Large dia GSM cutter may be used to make the result more accurate and reliable. The simple and accurate method to find the actual GSM of fabric is based on three basic parameters i.e. fabric weight, length and width of the fabric. It can be checked by producing the fabric / 20 round and then dividing the weight of produced fabric by the area (length*width) of the fabric as in the section 1.1. The actual GSM can be calculated as follows: GSM
=
(6) / (2) gram / meter 2
GSM
=
g / m2
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2.20.1 Guidelines for Checking of GSM The following are the further guidelines for checking the greige GSM:
Actual GSM of greige fabric (as explained above) should be measured at the start of new article
Greige fabric roll should be cut as per counter meter reading on the machine. In this practice, weight of each roll will be same. This is the easiest way to check the GSM of each roll
2.21 Stitch Length of Fabric Sample Stitch Length should be checked whenever starting the new order or problem arises. The use of round meter for setting the stitch length is better. However, if it is not available then, it may be checked manually. But in any case, it must be checked when starting the new article or in case of any problem.
2.22 Calibration of Round Meter Round meter is sometimes used for the setting of stitch length. It is advised that round meter must be checked and calibrated for the correct setting. Check the stitch length manually and compare the results with the round meter reading.
2.23 Measuring Actual Stitch Length To find the actual stitch length, take a sample of fabric and mark 100 needles and then take out at least three yarns each and measure the stitch length. Compare this value with the round meter value.
Example: We have a sample of fleece fabric produced on m/c having dia of 30 inch, Gauge 18 and total number of needles 1692. 100 needles were marked and then three knits, tuck and inlay yarn each were taken out. Stitch length of knit, tuck and inlay was measured. Mean value of the actual stitch length of knit, tuck and inlay was:
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Knit = 47 cm Tuck = 41.3 cm Inlay = 18.9 cm The round meter reading on the same machine having Machine dia of 30 inch, Gauge 18 and total number of needles 1692 was found to be: Knit = 782 Tuck =683 Inlay =300 Converting round meter value to the /100 needle stitch length Knit = 782/1692*100= 46.2 cm Tuck =683/1692*100= 40.4 cm Inlay = 300/1692*100=17.7 cm
Comparison Comparing round meter reading with the actual readings revealed that:
Actual Knit stitch length is 1.7 % higher
Actual Tuck stitch length is 2.2 % higher
Actual Inlay stitch length is 3.8 % higher
Conclusion The round meter should be checked at regular intervals to avoid any problem. However, when variation in GSM arises check actual stitch length as well.
2.24 Fabric Inspection It is worth considering a total inspection environment which can improve the overall standard of the inspection department. The main action of a fabric inspection machine is to unroll measure and re-roll the fabric, and to contribute to an environment in which it can be inspected by an examiner.
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This requires the following characteristics:
Suitable edge control to provide a finished roll of attractive appearance
Winding characteristics, which do not distort the fabric structure or dimensions, which suggests tensionless wind up through, overfeed in the case of stretch fabrics
Stopping and starting which will not disturb the roll, nor the fabric structure nor its dimensions
Winding characteristics should be such that any form of handling by the examiner is minimized
The machine should be simple to load and unload
Lighting should be controllable and of variable intensity, so that the most critical faults may be detected most easily without loss of detection of less critical faults
2.25 Analysis of Inspection Sheet Machine Wise The analysis of defects should be done machine wise. This analysis will show the individual record of every machine and the traceability of machine with too many faults will become easier to find the root cause of problems. The collected data should be analyzed and checked regularly, especially in case of same fabric construction running on different machines for controlling the variation of faults. Immediate actions should be taken after observing data for reducing rejection % age. (Sheet is attached in the annexure-V).
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2.26 Yarn Inspection Apart from checking the weight of yarn deliveries, following yarn properties may be checked to ensure the quality of raw material:
Further Yarn Checks (1st order priority)
Count Tests on Staple Fiber Yarns: Check on count variability, within cones and between deliveries: to be within tolerance of specification
Condition Checks: Check on incorrect condition
Yarn Unevenness (U %)
Further Yarn Checks (2nd order priority)
Yarn twist: On new deliveries and on demand for fault diagnosis. To be within specified tolerance
Co-efficient of friction: Test and compare to specification
2.27 Use of Compact Yarn Use of Compact spun yarn in knitting gives following advantages:
Less fly on the knitting machine
Knitting faults and interruptions are reduced and hence higher machine efficiency
Smoother surface of Fabric as compare to Fabric made from conventional ring spun yarn
More luster in fabric
Reduced pilling in the fabric
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2.28 Fabric Stability and Finished Width Fabrics knitted on circular machines have a set number of wales, determined by the knitting machine used, - its diameter and gauge (needles per unit length of cylinder circumference). The fabric will be knitted from a certain yarn type and knitted loop length, partly on economic grounds and partly to avoid being too dense or too light a fabric. There is a commercial incentive to finish fabric as wide and as long as possible. The loop structure of knitted fabrics makes it possible to stretch these fabrics to an appreciable extent. However, in the stretched state the forces on each loop are not balanced, and so the fabric becomes unstable, giving it a tendency to revert to a more natural, relaxed state during which an increase in fabric stitch density will take place, together with a consequent reduction on area, i.e. shrinkage will always occur. It is not possible to set a fabric at what are in effect unrealistic dimensions and at the same time achieves a stable fabric. Therefore, certain diameters of knitting machines are to be used (which is a must unless we are prepared continually to replace existing machinery). Since the fabric will be knitted within fairly narrow ranges of yarn type, count and loop length, then the fabric must be finished as near as practical to its natural width and length and not over stretched, if it is to be without excessive shrinkage in service (e.g. washing). In this state the fabric will have fairly definite width and length dependent on the machine, yarn and loop length used. Efficient lays should be planned on these dimensions, and not on some predetermined ideal. If shrinkage is not an important consideration, then extra width and length can be considered. The fabric characteristics can be determined by calculations form the fabric geometry and by trials, and the finished dimensions to be stipulated modified accordingly. Unless these factors are fully understood, a satisfactory fabric specification will not be possible.
