Test 2 Flashcards
Draft increase, Cv
increases
Tex in increases, CV
decreases
doubling increases, CV
decreases
Parallelism increases, CV
decreases
As fiber length increases, CV
increases
Doubling CV equation
cv in / sqrt(number of doublings)
Actual draft: direct
sum of n in/ n out
Actual draft: indirect
Count out/ count in
Mechanical draft
Vout/Vin
Roll Velocity
UpiD
CV2 out=
cv2in+cv2added
Draft zones
D(n-i + 1) + (i-1) / D(n-i)+ i
Productivity
P=Nvn
Actual vs mechancial
AD=MD(1-%fiber loss)
drafting
reduce material size
drawing
the process that preforms the drafting operation
doubling
feeding of several input materiala
what is the purpose of doubling?
to improve blending and minimize irregularities
4 objectives of drawing
reduce input linear density, improve fiber alignment, improve regularity, blending
how many slivers are inputed befoer drafting?
6 or 8
which roll is the fastest
front roll
what is the ratch
distance between nips of rollers
4 perimeters for perfect drafting?
- fibers are same length and this equals ratch
- ratch is constant
- roller speeds are constant
- fiber speed equals roller speed
4 possible sources of drafting irregularities
- drafting waves
- roller nip movement
- roller speed variation
- roller slip
cv is ?
amount of irregularity
3 drafting wave controls
- pressure bar
- more rollers
- Apron drafting
how to avoid roller nip movement?2
take weights off when not using and use round rolls
what is roller speed variation associated with 2
eccentric bottom roller and gears
roller vibration
fiber slips in rollers depend on what
weight on top of rollers, too light fibers wont have contact and too much fibers wont move
what is the problem with bigger roller sizes?
have limitation on minimum ratch setting
what is the problem with smaller roller sizes?2
easy to form laps
wear out easier from having to go faster
why is it better to not link draw frames?
better to mix outputs from different draw frames to give more consistent quality and minimize variations
what is used in long staple drawing?
gill-box or pin drafter
what hooks do u want for semi worsted?
trailing hooks
how many drawing processes for semi worsted
3
when does drawing take place for worsted
prior and after combing
Worsted drawing are based on what kind of drafting
single zone
what does a gillbox (pin drafter) use
faller bars
what speed do faller bars move at
back roller speed
what is an intersector gill box
two row of faller bars
what is a gill box
single row of faller bars
what is a circular chain driven pin drafter
it changed the regular rectangular motion route of gill box to circular route and driven by chain
what is the purpose of circular chain driven pin drafter 2
to enhance the process speed and less machine noise
purpose of combing fibers (4)
want to remove short fibers
orient the fibers
straight
want to remove neps/ trash
what are the 3 parts of combing
preparation
combing
finishing
what kind of hooks are needed for cotton combing?
leading hooks
cotton combing needs even or odd number of processes to get a leading hook?
even
what are the two routes for cotton combing preparation?
route 1: sliver lap and ribbon lap
Route 2: drawframe and lap former
which of the cotton prep routes are slower?
route 1
which route of cotton prep is used for lower grades of cotton
route 2
what is spin limit
finest yarn you can make with that particular fiber
what is the detachment setting?
distance between the nipper and the detaching roll
what is a top comb setting?
distance between the top comb and the detaching roll
increase top setting, amount of waste is
decreased
increase detachment setting, amount of waste is
increased
what is the beard
the portion of sliver being combed
2 big problems in combing
short fibers in combed sliver and long fibers in waste
how do we get short fibers in our combed sliver?
from leading hooks being broken by the comb cylinder when not captured by the top comb
how do we end up with long fibers in waste?
from trailing hooked fibers in the lap and they aren’t efficiently straightened by the comb and it appears as a short fiber or slippage at the nipper
what is the big difference between cotton comb prep and worsted comb prep
uses 3 drafting operations between the card and comb.
3 differences between cotton comb prep and worsted comb prep
fed w slivers rather than a lap
detaching section moves rather than feed section
only one combing station per machine
how many processes are needed before a worsted comb to fix the hooks?
odd number
what kind of hooks are best for a worsted comb?
trailing hooks
when is top finishing used
if combed sliver is the final product
what is top finishing?
twice drawing
what does top finishing due 2
improves uniformity, and produces a format that is easily transportable
draft should always be
greater than 1
bigger draft means
finer fiber
spectrogram shows
machine error
what is apron drawing
it is put in between the front and middle rolls and goes at back speed to help control fiber speed
what is a noil
short fiber brushed out in combing
what units should productivity be in?
lbs/hr
what units shiuld v be in
inch/min
