This document discusses roller slip that occurs when fibers pass between two rollers in a drafting system. Roller slip is when the top roller moves at a slightly slower surface speed than the bottom roller due to friction. The amount of roller slip depends on factors like fiber bulk, roller distances, fiber orientation, and draft level. Roller slip can be remedied by using narrow fluted rollers or closer roller settings. The document also discusses roller settings, autoleveling systems, common draw frame defects, and provides some example calculations.

1. Roller Slip
 The bottom rollerisindirectcontact withthe bottomsurface A of the fibers,&the motion
reachesB whichinturn movesthe toprollerconsequently,thereisacertainamountof slippage
occurring,& the topsyntheticcoveredrollerdoes notexactlyshow the same surface speedwith
whichthe bottomflutedrollerisrunning.
 Thisfall insurface speed of top roller,whenmaterialispassingbetweenthem, istermedas
“rollerslip”
Causes:
The amount of rollerslipdependsmainlyupon:
 Bulkof fibers&nature of fibers
 Centertocenterdistancesof the two pairsof rollers.
 Degree of orientationof the fibersinthe material.
 The amount of draft betweenthe twopairs.
 Conditionof the rollersincludinghardnessof topsyntheticcovering.
 Amountof weightingonthe toprollers.
Remedies:
 By usingnarrowflutedroller.
 By usingclosersettinginthe middle zone of draftingsystem.
 Use correct rollertorollerpressure.
RollerSetting
Factors consider for selection of roller setting:
1. Staple lengthof the fiber.(staple length+allowance)
2. Amountof draft required. ↑ Allowance ↑
3. Thickness/Bulkof the material.↑ Allowance ↑
Measurement of roller setting:
Front Zone (FZ)=SL+1/8inch

2. Middle Zone(MZ)=SL+1/4 inch
Back Zone(BZ)=SL+1/2 inch
SL= Staple length
Auto levelling
Draw frame isthe bestautomaticcontrol of sliverregularity.Indrawingdraftiscontrolledbyservo
motor forconstantcount. The programme of controllingdraftbyservomotor iscalledauto
levelling.Itisdone bytwo ways:
1. Openloopautoleveller
2. Close loopautoleveller
Open loop autoleveller:
Whensensorsense the feedcount&actionis done onthe feedmaterial tochange the draftis
calledopenloopautoleveller.
Close loop autoleveller:
In thisprocesssensorsense the deliverycount&sendthissense tofeed & draftis changed
accordingly
Defects/Faults of Draw frame
1. End missing/Fine sliver:When5or6sliverare doublinganyslivermaybreak.Thisisendmissing.
Causes:
(i)Faultystopmotiondevice
(ii)Operatorcarelessness
2. Irregularsliver
Causes:
1.Rollerslip
(a) Improperrollerpressur
(b) Worn top roller
(c) Eccentrictop roller
(ii) Defective draftingsystem

3. (iii)Improperrollersetting
3. Long fiberinthe waste
4. Rollerlapping
Causes:
(a) Impropercleaningof the roller
(b) Impropertemperature &RH
5. Excessive sliverbreaks
Causes:
(a) Feedzone:Feedtension
(b) Draft zone:(i)Rollerlapping
(ii)Entanglementof sliverincan
(c) Deliveryzone:(i)Improperselectionof trumpet
(ii) Impropersurface of trumpet
6. Improperstockfilling.
Draw Frame(Calculation)
1. A certainDraw frame witha 56 teethdraftchange pinionisdelivering a48 grain/yardsliver
from45 grain/yardfed.Whatwill be the pinionrequiredif 52grain/yardslivertobe produced
2. Calculate the productionpershiftof 8 hoursof a draw frame whichisrunningat 85% efficiency.
Speedof 1.25 inch front
Chayan