PROCESS PARAMETERS IN CARDING

INTRODUCTION:

Carding
                     is the most important process in spinning. It contributes a lot to the yarn quality. The
following process parameters and specfications are to be selected properly to prodce a good quality
yarn with a lower manufacturing cost. 
 
cylinder wire(wire angle, height, thickness and population) flat tops specification licker-in wire specification doffer wire specification feed weight draft between feed roller and doffer cylinder grinding doffer grinding flat tops grinding cylinder, falt tops, doffer wire life Licker-in wire life Cylinder speed flat speed Licker-in speed setting between cylinder and flat tops setting between licker-in and feed plate setting between licker-in and undercasing elements like , mote knife,combing segement etc. setting between cylinder and doffer setting between cylinder and back stationary flats setting between cylinder and front stationary flats setting between cylinder and cylinder undercasing

CYLINDER WIRE AND CYLINDER SPEED

Cylinder wire selection is very very important , it depends upon cylinder speed ,the raw material
to be processed and the production rate. The following characteristics of cylinder wire should be
considered.

• wire angle
• tooth depth
• wire population
• rib thickness
• tooth profile
• tooth pitch
• tooth point
• overall wire height
  
• Wire front angle depends on mainly cylinder speed and coefficient of friction of raw material.
  Higher the cylinder speed, lower the angle for a given fibre. The cylinder speed in turn depends upon the production rate.
  
• Higher production means more working space for the fibre is required. It is the wire that keeps the fibre under its influence during carding operation.Therefore the space within the wire should also be more for higher production. Higher cylinder speed also increase the space for the fibre. Therefore higher cylinder speed is required for higher production.
• 
  
• In the case of high production carding machines, the cylinder surface is very much higher,
  therefore even with higher number of fibres fed to the cylinder, the cylinder is renewing the
  carding surface at a faster rate.
  
• Higher the cylinder speed, higher the centrifugal force created by the cylinder, this tries to eject
  the fibre from the cylinder, along with the trash.It is the cylinder wire's front angle which overcomes the effect of this force. Low front angle With too low cylinder speed and with high frictional force, will result in bad quality, because the fibre transfer from cylinder to doffer will be less. Hence recyling of fibres will take place, whihc result in more neps and entanglements.
  
• The new profile with less free blade avoids loading of the cylinder with fibre and/or trash.
  This helps in keeping the fibres at the tip of the tooth. The movement of the fibres towards the
  tip of the tooth, coupled with centrifugal action demands an acute front angle to hold the fibre in
  place during carding.
  
• Lack of stiffness associated with fine and/or long fibres necessitates more control during the
  carding process.This control is obtained by selecting the tooth pitch, which gives the correct
  ratio of the number of teeth to the fibre length. Tooth pitch reduction is therefore required for
  exceptionally short fibres and those lack stiffness.
  
• Number of points across the carding machine is decided by the rib width. It is selected based on the production rate and fibre dimensions. Finer the fibre, finer the rib width. The trend is to finer rib width  for higher production.
  
• The population of a wire is the product of the rib thickness and tooth pitch. The general rule
  is higher populations for higher production rates, but it depends upon the application.
  
• Sharp tooth points penetrate the fibre more easily and help to intensify the carding action. Cut-to-point wires are sharp and they have no land at all.-
  
  
• The effective working depth of a cylinder wire tooth for cotton is approximately 0.2mm and
  for synthetic materials approx.0.4mm. Manmade fibres require more space in their cylinder wire
  than does cotton.More tooth depth allows the fibre to recyle, resulting in damaged fibres and neps. If tooth depth is insufficient, there will be loss of fibre contro. This will result in even greater
  nep generaion. Looking into the above details, the following specifications can be used as a guideline

MATERIAL	PRODN. RATE	RIB WIDTH	ANGLE(degrees)	POPULATION
Cotton low grade	low	0.6	65	700
Cotton low grade	high	0.5	55	840
Cotton Medium	low	0.6	60	800
Cotton Medium	high	0.4 to 0.5	55	840 to 950
Cotton fine	low	0.5	60	840
Cotton long	high	0.4 to 0.5	55	900 to 1100
Synth.coarse	low	0.7 to 0.5	70	550 to 650
synth.coarse	high	0.6	65	760
Synth.medium	low	0.7	65	700
synth.medium	high	0.5	65	760
Synth.fine	low	0.6	65	700
synth.fine	high	0.5	60	840

MATERIAL	PRODCUTION RATE	CYLINDER SPEED
cotton	low	360 to 400
cotton	medium	430 to 470
cotton	high	500 to 550
synthetic	low	300
synthetic	medium	380
synthetic	high	460