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Best Practices Knitting Manual
Machine Maintenance 3.1
Machine Maintenance Schedule
Maintenance of knitting machine is very important that affect the machine efficiency, machine life and fabric quality. The management should prepare a maintenance schedule and it should be followed strictly. The main parts of the knitting machine should be checked with extreme care and responsibility. If the knitting machine is too old, then maintenance became more important to avoid any major breakdown. The following are the guidelines for machine maintenance (Daily, Weekly, Monthly, Bi- Annually and Annually). Also maintenance schedule is attached in the annexure-VI.
3.1.1 Daily Maintenance The check points for daily maintenance are as follows:
Yarn feeding device and related parts:
Check yarn feeding device (MPF,IRO), Slipped-off, Loose or broken MPF drive belt
Malfunction of clutch, IRO tape flipper, etc
Check MPF teeth
Clean fluff from MPF area
Remove fluff from tension washers
QAP (Quality Pulley): diameter, loose lock nut
Lubricators:
Oil level of mist lubricator
Check oil drop rate (should be 100-120 drops/ min)
Supply amount of compressed air
Check lubrication points for disconnection, leakage etc.
Check compressed air pressure
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Abnormal Noise:
Knitting elements (cam holders, sinker cap and dial cap)
Yarn feeding units and related parts (QAP, change gear box, drive tape, etc)
Frame (machine bed, take-up unit, motor drive, etc.)
Oil leakage:
Lubricator main body
Part underneath the bed
Oil amount in the oil sump bottle
Connection between oil mist pipes and nozzles
Part underneath the gear ring
3.1.2 Weekly Maintenance The check points for weekly maintenance are mentioned here under:
Piping for lubrication oil and compressed air
Oil amount in the bed & gear box and make up if required
Check oil sump mist lubricator
Draining of water from the air compressor
Clean the lint fan
3.1.3 Monthly Maintenance The check points for monthly maintenance are as follows:
Lint accumulation (Check for lint and clean.):
Lint in the control panel
Lint around lint fans and other areas
Lint in the motor cover
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Belt tension:
Check main drive motor belt tension
Check drive belt tension for yarn feeding device
3.1.4 Bi-Annual Maintenance The check points for bi annual maintenance are mentioned here under:
Change the oil in gear box
Change the oil in needle bed
Remove the MPF pulleys and clean with kerosene oil
Machine cleaning should be checked very carefully for all parts
3.1.5 Annual Maintenance The check points for annual maintenance are mentioned here under:
Change grease in fabric roll winder
Change grease in gear box of yarn feeding system
3.1.6 Machine Overhauling Each knitting machine should be overhauled once a month. It is a guide line for overhauling which is followed worldwide.
3.2
Lubrication
Shell Vexilla G or Mobil Vilocite CX 22 or Vickers CL22 or oil of same specs by any other manufacturer is recommended as knitting oil for needles, sinkers and cams. The selection of oil should be done keeping in view both the quality of the fabric and the machine lubrication requirement. In fact it is a compromise between machine safety and fabric safety. Very good washable knitting oil may not have good lubrication property and vice versa.
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For machine bed, the Sell Tonna Oil S68 (viscosity @40c°55 to 70 CST) or corresponding oil from any other manufacturer (format for selection of oil, lubrication procedures and locations is attached in the annexure-VII).
3.3
Sinker Timing Gauge
Sinker timing reference points should be available on all machines for correct setting of sinker timing gauges.
3.4
RPM Meters and Counter Meters
RPM meters and Counter meters on knitting machines should always be in working conditions. The advantage of using these meters is the ease in daily production calculations and minimum roll weight variation.
3.5
Machine Cleaning
The following are the guidelines for machine cleaning:
Each operator should individually take care of the proper machine cleaning
At each doff machine should be cleaned including the net cover
Waste cloth should be used for bed and underside cleaning
Machine cleaning with air pressure should be done only by operator
Cleaning of the creel should also be done
Those machines which are not in production should be covered to avoid accumulation of fluff on the machine
Operator must be trained to follow the above guidelines and it should be made a custom.
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3.6
Best Practices Knitting Manual
Needle Life
The needle life depends upon various factors i.e. the quality of yarn being used and the design of knitted fabric. The marks on needle buts are due to the uneven surface of cams. Uneven surface cams should be buffed or new cams should be used to save the life of needles. After changing the complete set of needles with the new one, better condition needles should be sorted out from old set of needles and should be used as replacement whenever, needle brakes on any machine. It is very difficult to determine an ideal needle life even for particular design and machine. It differs with the yarn quality and machine condition. Polyester yarn generally damages the needles more than cotton. Similarly it also depends upon the GSM of the fabric to be produced. Keeping the all said factors in mind, the needles should be used until at least 30000 to 50000 Kgs fabric is produced.
3.7
Needle Break Data
The record of broken needles and individual needles replaced on daily basis should be prepared. Needle and sinker change schedule should also be maintained properly. The concerned in-charge must ensure that all the data being collected should be accurate.
