Wednesday, December 25, 2019

PRECAUTIONS IN CARDING PROCESS, PROCESS CONTROL IN CARDING

PRECAUTIONS IN CARDING PROCESS:

Pre- cautions always reduces the defects in the output product in any operation. The output quality is also improved if we take the required precautions in any process. Some important and useful precautions to be taken in carding process are given below:

The variation in linear density (weight per unit length) is a common and serious problem in the carding process. This problem needs regular monitoring of weight per unit length of sliver.

• The required correction in the draft is done to find a uniform sliver.

• The weight per unit length of sliver should get analysed three times in a shift of 8 hours.

regular machine maintenance also helps to minimise the chances of variation of weight per unit length of sliver up to large extent.

• The regular maintenance of a carding machine always results in the form of improved quality and productivity.

• The maintenance schedule should always be followed properly as per the machine manufacturer's instructions manual.

Today’s carding machine is equipped with auto-levellers. These auto-levellers help to keep the linear density of sliver almost constant. The technician should always ensure the proper and precise working of auto - leveller.

• The auto-leveller should be calibrated manually. The linear density should be determined manually before calibration of the auto-leveller. The changes should be made in upper and lower limits according to the result of the analysis of the linear density of the sliver.

The maintenance of a carding machine is so important job. It should be performed by well-trained technicians. All the settings should be done precisely during the overhauling of the machine.

• The consumable parts of the carding machine should get replaced after a definite life of the part as per the instruction manual.


• All the machine settings should be checked and corrected. The flat-top setting especially requires extra attention because it has a great impact on the nep formation.
• Even the setting of the flat top should always get done.

 The proper working of suction waste points should be ensured.

• The suction waste point should be cleaned regularly to prevent choking because chocked suction waste point creates neps formation problems in the carding process.

Higher cylinder speed helps fibre transfer. A higher production rate requires higher cylinder speed

Higher cylinder speed is also improved carding action. Thus imperfection in the sliver also gets minimized.

When coarse and dirty cotton is processed in carding, Higher Licker-in speed helps to remove the trash from the cotton. Thus improved yarn quality results.  Higher licker-in speed causes fibre rupture during the processing of fine and long-staple cotton. Therefore flat waste is increased.

When flat speed is increased, better yarn quality is obtained but same time flat waste increases.

The draft between feed roller to doffer is varied between 75 – 95. Very high tension drafts affect U% of the sliver. 

• The flat tops and cylinder wire should be replaced together to find improved and consistent yarn quality.

The licker-in wire clothing should be replaced after every 150000 kgs of production. 

The stationary flats should be replaced after every 150000 kgs of production.

• The stationary first 3 to 6 flats at licker-in side work than remaining flats, so that these flats need early replacement. Replacement of these flats after every 100000 kgs of production

The setting between cylinder and cylinder under casing is done as per the instruction manual of the machine manufacturer. This is a very important setting. An improper setting between cylinder and cylinder under casing affects the fibre transfer and create air turbulence also. 

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