Factors affecting the lap rejection and the CV % of 1 metre wrapping of lap & causes for high lap weight variation

How the uniformity of the lap is controlled in a scutcher?

Lap rejection % indicate the variability between lap weight and CV % of 1 metre wrapping of lap indicate the variability of weight/metre of with in the lap.

Both these measures are particularly importance in control of yarn count. Both the with in and between lap weight & its regularity are the first steps in the control of count variation.

Factors affecting the both with in & between Lap weight variations and steps to be taken to control the same are:

In sufficient opening of cotton.

Wide variation in tuft size,

Variation in level of cotton in reserve box of hopper feeder

Fluctuations in the feeding rate to the scutcher.

Ineffective working of feed control devices like swing door, BE cell, micro switch, piano feed regualting motion etc.

Irregular & faulty air flow on cage

Unnecessary and frequent adjustment of feed regulating motion.

Uneven mixing of soft waste with cotton

Worn pedal links, knife and cone drum bearing.

Malfunctioning of length measuring motions.

Uncontrolled variations in atmospheric condition in the dept.

Fluctuations in the feeding rate to the scutcher are caused if the different machine's in the sequence are not properly synchronised and if the feed controls like swing door, 1 solenoids, micro switches and relays do not function efficiently.

• The production rate of the blending hopper feeder and other
should be so adjusted that they run for about 80 to 90% of the
running of the scutcher and there should always keep the hopper
with cotton in 3/4 level at all time.

The cotton should be fed at uniform rate to the scutcher. The 1 front sheet of the reserve box of the scutcher Hopper feeder is capable of moving forward or backward to increase the volume of the chute, to suit the require weight per yard of lap. So front sheet setting should be corrected according to the lap hank & weight required.

Backsheet in the reserve Box of the scutcher Hopper feeder reciprocates alternatively. This ensures the maximum regularity of the feed to scutcher. So back sheet should function efficiently.

Swing door in the Hopper Feeder, photo electric cell in the reserve box of hopper feeder, step cleaner should be sensitive to

avoid fluctuation in the level of cotton in the reserve bin.

Pedal feed regulating motion should be so set that the cone drum belt operate about the centre of the drum, otherwise full correction is not achieved.

Free movement of the pedal lever and connecting rod must be ensured and care should be taken to see that the movement of the pedal levers is fully transmitted to the belt fork.

Uncontrolled variation in atmospheric conditions can lead to high lap weigh variation. with an average lap out of 16kg, the natural fluctuations in temperature and humidity may account for as much as 1/2 kg variation in lap weight merely due to change in moisture regain. To over come this, Direct reading measuring instruments are recommended in preference to the correction table since the later assume that the lap, as it is produced, is in equilibrium with departmental humidity which is not really true because of 1. the effect of heat developed by the machine and huge velocity of air coming in contact with cotton during its passage through the machine.

Large variations in weight between lap rods can give factious values of full lap weight. So, lap rods must be weighted once in three months' and standardised.