3.8
Operator Responsibilities
Some basic responsibilities of knitting operators to ensure good quality and production are as follows:
To minimize the faults on the same setting
The yarn path must be as start as possible and hindrance free
The yarn wrapping on the MPF (Main Pully Feeder) should be even
Feeders setting must be OK
Even smaller fault should not be ignored
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Daily machine maintenance checking
Fluff should not go inside the machine
Each operator must be allocated with space around its machine(s) and it must be his responsibility to make sure the cleanliness of that area
3.9
Minimum stoppage of the machine
The healthy production should also come with quality
If operator sees any fault he must inform the concerned person
Operator should not start work in case of any noise in the machine
Analysis of Machine Stoppages
It is better to record the machine stoppages. This data then should be analyzed for improvement in production. Use problem solving techniques explained in sections to follow to analyze the data.
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Cost Control 4.1
Yarn Waste
It is observed that many baby cones (Pochey) are left over after the completion of fabric. The yarn from one truck is not being mix used with yarn of other truck (even yarn of same lot). The mills management normally does not mix the different trucks of yarn in order to avoid the yarn variation. But this is the wastage of money. The yarn from truck to truck can be used by confirmation of the same lot from spinning mills. The yarn that is left over after the knitting of fabric (in the form of Pochey) is not being analyzed from productive point of view. This yarn waste (Pochey) should not be more than 10 kilograms/lot. If this waste will increase more than 10 kilograms/lot then it should be analyzed that how to control this loss. For example, there is requirement of five trucks of yarn against any order. The mills management are performing yarn test sample five times to avoid yarn variation. Each yarn test sample is not more then 5 kgs and after completion of fabric, the left over yarn in the form of Pochey is 20 kgs of each truck. It means yarn used 25 kgs for yarn test samples and 100 kgs for wastage (in the form of Pochey). This is totally wastage of yarn. If the management confirms the yarn lot number then it will save the 100 kgs of yarn which is being used in unnecessary areas. After the confirmation of yarn lot, the yarn sample should be tested only one time. It means that in routine practice, the extra yarn is being wasted four times. In the same way the yarn that is left over after the knitting of fabric (in the form of Pochey) is too much.
4.2
Oil Leakage
The problem of oil leakage is due to the absence of oil seals and oil nozzles on machines. If this problem continues, then this is not beneficial from cost point of view as more consumption of oil. Also it affects the needle life and accumulates fluff on the machine.
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4.3
Best Practices Knitting Manual
One Operator for at least Two Machines
In routine practice, one operator handles only one machine. In this case the operator has too much idle time. One operator should be used to handle at least two machines because the machines are very close to each other in the knitting floor. Therefore, the operators can easily handle two machines at a same time.
4.4
GSM Measurement
Normally in industry, GSM of greige fabric is being measured with GSM cutter; this will produce holes in the fabric surface and also increase waste percentage. GSM of greige fabric should be measured one time in the start of new article by 20 round method. If there are some doubts in GSM, then it is better to check fabric stitch length. There is no need to check GSM of each roll. In this practice waste percentage would be minimized. Any further adjustments in GSM should be made on stitch length base rather than using GSM cutter.
4.5
Individual Work Order Closing Report
The analysis of rejection percentage should be performed by work order closing report. This analysis will show the individual record of every work order. It makes easier to trace out the root cause of rejection. The manager should be checked the work order report regularly.
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Best Practices Knitting Manual
Fabric Development 5.1
Stitch Length of Fabric Sample
The following is the method of checking stitch length manually:
Take a small piece of fabric (40-50 cm in length)
Mark length of hundred wales on both sides of fabric
Take out ten threads and find out the average length of the threads. This will be the stitch length of that sample
Note: If fabric sample size is too small, then mark length of thirty wales on both sides of fabric. Take out three threads and find out the average length of these threads.
5.2
Determination of Count/ Denier of Given Yarn
The method to find out the Denier / Count value of the yarns in a fabric sample is as follows:
Put two cut marks at certain distance (30-40 cm) on the fabric sample
Take out different yarns (Count / type) by undoing the knitted structure
Take out at least 10 yarns for each count or type of yarn
Measure the length of each count or type of yarn and add them to get the total length of yarn (in m) for each count
Now determine the weight of the yarns count wise
Calculate the denier value using the formula:
Denier value = Weight of the yarn in gram x 9000 Length of yarn in meters For determining the corresponding count value, the denier value can be converted to Count using the following conversion formula: Count= 5315 / Denier
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Example: Suppose undoing of the knitted fabric provided the following observations: Type of yarn = 2 (i.e. 2 cotton yarn & 1 Lycra) No of yarn taken out for each type of yarn= 30 Length of each yarn = 71.23 cm Total length of Cotton yarn = 30 x 71.23 cm = 2136.9 cm= 21.369 m Weight of Cotton yarn using weighing balance with a least count of 0.001 g = 0.31g
Thus Denier value of the Cotton yarn will be: Denier value = Weight of the yarn in gram x 9000 Length of yarn in meters Denier value =
0.31 x 9000 = 130.56 denier (approximately) 21.369
Converting it into count, Count = 5315 / Denier = 5315 / 130.56 = 40.7 Count = 40/s (approx.)
5.3
Actual consumption of yarn
In planning a certain order, knowing the consumption of yarn is important so that, required quantity of yarn can be purchased. It becomes more important when we are using different yarn in the same fabric. If we have the three end fleece with one type of yarn in Knit and Tuck, and another yarn the in Loop. To calculate the actual yarn consumption or yarn mixing ratio following is the procedure to be followed:
Take the a small piece of fabric
Find out the weight of sample fabric
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then take out the loop yarn from sample fabric and find out the weight of Loop yarn
The subtraction of loop yarn weight from sample fabric will give the weight of knit & tuck yarn
Now the consumption of yarn or mixing ratio can be calculated
EXAMPLE: There are two methods of calculating Consumption of Yarn in 3 End Fleece. Suppose we have the three end fleece fabric with 30/s of yarn in Knit and Tuck and 16/s yarn the in Loop.
