Reasons for Poor Quality in Ring Spinning

Last Updated on 26/01/2021

Introduction:
Poor quality in spinning may be defined as a combination of factors such as the technical parameters of yarn being out of the acceptable tolerance limits of the customers, presence of objectionable faults and labels, improper packing leading to damages while handling, shabby packing resulting in time consumption while opening and extra space for storage, delay in despatch causing loss to the customer and penalty to the company, increased cost of manufacturing pushing the organization to a loss, short supplies and over productions leading to accumulation of finished material as stock. However, in practice, the terminology of quality is used for product parameters by the technicians in shop floor, but for the top management, everything is important as the company’s profitability depends on the total quality and not only on the technical parameters. The technicians, therefore, are suggested considering everything together and not concentrating only on the technical parameters.

Poor Quality in Ring Spinning — Fig: Poor quality in ring spinning

It is a normal belief that adapting latest machinery with good technology results in good quality of yarns compared to old machinery and technology. Therefore, the mills invest on latest technology. There are number of factors responsible for the poor quality in spinning. They are raw materials, work methods, the condition of the machinery and the management systems adapted.

Raw material
There is a direct relationship between certain quality characteristics of the fibre and those of the yarn. Seventy to eighty percent of basic yarn quality is decided by the raw material. The fibre properties like the staple length, uniformity in staple length, short fibre contents, fineness, strength, elongation, maturity, etc., play a role. If the micronaire is coarse, the number of fibres in the yarn cross section will be less. This always results in lower strength and lower elongation. But it is easy to process coarse micronaire fibres in blow room and cards. Nepping tendency is less for coarse micronaire fibres. On the contrary, spinnability (in both speed frame and ring frame) is not good with coarser micronaire fibres. U% is affected by micronaire. Coarser the micronaire, higher shall be the U%. Coarser the fibre, higher the end breakage rate in spinning. Uster thin place (30%) in the yarn vary depending upon the fibre micronaire. Lower the micronaire lower the thin places and vice versa.

Raw materials if not suitable for the product being produced cannot give the quality parameters as needed. We need to understand the quality objectives of the product and decide the raw materials. The factors like feel of the fabric, hairiness in the surface of fabric, strength of the yarn and the fabric and dye ability are governed by the raw material properties. Just by spending more money on superior fine cotton cannot give the quality required by the customer, but shall increase the cost of manufacture leading to a loss to the company.

Raw material should be suitable for the machine being worked. The machines are normally designed for a range of raw materials, and we need certain modifications while working. The type of opening machines differs from cotton to synthetics, and also with in the cottons itself from fine to superfine cottons. Coarser wire points are used for carding polyester, whereas for cottons we have different wire configuration. The nose plates are different for cotton and polyester. In ring frames, large diameter bottom rollers of 30 mm are used for long staple synthetic fibres compared to 27- or 25-mm diameter for cottons. The cradle sizes used in drafting are different for different staple lengths. Similarly, there are number of changes in the machine configuration to suit different raw materials. If we are not clear about the same, inspite of having latest machinery and good raw materials, we might produce bad quality yarns.

Variations, mix-ups, contaminations and damages in raw materials are also responsible for poor quality yarns. The selection of raw materials for the product and the machines play a vital role in getting the required quality. Apart from the selection of raw materials, the ways in which they are handled and used also play an important role.

Following are some examples for poor quality in ring spinning:

Improper selection of raw material
Variations in raw material
Handling and storage damages
Damages due to improper ginning in case of Cotton
Fused fibres in case of synthetic staple fibres
Presence of uncut fibres in staple fibres
Packing of cotton bales with polyester cotton cloths/HDPE/polypropylene cloths
Inadequate number of lots in a mixing

Work Methods
The work methods are very critical for getting the required quality of yarn. One can get a good result inspite of fairly poor raw material or old machine provided appropriate work methods are followed. We can group the work method related factors as follows:

Old systems/practices not modified as per the new requirements
Inadequate training and lack of knowledge

Let us discuss the normal bad work practices seen at different processes of a spinning mill.

