Research regarding the factors of increasing the work productivity for the sewing the pockets of garment products.

Neagu, Ioan ; Coman, Diana

Abstract: The paper presents the results of research made in textile clothing factories. There are analyzed, on the basis of the made timings, the increase in productivity obtained when sewing the pockets of the trousers with two piped pockets. These results are compared for the case when sewing is done with a simple sewing machine and for the case when the sewing is done with an automatic sewing machine.

Key words: pockets, clothing, sewing machine, productivity.

1. INTRODUCTION

There are presented problems regarding the techniques of sewing piped pockets. In literature there evidenced too little the influences of the methods of organizing the work, being insisted more on the use of the automatic sewing machines (Ondogan et al. 2005). On the basis of our research, but also by using technical and organizational solutions, there will be put into evidence the factors of influence in the sewing operations for the piped pockets at the front sides of trousers (fig. 1a). There are established in this way, for both cases, the efficient methods that should be used for increasing work productivity. These researches can after that be extended to other models of piped pockets, pockets with stitches, or with no stitches: piped pockets with zip, flap or strap, with only one pipe, for other products. There can be obtained this way results that can be applied for increasing work productivity.

2. PRESENTATION OF THE WORK METHODS

This research was made in two factories producing trousers, which have machines with different complexities. Regardless of the technology used in making piped pockets, the whole semi-finished product is obtained in two steps:

--sewing the piped pockets using the two methods;

--finishing the pocket, operation which is not of interest in this paper.

2.1 Sewing with the simple sewing machine

The pocket consists of two pipes, two pockets and a gusset. The two pipes are cut from a single piece of material.

The work steps are the following (Neagu & Mitu, 2000):

--thermal gluing of the insertion on the base detail and on the pipes;

--the overcast of a longitudinal side of the piped pocket;

--the ironing of the pipe;

--marking the position for sewing the pipes;

--positioning the pocket and the front side of the trouser on the machine table;

--positioning the piped pocket on the markings made on the trouser;

--carrying out two simple parallel sewings (fig. 1b);

--manual cutting of the: threads, opening of the pocket and the zones in "V" (fig. 1c).

Figure 1. The piped pocket, aspect and phases of implementation

[FIGURE 1 OMITTED]

2.2 Sewing with the automatic machine (Morar, 2000)

--thermal gluing of the insertion on the base detail;

--overcasting the pipe

--positioning on the ironing machine table, in function of the spot lights, of the front side of the trouser, over the pocket bag and fixing them with clamps;

--positioning the pipe and insertion on the sewing machine slide;

--automatic preforming of the pipes and automatic transport in the sewing zone of the positioned and preformed details;

--automatic sewing of the pipes (fig. 1b) and the automatic cutting of the threads, of the opening of the pocket and of the zones in "V" (fig. 1c);

--automatic stopping of the machine and automatic stacking of the semi-finished product on the stacking bar;.

Regardless of the method of sewing the pipes, the following technical conditions are necessary:

--the width of the sewing must be the same on all the length of the pipes;

--the two seams must be parallel;

--the length of the seams must be the same with the length of the finished pockets;

--the extremities of the seams must be positioned on the same perpendicular traced on the seams;

3. ESTABLISHING THE TIME NORMS

For the efficient production of the pockets, it would be ideal if the new technologies would be used, but these can not be applied in all factories. For the case when there are used simple sewing machines, which have a low complexity, there are necessary workers with experience in executing the operations.

They must adapt to the changes in quantities, assortments and product categories. In this paper there were made researches regarding the increase in work productivity, being made comparisons between the two methods of sewing, as well as for each one of these methods of sewing.

The time norms were established by calculating the average of the obtained experimental results, using a digital chronometer. There was used the method of study of work MPM-REFA. The duration for each phase in the work process was determined, taking into consideration textile materials of different fibers, thicknesses and contexts (Neagu, 2001).

4. THE RESULTS

The time norms (minutes/piece) were established for trousers with two lateral pockets. The obtained results were compared between the two technologies of work, as well as within each of these two technologies.

Table 1 presents on phases, for example, the work times in the case of processing base materials with fabrics made of wool and PES--65/35 %, with thickness of 0.4 mm and smooth surface.

Choosing automated machines for sewing the pockets is justified for using them at maximum capacity, the amortization time of the investment being approximate 0.5 years.

The calculation was made in function of the net profit that must be accomplished so that it covers the cost of the automatic machine, the fixed costs, maintenance, repair, as well as the costs with the salaries (Neagu, 2001).

