TWIST:
The strength of a thread twisted from staple fibres increases with increasing twist, upto certain level.
Once it reaches the maximum strength, further increase in twist results in reduction in yarn strength
· Coarser and shorter fibres require more Twist
per unit length than finer and longer fibres.
· Twist multiplier is a unit which helps to
decide the twist per unit length for different counts
from the same raw material.This is nothing but the angle of inclination of the helical disposition
of the fibre in the yarn. This is normally expressed as
TWIST PER INCH = TWIST MULTIPLIER * SQRT(Ne) from the same raw material.This is nothing but the angle of inclination of the helical disposition
of the fibre in the yarn. This is normally expressed as
· If the two yarns are to have the same
strength, then the inclination angles must be the same.
· For 40s combed knitting application, if the
average micronaire of cotton is 3.8 and the 2.5% span length
is around 29 mm, Twist multiplier of 3.4 to 3.5 is enough . If the average micronaire is around 4.3,
it should be around 3.6 to have better working in Ring frame.
is around 29 mm, Twist multiplier of 3.4 to 3.5 is enough . If the average micronaire is around 4.3,
it should be around 3.6 to have better working in Ring frame.
· cotton combed knitting T.M. = 3.4 to 3.6
· cotton combed weaving T.M. = 3.7 to 3.8
· cotton carded knitting T.M. = 3.8 to 4.0
· cotton carded weaving T.M. = 3.9 to 4.2
The above details are for cottons of 2.5% span length of 27 to 30 mm and the
average Micronaire of 3.7 to 4.4. For finer and longer staple, the T.M. will be lower than tha above.
In general for processing poly/viscose , the T.M. is as follows
· 51 mm, 1.4 denier fibre : T.M. = 2.7 to 2.9
for knitting application
· 51 mm, 1.4 denier fibre : T.M. = 2.9 to 3.1
for weaving application
· 44 mm, 1.2 denier fibre : T.M. = 2.9 to 3.0
for knitting application
· 44 mm, 1.4 denier fibre : T.M. = 3.0 to 3.1
for knitting application
· 38 mm, 1.2 denier fibre : T.M. = 3.1 to 3.3
for knitting application
The above detail is self explanatory
OTHERS:The above detail is self explanatory
The following ROVING parameters will affect the ring frame process parameters
· Roving T.M.
· Bobbin weight
· Bobbin height
· Higher the roving T.M., wider the back bottom
roller setting or higher the break draft in ring frame.
· For combed material the creel height should
be as low as possible in ringframe.
· Very long creel heights in ringframe, lower
roving T.M. and heavier roving package will result in
many long thin places in the yarn.(especially in combed hosiery counts)
many long thin places in the yarn.(especially in combed hosiery counts)
· In general 16 x 6 " bobbins are used.
This helps to increase the spare rovings per machine with
higher creel running time. Therefore one should aim at increasing the bobbin weight as well as increasing the number of spare rovings in the ring frame.
higher creel running time. Therefore one should aim at increasing the bobbin weight as well as increasing the number of spare rovings in the ring frame.
· Normally 6 row creels are used in modern ring
frames. Six row creels will accomodate more spare rovings compared to 5 row
creels.(around 150 rovings for 1000 spindle machine.) Creel height should be as
low as possible for cotton combed counts.Spare rovings will improve the
operators efficiency.
· Shorter machines are always better compared
to longer machines. But the cost per spindle will go up.
For cotton , polyester/cotton blends, poly/viscose(upto 44mm length), number of spindles upto 1200, should not be a problem. But maintenance is more critical compared to shorter machines.
For cotton , polyester/cotton blends, poly/viscose(upto 44mm length), number of spindles upto 1200, should not be a problem. But maintenance is more critical compared to shorter machines.
· For synthetic fibres with very high drafting
resistance, it is better to use shorter machines,
because the load on break draft gears and on second bottom rollers will be extremely high. If long
machines are used and the maintenance is not good for such application, the bearing damages, gear damages, bottom roller damages etc. will increase. This will result in coarse counts, higher count C.V., long thinand thick places.
because the load on break draft gears and on second bottom rollers will be extremely high. If long
machines are used and the maintenance is not good for such application, the bearing damages, gear damages, bottom roller damages etc. will increase. This will result in coarse counts, higher count C.V., long thinand thick places.
· Four spindle drive is always better compared
to Tangential belt drive. Because small variation in
machining accuracy of bolster , spindle beam etc will affect the spindle speeds, thereby the twist
per inch. Waste accumulation between contact rollers, bent contact rollers, damaged contact rollers,
oil spilling from any one spindle etc. will affect the spindle speeds and thereby TPI. The spindle
speed variation between spindles in a 5 year old ringframe will be verh high incase of tangential belt
drive compared to 4 spindle drive.
machining accuracy of bolster , spindle beam etc will affect the spindle speeds, thereby the twist
per inch. Waste accumulation between contact rollers, bent contact rollers, damaged contact rollers,
oil spilling from any one spindle etc. will affect the spindle speeds and thereby TPI. The spindle
speed variation between spindles in a 5 year old ringframe will be verh high incase of tangential belt
drive compared to 4 spindle drive.
· Noise level and energy consumption will be
low in 4 spindle drive compared to Tangential belt drive.
· Compared to Contact rollers, Jockey pully
damages are nil. I have worked with 20 year old ring frames with Jocky
pulleys,but the variations in spindle speed between spindles is very less
compared to a 5 year old ringframe with Tangential belt drive. I have made this
comment based on my personal experience.
· When processing coarse counts at higher
speeds, the air current below the machine is a big problem with 4 spindle drive
. This is due to the more running parts like tinrollers and jockey pullys. This
will lead to more fluff in the yarn, if humidification system is not good
enough to suck the floating fluff.
· If spindle speeds is high for cotton counts,
every end breaks will result in more fluff in the
department due to the free end of the yarn getting cut by the traveller when the distance between
traveller and the bobbin with the yarn is less. Higher the delay in attending the end break , higher the
fly liberation.If the number of openings of return air system for a ringframe is less and the exhaust
air volume is not sufficient enough, then fly liberation from an end break will increase the endbreaks
and thereby will lead to multiple breaks. End break due to a fly entering the traveller will get struck
with the traveller and will result in heavier traveller weight and that particular spindle will continue
to work bad.
department due to the free end of the yarn getting cut by the traveller when the distance between
traveller and the bobbin with the yarn is less. Higher the delay in attending the end break , higher the
fly liberation.If the number of openings of return air system for a ringframe is less and the exhaust
air volume is not sufficient enough, then fly liberation from an end break will increase the endbreaks
and thereby will lead to multiple breaks. End break due to a fly entering the traveller will get struck
with the traveller and will result in heavier traveller weight and that particular spindle will continue
to work bad.
· Multiple breaks are very dangerous, as it
will result in big variation in yarn hairiness and
the ringframe working will be very badly affected due to heavier travellers because of the fluff in the
traveller.
the ringframe working will be very badly affected due to heavier travellers because of the fluff in the
traveller.
· Dry atmosphere in ringframe department will
result in more yarn hairiness, more fly liberation
and more end breaks.
and more end breaks.
· It is a good practice to change spindle tapes
once in 24 months.Worn out spindle tapes will result
in tpi variations which is determinetal to yarn quality.
in tpi variations which is determinetal to yarn quality.