HOW TO ASSESS A SPINNING MILLS PRODUCTIVITY?
THE SOUTH INDIA TEXTILE RESEARCH ASSOCIATION COIMBATORE
This publication prepared by the following staff members of Liaison & Consultancy Division, SITRA. Mr.D.Shanmuganandam Mr.N.Ravichandran Mr.J.Sreenivasan Mr.N.K.Nagarajan Mr.S.Rajesh Kumar
Published by: The South India Textile Research Association Post Box No. 3205, Coimbatore Aerodrome Post, Coimbatore - 641 014, Phone : 0422-2574367-9, 4215333, 6544188 Fax :0422-2571896, E-mail:email@example.com Website :www.sitra.org.in
PREFACE This edition replaces the last SITRA publication How to Assess Your Mills Productivity by (Vol.48, No.4,
Mr.R.Ranganathan and Ms.R.Suganthi. As the norms for spinning as well as cone winding productivity have been revised since the last publication, the conversion factors have been reworked and given in the report. This
publication explains with illustrations, the method of assessing the various productivity indices both spinning and cone winding that are used in the SITRA productivity surveys.
Page no. I Up to ring frames 1. Definitions of various productivity parameters 2. Operatives considered for the productivity assessment up to ring frames 3. Productivity estimation an illustration II Cone winding 1. Definitions of various productivity parameters 2. Productivity assessment in automatic cone winding an illustration Tables A. Conversion factors for calculating standardised production up to ring frames cotton yarns B. Conversion factors for calculating standardised production up to ring frames synthetic and blended yarns C. Drums per tenter, machine efficiency, production per tenter and conversion factors for automatic cone winders D. Drums per tenter, machine efficiency, production per tenter and conversion factors for conventional cone winders 17 30 1 2 4 4 11 11 13
I. UP TO RING FRAMES This section describes the method of assessing labour and machine productivity up to ring frames. Briefly, the method consists in adjusting the various productivity parameters to 40s count. A mill can compare its productivity between months and also judge its performance against SITRA standard, regardless of the differences in the counts being produced. The standards are fixed such that they reflect the productivity levels being attained or excelled by the top 10% of the mills in the industry. The revised SITRA standards for HOK and OHS are given in Table 1. Table 1 Standard HOK and OHS for different categories of operatives up to ring frames (40s)Categories of operatives Mixing attendant Blow room tenter Card tenter (chute feed) Draw frame tenter Fly frame tenter Fly frame doffer Ring frame tenter Ring frame doffer Ancillary operatives* Total HOK 0.6 0.2 0.2 0.3 0.4 0.5 3.1 2.7 4.0 12.0 OHS 0.08 0.03 0.03 0.04 0.06 0.07 0.42 0.37 0.55 1.65 110
Production per spindle per 8 hours adjusted to 40s (g)
* blow room to ring frames (excluding combers) including jobbers, maintenance operatives, materials handlers, roller coverers, etc. Notes: 1. Level of modernisation assumed is as follows: Chute feed blow room line, cards fitted with automatic can changer, automatic waste evacuation system and auto leveller, draw frames fitted with automatic can changer for 1st passage, draw frames fitted with automatic can changer and autoleveller for 2nd passage, high speed fly frames and long length ring frames. 2. For work assignments, ancillary operatives as well as production rates assumed in various departments, reference may be made to SITRA publication Norms for Spinning Mills, 2010 edition.
3. HOK for combers and preparatory tenters and maintenance operatives may be taken as 1.0 (40s count). 4. Throughout this publication, 40s or 40s count always refer to 40s cotton carded yarn, unless otherwise qualified. Also, the phrase adjusted to or conversion to or standardised or conversion are used interchangeably.