1st method: When Stitch length of knit and tuck are same and loop is deferent:
KNIT
TUCK
LOOP
Cotton
Cotton
Cotton
Count
30
30
16
Stitch length
22 cm
20.5 cm
7.5 cm
Knit and Tuck the count is same, so added Knit and Tuck =
22 + 20.5
=
42.5 cm
=
=
42.5 × 1 / 30
= 7.5 × 1 / 16
A =
1.417
B=
7.5 cm
0.469
Total= A + B = 1.417 + 0.469 = 1.886 % of 30/s
% of 16/s
= 1.417 / 1.886 × 100
= 0.469 / 1.886 × 100
30/ Ѕ = 75.1%
16 /Ѕ = 24.9%
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For 50,000 Kg fabric quantity of yarn required (including 2 % knitting loss) A= 30/s = 50000 × 1.02 × 0.751
= 38301 kg
B = 16/s=50000 × 1.02 × 0.249
= 12699 kg
2nd method: When Stitch length of knit, tuck and loop are deferent: KNIT
TUCK
LOOP
Cotton
Polyester
Cotton
Count
30 / Ѕ
45 d
16 / Ѕ
Stitch length
22 cm
20.5 cm
7.5 cm
To convert count into denier using formula D
= 5315 / S
5315 / 30
45d
5315 / 16
177.2 d
45 d
332.2 d
Multiplying to stitch length
177.2 × 22 3898.4
45×20.5 +
922.5
332.2 × 7.5 +
2491.5
Total = 7312.4
3898.4 / 7312.4
922.5/ 7312.4
2491.5 / 7312.4
0.533 × 100
0.126 × 100
0.341×100
12.6%
34.1%
53. 3 %
Consumption of yarn A = Cotton
(30 s) 53.3%
B = Polyester
(45 d) 12.6%
C = Cotton
(16 s)
34.1%
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For 50,000 Kg fabric quantity of yarn required (including 2 % knitting loss) A = 50000 × 1.02 × 0.533
= 27183 kg
B = 50000 × 1.02 × 0.126
= 6426 kg
C = 50000 × 1.02 × 0.341
= 17391 kg
5.4
Ratio of Cotton to Lycra Feed
It is common practice in the industry that Lycra percentage is always set on the machine by hit and trial method which is not an efficient way. Setting the exact percentage of Lycra is difficult in this way. If we have to set the 3 percent of Lycra than, by hit and trail it is possible that, this value may be set to somewhat higher. In case of a large order a small increase in this percentage will increase the cost of production as Lycra is very costly. In order to set the Lycra percentage in more efficient way the following method is very useful.
5.4.1 Finding the Percentage of Lycra If we have a sample of Lycra knitted fabric and wants to produce that fabric with same percentage of Lycra. For this purpose we have to calculate the ratio of the feed speed of cotton and Lycra to determine how slower the Lycra must be fed as compared to cotton yarn so that we get same percentage of Lycra in the fabric. The following is the procedure:
Put two cut marks at certain distance (30-40 cm) on the fabric sample
Take out different yarns (count / type) by undoing the knitted structure
Take out at least 10 yarns for each count or type of yarn
Measure the length of each count or type of yarn and add them to get the total length of yarn in meters for each count
Now determine the weight of the yarns count wise
From weight find out the Lycra percentage
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Calculate the denier value of cotton yarn using the formula: Denier value =
Weight of Cotton yarn (g) × 9000 Length of Cotton yarn (m)
Now find out the Denier value of Lycra by using following formula: Denier of Lycra
=
Weight of Lycra × Cotton Denier Weight of Cotton Find the Lycra Feed ratio using following formula: Lycra Feed Ratio
=
Calculated Denier Actual Denier to be used
Example: Suppose we have a Lycra based Fabric sample. Un-roving of the knitted fabric provided the following observations: Type of yarn = 2 Feed of yarn = 2 cotton yarn & 1 Lycra No of yarn taken out for each type of yarn= 15 Length of each yarn = 110.4 cm Total length of Cotton yarn = 110.4 x 15x 2= 3312 cm = 33.12 m Weight of 30 Cotton yarns = 0.66 gm Weight of Lycra = 0.02 gm Cotton Yarn Denier = 9000*0.66/33.12= 179.35 Cotton Count = 5315/179.35 =29.6
30/s
Lycra Denier = 9000*0.02/ (15*1.104) =10.87 If we have to use 40 D Lycra than, the ratio of feed speed should be
Lycra Feed Ratio = 40/10.87 = 3.68
i.e. Lycra should be fed at 3.68 times slower in speed than cotton. If we adjust the Lycra feed according to this calculated value then we will get the same percentage of Lycra in the fabric.
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Consumption of Yarn % age of Cotton
Lycra %
5.5
=
Cotton Weight / (Lycra Weight + Cotton Weight)
=
0.66 / 0.68 ×100
=
97.06 %
=
Lycra Weight / (Lycra Weight + Cotton Weight)
=
0.02/0.068*100
=
2.94 %
Determination of Finish Fabric Gauge
Sometimes, we may receive the finish fabric from the customer to knit. In that case, the following is the method of finding the gauge of the machine used to produce that fabric:
In case of full width finish fabric
If we have full width finish fabric then:
Find the total width of fabric
Count 100 wales and measure the corresponding length and find the wales / length
Calculate the number of needles using following formula:
Total no. of Needles / Total Width of Fabric in cm
=
Wales/ cm
Find the Dia of the machine keeping in view the following guidelines: Total Width of Fabric
Dia of the Machine
(cm)
(inch)
120
24
130
26
140
28
150
30
165
32
Note: This table is based on the experience. So, it is for reference only to start with.