Reasons for poor quality in mixing:

Not verifying the lot numbers and bale numbers before taking the mixing
Taking more bales from a lot for mixing
Not clearly defining/understanding the quantity of materials to be taken from each mixing component
Uncontrolled mixing of soft wastes
Putting all soft wastes at one place in a stack
Not taking materials from each bale uniformly while making a stack mixing
Not keeping the bales in allocated place while mixing or feeding to bale pluckers
Not removing the Hessian/HDPE covering and bale hoops properly
Not opening the cottons thoroughly
Not removing the big visible contamination while opening the bales and doing mixing
Keeping chappals/slippers, etc., near the mixing bin
Not cleaning the floor thoroughly before laying a new mixing
Not updating the identification boards
Pouring more water/cotton spray oil at one place
Handling the mixing in wet condition
Sleeping on the mixing bin during leisure hours

Reasons for poor quality in blowroom:

Improper selection of cleaning and opening points for the mixing in hand
Not cutting the mixing vertically while feeding to mixing bale opener
Using improperly conditioned mixing in case of stack mixing
Feeding big lumps of cotton to bale breaker
Widening the settings to have more production
Too close a setting resulting in over beating and fibre damages
Laps of longer lengths
Applying excessive weights on lap spindles to get a compact lap
Not removing the accumulated wastes in time resulting in back firing and waste contaminations
Not cleaning the magnets on time
Not properly closing the doors
Not properly following colour codification for laps
Not maintaining the work area clean
Not cleaning the sensors in photo electric controls
Using of bent lap rods
Using torn filter bags
Cleaning the machines with brooms while working
Using compressed air for cleaning while machines are working

Reasons for poor quality in carding:

Bringing the laps on head or by touching it to the body
Not properly feeding the laps resulting in doubles or singles in sliver
Not removing the doubles and singles
Not removing the wastes in time
Not keeping the carding area clean
Not cleaning the card sides with a clean broom stick regularly
Twisting too much while piecing the slivers
Not following the correct colour codification and channeling
Not stripping the cards in time
Not removing the accumulated flat strips in time
Not cleaning the Phillipson rollers in time
Making the stop motions inactive
Keeping the doffer cover up while running
Keeping the side covers and belt guards open
Over filling the cans
Not removing the wastes from can bottom before placing below coiler
Using damaged cans and spring plates
Not cleaning the castors regularly
Pressing the sliver in the can by hand
Not covering the sliver in cans that are in stock
Use of compressed air for cleaning while machine is working

Reasons for poor quality in draw frames:

Not creeling the cans as per the allocation given (Card number wise or drawing delivery wise)
Keeping the feeding cans much away from the creel
Overlapping the slivers while piecing in the creel
Cutting the sliver in cans at creel and reversing for adjusting the cans in creel
Not removing the sliver wastes from the spring bottom before putting cans in the machine
Not removing the slivers from the can whenever there is a lapping
Making the stop motions inactive
Not getting the cots buffed in time
Replacing the top rollers without verifying the diameter and surface condition
Not greasing the top roller bushes in time with proper grease
Using sharp knives to remove lapping resulting in damaged cots
Not removing the suction box wastes in-time
Keeping the suction box doors half open
Putting cotton pads to get pressure on drafting rollers
Using damaged cans and springs
Using nails and hammer to remove cotton from jammed trumpets
Using trumpets without verifying their size and condition
Not ensuring proper alignment of can
Not following the correct colour codification and channeling
Over filling the cans
Pressing the sliver in can by hand
Use of compressed for cleaning while machine is working
Un-staggered sliver piecing
Checking the wrapping periodically and correcting the hank by changing the pinion

Reasons for poor quality in combers:

Bigger laps
Applying excessive pressure to take compact laps
Use of worn-out bare spools in lap forming machine
Allowing overlapping of slivers being fed to lap former
Overlapping the lap sheet while piecing
Overlapping the slivers on table for piecing
Not cleaning the top combs in-time
Not removing the accumulated comber noils in-time
Keeping tools, etc., on the sliver table
Inactivating the stop motions
Piecing the slivers by over twisting
Not following the correct colour codification and channeling
Over filling the cans
Using damaged sliver trumpets
Pressing the sliver in the cans by hand
Use of compressed air for cleaning while machine is working

Reasons for poor quality in speed frames:

Cutting the slivers at cans in the creel and distributing to other cans
Overlapping the slivers while attending a sliver run out
Cross creeling of cans
Sliver falling out of guide roller
Twisting too hard while piecing
Applying cotton to the top arms to get pressure
Pressing the front top cot to correct a loose end
Not verifying the spacers and condensers while replacing
Not putting back the fallen floating condenser while attending a break
Not following the correct colour codification and channeling
Not removing the accumulated clearer wastes on time

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Reasons for poor quality in ring frames:

Keeping roving bobbins on the top of creel for long time
Overlapping of roves while replacing
Putting cotton in top arms for getting more pressure
Using sharp knives/hooks for removing lapping
In active bottom clearers resulting in partial lapping
Not attending a break for a long time
Cross-creeling
Not removing the last layers in the roving bobbin and allowing it run out fully
Keeping roving bobbins in the path of roving or on the top arms
Keeping the bobbins in the path of air flow of overhead cleaners
Not removing the bobbins while a tape is cut
Not following the running-in schedule of rings properly
Keeping excess travellers in the cup and not removing them while changing counts
Not cleaning the rings with dry cloth/cotton before replacing a burnt traveller
Piecing from over the cot
Double piecing at cop bottom

