PROJECT 2:
COMBER DATA
This program is for use on IBM-compatible PCs to compute important fiber parameters and optimum noil percentage as well as to check the functioning of nippers, top comb and combing cylinder through" Knowledge Based Problem Analyses and Problem Solving Techniques" developed by ITRU GROUP LTD.
2.1 Purpose of the program
COMBER DATA BY ITRU GROUP LTD. program has been developed through many years of research and experience carried out in spinning mills. This program makes use of the fibrogram instrument to be more valuable to the spinning mills by determining short fiber content by number, coefficient of fiber length variation by fiber number and mean fiber length by fiber weight as well. Drawing the fiber weight staple curves from only two readings of span length values 2.5 and 50% by comparison of the staple curves of comber lap and combed sliver, one could analyze the efficiency of combing action.
Combing of cotton is a high cost of yarn manufacturing process. The yarn must meet required quality parameters with a minimum noil percentage possible. The intention in mills is usually to increase the noil percentage to achieve better yarn quality parameters. But it is clear from our experience that optimum yarn quality could only be achieved if the combing action is carried out well i.e. by removing short fibres. An increase in noil % does not necessarily mean that the short fiber content is reduced in sliver, it could even get worse. Therefore, this program checks whether the combing action is successful or not by comparing short fiber content in the comber lap and in the sliver as well as checking the trailing and leading hooks fiber breakage.
The program also compares the actual and recommended combing noil percentages and suggests an advisable noil range. Therefore, it is possible to carry out tests to achieve best results till the combing is OK.
2.2 Computation of short fiber content by fiber number
This program computes short fiber content by fiber number from the 2.5 and 50% span length values measured on fibrogram of comber lap, combed sliver and combing noil. Computation of short fiber content by fiber number would give information to check the combing efficiency of top comb, combing cylinder and nippers. By comparison of back and front clamps one could determine the hooked fiber content and fiber parallelism. It should be stated that 2.5 span length values would not only be taken into account to determine the cleaning efficiency of short fiber content. The reasons are as follows: An increase in 2.5 span length values could be due to removing fiber crimp or permanent extension of fibres. Therefore having greater 2.5 % span length values in combed sliver could lead to fiber breakage in draft zone of ring spinning. Therefore, we advise you to just check the span length values of combed sliver and ring pnomophil waste values, which make the actual yarn. According to our experience carried out in different mills that setting the draft zones according to the 2.5% span length or minimum evenness values would not lead to good quality of yarn and does not represent the real facts. Therefore, after combing the processes should be checked in accordance with the short fiber content by fiber number rather than 2.5 % span length values. However, we must state that the short fiber content by fiber number is more important at combing than the processes after combing. In order to achieve optimum yarn quality draft zone settings and draft Organization should be taken into a consideration. For this purpose according required linear irregularity value (CV%), we have developed a new program called "LOG-CV- DRAFT ZONE SETTINGS" which would give you the information whether your draft zone settings are in accordance with the yarn quality and whether producing H1, H2, I1 and I2 faults on yarn. This program will be available upon request.
2.2.1 Computation of mean fiber length by fiber weight
This program also computes mean fiber length by fiber weight from 2.5 and 50 % span length values. Mean fiber length by fiber weight is important especially in combing because it is not possible to determine the percentage of short fiber removal from fiber-number distribution diagram. Therefore, by comparison of mean fiber length of combed sliver, comber lap and combing noil it is possible to evaluate the combing quality.
2.2.2 Computation of coefficient of fiber length variation by fiber number
The program also computes the coefficient of fiber length variation by fiber number, which is a very important parameter, which would give valuable information about the fiber parallelism, and distribution of single fiber length values. Higher the coefficient of fiber length variation greater the fiber problems would be in subsequent processes after combing.
2.2.3 Computation of minimum and maximum noil % according to comber lap
Percentage of short fibres should be removed from comber lap, would depend upon the fiber-length by fiber weight staple diagram of comber lap, which could not be obtainable from fibrogram. Therefore, we have developed a program, which determines the staple curve of comber lap by fiber weight. From this curve it is possible to fix fiber length, which could be taken as a short fiber. We have taken fibres shorter than 12.5 mm as short fibres to start with. Maximum noil percentage would then only be decided upon the quality of yarn but should not exceed the value given by us.
2.2.4 Computation of combing quality index
The program computes the efficiency of combing action by the effective short fiber removal according to combed lap. Therefore, by making comparison of different combing machines one could identify the off-standard functioning machines. In theory 100% combing efficiency is possible, but in practice this never occurs. No combing machines could remove all the short fibres because some long fibres are dragged long with short fibres.
