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close this bookSmall-Scale Weaving (WEP, ILO; 1983; 144 pages)
View the documentPREFACE
Open this folder and view contentsCHAPTER I. INTRODUCTION
Open this folder and view contentsCHAPTER II. PRODUCTION OF WARPS AND PIRNS
View the documentI. Weaving fundamentals
View the documentII. Loom types in relation to scale of production
View the documentIII. Hand looms
View the documentIV. Non-automatic power looms
View the documentV. Automatic power looms
View the documentVI. Shuttleless looms
View the documentVII. Ancillary equipment
View the documentVIII. Yarn requirements
View the documentIX. Product quality
View the documentX. Factory space requirements and layout
Open this folder and view contentsAPPENDICES
View the documentQUESTIONNAIRE
View the documentBACK COVER

V. Automatic power looms

Automatic shuttle looms are essentially simple power looms to which has been added means of automatic weft replenishment. However, in order to gain full advantage of this latter feature, thus enabling a weaver to look after more looms, shuttle looms should also be equipped with an automatic warp let-off motion and an automatic ‘warp-stop’ motion (which immediately stops the looms if a warp thread break occurs). All these features are considered standard fitments on an automatic loom. Figure III.9 shows an automatic Pirn change loom with under-pick motion.

Figure III.9 Automatic pirn-change loom with under-pick motion

V.1 Weft replenishment

The operation of automatic weft replenishment can be performed in two ways. In the first method, the empty shuttle is ejected from the loom at some convenient time in the loom cycle (i.e. when the shed is changing) and a new shuttle is inserted with a full weft package. In the second method, which is currently by far the most common, the empty weft package (pirn) is ejected and immediately replaced with a new full pirn of weft. The first method requires at least two shuttles per loom and to the extent possible, these have to be identical in all respects, including the degree of wear due to service. The second method requires only one shuttle per loom, but this shuttle is of a special shape.

Apart from the above features, there are two distinct categories of automatic shuttle looms: shuttle changers and pirn changers. These are briefly described below.

V.2 Shuttle changers and pirn changers

In operation, shuttle changers require that a magazine be kept supplied with charged and threaded shuttles, whereas the magazine only requires to be loaded with pirns in the case of pirn changers. In times when hand-spun and mule-spun weft were commonly used, the shuttle changer had a possible advantage in that miscellaneous cops taken directly from the spinner could be loaded into the shuttles. This was not possible in the case of pirn changers which require that the yarn be wound on to special bobbins furnished with means for automatic retention by, and ready ejection from, special shuttles needed for this purpose. Lately, the production of fabrics for high-income consumers requires a low permissible fault rate, and since present demands cannot be met without very stringent clearing of both warp and weft yarn, the advantage of the shuttle changer has largely disappeared. Thus, rewinding from the spinner’s package is essential for yarn clearing, and no further cost is therefore incurred in the preparation of weft pirns suitable for the particular type of automatic pirn changer. Consequently little advantage remains in the use of a shuttle able to accept weft in packages of a variety of forms.

This situation does not occur where fabrics for low-income consumers are being woven. Consequently, a number of shuttle changers are still in use in developing countries although it is very common to find looms which are only nominally automatic. The reason for this is the high cost of shuttles used in this type of loom. Often, the expense of the additional capital needed to keep each loom supplied with sufficient shuttles (which have a relatively short life and must be regarded as consumables) is so high that it becomes more economical to operate such looms as non-automatics. On balance, one must conclude that, in most circumstances, the pirn-changer is to be preferred except where yarn suitable for the types of cloth covered by this memorandum is readily available only for use in plain (i.e. non-pirn changing) shuttles. For these reasons, the single-shuttle pirn changer is currently the most commonly used power loom world-wide. Such a loom has been further improved and is now being produced in large quantities which allowed a considerable reduction of the price of the automatic pirn changing facility.

In response to demand by high-income consumers for nearly perfect machine-made cloth, most loom makers now work to very high engineering standards in regard to both design and manufacture. Consequently, the cost and the standard of engineering precision of looms of all kinds have also increased. It is nevertheless true that some makers are still able to supply automatic looms which are broadly similar in design and construction to those produced in Europe and North American between 1930 and 1960. These are therefore available at somewhat more modest price levels.