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Calculate the gauge of the machine used to produce that fabric by using following formula: Gauge = Total No. of Needles / (п× Dia of the machine)
Example: Measured Width of the fabric
=
75.5 cm
Total Width of the fabric
=
75.5 × 2
Length of 100 wales
=
8 cm
=151 cm
Suppose X is the total number of needles. Therefore, X/151 =
100/8
X
1887.5
=
Referring to the above table the dia of the machine comes out to be 30 inch. Now,
Gauge =
1887.5 / (3.143 × 30)
Gauge =
20
In Case of Swatch of Finish Fabric
Sometimes, we do not have full width finish fabric instead; we receive a swatch of finish fabric from the buyer. In that case to find the gauge the following method should be followed:
Assume the total width of the fabric or if factory is producing the fabric for its garment division then, get the width of the fabric from cutting department who will provide the same on the basis of the garment to be made from that fabric
Count 100 wales and measure the corresponding length or if swatch is too small count Wales / inch
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Calculate the total number of needles using following formula:
Total No. of Needles / Total Width of Fabric in cm
=
Wales / cm
Total No. of Needles / Total Width of Fabric in inches =
Wales/ inch
OR
Find the dia of the machine keeping in the view the above table
Calculate the gauge of the machine by using following formula:
Gauge = Total No. of Needles / (п× Dia of the machine)
5.6
Setting of GSM in Greige Fabric
There is no formula for setting GSM of greige fabric with respect to finished fabric. However, as a starting point GSM in greige fabric may be adjusted at approximately 55 to 60 digits less than the GSM of finish fabric. But it requires experimentation to get the final result.
5.7
Knitting process
The following are the steps to follow for analyzing a particular knit sample and to reproduce it:
5.7.1 Analyze the Sample The following are the steps to analyze a particular knitted fabric sample to be produce:
identify types of yarns in sample
count courses and wales per cm in each structure
determine stitch length and counts of yarns used by unroving
estimate likely gauge of machine on which sample knitted
determine the design, pattern repeat
check GSM
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5.7.2 Development of Knitting Specification
select nearest suitable commercial yarn available and gauge of machine to be used for adaptation to reproduce sample
knit swatch for each structure at calculated course length based on experience of machine settings
check course length by un-roving or marked yarn method
adjust until correct (tolerance of +- 2% suggested)
record settings (on knitting condition data chart explained earlier) e.g. input tension, weight of take down, knock over depth
knit sample panels
check and record complete panels for appearance, dimensions and weight
on the basis on data recorded set up other machines similarly
check for course length and adjust necessary
N.B. if (c) has been correctly carried out machine adjustment should not be required.
5.8
Knitting Construction and Layout Graph
The knitting construction and layout graph sheets for single knit, rib and interlock are attached in the annexure-VIII. This will help to understand the construction of fabric. Graphs should be made and maintained for each type of fabric as a future reference.
5.9
Use of 1/1000 Gm Graduation Scale
It is better to have the weighing scale of 1/1000 gm least count. It is very useful whenever finding count of yarn, % of any particular yarn in the fabric or GSM of fabric. In these cases, a great accuracy of weight is required for correct results.
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5.10 Knitting of 100 % Polyester or 100 % Lycra When 100 % Polyester yarn or 100 % Lycra yarn is used for knitting fabric then it is necessary to arrange a new set of needles on knitting machine. It is impossible to knit fabric with existing settings and needles of knitting machine. Otherwise, needle line appears in fabric. First of all a small sample of fabric should be prepared and after processing its conditions should be checked carefully. If there is some severe needle marks in fabric then immediate action should be taken for removing needle marks. In case of 100 % Polyester knitting, management should be more conscious about yarn tension. Otherwise, when Polyester yarn is broken; it is very difficult to watch with naked eye during knitting or in running condition.
The coordination between knitting and dyeing department is very essential for producing this type of fabric. The management should first try to produce Polyester Cotton blend fabric. After getting successful results in knitted blend fabric, management should try for knitting of 100 % Polyester or 100 % Lycra fabric.
