D E PA R T M E N T O F YA R N M A N U FA C T U R I N G

P R O J E C T R E P O RT P R E PA R E D

B Y

H A D I U L L A H R A H A M A N

PABNA TEXTILE ENGINEERING COLLEGE

Effect of waste reduction on production cost and waste extraction system of different m/c on different section

PRESENTATION ON

INTRODUCTION

Textile engineering is the oldest branch of Science. Many Scientist played a vital role for its development. But today textile engineering is the most modern, sophisticated and a prestigious degree in the world. It is a practical oriented subject. That is why the textile engineers must have sound practical knowledge. Besides this , a textile engineer must have knowledge on Electrical, power , mechanical & maintenance also. An engineer must look after the quality production and he has know man handling. It is beyond saying that textile industry is the backbone of Bangladesh economy & 76% foreign currency is achieved from this sector. It is the largest private sector in Bangladesh. That is why here needs a lot of skilled manpower to run this factory. To gather this skill, there is no alternative to practical knowledge.

Pabna Textile Engineering College is serving the nation with her education, building meritorious engineers. At the same time arranging an industrial attachment for each batch to different industries. This college is contributing to increase the practical knowledge of the students. The college has a number of experienced teacher. They give the proper direction to the student. They are very friendly and helpful.

Industrial training, offered by the college, is very useful which gives clear concept about the production, quality control, maintenance, administration etc. of a certain mill and this concept will help a student to flourish his engineering career.

We had been attached in The Delta Spinning Mills Ltd. for duration of 2 months, starting from 28.09.10 to 28.11.10 We successfully ended our training & gathered some useful things like production, maintenance, production management and production evaluation, efficiency, mill management, administration, working atmosphere, worker management quality, production planning, utility and machine operation etc.Finally we have completed our Training Work successfully overcoming all the difficulties and shortage of time. Therefore, we would like to present our Project Work.

DISCUSSION

If a given mixing is not handled properly, some of the fibers may be damaged during its passage through various machines. As a result the waste percentage would increase and the quality of yarn would deteriorate. Moreover, the yarn manufactured under such conditions would result in reduced profit margin due to increased costs.

Conversion of lap into yarn is a question of reducing weight per unit length of the input material, and, at the same time, maintaining product uniformity. The uniformity is achieved by appropriate rate of draft; higher drafts above certain optimum limits produce irregularity with the advent of high drafting, much more attention has to be paid to accurate setting for maintaining quality. In practice, the reduction in weight per unit length is carried out in stages; each drafting operation introduces fresh irregularity; the irregularity of final yarn being the summation of irregularities produced at each operation.

Fiber breakage is a very important factor, because any increase in breakage can lead to additional fly waste and greater number of ends down. Fiber breakage is a function of two main factors; the ratch setting (the distance between consecutive roll pairs in a roller drawing system) and the roving twist. To avoid breakages, it is necessary to set the ratch longer than the longest fiber, because a shorter ratch will break all fibers greater in length.

For a given ratch the extent of machine control over the fiber depend on the length distribution; a wider distribution and a longer ratch lead to lesser fiber control. The strain and distortion imposed on fiber ends during drafting due to the initial pull, continually repeated at each operation also lead to an increase in breakages. It is to be expected, therefore, that fiber will be beheaded as a result of this stress and fatigue, the effect being more pronounced in case of longer fibers.

Blending of different varieties of cotton is usually the responsibility of the spinner. With natural fibers, like cotton maintenance of a completely uniform blend can be very difficult.

A spinner’s first concern is to control staple length and fiber fineness so as to maintain consistent conditions and standard yarn properties. His second concern is with yarn’s appearance. Generally speaking a spinner has to sure, that if yarns

out of different dispatches (lots) from the factory are compared, the weaver/ user should not be able to see any difference between different lots).

For achieving uniform blend, good quality, higher production, sandwich/ Stack mixing, block creeling and cross creeling / color coding at each operation is must.

