Last updated on July 20th, 2023 at 11:55 pm
Given below are some checkpoints which will guide the technicians about some common deficiencies in the blow room and the corrective action to be taken in such cases with regard to quality control, maintenance or work practices.
- Check whether blend consistency is maintained, i.e. at any point of time, the amount of cotton of each variety that is fed should conform to the mixing proportion desired. Very often supervisors only check up that the required total number of bales is consumed in the shift, but it is more important to see that the proportions of bales of each variety taken for feeding compares with the set proportion.
- The level of stock in the different bales taken for feeding should be about the same at any point of time.
- Visually check whether the setting between the inclined spiked lattice and evener roller is uniform along the width of the machine. Some idea about this can be had by comparing the amount of cotton dropping off from the extreme ends of the inclined spiked lattice.
- Ensure that the soft waste added to the mixing is free from oily and dirty sweepings, and the roving ends and bonda are well opened.
Opening and Cleaning
- Magnets installed in the line should be checked for their effectiveness and condition. If too much accumulation of metallic substances is found, their cleaning frequency may have to be improved as there is risk of a part of the metallic substances being carried forward with the cotton.
- Check the condition of the grid bars at all beating points. Grid bars should be smooth and clean and should not be choked or bent.
- Check beater blades for sharpness and freedom from burrs and damages.
- Check the condition of the lap fringe. This will throw light on whether the setting between the beater and feed roller is correct, whether the grip on the lap sheet is proper and also whether the opening of the material at the earlier stages is adequate.
- Inspect the trash chamber to check the richness of waste and also to observe whether the trash box is getting overfull. If the latter is observed, there is danger of trash getting recombined with the lint and the schedule for waste removal will have to be accelerated. If excessive lint loss is observed, a detailed quality control study will have to be undertaken to look into the cases and remedies.
- Check condensers for the condition of the screens. Screens that has become dented, or with bent or broken wires, collect and deliver stock unevenly, resulting in high lap variation at the scutcher.
- Ensure that the pedal levers do not meet with any obstruction during working, as this is not only affects the pedal weighting, but also the feed regulation. A safe clearance should be maintained between the tail end of the pedal and the cross bar when the material is in process and in no case should the pedals rest on the cross bar.
- Check whether the level of material in the hopper reserve box is as per the prescribed level. Also check at what level the signals for starting and stopping the supply are given. Under normal conditions, these should not vary widely. If the two levels are found to differ widely, a detailed check up of the swing door mechanism, the working of the solenoids and micro-switches will have to be undertaken.
- Through the glass panel or side window, check the level of material in the reserve box. If the level is not found to conform to the standard marked level, prompt corrective measures are to be taken.
- Open the cone drum box and check the position of the belt. The belt should operate in the central region most of the time.
- The width of the belt fork should conform to the width of the cone drum belt.
- Check for loose links in the pedal regulating motion and ensure that the pedal lever is properly weighted; otherwise transmission of motion from the pedals to the cone drum belt will not be faithful.
- Worn-out leather linings in cages lead to excessive loss of good fibres in the gutter fly. Careful check should therefore be kept to prevent such a condition.
- In case lap filters being used, care should be taken to see that they are set properly.
- Check the leather lining of the brake. Worn-out leather linings lead to laps of improper build.
- The load on the calender rollers is transferred to the calender roller shaft through the calender roller bearings. Consequently, worn-out bearings need prompt replacement.
- Unroll a couple of doffed laps for a short distance to see whether the lap is properly made. The sheet should be able to unroll cleanly without splitting and at the same time the sheet should be of uniform thickness without holes and other defects.
- Check selvedges of lap for thin, ragged edges. Any obstruction in the passage of material interferes with even flow and shows up as irregularities in the edges of the lap.
- Where lap guards are used, care should be taken to see that they do not rest on the lap as this can lead to imperfections in the lap build and also disturbance to fibre tufts in the lap.
- The flutes of shell rollers should not be too rough or have burrs.
- Ensure that the lap width is about 5 cm less than the card width. Carelessness in this respect gives rise to imperfect selvedges of the web and also improper carding of the edges of the lap.
Thus, if the technicians make it a point to inspect the above-mentioned checkpoints during their round in the department, they can bring about significant improvement in the line in course of time. It is expected that it will normally take the supervisor about an hour to complete the supervision of one line. No fixed schedule for frequency of inspection of the blow room line can be given, as this will depend upon a variety of factors, but it is recommended that such inspections be carried out once in a fortnight or once in a month.