Air Consumption Analysis of Air-Jet Weaving

In Textile industry, production is mostly key concern for Industry owner. This always has attracted researchers and machines manufacturers to make new developments in process and machines. Air-jet is one of the leading and successful highest productive weaving machines. However, it is now well established that due to add of charges of compressed air, manufacturing cost of air-jet weaving machine is higher as compared with rapier and projectile weaving machines. This is why countries having energy issues do not prefer air-jet weaving machines comparing projectile weaving machines. In this regard, several researchers and machine manufacturers have continuously been working to improve the efficiency of air-jet weft insertion. However, industry practice is as important as design made by researchers. The aim of this research is to investigate the air consumption of air-jet weaving on industrial scale practice. In this study, five weaving machine of same manufacturer and model were selected. It was observed that despite of manufacturing same quality of fabric, air consumption was varying almost in all weaving machines. Conventionally, mill workers adopt hit and trial practice in weaving industry including airpressure setting which leads to variation of nozzle pressure. Main reason of disparity of air consumption in air-jet weaving machines may be variation of distance from compressor to weaving machines, number of joints, un-necessary valve opening and pipes leakages cause an increase of compressed air consumption.


INTRODUCTION
A ir-Jet weaving machine is one of the successful and high productive shuttle less weaving machine in Textile industry [1]. An air-jet is device used to insert the weft yarn by using high air pressure. The air is filtered and compressed before using in air-jet weaving machine. Due to significant compressed air consumption and extra cost of compressor electricity, the manufacturing cost of airjet weaving increases. This is making air-jet weaving less preferable where energy cost is the problem despite their high production speed.
Though air-jet weaving machines manufacturers and researchers have been continuously working on reduction of air consumption in their new design to overcome this drawback. Yet, there is still deficiency of reliable information on energy efficiency of compressed air for industries [2][3][4][5][6][7]. Adanur and his team analyzed the use of compressed air for weft insertion process and investigated the effect of yarn characteristics and compressed air [8][9][10][11][12]. Beside the researchers air-jet weaving machine manufacturers put several efforts to improve the weft insertion by compressed air. Picnol developed air-index system to measure the weft yarn suitability for air-jet weaving [13]. Donier introduced PIC (Permanent Insertion Control) for monitoring of insertion element [14].
Despite the efforts made by researchers and machines manufacturers, it is observed that efficiency and air consumption has not been achieved at industrial scale.
This study aims to analyze the air consumption of air jet weaving at industrial scale practice. Focus was made on important parameters such as air consumption on main nozzles, sub nozzles, opening and closing of nozzles with respect to degrees etc where significant percentage of compressed air is consumed.  There are various factors involved to set the air pressure such as distance from compressor to weaving machine, elbows etc.  Fig. 4 presents the pick insertion position in (TO) and pick arrival position (TW) of different looms. In air-jet weaving machine number 5, pick insertion beginning to pick arrival cycle is short whereas air-jet weaving machine number 4, pick insertion beginning to pick arrival is high. This observation validates the Fig. 3 where air pressure of sub nozzles of air-jet weaving machine 5 is greater as compared with air pressure of sub nozzles of air-jet weaving machine 4. It is found that higher pressure is required to minimize the insertion time or increase in picking speed, however higher pressure may lead to high consumption of air. Fig. 5(a) presents the air consumption of Air-Jet weaving machine at stop position. Though there is no any primary or secondary motion active. Yet, it is clearly visible that compressed air is continuously consumed by air-jet weaving machine. Airjet weaving machine number 2 consumed lowest quantity of air (110cfm) and air-jet weaving machine number 5, consumed higher quantity of air 470cfm which is quite surprising and it may be because leakages in machine pipes and long distance from air compressor. Fig. 5(b) shows the air consumption of Air-Jet weaving machine at running position in which fabric is manufacturing. While manufacturing of fabric, picking, cutting process and nozzles are the key parts requires compressed air is required. Air-jet weaving machine number 2 consumed lowest quantity of compressed air 1380cfm, whereas air-jet weaving machine number 5 consumed higher quantity of compressed air 1860cfm.

Air Consumption of Air-Jet Weaving Machines at Stop and Running Position:
Results of both machines are almost at similar trend Fig.  5(a). However, its consumption rate is different because of various parameters such as main nozzles pressure variation, sub nozzles pressure variation, opening and closing timing of sub nozzles, main nozzles and pick insertion timing variations. It is also visible that as the number of air-jet weaving machine increases, the air consumption increases. This may be due to distance increases from air compressor to the air-jet weaving machine location.

Relation of Opening Duration of Sub Nozzles: Sub
nozzles are the main air consumers of compressed air where 80% of compressed air is consumed [1]. Thus its operation should be optimized. However, no machine manufacture recommends any pressure with respect to yarn type. Hit and Trial experiment is common practice of all weaving industry workers. Table 2

CONCLUSIONS
Compressed air is the today's main issue in Air-Jet weaving machines Industry. This leads to expensive cost to produce fabric comparing to conventional ways. In this regard, several efforts are made by machines manufacturing industries as well scholars. In this study, we have focused on air consumption of air-jet weaving machines. Five air-jet weaving machines (Toyota JAT710) were selected which were manufacturing same quality of fabric. Following are the key observation found during air-consumption analysis and inspection of key areas of weaving shed.
(i) Air consumption may be reduced by utilizing proper pressure setting of main nozzles, sub nozzles according to the required quality of fabric construction.
(ii) Higher air pressure is required to minimize the insertion time or increase in picking speed, however higher pressure may lead to high consumption of air.
(iii) Un-necessary valves opening, leakages at different air pipes at different location and lack of awareness causes the increase in air consumption.
(iv) Distance between loom to compressor department should be reduced.
(v) Compressor delivers high pressure to the looms but due to junctions or elbows the pressure slow down at the looms.
(vi) Untrained workers and lack of professional knowledge causes variation of pressure and air consumption for even same part and fabric manufactured.