Yarn breakages and their gradual increases with higher spindle speed poses another bit problem. Frequent yarn breakages result in higher waste percentage and the quality of yarn is also impaired due to thick places emerging from piecing of yarn; moreover, extra labor is required as an operative can only piece a limited number of threads per unit time. The amount of waste produced is proportional to the product of end breakage rate and the average time an end is down.

If the RPM of a machine is increased without considering the spinning conditions, the result will be retardation of the spinning process; not only the expected production would be unachievable but also the quality would deteriorate.

For example, if 5% increase in spindle RPM of the ring spinning frame results in 4% increase of ends down and, in order to control yarn breakages, 1% increase in twist is introduced, the production will remain the same, but the yarn will give more defects and unnecessary additional energy and materials would be used/wasted. Therefore, without giving due wastage over all spinning conditions, an increase in machine speed means deliberately inviting reduction in efficiency.

Current spinning technology is developed, with an aim to maintain higher productivity, with effective quality control, by selecting suitable equipment and spinning conditions to match with the raw materials. Modern developments of machinery, labor demands and increased market competition compel the spinner to produce as satisfactory yarn as economically possible.

TERMS , DEFINATION & OBJECT

Wastage: When any industry starts its production from raw material then some kinds of unusable things

have been produced. These unusable things are produced from different m/c. The unusable things are called wastage. The quality of the product is depended on the waste percentage. If quality is high then the wastage percentage is high. But production cost is also be high and production rate would be low. So wastage should be controlled as perfectly in different m/c. In a spinning mill the raw material is cotton. So unusable things in cotton are short fibre , seed coat, foreign material, neps, color material, metal etc. We should remove this unusable things carefully for increasing the quality of yarn.

  Waste extraction: By which process we can remove the wastage from raw cotton in different m/c that is

called waste extraction.   Cleaning intensity: Cleaning intensity is one of the setting system in Blowroom. This setting is given in

the Uniclean & Uniflex m/c. The main object of this setting is to maintain the wastage percentage in the Blowroom. The range of cleaning intensity 0.1 to 0.5.

Relative wastage: Relative wastage is one of the most important setting system in Blowroom. This

setting system is given in the Uniclean & Uniflex m/c. The range of relative wastage is 1 to 10. When the relative wastage is high then wastage extraction would be high. When relative wastage is low then waste extraction also be low. Now we can tell that relative wastage is the main wastage extraction system in B/R.

Relative Waste rate

Setting «1» (Low): Setting «10» (High):Grid closed, lowest waste rate Grid open, highest waste ratedark waste composition light-colored waste composition

NRE: NRE means neps removal efficiency. NRE is depended on the relative waste

rate on Blowroom. When the removal of neps is expressed as percentage with respect to feed neps then it is called NRE. If relative wastage is increase NRE is increase. So NRE is one of the wastage extraction system in carding m/c.

  NGP: NGP means neps generation percentage. NGP is depended on the relative

waste rate on Blowroom. When the removal of neps is expressed as percentage with respect to delivery neps then it is called NGP. If relative wastage is increase NGP is increase. So NGP is one of the wastage extraction system in carding m/c.

  Object: To know about raw materials of spun yarn. To know about different types of waste produced in spun yarn. To know about waste extraction system in spinning mill. To know about waste reduction system in spinning mill. To know about the effect of waste reduction on production cost.