2.2.5 Computation of combing noil percentage according to comber lap and detaching roller setting and total draft
The program also computes the noil percentage according to computed comber lap fiber weight staple curve and detaching roll setting which correlates 95% with the actual results obtained. The program in addition to that given total draft lap weight, count delivered also computes noil percentage.
2.2.6 Computation of Fiber weight staple curves
This program plots 7 fiber weight staple curves comber lap, combed sliver and combing noil respectively. By comparing the staple curves of comber lap, combing sliver and combing noil one could analyze how the actual combing action is carried out whether there are long fibres in the combing noil and short fibres broken in the combed sliver.
2.3 Program structure
The program is composed of 4 subsequent programs linked to each other. Program is structured in such a way that all the information could be stored in another file and then could be edited and sorted for future analyses and the relevant data could be written. Therefore, these programs would motivate your technical staff to work harder and to overcome problems in combing and subsequent processes.
The program also analyses the actual combing action .If the actual noil percentage is higher than computed value due to leading or trailing hooked fiber breakage and not properly functioning of top comp, combing cylinder and nippers it states that COMBING IS NOT QK. For this purpose the program makes use of other information developed by ITRU GROUP LTD.-International Textile Consulting & Management "KNOWLEDGE BASED PROBLEM ANALYSES AND PROBLEM SOLVING TECHNIQUES."
2.3.1 Data and results output
INPUT VALUES
2.5 and 50 % span length values back comber lap in mm =?
2.5 and 50 % span length values front comber lap in mm =?
2.5 and 50 % span length values back-combed sliver RH in mm=?
2.5 and 50 % span length values front-combed sliver RH in mm=?
2.5 and 50 % span length values back-combed sliver LH in mm=?
2.5 and 50 % span length values front comber sliver LH in mm=?
2.5 and 50 % span length values combing noil in mm................=?
LAP WEIGHT G/M................................................................... =?
COUNT DELIVERED G/M ......................................................=?
TOTAL DRAFT..........................................................................=?
DETACHING ROLL DISTANCE IN MM................................=?
NOIL % MEASURED ACCORDING TO FORM PQ-#101 BY ITRU GROUP LTD.=
Output values are shown in the SUMMARY OF FIBRE DATA RESULTS AND STAPLE DIAGRAMS
2.3.2 Mill trials with comber data pc-program
It has been observed through our YIELD PERFORMANCE IN RING SPINNING PC-PROGRAMS and MILL WORKS that combing noil constitutes approximately 50 to 65 % of total waste in ring spinning. Therefore, reduction in combing noil percentage with optimum yarn quality will reduce the manufacturing costs and improve the spinning and weaving performance. We have observed that combing noil could be reduced and better yarn quality could be achieved. Following figures compares two combed spinning mills using the same fiber type with different combing noil percentages but achieving different yarn strength values. It is interesting to note that MILL a having 17% of combing noil percentage has achieved better yarn strength and strength variation than MILL B running with 22% of combing noil percentage. We have also observed that combing noil % could be reduced to 12% in MILL A for weaving yarn. It is very clear our works carried out in spinning mills that PC-PROGRAMS certainly bring new conceptions to spinning and weaving mills to achieve minimum manufacturing costs and optimum quality of yarn.
MILL A MILL B MILL C Fibre Type Izmir 1 1/8 Izmir 1 1/8 Izmir 1 1/8 Combing Noil % 14 17 22 CV% Evenness 11 13.4 13.2 Yarn strength cn/tex 15.6 15.8 15.2 CV% Yarn strength 6.5 5.6 9.9 Elongation % 5.5 7 5.2 CV% Elongation 6.5 5.5 9.8 Yarn Count 30/1 hosiery 30/1 hosiery 30/1 hosiery |
Table 1.Comparison of combing noil % in three spinning mills
It is clear from experimental results that combing noil % should not be determined by trial and error method but it should be carefully analyzed and minimum combing noil % should be obtained with optimum yarn quality. Combing noil percentage depends upon mainly following factors:
Therefore, we have following mill control systems and PC-programs to achieve lower combing noil % with optimum yarn quality.
To improve spinning mill performance is a complete process of work. And small changes make larger differences in the profitability ratio of any mill. And PC-programs are without doubt the main key for these aims to be accomplished. Any mill could see the effects of small changes making large differences in the quality and productivity levels of mills will have a greater chance of competitiveness in the international trade. For minimum cost of manufacturing and optimum quality and better spinning and weaving performance level, our PC-PROGRAM is must for all spin mills.
Knowledge Based Quality Systems Proses Optimization and R&D Projects for Textile Mills