Winding

Bypassing the yarn clearers
Not keeping the clearer area clean
Keeping tighter setting to get good yarn
Keeping excess tension to get a compact cone

Machinery condition
The poor quality of yarn from machinery can be attributed to the following:

Worn out parts
Improper maintenance and settings

Technology and parameters adapted
Technology and the parameters adapted play a vital role in deciding the quality of the yarn spun. Poor quality can be a result of the following:

Adapting a technology verifying its appropriateness for the product and the activity, but just because it is latest.
Not updating the technology for the requirement of the product.
Not understanding the available technology, and hence not optimizing the parameters as needed.

Blow room
The operations in blowroom need to be controlled depending on the quality characteristics desired in yarn. Some of the important yarn quality characteristics influenced by blow room performance either directly or indirectly are as follows:

Evenness – by level of short fibres generated (increase in fibre rupture)
Imperfections – by level of short fibres generated, degree of cleaning and opening and neps generated in blow room
Neps – by additional neps generated in blow room
Hairiness – by level of short fibres generated
Consistency in count – by delivery of uniform product either lap or the feed to cards
Consistency in property – by degree of mixing achieved
Cleanliness – by degree of cleaning achieved and possible rupture of large trash particles

Different parameters and technology are given below:

Improper selection of cleaning and beating points
Improper selection of speeds, settings and ratio of beater and fan speeds
Inadequate controls
Longer lengths of pipes/ducts and excessive bends in the material passage
Improper control of air currents

Carding

Wrong selection of feed and hank organization
Wrong selection of wire points for the material and hank
Wrong selection of speeds and settings of different parts
Wrong selection of feed plates for the fibre in use
Improper control points for the activity
Inadequate control of humidity and temperature
Improper setting of auto-levellers

Draw frames

Improper adjustment of break draft and final draft combination
Improper settings for the hank and material being worked
Improper settings of the autoleveller
Hooks formations because of the type of trumpets used

Combers
While designing lap preparation, total draft, fibre parallelization, number of doublings, lap weight, etc., should be decided properly. This can be

Improper selection of half lap
Improper selection of trumpets
Inadequate control of humidity and temperature
Improper selection of feed for the noil% extracted

Speed frames

The drafting system not suitable for the fibres and hank
Improper selection of break draft and main draft for the fibres and the hank
The flyer size/type not suitable for the hank and the material in use
The bobbin lift and diameters not suitable for the hank of material produced
Improper selection of condensers and spacers
The twist multiplier not compatible with fibre length, hank and the drafting system at ring frame

Ring frames

The drafting system not suitable for the fibre, count and the hank organization
Improper selection of break draft and main draft combination for the hank and count
Improper selection of empty bobbins
Improper settings
Improper selection of spacers
The hardness of the cots not suitable for the fibres, hank, the counts spun and the rings and traveller not suitable for the fibre, count and the speed
Improper synthetic rubber
The rings and traveller not suitable for the fibre, count and the speed
The lappet eye not suitable for the fibres and count spun
The combination of winding and binding coils not suitable

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Winding

Selection of cone angle to the speed of the machine
Improper selection of empty cones

Management systems adapted
The management systems adapted play a major role in getting the required quality of materials in time at the estimated cost. Following are some of the mistakes normally done:

Following a system designed in the past that is not suitable today
Following a system followed at another mill not suitable for us
Poor house keeping
Improper/Inadequate communication
Not maintaining log books and records in a simple way

Following are some of the examples of the effect of management systems adapted on the yarn quality:

Not clear about the quality requirements of each process
Not clear about the capability of the systems
Poor interactions with the people working on shop-floor regarding the quality requirements of the customers/products
Poor house keeping
Congested layout of machinery and processes
Keeping excess materials in stock and process as stand by
Keeping excess spares in the work area for emergency operations
Improper maintenance of records
Not reviewing the quality aspects periodically
Not taking sincere action on the quality control reports
Not analyzing the reasons for poor quality and taking ad-hoc decisions
Not respecting the experience, knowledge and intentions of the juniors

Frequent shifting and re-erections: In mills where, long-term planning is not there, we see frequent shifting and re-erection of machines. This results in wearing out of the parts, misbalancing of the running parts and disturbance in levels and finally leading to breakdowns. The technicians have to spend more time on the dismantling and erection activities and cannot concentrate on maintaining other machines and monitoring the quality.

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.