PROCESSING VARIABLES

Yarn waste The yarn waste in a spinning mill should not normally exceed 0.1% with conventional

cone winding. In the case of automatic cone winding, the yarn waste generally varies from 05% in winders fitted with round magazine feed to 0.8% in winders with auto bobbin feed system. However, if the yarn under goes additional processes such as reeling, doubler winding and TFO twisting/ring twisting, the waste would be somewhat higher. A high incidence of yarn waste, apart from leading to a loss of Rs.6 to Rs.15 per spindle per year for every 0.1% waste (savings increase with decrease in count), is an indication of poor machinery condition and maintenance, and inappropriate work practices of operatives. A number of factors such as vibrating spindles, spindle out of center, soft cops, oil stain on yarn, improperly built cop bottom, yarn left over in cops during winding and operatives using excess length while piecing, leads to high yarn waste. For further information on yarn waste control reference may be made to SITRA publication “Measures to Control Hard Waste in Spinning” Vol. 41, No.11 March 1996.

Sweep waste The sweep waste in all departments of a spinning mill together should be within 1%. A

high sweep waste arises invariably due to operatives throwing away the wastes like bonda waste, lap bits, sliver bits, roving ends etc. on the floor and generation of fly and fluff. The fly frame and ring frame tenters should be provided with hip bags and it should be ensured that the bonda waste and roving ends are deposited in the bags during piecing. Good waste, if any, should be picked before sweeping instead of sorting out the waste later. A high price fetched for sweep waste would give an indication of the presence of good fibers in the waste.

Invisible loss Invisible loss in a spinning mill occurs due to a number of factors such as short

fibers (fluff) escaping from the departments, improper accounting of wastes produced, weighment errors in cotton purchased and wastes sold, excess give away of yarn and inaccuracies in the estimates of stock held in process. Since it would be difficult to accurately assess the process stock, it is suggested that the invisible loss be assessed only once in 4 months for control purposes. This will help in minimizing the variation in invisible loss due to errors in process stock estimate. From the data compiled every month, a cumulative average could also be taken for control purposes. However, not much importance should be given for estimates made from data less than 4 months. To maintain the invisible loss within 0.5%, the Mill should also ensure that moisture content in the finished goods is at par with the level prevailed in cotton at the time of purchase.

Usable waste By exercising good control over end breaks in various machines material handling and storage and work practices of operatives a mill could maintain the usable waste below 5%.

WASTE PRODUCE IN DIFFERENT SECTION

  Waste produced in different production processes:   Blow Room (4-5%) : Dropping 1, Dropping 2 Fine dust Carding (5-6%) : Flat strip, Taker in   Drawing (0.5%): Filter waste, Sliver waste Sweeping Dust. Unilap (0.2%) :Sliver waste, Lap waste. Comber (15-20%) :Noil, Lap waste, sweep waste. Simplex (0.5%) : Sliver, Roving Sweep waste, Apron clearer

waste Ring Frame (2-3%) : Roving, Sweeping Pneumafil, Soft waste Wooden roller clearer, Winding (0.5%) : Hard waste, Sweeping Invisible waste Rotor : Pneumafil dust, Hard waste, Sliver waste Soft waste

BLOWROOM AND CARD WASTE MEASUREMENT

From the all report we get the various setting points of B/R and Carding m/c: B/R setting of Ring line: Uniclean→ 1.Cleaning Intensity 2.Relative Waste rate Uniflex → 1.Cleaning Intensity 2.Relative Waste rate B/R setting of Rotor line: Uniclean→ 1.Cleaning Intensity 2.Relative Waste rate Uniflex → 1.Cleaning Intensity 2.Relative Waste rate Setting Point of Carding m/c: 1.Cylinder-Flat setting 2.Back Stationary Flat 3.Front Stationary Flat 4.Cylinder Speed 5.Flat Speed  

We get following setting statistics from the report no.1   For keeping the setting point of Uniclean and Uniflex at Cleaning Intensity= 0.2 Relative Waste rate= 8 Mainly two types of waste found in B/R 1.Dropping 2.Flat strip Dropping found from Ring and Rotor. From the report one, we can get total neat production of 23 carding m/c=1684 kg/hr, but

the total production with waste is 1845 kg/hr. Here, we get ring dropping=60.95 kg Rotor dropping=15.10 kg Flat strip =85.40 kg The waste percentage are 3.30,0.82&4.63 respectively of total production. Total waste= Ring dropping+Rotor dropping+ Flat strip =(3.30+0.82+4.63)% Here, total waste is 8.75% of total production [Note: Obs. Time = 1 hour]