On the basis of the results in the table, the accomplished production (pieces/person), at one work place is 82, at another one 326, thus the productivity increases approximately 4 times. In the case when the simple sewing machine is used, by comparing more work variants, there was obtained an increase in productivity of maximum 46%.

Also, in the case when automatic machines are used, on the basis of the comparison for the same variants as above, the increase in productivity was smaller (approximately 28.5%), but the accomplished production being much greater.

5. CONCLUSIONS

The causes of increasing the productivity by using the automatic machine are the following ones (Neagu, 2002):

--the fast positioning of the details on the ironing table, in function of the spot lights

--the elimination of the operation of thermal gluing of the pipe, this operation being done at the end, when the product is finished

--the automatic preforming of the pipe through the use of the forming device

--the automatic execution, fast and simultaneous, of the two seams, the machine having two sewing needles and clamps for fixing the details

--the fast automatic cutting of the opening and of the zones in "V", through the use of fixed and mobile cutting tools

--the automatic cutting of the needles at the extremities of the pocket opening the automatic stacking of the sewed semi-finished products

The main benefits implied by the use of the automatic machine:

--increased speed in preparing, sewing and stacking after the sewing

--a smaller number of workers can be used

--increased quality of the semi-finished products

--reducing the interruptions during the sewing Using a simple machine, the productivity increase is smaller, due to the following causes:

--the necessity of executing more manual phases: the marking of the pocket position, the thermal gluing, the preforming and manual ironing of the pipe

--the manual cutting of the opening and of the zones in "V", which needs more time

--difficulties for the preforming of the pipe

--the dimensional stability when ironing the velvet is greater

--smaller sewing speed for the materials with small thickness

--the structure of the materials, which influence the unwinding

--the constructive and technological peculiarities of the pocket, which determine additional phases of positioning other details (e.g.: pocket cover)

--the position and length of the opening of the pocket

--the qualification and experience of the worker

When using the automatic machine for creating the pockets, the causes for obtaining a smaller productivity increase are the following ones:

--execution times on phases which are relatively constant

--the necessity of executing additional phases (e.g.: positioning the flap)

For implementing other types of piped pockets (with one pipe, with overlapped pipes, with flap for the pocket), the sewing times differ in function of the following factors:

--the position of the pocket on the main detail;

--the number of overlapped details in the same zone of the product;

--the characteristics of the used materials;

--the used insertions;

--the adopted method of work;

--the characteristics of the sewings machines;

6. REFERENCES

Morar, L., (2000), Automatizarea operatiei de efectuare a buzunarelor taiate, cu refileti (The automation of the operation of creating the cuted pockets, with piped pockets), Lucrarile Conferintei Internationale Altexim-II, Editura Universitatii "Lucian Blaga", pp. 307-312, ISBN 973-651-157-X, Sibiu, nov. 2003, Sibiu (Romania).

Neagu, I., Mitu, S., (2000), Tehnologii de confectionare a imbracamintei (Technologies of manufacturing clothing), Editura Universitatii "Lucian Blaga", pag. 164-169, ISBN 973-651-053-0, Sibiu

Neagu, I., (2001), Studiul muncii in industria confectiilor (The work study in the confection industry), Editura Universitatii "Lucian Blaga", pag. 57-67, ISBN 973-651-289-4, Sibiu

Neagu, I., (2002), Masini si instalatii pentru croit si confectionat (Machines and instalations for cutting and clothing), Editura Universitatii "Lucian Blaga", pag. 143-173, ISBN 973-651-289-4, Sibiu

Ondogan, M., Erdogan, C., Unal, Z., Pamuk, O., (2005), A Research about the Comparison of Classical Lockstitch Sewing Machines and Sewing Automats, Fibres & Textiles in Eastern Europe April, Vol. 13, No. 2 (50)

Table 1. Comparative analysis of the work time

 Phases at the Phases at the
No. simple machine Time automatic machine Time

1 Thermal gluing of the 0,36 Thermal gluing of the 0,36
 insertion in the sewing insertion in the sewing
 zone zone

2 Marking of the pocket 0,56 Positioning of the 0,18
 position details

3 Application of the 2,4 Fixing the details and 0,35
 insertion and preforming the pipe
 preformation of the
 pipe

4 Sewing the pocket 1,2 Sewing the pocket 0,40

5 Cutting the opening 1,3 Cutting the opening 0,18

 Total 5,82 Total 1,47