L5-6-7 Yarn Realization.pptx happens when

Happy birthday my

1. PROCESS AND QUALITY CONTROL IN SPINNING Yarn Realization

2. Lecture - 5

3. What is Yarn Realization Yarn Realization is the ratio of yarn output produced from the given input. Yarn Realization depends on the level of trash in cotton. Yarn Realization is very important factor in production economics of spinning mill. 1% reduction in YR has similar effect on mill’s profit as 1% increase in raw material cost. E.g. 1% improvement in YR lead to a saving of Rs. 20 lac per year for a 30000 spindle mill manufacturing 40s yarn.

4. Yarn Realization

5. Yarn Realization Two types of wastes: Process Waste : BR, cards & comber’s waste, which together form 80% of total waste. These wastes are extracted for cleaning. So direct measurement and control is possible. Product Waste : Are generated at each stage of processing. This waste can be controlled through proper supervision.

6. Usable Wastes Lap bits and card web Sliver waste in drawing and fly frames Waster at comber preparatory and combers Roving ends Pneumafil and roller waste (ring frames)

7. Non-Usable Wastes (Product and Process wastes) Blow room droppings Card waste (licker-in, flat strips and other wastes) Gutter/filter waste Micro dust Comber noils Yarn waste (hard waste) Sweep waste (includes fan wastes and draw frame and speed frame waste) Invisible loss

8. Yarn Realization Calculation

9. Norms for Type of waste

10. S tandards for YR and Waste %

11. S tandards for YR and Waste % Hard waste, soft waste and sweep waste – should be checked weekly. Causes for these wastes may be: Negligence of worker. Rough handling of material. Poor working conditions. Sweep waste should be checked for good fibres periodically. Process waste – once a month. Invisible loss – calculated by total cotton consumed and data of all type of waste.

12. Norms for usable waste

13. Lecture - 6

14. Cotton Varieties

15. Effect of Fibre Parameters on YR Trash % in mixing. Short Fibre Content (SFC) in mixing. Moisture Content in mixing. Micronaire . Maturity Ratio. Stickiness of cotton

16. Records for estimating YR and Waste

17. Control of Invisible loss Wastes which are not weighable or quantifiable due to evaporation of part of the moisture content in the cotton and the escaping of short fibres and dust at various stages of spinning of cotton such as micro dust, flies etc. are called as invisible loss. Invisible loss = 100 – packed yarn production % - packed waste % Actually, invisible loss is the total unaccounted loss which reflects immediately any mistake in record keeping. A small inaccuracy in the waste or production records would cause a large proportional change in the invisible loss.

18. Reasons for Invisible loss

19. Control Measures for Invisible loss Moisture content in yarn should be equal to or little higher than the moisture content in mixing. The loss due to this would be very significant, so the mill should keep a constant check on the cotton mixing. Mill should weigh a few bales at random after a lapse of 3-4 months and compare the same with the weight at the time of purchase. Normal moisture content in mixing = 6-7 % Normal moisture content in yarn: Before conditioning = 4.5 – 5.0 % After conditioning = 6.0 – 6.5 %

20. Control Measures for Invisible loss Maintain the relative humidity at 65% in winding and 70% in packing departments. Condition the yarn at least for 12-16 hours in humidified atmosphere before packing. Use yarn conditioning plant. The objective of this plant is to restore moisture content, to improve the strength and elongation; and to produce balanced yarn (twist setting). So, due to this, the invisible loss is compensated.

21. Control Measures for Invisible loss Balances used in cotton godown , cone winding, packing departments must be calibrated as per schedule and cross-checked periodically with standard weight. Under estimation in weight would be a financial loss to the mill and over estimation would lead to market complaints. Tare of different packs: bags, cartons and pallets must be checked every week.

22. Control Measures for Invisible loss Saleable wastes like blow room droppings, card waste, comber waste etc. should be weighed shift-wise and proper records should be maintained. Reconciliation of weight of wastes should be done during selling. Yarn issued to workers (for cleaning purpose) must be weighed and recorded. A high invisible loss can arise due to excess bundle weight in reeling, either due to coarser count or longer length. The quality control department should keep a periodic check of the net weight after conditioning and length of yarn in cones and knots.

23. Lecture - 7

24. Control of Hard Waste A high incidence of yarn waste is an indication of poor machinery conditions and maintenance; and inappropriate work practices of operatives. There is a loss of Rs . 6-15 per spindle per year for every 0.1% waste.

25. Norms for Hard Waste

26. Reasons for Hard Waste End breaks and feed package replacement. Work practices. Quality of feed packages, housekeeping and material handling.

27. Control of Hard Waste in Ring Frame Ring cops are the feed packages for single yarn winding, so the quality of ring cops must be maintained at good level. Whenever there is a count change in ring frame, the cop quality should be checked. Proper quality of cop ensures higher winding efficiency.

28. Quality parameters for Ring Cop

29. Cop Content Depending on the spindle lift and ring diameter, the cop content in grams should be as given:

30. Diameter of Cop The actual cop diameter must be checked against standard cop diameter. Standard cop diameter = Ring diameter – 3 mm.

31. Back winding and Under winding in Cop Back winding: The number of back winding coils should be around – and the maximum length of back winding should not be more than 80 cm. Under winding: the number of under winding coils should be around 2-3 and the maximum length of back winding should not be more than 20 cm. As the back winding and under winding increases, more time is wasted to open them up before feeding in the magazine and also hard waste is increased.

32. Top and bottom clearance in Cop Top clearance : The clearance from bobbin tip to yarn body of a full cop should be approx. 10 mm. if the top clearance is too less, it may cause slough off at the start of the bobbin unwinding. Bottom clearance : The clearance from bobbin bottom to yarn body should be approx. 10 mm. If the bottom clearance is too less, it may cause bottom spoiled bobbin.

33. Chase length and bobbin hardness Yarn length per chase: The length of yarn per chase should be around 3.5-5.5 m. If the length is too long, it may lead to slough off during high speed unwinding. Bobbin hardness : The bobbin hardness should be around 50 – 55 soft bobbins results slough off.

34. Poor Work Practices Faults in cops: Double gaiting Over-end piecing Upward and downward ratcheting Not engaging the pawl on the ratchet wheel while starting the frame after doffing Not stopping the frame properly for doffing

35. Parameters influence cop content Maintenance of machines. Low utilization of tube length. Frequent ratcheting. Not providing cop bottoms. Improper ratchet wheel and lifter wheel combination. More chase length.

36. Causes for Hard waste in Ring frame

37. Mesaured to reduce Hard waste

38. Control of Hard waste in cone winding

39. Control of Hard waste in cone winding