We get following setting statistics from the report no.2   For keeping the setting point of Uniclean and Uniflex at Cleaning Intensity= 0.2 Relative Waste rate= 9   Dropping found from Ring and Rotor. From the report one, we can get total neat production of 23 carding m/c=1684 kg/hr,but

the total production with waste is 1869 kg/hr.   Here, we get ring dropping=68.55 kg Rotor dropping=20.65kg Flat strip =95.85kg   The waste percentage are 3.67,1.10&5.13 respectively of total production. Total waste= Ring dropping+Rotor dropping+ Flat strip =(3.67+1.10+5.13)% Here, total waste is 9.90% of total production [Note: Obs. Time = 1hour]

We get following setting statistics from the report no.3   For keeping the setting point of Uniclean and Uniflex at Cleaning Intensity= 0.2 Relative Waste rate= 10   Dropping found from Ring and Rotor. From the report one, we can get total neat production of 23 carding m/c=1684 kg/hr,but

the total production with waste is 1887kg/hr.   Here, we get ring dropping=74.30 kg Rotor dropping=23.70 kg Flat strip =105.0kg   The waste percentage are 3.94,1.26&5.56 respectively of total production. Total waste= Ring dropping+Rotor dropping+ Flat strip = (3.94+1.26+5.56)% Here, total waste is 10.76 % of total production [Note: Obs. Time = 1hour]

ANALYSE THE USTER TESTER REPORT

For the report no.1 we get the following Uster statistics: Mean of U% = 12.04 Mean of CVm = 15.39 Mean of Thin(-50%) =5.8 Mean of Thick(+50%)=262.8 Mean of Neps(+200%)=390.3 So Imperfection Index(I.P.I)=(Thin+Thick+Neps) =5.8+262.8+390.3 = 659     For the report no.2 we get the following Uster statistics: Mean of U% = 11.89 Mean of CVm = 15.17 Mean of Thin(-50%) =1.5 Mean of Thick(+50%)=232.5 Mean of Neps(+200%)=334.5 So Imperfection Index (I.P.I)=(Thin+Thick+Neps) =1.5+232.5+334.5 =568

For the report no.3 we get the following Uster statistics: Mean of U% = 11.54 Mean of CVm = 14.72 Mean of Thin(-50%) =3.5 Mean of Thick(+50%)=181.8 Mean of Neps(+200%)=257.3 So Imperfection Index(I.P.I)=(Thin+Thick+Neps) =3.5+181.8+257.3 = 443 Now ,we can say that when the relative waste rate is gradually increased then the

waste production is also increased and the quality of the product get increased. Here from the report no.1,2,3 we get the relative waste rate is 8,9&10 respectively. As a result ,the production of waste is gradually increased and requirement of raw cotton is also increased. But on the other hand the quality of the product is better when the relative waste is 10 than the other. Here from the Uster statistics of report no.1 & 2 the mean of U%,CVm & neps are high but also the I.P.I is high. So we can not make the better quality of product. But from the report no.3 we can make the better quality of product, here all the standard of quality are maintained & I.P.I is very low. For this reason the production cost of product is increased.

conclusion

In this research we investigate the waste extraction system and effect of waste reduction on production cost. The production of the high quality yarn free from faults and its production in bulk quantities are the major considerations in spinning. Yarn breakages and their gradual increase with spindle speed causes a problem.

A spinner’s first concern is to control staple length and fiber fineness so as to maintain consistent conditions and standard yarn properties. His second concern is with yarn’s appearance. Generally speaking a spinner has to sure, that if yarns out of different dispatches (lots) from the factory are compared, the weaver/ user should not be able to see any difference between different lots).