V.5 Automatic power loom manufacturers

Over the past thirty years, the standard of manufacture of automatic shuttle looms which require low labour inputs has risen to a very high level. Most European and North American makers now offer only looms to these very high engineering standards with a view to minimising skilled labour inputs over the useful life of the equipment. The cost of these looms is very high in relation to conditions obtaining in developing countries for which they are therefore not suitable.

Most western loom-makers used to make suitable low-cost automatic looms. This is not anymore the case as few manufacturers can now produce these looms profitably: the available machine tools and production methods used for the manufacture of “super-looms” are unsuitable for the manufacture of the less sophisticated low-cost looms. A small number of Western loom makers still offer simple, low-cost machines based on pre-1950 designs. One such company is British Northrop Ltd., Blackburn, United Kingdom. Pioneers of the pirn change automatic loom in Europe 75 years ago, Northrop has produced the well-tried ‘S’ model, of which there are more than 30,000 units in operation worldwide. In 1976, Northrops completely equipped a new mill in the Sudan with this simple and robust automatic loom. While not known precisely, it is inferred that the price per loom was not greatly in excess of £2,000 at January 1980 values.

India is one of the few developing countries which produces and exports both automatic and non-automatic looms suitable for the needs and conditions of the developing countries. Three important manufacturers are (i) Cooper Engineering of Poona who, in collaboration with North American Rockwell, offer a loom based on the Draper (X2) model, a loom of essentially pre-1940 design; (ii) National Machinery Makers Ltd., of Kalwe Thana, produce the Ruti ‘B’ type automatic shuttle loom, one of the best of such looms made during the 1950/60 period; and (iii) Central India Machinery Manufacturers Company (CIMMCO) of Gwalior which, in collaboration with Sakomoto of Japan, offer an automatic loom based on a Japanese design of about 1950.

V.4 Trade in second-hand textile machinery

There is considerable trade in second-hand textile machinery of all types. In some cases, complete installations are bought in situ, dismantled and re-erected in a new location. Alternatively, machinery is bought from stocks held by a dealer. The greatest proportion of the trade is, by far, in re-conditioned shuttle-looms, both automatic and non-automatic. Bestex Textile Machinery of Blackburn, United Kingdom is an example of a typical secondhand machinery dealer offering a comprehensive, world-wide service. Other companies offering a similar service are ‘Reconditioned Looms’ of Blackburn, United Kingdom and Josef Kruckels of Munchengladbach, Federal Republic of Germany. In addition, some loom-makers, such as British Northrop, will recondition looms of their own manufacture to an ‘as new’ condition either at their works or on site.

The decision to invest in second-hand weaving equipment is not an easy one to make as it involves complex considerations of a technical and economic nature. Producers interested in buying such equipment should therefore obtain detailed information on what is being offered by second-hand equipment dealers, and undertake careful feasibility studies prior to deciding on the acquisition of a piece of equipment. Interested readers may obtain useful clues on the approach to be used when looking for second-hand equipment from the ILO publication (Cooper and Kaplinsky) listed in the attached bibliography.

V.5 Skill requirements

All automatic looms are more demanding of technically skilled labour than are non-automatic looms although the latter may sometimes demand a higher level of ‘practical’ expertise. In comparing automatic and non-automatic shuttle looms, it will be found that a higher standard of technical training and diligence are required to ensure satisfactory operation of the automatics. This is partly because of the relatively complex mechanism by which automatic weft replenishment is achieved. In addition, it is necessary to be more meticulous in the care and adjustment of the picking mechanism that might otherwise be the case: automatic changing of either the shuttle or the pirn requires more accurate timing and positioning of the shuttle than is necessary when the shuttle is being removed and replaced manually.

In conclusion, in view of the various factors considered in sections IV.2 and V.3, and given the types of cloths considered in this memorandum, no real benefit should be gained in using automatic looms as an alternative to non-automatic looms. The latter should also be preferred at all three levels of production covered by this memorandum given the relatively low wages paid in developing countries. This matter will be further analysed in chapter IV.

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