loom shed

Process Control in Loom shed

It consists of two parts:
1. Increasing machine productivity
2. Improving quality or reducing defects

Control of the productivity can be done with

1. controlling nominal loom speed close to currently set standards.
2. Ensuring that loss of speed through belt slippage is minimum
3. Control of loss of loom efficiency by minimising:
a. Loom stoppage rate through correct maintenance
b. Control of down time of loom through corrective action on the basis of data collected by snap reading.

1.
2.

3. Factors effecting Loom efficiency

Various factors that affect the loom shed efficency are

1. Technical
2. Human ( Related to weaver skill and work methods)
3. Organisational

Relating the three factors

The technical and human (weaver related) factors have a very basic relationship with loom efficiency. The relationship is

P = NEX
= NE at

or E = P/ Nat
Where P= operative efficiency
N= number of machines per operative
E= Machine efficiency

X= Service factor, and it is equal to the average time taken to clear the stops in unit running time of a machine and equals at.
a= average no of stops per unit running time of a machine
t= average time to clear a stop including walking time

Thus if during an hour, the operator spends on an average 30 minutes in clearing stops, 15 min in ancillary durites like bringing raw materials etc and 15 min on rest and relaxation then
operative efficiency = (30 x 100)/60 = 50%
Work load = (30+15)x100/60 = 75%

Thus to maximise loom efficiency
- The stoppage rate should be low
- the weaver should be trained so that he takes the minimum possible time for clearing a stop.
- the operative efficiency should not fall below the optimum level
- loom allocation should be optimum

Costing in Drawing-in

Costing in Drawing-in

Drawers and reachers are paid their basic wages on piece rate system. The rates are related to the type of cloth to be woven. the basis of allocation of expenses to the different types of cloths are

1. Basic Wages of drawers and Reachers= Rate per 1000 ends x total production in 1000 ends.
2. DA to drawers and reachers and all other expenses = total production/production per shift

Cost of Drawing-in

Unit costs of this process as cost per 1000 ends. The cost of this process is calculated as shown below:

Cost of drawing-in per piece lengtrh = (cost per 1000 ends x total no of ends x tape length)/ weaver's beam length

Reed Calculations

Reed Calculations

Reeds are generally counted using STOCKPORT system, which is based on the number of ends in two inches.
Ex. A 72s stockport reed means 72 dents on 2 inches or 36 dents per inch.

Particulars of reed while ordering

100s ST, 18 G., 44"x 5" blue

- Stockport reed of
- 100 count
- using dents of 18s wire gauge
- Reed is 44" long
- 5" deep
- there will be blue paper on baulk of the reed.

Ex. What will be the number of ends/inch in a reed of 3/80s stockport

80s stockport= 80 dents per 2 inches
= 40 dents per inch

Therefore no of ends per inch = 3 x 40 = 120

Plain Set

When a set contains 4 shafts, it is called a plain set.

The number of heald eyes per inch across the healds in a set expresses the count of the heald.

Ex: 60s count for a plain set means 60 heald eyes on 4 shafts per inch i.e. 15 eyes per inch per shaft. For a 6 shaft set, it becomes 60 heald eyes on 6 shafts per inch i.e. 10 eyes per inch per shaft.

Ex. Find the count of healds that will be required for weaving a 6 shaft satin fabric using 72s stockport reed, drawn 3 ends per dent.

No. of ends per inch in the reed = (3x72)/2 = 108 ends
Therefore no of healds /inch = 108/6= 18 healds per inch.

Thus we require 72s count of reeds in a plain set.

 

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.