1. Definitions of various productivity parameters Definitions of various productivity parameters that are covered in SITRAs intermill productivity surveys are given below: HOK Adjusted HOK : Operative hours to produce 100 kg of yarn. : The HOK is adjusted to a common count of 40s by multiplying the actual production in ring frames in different counts by relevant conversion factors. The production so converted is termed as standardised production. Thus the adjusted HOK is calculated from: Operative hours = x 100 Count-wise standardised ring frame production in kg : The conversion factors are the ratios of the HOKs of individual count to that of 40s count under given conditions. HOK for a given count = HOK for 40s count The count-wise HOKs are estimated taking into account count-wise production rates, work assignments, etc., that correspond to those for the standard mill. The conversion factors are different for various categories of operatives and for 40s count, they are unity for all the categories of operatives. Another major practical advantage of this method is that it is not required to obtain a break-up of the operatives according to each count (For count-wise, raw materialwise and category-wise HOK conversion factors, refer Tables A and B). Standard HOK : HOK for 40s count under the specified conditions. The standard HOKs for different categories of operatives are given in Table 1 and the conditions under which they can be attained are given in the footnotes to this table. As can be seen, the total standard HOK up to ring frames is 12. 2
Conversion factors for HOK
Composite : A measure of productivity calculated by expressing the standard productivity total HOK of 12 as a percentage of a mills total actual HOK adjusted to 40s count. It reflects the effect of both labour and index (CPI) machine. P : Production per spindle per shift of 8 hours (adjusted to 40s count) in grams. The overall production per spindle in ring frames, adjusted to 40s count, can be obtained by using the conversion factors. Count-wise standardised ring frame production in kg = x 1000 Total spindle shifts (of 8 hours each) corresponding to the above production
Conversion : These conversion factors are the ratios of the standard production per spindle in 40s count to the standard production per spindle in factors for P the given count. 110 g = Std. prodn. per spl. per 8 hrs. (g) in the given count(for count-wise and raw material-wise conversion factors, refer Tables A and B)
: Number of operatives employed per 1000 spindles adjusted to 40s count. P x HOK = , where HOK and P are adjusted to 40s count 800 : OHS modified to allow for a valid comparison of a mills OHS with the standard OHS of 1.65 taking into account the deviation of the mills production per spindle from the standard production per spindle. 1.65 x OHS = [1.65 0.0065 (110-P)] : A measure of spindle utilisation expressed in terms of number of hours worked per spindle per day. It is calculated by dividing the total spindle hours worked per day by the installed spindles. The spindle utilisation is also expressed as percentage. SH ie. x 100 24 : A combined measure of production per spindle and spindle utilisation. It is calculated by expressing the product of production per spindle (P) adjusted to 40s count and spindle utilisation (SH) as a percentage of 2640 (110 x 24). The index would be reduced by one-seventh if the mill works for only 6 days a week. P x SH = x 100 110 x 24 3
2. Operatives considered for the productivity assessment up to ring frames A mills HOK - overall as well as category-wise, production per spindle and other productivity parameters up to ring frames can be assessed based on one month data with respect to operatives engaged in various departments, ring frame production and spindle shifts worked in all the counts. Operatives Operatives actually engaged in different departments irrespective of whether they are permanent, badli and temporary are considered. The categories of operatives to be included for the calculation of HOK are as follows: Mixing attendants, machine tenters, doffers, interval relievers and ancillary operatives such as jobbers (maistries/overlookers), fitters, fitter helpers, machine cleaners, oilers, tape stitchers, roller coverers, top arm draft zone cleaners, sweepers and materials handlers (lap/sliver cans/ bobbins/cops/ waste). The following categories of operatives are not considered for the productivity assessment: Contaminants removers, operatives pertain to comber and its preparatory machines, electricals, generators, humidification plant and workshop workers, watch and ward, attenders, investigators, gardeners, hostel/guest house/quarters workers, dispensary workers, canteen/mess workers, drivers, sanitary workers, civil workers, etc. 3. Productivity estimation an illustration This section explains the method of assessing the various productivity parameters up to ring frames with an illustration. The data correspond to one month period. i) Mill : XYZ Ltd. ii) Size : 21744 spindles iii) Shift duration: I shift: 8.5 hrs.; II shift: 8.5 hrs.; III shift: 7 hrs.; General shift: 8 hrs. iv) Working days during the month: 30 v) Yarn production obtained in different counts in the ring frames and the corresponding spindle shifts (Table 2).
Table 2 Count-wise spindle shifts and yarn productionSpindle shifts worked Count 20s CH 24s CH 24s 30s CH 34s CH 40s CH 40s H Total I 104356 32991 75379 61006 66685 153946 119507 613870 II 104856 33393 75680 61605 67186 154623 120507 617850 III 97020 27720 75600 54566 55123 126043 98033 534105 Total yarn production (kg) 96463 23078 54396 34593 31373 53561 42932 336396 Prodn./spl./ 8 hours (g) 314 244 240 194 165 122 126 -