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Useful Calculations 6.1
Calculating GSM of Swatch
The method to calculate the GSM of swatch using following formula:
GSM
=
Weight
100×100
Width × Length
For example:
0.37g
3cm
5cm
Width
=
3(cm)
Length
=
5(cm)
Weight
=
0.37g
GSM
=
0.37
100×100
3×5
GSM
=
0.0246 × 10000
GSM
=
246.7
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Best Practices Knitting Manual
Calculating Length from Fabric Weight
Calculation formula for converting Kilograms of fabric to Meters is as follows: Since, GSM
=
Weight (g) Length (m) × Width (m)
Therefore,
Length (in meter) =
Weight (g) GSM × Width (m)
6.3
Conversion Formulas for Cotton Count and Polyester Denier S
= 5315 / D
OR
D
= 5315 / S
Where, S = English Count D= Denier
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Best Practices Knitting Manual
Formula for Finding Gauge of the Yarn Count If, S = Cotton Count G = Gauge C = Metric Count Then, G= K √C OR G² = C÷ K² Since, C = S × 1.6936 G² = (Sx1.6936 ÷ K²) G²= S × (1.6936 × K²) Where K= Constant For Single Needle For Double Needles
K= 3.5 K = 2.5
Example: For S = 20 s
K = 3.5
Using above relation G = 20.36 →
20 G
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Best Practices Knitting Manual
Calculations for Finding GSM
The following is the method for finding the GSM with respect to stitch length. When we know the value of Stitch Length, Dia, Gauge, Finish Width and Yarn Count then, we can find the GSM. If, Dia in Inches
=
D
Gauge
=
G
Count
=
S
Number of Needles
=
D × 3.14 × G
Fabric Width in Inches
=
F
=
F × 2.54
=
D ×3.14 × G
Wale
F × 0.0254
=
123.6 × G × D F
Course
=
D ×3.14 × G
×
4
F × 0.0254
=
D×G
×
154.53
F One Loop Length L (m)
=
Stitch Length No. of Wales
Yarn Length
=
Wale × Course × L
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Best Practices Knitting Manual
123.6 × G × D ×D × G × 154.53 × L F×F
=
19099.9 × G² × D²
×L
F²
W (GSM)
=
5315 × 19099.9 ×
G² × D²×L
S =
F²× 9000
11279.6 × G² × D²×L F²× S
For Example Dia
=
30
Gauge
=
20
Count
=
22
Number of Needles
=
30 × 3.14 × 20 = 1884 ↔ 1860
Fabric Width
=
62" = 62 × 2.54 = 157.48 cm = 1.5748 m
Wale
=
1860 ÷ 1.5748 m = 1181
Course
=
1181 ×
One Loop Length
=
61.5 cm 200 (wale)
Yarn Length
=
1181 × 1476 × 0.003075 = 5360.2 m
D
=
9000 × W L
W
=
D×L 9000
=
5315 × 5360.2 9000 × 22
=
143.9 g / m²
W (GSM)
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5 4
= 1476 =
0.003075 m
SMEDA-JICA Industry Support Program
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Best Practices Knitting Manual
5 S (A Japanese Management Technique) 5S is a Japanese quality management concept that was introduced and advised to practice in the factories for creating a high quality, a highly productive and a safe working environment. 5S is a simple and systematic five step Japanese approach for clean, neat, properly organized workplace through employee’s initiatives. It should be gradually adopted and than it will become the habit. It is an acronym for five Japanese words Seiri, Seiton, Seiso, Seiketsu, and Shitsuke. The meaning of 5S is explained as follows: Seiri:
To sort and throw away unnecessary items
Seiton:
A place for everything and every thing in its place
Seiso:
Maintain high standards of Cleanliness
Seiketsu:
Standardize all procedures
Shitsuke:
Train and maintain Discipline
5S can provide a solid foundation for other productivity and quality programs such as Total Quality Management, Total Productive Maintenance, Waste Reduction and Just in Time Production and Inventory Management. 5S reduces the gap between the top and bottom levels of employees and develop a team work.
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7.1
Best Practices Knitting Manual
How to Practice 5S
7.1.1 Seiri Identify the things which are not of use anymore. Examples are defective equipments, outdated material and obsolete documents etc. The following guide can be used to classify all the necessary items.
Guide to Classify Unnecessary Items
Sorting
Action Require
Unnecessary Items
Items of no Value
Throw away Immediately
Items of some Value
Relocate or Sell
Items required special disposal
Look for an inexpensive safe way for disposal
The company should have a set of objective criteria on the retention and disposal of items.
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7.1.2 Seiton It is important to prepare a plan for the location of the objects. The plan will make it easier to locate items when they are needed. It is important to return the items to their original place after use. The following guide can be used to help in arranging the necessary items.
Guide to classify Necessary Items Sorting
Action Require
Necessary Items
Items used Constantly
Must be placed nearby
Items used Occasionally
Can be placed further away
Items not used frequently but still in-need
Must be stored separately in a designated place
It is likely to forget the location of certain objects not often used. To prevent this, “Visual Control” can be used to mark out the items and their locations. With properly marked storage places, out of place items can be easily spotted. The use of colors, labels, charts can be used for visual control.
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7.1.3 Seiso The practice of Seiso is important for the company’s image and health of its employees. It is also prerequisite for the production of quality goods and services. Following are the some ways to implement Seiso at the workplace:
Organize a big cleaning day once or twice a year that involves everyone
Set aside some time each day to clean workplace. Cleaning work is easier and faster when done daily as the dirt accumulated would be minimal
Employees to be made responsible for the cleanliness of their own immediate work areas
Conduct regular cleaning of machines and tools that are in use. This would be a good starting point for productive maintenance because clean machinery and equipment encounter fewer breakdowns
7.1.4 Seiketsu To maintain a high standard of workplace by keeping everything clean and orderly at all times the 5S movement must be sustained within the company by repeating Seiri, Seiton and Seiso activities. The 5S must be implemented according to a company wide standard. The purpose is to make sure that the entire organization follows the same rules; same names and colors etc. Following are some guidelines for Seiketsu (Standardization):
Create a cleaning system for house keeping. For example, make a weekly schedule for cleaning and organizing the workplace
Form 5S teams among the various departments to brainstorm on possible housekeeping projects. These will help in creating a sense of ownership and participation among the employees. The achievements by these teams should be exhibits to both management and colleagues to share their experiences
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Organize inter-departmental competitions on housekeeping. These will bring motivation and create the importance of housekeeping at the workplace. Also it will help to create new ideas on visual control to be implemented resulting higher productivity
7.1.5 Shitsuke The 5S program is a long term approach to improve the work environment. The benefits could only be fully realized through the continued efforts of every employee in the organization. Total participation is must for Shitsuke to succeed. The organization should train all the employees and develop a company culture whereby good housekeeping becomes a habit for everyone. Following are some ways to implement it:
Every one should play an effective role in housekeeping efforts at the workplace to set good examples for others to follow
Plan a comprehensive training on 5S and implement it
With continuous improvement in mind the changes brought at workplace to convince employees and create positive attitude towards 5S
Create a 5S culture where everyone willingly participates and give rewards on good practices
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SMEDA-JICA Industry Support Program
8
Best Practices Knitting Manual
Fish Bone Theory The Fish Bone Theory is a simple and systematic Japanese approach for solving the problems. It should be gradually adopted than it will become the organizational habit. After analysis of the data, this theory must be used for solving different types of problems. Fish Bone Diagrams help you to think through causes of a problem thoroughly. Its major benefit is that it push you to consider all possible causes of the problem, rather than just the ones that are most obvious. The approach combines brainstorming with use of a type of Concept Map. Follow these steps to solve a problem with a Fish Bone Diagram:
8.1
Identify the Problem
Write down the exact problem you face in detail. Where appropriate identify who is involved, what the problem is, and when and where it occurs. Write the problem in a box on the left hand side of a large sheet of paper. Draw a line across the paper horizontally from the box. This gives you space to develop ideas.
