Process Control in Drawing-in

Process Control in Drawing-in

The term drawing-in and warp tying refers to the operations involved in preparing the weaver's beam for the purpose of weaving fabrics on the loom.

The drawing-in process primarily consists of drawing ends from the weaver's beam through heald eyes of different harnesses and then through the dents of a reed in the order that is determined by the design of the fabric.

If a beam is to be worked with warp stop motion on the loom, specially when using closed drop-pins, the ends have to be drawn through these pins before drawing them through the heald eyes and reed dents.

conventionally drawing-in is carried out manually by two persons-one, the reacher for selecting and presenting the ends from the beam, and the other, the drawer for pulling ends through the drop-pins, heald eys and reed dents.

The main requirements of carrying out this process properly and efficiently are:

1. The operator should be aware of the principles of drawing-in and be trained to do the job speedily because any mistakes or delays in carrying out the process would prove to be costly.

2. The healds and reeds should be in good condition and of suitable specifications for ensuring that these are not the cause of warp breaks on the loom and of defects in the fabric.

3. The drawing of the beam should be done properly to avoid cross ends on the beam.

4. Suitable precautions should be taken to reduce the incidence of extra-ends and to compensate for the missing ends during the weaving of the loom.

CARE OF HEALDS AND REED

1. The healds and reed from the exhausted beam of the loom must be cleaned throughly to free them from fluff, size, rust etc. before using them for a new weaver's beam.

2. When warp tying is practiced, it should be ensured that the same set of healds and reed do not work on the loom for a long time, even if no apparent defect is noticed in them. This is because through cleaning of healds cannot be done on the loom itself and dirty healds are prone to give high warp breaks.

COMMON DEFECTS IN DRAWING-IN

1. Cross ends- To minimise the incidence of cross ends on the beam during weaving, the ends presented for drawing in or warp tying should be made to be parallel and in their respective positions as in the beam. Proper dressing of ends is, therefore, of great importance.

2. Extra Ends- some ends are generally cast out during drawing-in/warp tying to compensate for long missing ends on the weaver's beam.Whether to leave these ends or not should be governed by the method of cutting lappers at sizing.

If the lappers are cut and mended only after completion of a weaver's beam, there is no need of leaving extra-ends at drawing-in or warp tying. If however, the lappers are cut no sooner these are detected, the same ends should not be withdrawn or not taken for tying.

Cost of Sizing

Cost of Sizing

The cost of sizing ( excluding cost of sizing chemicals) is generally expressed as cost per unit length. Hence contribution of sizing cost can be calculated as:

cost of sizing= cost per unit length x tape length

cost of sizing chemcials is expressed as cost per unit length of size mixture. The cost per piece of fabric can be calculated as:

Cost of sizing chemicals per piece length= cost/kg x (warp weight per piece length x size add on %)

Basic stitches- Animation

Basic Stitches Animations

This site talks about how sewing machine works. It is replete with animations. It starts by saying that it was inefficient to mechanically copy the process of hand sewing. This site has animations for the following stitches:

1. Basic chain stitch
2. Twisted chain stitch
3. Lock stitch
4. Oscillating hook lockstitch
5. Rotating hook lockstitch
6. Double locking chainstitch

A very nice site to visit !

Should I mention that on the same parent site there is this amazing guitar tutorial !!

Efficiency of Sizing

Efficiency of Sizing Department

The major causes of loss of machine efficiency are:

1. Creeling, which includes removing the exhausted beams, mounting new beams, denting, leasing etc.
2. Replacement of weaver's beam on consumption

Efficiency in sizing

Let yarn count= 34
Set length on warper's beam= 18000 m
length of yarn on weavers beam= 1500m
Total number of ends= 4000
Full running speed= 50 m/min
No of lappers per 3000 ends per 1000 m = 3
Time to cut a lapper = 90 sec
Time to doff a beam and put new lease rods = 600 seconds
time to change a set = 6300 sec
Time loss/1000 m due to miscellaneous causes= 60 sec

Calculations

Sizing time of one beam with no stops : R = (1500x60)/50 = 1800 seconds
Lappers per beam of 1500 m per 4000 ends = 6
time lost in cuttin glappers per beam = 540 seconds
Number of weavers beam per set= 12
time lost per beam in a set change = 6300/12=525 seconds
time loss in beam doffing and leasing per beam = 600 seconds
Miscellaneous losses per beam of 1500 m = 90 sec
total time to size one beam = 3555 seconds
Machine efficiency = (1800 x 100)/3555 = 50.6%