Of Raw Cotton and Yarn
Since 100% testing is not possible, random sampling
Zoning Technique For Raw -Cotton
As cotton in bulk is not homogenous, a number
of sub-samples must be taken at random from different places in
the bulk. When we do sampling from cotton bales, the require number
of fibers should be taken one by one at random from different parts
of bale. Following method is used for sampling of cotton:
||A sample of 2 OZ (Approx.906.72gms) is made by
selecting about eighty large tufts chosen over the bulk.
||This sample is divided into four quarters.
||Sixteen small tufts are taken at random from each quarter
||Each tuft is halved four times, discarded alternately turning
the tuft through right angle between successive halving. Sixteen
whips are thus produced from each quarter.
||These whips are combined to from a tuft.
||Each tuft is mixed by doubling and drawing between fingers.
||Each tuft is divided into four pieces.
||A new tuft is obtained by combining a part of each of four
||Sample is mixed again by doubling and drawing.
||A quarter of sample is taken out to form final sample.
The aim of the process control is to ensure
ourselves that the manufactured goods are according to the specification
of the customers and do not contain many defects. For this, it is
imperative that the product should be examined at strategic points,
which is designated as receiving inspection. The basic tool used
for examination of raw-material, in-process and finished product
are called acceptance sampling in which a decision to accept or
reject a lot is made on the basis of random sample drawn from it.
These plans are basically designed for lot quality protection so
that a lot having poor quality has virtually no chance of being
accepted. The main objectives of random sampling are:
1. To determine the acceptability of incoming
products and outgoing products.
2. Providing a definite assurance against accepting any lot.
3. For taking corrective action on the processes as and when required.
4. To determine the acceptability of the product from one department
to another within the unit.
5. To improve quality of the material supplied by vendors.
As yarn is available as a number of independent
packages and the problem of sampling is the selection of a small
number of such packages from a large number, so to avoid biased
sampling we use Cambridge Elementary Statistical Tables for random
BIAS Bale inventory analysis system is developed
by M/S Zellweger Uster. According to this system, mix is formed
in a way that bales taken from stock are having min variation in
quality parameters from bale to bale and from day to day.
|1. 100% testing of bales
||All the bales received are tested in HVI. Tested
results are exported to BIAS either directly or by floppy disk.
|2. Categorization of Bales
||All bales tested are numbered and divided into categories.
Eg. if categorized according to SCI & MIC.
|3. Mix Formation
||Eg. mix for 20 bales
SCI total = DSCI
MIC total = CMIC
FOR SCI- Make 6 categories<80,80-90,90-100,100-110,110-120,>120
FORMIC- Make 6 categories<3.0,3.0-3.3,3.4-3.6,3.7-3.9,4.0-4.2,>4.2
These categories are decided by analyzing
at least 1000 bales for particular Season. Since total categories
are 6 x 6 = 36, so all the bales tested are stocked in to
|In this mix plan
| In other words, total of SCI category MIC category
in any direction will be the same. Now bales issued are subtracted
|4. Printout Of Mix Plan
||Enter bale number of each bale issued. Average of all quality
parameters will be printed. Thus, BIAS helps to reduce variation
in quality parameters on a day to day basis for particular mixing.
Process Control Methods
In large scale industrial production, it is found
that variation in quality are unavoidable. We can prevent large
variations by imposing proper checks and controls on the production
process. One advantage of ensuring the absence of factors responsible
for large variations in the process is that quality follows a regular
statistical level. A production is said to be in a "stage of
control" if it is under the influence of factors responsible
for small variations only. The quality control is an activity which
assures that goods conform to specified standards. Thus, it is an
assessment of quality in either or all three of the input transformation
or output phases of a production process. The control of quality
involves measurement, feedback, comparison with standards and corrective
action when necessary.
How do we do
Preventive maintenance of our machinery
Routine and preventive maintenance generally
focus attention on continuous smooth working of the machine over
its life time of many years. The system of machinery assessment
concentrates on the following:
1. Quality of the material being processed.
2. Production of the material / unit machine time.
Those machine conditions, which influence the
quality and production are identified and special attention is given
to improve these conditions. It is necessary to have a critical
assessment of the machinery condition and other related activities
through an in-depth study and to take the appropriate action to
keep the machine in 'Best Working Condition'. This
will aim at implementation of machinery maintenance management which
is essential for any quality conscious manufacturing unit. We are
covering following major areas of various activities related with
maintenance to achieve this goal:
A. Evaluation of maintenance schedules, its follow-up
B. Assessment of the mechanical conditions of machines and their
C. Checking of critical settings and gauges for its better accuracy.
D. Identifications of the scope of improvements in general maintenance
practices and methods.
E. Assessment of existing resources in terms of skilled man power,
maintenance accessory equipment, tools & gadgets etc.
F. Assessment of investment in maintenance activity.
G. 'On the spot' demonstration for achieving the
effectiveness in maintenance operations.
1. The machine is taken into maintenance
2. The machine-parts, wear-tear, settings and gauges critically
3. The lacuna is pointed out on the spot and corrected immediately.
4. The maintenance practice and methods of the work-force are critically
5. The existing maintenance schedules, record keeping is scrutinized
and scientific computerized methods adopted for the maintenance
scheduling and record keeping.
6. Finally a detailed comprehensive report is prepared for machine
wise grading, where suggestions and recommendations are shown in