8.2
Work out the major factors involved
Next identify the factors that may contribute to the problem. Draw lines off the spine for each factor, and label it. These may be the people involved with the problem, systems, equipment, materials, external forces, etc. Try to draw out as many factors as possible. If you are trying to solve the problem as part of a group, then this may be a good time for some brainstorming. Using the 'Fish bone' analogy, the factors you find can be though of as the bones of the fish.
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8.3
Best Practices Knitting Manual
Identify Possible Causes
For each of the factors you considered in stage II, brainstorm possible causes of the problem that may be related to the factor. Show these as smaller lines coming off the 'bones' of the fish. Where a cause is large or complex, then it may be best to break it down into sub-causes. Show these as lines coming off each cause line.
8.4
Analysis your diagram
By this stage you should have a diagram showing all the possible causes of your problem. Depending on the complexity and importance of the problem, you can now investigate the most likely causes further. This may involve setting up investigations, carrying out surveys, etc. These will be designed to test whether your assessments are correct. The examples of fish bone diagram as applied in knitting are attached in the annexure-IX.
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9
Best Practices Knitting Manual
Employee Participation & Training Organizations should make full use of its employees- its most valuable resource. Employees actually performing the operations often have the best idea for improving them. Human resource is as essential an aspect of processes as technology. The abilities of managers and workers, and how they are organized, trained and motivated can give a firm a competitive edge. Firms can capitalize on the insights and experience of their employees in various ways, ranging from departmental problem-solving teams to cross-functional, self-directed teams. However, to utilize fully the talents of their work force, firms must establish the proper environment, which includes restructuring the organization and its incentives, appropriately designing jobs, and using the proper tools to measure performance.
9.1 Employee Training Organization must rely on their employees to anticipate possible problems, develop new product, increase productivity and quality to remain competitive. In order to make it possible On-job training is one of the useful tools. Teaching new work methods to experienced workers or training new employees in current practices helps to achieve our goal. Managers too need to develop new skills not only those directly relating to their own duties but also those needed to teach their sub ordinates. Systematic training involves the training of a person in:
Basic knowledge
Correct methods
Quality standards (It means the establishment of the threshold at which level of severity a defect becomes unacceptable, i.e. a fault.)
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Without this last item defective production cannot be prevented. It is vital that all faults and defects that are likely to arise in any job should be taught to all trainees during their instruction. An operative must be able to recognize these faults and take action on them, that is, to report, correct or prevent them and where possible, to prevent their recurrence. Training of Quality standards is greatly assisted by a library of faults, each fault being illustrated in the various degrees of severity, - from certainly acceptable to definitely no. Good quality products can only be produced by the operatives, or those who fold and pack no one else. They cannot produce quality without being fully aware of what exactly is required. Responsibility for the production of good quality lies with, and is in the hands of, the person teaching the job, primarily by good communication, by making the newcomer aware of specifications and tolerances, faults themselves, their effect and the appropriate action to take. Such communication or training if properly planned and executed will greatly assist in minimizing the cost of poor quality. The operatives will know from the start what is required, and equally important be able to spot trouble before it gets out of hand and know how to handle it. It will also help to avoid the painful scenes of huge piles of sub-standard work being returned for rectification, which more often than not are due to a lamentable lack of positive communication. Only in this way will quality be controlled, costs remain at an acceptable level and customers be satisfied.
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Best Practices Knitting Manual
ANNEXURE
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Best Practices Knitting Manual
Annex-I: Knitting Program Chart
Machine # Machine Type Machine Gauge / Dia Machine RPM Work Order # Yarn Count Yarn Brand Fabric Type Slitting Line Stitch Length GSM
YES
NO
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Annex-II: Data Chart for Knitting Conditions Date
Work Order No.
Machine No.
Pattern
Dia
Gauge
No. of Feeders
RPM
Yarn Count Stitch Length
1
2
3
4
1
2
3
4
Round Meter Yarn Tension Sinker Timing / Needle Timing Master Wheel Gear Teeth Greige GSM
Possible Problems that Occurred
Possible Solution must be kept Future Reference
Feeders Position Master Wheel MPF Tape No. Finish GSM
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Annex-III: Machine Counter Status
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Annex-IV: Production Analysis Graph
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Annex-V: Machine Wise Inspection Report
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Annex-VI: Machine Maintenance Schedule Periodical Maintenance Sheet Items to be inspected
Frequency or timing Before Installation
Daily
Weekly
Monthly
Semi-annual Annual
Enough room space for machine installation Electric wiring by qualified electricians Air piping work by qualified technicians Yarn feeding device and related parts: Yarn feeders (MPF, IRO, YS2, etc.):Slipped-off, loose or broken drive belt Positive yarn feeders (MPF**, MFD**, etc.): Malfunction of clutch, IRO tape flipper, etc. Lint accumulation onto yarn feeders including tension cymbals QAP (Quality pulley):diameter, loose lock nut Lubricators: Oil level in the tank Supply amount of compressed air Lubricating condition for knitting elements (disconnections, leakage, etc.) Compressed air pressure Supply amount of lubrication oil Abnormal noise: Knitting elements (cam holders, sinker cap and dial cap) Yarn feeding units and related parts (QAP, change gear box, drive tape, etc.) Frame (machine bed, take-up unit, motor drive, etc.) Oil leakage: Lubricator main body Part underneath the bed Oil amount in the oil sump bottle Connection between oil mist pipes and nozzles Part underneath the gear ring Piping for lubrication oil and compressed air Oil amount in the bed Oil sump channel(for oil mist sump) Draining of water in the air compressor Lint accumulation (checks for lint and clean.): Lint in the control panel Lint around lint fans and other areas Lint in the motor cover Belt tension: Drive motor belt Drive belts for yarn feeding device Oil change for the gear box and the bed
Grease change for the take-up unit and the yarn feeding units
If any abnormality should be found during operation, please stop the machine immediately and take necessary corrective measures.
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Daily Machine Inspection Check Sheet
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Best Practices Knitting Manual
Weekly Machine Inspection Check Sheet M O N T H
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Draining of water in the air Oil amount in the bed Oil sump channel for oil Piping for lubrication oil & compressor mist sump compressed air Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week week 3 2 1 4 1 2 3 4 1 2 3 4 1 2 3 4
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Monthly Machine Inspection Check Sheet M O N T H JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Lint accumulation (check for Lint &Clean) Lint in the Lint around lint Lint in the motor cover fans & other areas control panel
Belt Tension Drive motor belt
Drive belts for yarn feeding device
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Inspection Check Sheet Semi-Annual OIL CHANGE MONTH BED GEAR BOX
YEAR
Annual GREASE CHANGE TAKE-UP YARN FEEDING UNITS UNIT
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Annex-VII: Lubrication Lubrication Location Bed (Gearing) Gear Box
Take-Up Device (Ratcht Wheel, Super Gear, Stationary Bebel Gear & Bearing)
Needles, Sinkers & Cams
Lubrication Procedures & Number of Time After test running of 1 month, Thereafter every 6 months
Manually---- once a year
Continuously by automatic oil mist lubrication
Oil Used SHELL: TONNA OIL S68 (Please use the oil described in above or same quality of Viscosity@40˚C 55 to 70)
SHELL : ALVANIA GREASE # 2 MOBIL : MOBILUX GREASE #2
SHELL: VEXILLA G MOBIL: VILOCITE CX 22 VICKERS: SPOTLESS C. N. 22 : VICKERLUBE L. C. 22 (Specially develop for use with Lycra when heat setting is the first finishing operation.) MILLERS: KAYSTOL GULF : LORTEX 22 ESSO : TELURA KLUSER : Text- 22N
NOTE 1. Please use the oil described in above the table or same quality, pure and clean oil. When adding oil, please ensure dust lint etc. does not get in to the machine. 2. If the machine becomes too hot or if there is an unusual noise, stop the machine immediately and check the lubricating conditions. 3. The bed, gear box and stationary bevel gear are each design with an oil bath system. Please exchange oil periodically, as recommended in the table. If any of the oil amount falls to the minimum level. Please immediately add oil. The bed oil gauge will not shown accurate amount of oil during the operation of the machine (There are cases when showing as “0”), so when confirming the amount, stop the machine, and after about 5 minutes, please confirm the oil amount.
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Best Practices Knitting Manual
Annex- VIII: Knitting Construction Graph
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Knitting Construction Graph
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Best Practices Knitting Manual
Knitting Construction Graph Sample No.
Single Knit
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Annex-IX: Fish Bone Chart For Productivity Improvement K nitting C ondition C one Loop Length
Yarn
Speed
Fluff Paper Tu be
G auge
Shape of Cone
K ind of Pattern C rush
D ent or H ollow
C ount Yarn Speed
N o. of Feeder
Im provem ent of Productivity Stopper C entering of C reel
Scratch
Tension
M ind M PF Tape
Positioning of Yarn C arrier
Tail K not
Education O peration
N eedle Production C ontrol
N eedle Bed N eedle D itch R egular C heck
O perator
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For Oil Stain Winding
Production Control
Periodic Upkeep Guide
Inspection
Storage Standard Action Needle Place of Lubrication Needle Bed
Transport Lubrication
Needle Ditch
Oil Oil Volume
Pack
Stain Oil Volume
Storage Place of Check
Knot
Lubrication
Reception Dyeing Dyeing Factory
Transport
Tail
Periodic Upkeep Yarn
Cone Guide
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Best Practices Knitting Manual
For Vertical Line Needle ditch & Bed
Difference of Pattern
Friction Declination of Pattern
Bend
Difference of Design High Wearing
Vertical Line Friction
Friction Motionless
Measure Frame Latch Friction Rivet
Bend Damage
Touch Line Friction
Loose Fitting
Hook
Roller
Needle Friction Butt
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For Dropped Stitch Latch
Production Control
Knitting Condition
Needle
Kind of Pattern Loop Length
Yarn Speed
Gating
Yarn Speed
Bend Tension
Timing
Levering Position
Creel
Guide Winding Tension
Scratch
Space of Guide
Dropped Stitch Hardness Slipping from Cone
Cone
Dent or Hollow
Hairiness Tight
Snarl Quality
Tail Paper Tube
Yarn
Tail Knot
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For Needle Break
Knitting Condition
Loop Length Yarn
Kind of Pattern
Cone Yarn Speed
Needle Break Adjustment Needle Ditch Cam Friction Gating Needle Bed
Needle
Needle Latch
Operation
Regular check
Pressure Weight Production Control Winding Tension
