Researches regarding the factors of influence over the time rate at the operation layering of the textile materials.

Neagu, Ioan

Abstract: The operation of layering the textile materials influences the reduction of the cost, as well as the cycle of clothing fabrication. In this paper there are evidenced, based on my research, the factors that determine the norm levels for the layering operation. It is necessary to determine factors that influence tha time rate at this operation.

Key words: layering, clothing, textile materials, norm.

1. INTRODUCTION

The layering of the textile materials is done through manual or automatic methods at the base materials, lining and insertions. In the present situation, the workers do different operations at the cutting department, which determines a low productivity (Wong et al., 2001). At the acquisition of the cutting tools it is necessary to evaluate the lucrativeness of the investment (C. L. Hui Patrick et al., 2000), this depending on the reduction of the time norms for the piece of product. In this paper I analyzed only the manual operation of layering the base materials, taking into study more research variants that differ in function of the length of the layering, as well as in function of the way the layering is done.

The way the layering is done can be (Neagu & Mitu 2000):

a.) simple material sheets, front to front and in one way;

b.) simple material sheets, front to front and in opposite ways;

c.) simple material sheets, front to back and in one way;

d.) simple material sheets, front to back and in opposite ways;

For establishing the time norms, a digital chronometer was used, these being obtained by calculating the average of the obtained experimental values. There was used the method of work study MPM-REFA (Neagu, 2001). The novelty consists in quantifying the influences of the layering factors over the layering time. This research method can be also applied at the layering of other textile materials: linings and insertions, both for the manual layering, as well as for the automatic layering.

2. WAY OF WORKING

2.1. Presentation of the base variant

The work methodology is based on the analyzing of the variant with simple material sheets, front to front and in one way.

The time (minutes) to create one layering shall be determined with the relation (Neagu, 2001):

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (1)

where: [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]-constant times

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII]-variable times

There must be taken into consideration specific conditions of creating the layering: the number of sheets that determine the thickness of the layering and the number of sizes or products that determine length of the layering (Springer 2003).

In tables 1 and 2 there are evidenced the average values of the constant times and respectively, variable times, for the following hypothesis of work: cut product-men's coat, number of products / 8 hours - 450 pieces, average number of material sheets in the layer - 20, transversal sectioning of the layering at 0.75 m, number of products in one framing 1 / 4, the length of the layering--variable

Table 3 presents the work times, in the order of executing the work phases, taking into consideration other variables:

--the number of material sheets in the layering (n);

--the number of colors of the materials in the layering (m);

--the number of sectionings done at layering (p).

It is mentioned that in function of the length of the layering, specified in the table, the framings corresponding to the layerings contain 1, 2, 3 or 4 products

Because the operation of manual layering is done by two workers, the total time to accomplish a layering [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] shall be of 67.16 minutes, 76.62 minutes, 87.26 minutes and respectively, 92.22 minutes.

The number of framings needed in one work shift is determined with the relation:

[n.sub.framings] = [N.sub.p.sup.*] [n.sup.*] q (2)

where:

Np--the number of products that need to be made

n--the number of material sheets superimposed in one layering

q--the number of products in one framing

There shall result 23, 12, 8 and respectively 6 framings, in function of the length of the layerings, specified in table 3.

The total time for accomplishing a layering can be calculated with the formula:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (3)

For the layerings needing to be made there shall result a total time of layering of 1544, 919, 695 and respectively 557 minutes, in function of their length.

The number of workers necessary for accomplishing the layerings is determined with the formula 4, where T is 480 min:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (4)

2.2. Research variants

There were established the time for the other three ways of arranging the material sheets in the layering.

--The variant wieh the simple material sheets, front to front, in opposite ways.

In this case, there is an additional phase, which consists in turning over the material sheets, the time of work for a layering being 0,12 minutes. The total time for the layering shall be 1655, 979, 736 and respectively 582 minutes.

--simple material sheets front to front and in one way. In this case the time needed to put each material sheet in the layering is reduced, the values being 0,19 0,23, 0,26 and respectively 0,29 minutes. The total time needed for the layering shall be 1507, 902, 678 and respectively 541 minutes.

3. CONCLUSIONS

--the time needed for the layering does not increase proportionally with the increase in the length of the layering and of the number of products in a framing: 14% (2), 30% (3) and respectively, 37 % (4);

--the percent of the constant timings out of the total needed time, decreases with the increase of the layering length, beginning with values of 60% and ending with values of 54%;

--for great layering lengths, the decrease in the percent of the constant times is less evident;

--the time consumption is greater for the layering with the directions of the material sheets in opposite ways;

--the positioning front to front of the material sheets needs more time, in comparison with the variant of front to back;

--as a result of decreasing the layering time together with the increase in the length of the layering, there were obtained for all research variants, significant decreases of the number of workers necessary to accomplish these operations.

As a general conclusion, it results that layerings with length greater than 6 meters are more efficient, having simple sheets front to back and in the same direction, the framings containing four combined products.

There were established the time norms for the other three ways of arranging the material sheets in the layering.

--simple material sheets front to back and in one way.

In this case, the time needed to put each material sheet in the layering is reduced the values being 0,19, 0,23, 0,26 and respectively 029 minutes.

The total time of this operation is 1507, 902, 678 and respectively 541 minutes.

It is necessary 3.14, 1.88, 1.41, and 1.12 workers

--The variant with the simple material sheets, front to front, in opposite ways.

In this case, there is an additional phase, which consists in turning over the material sheets, the time of work for a layering being 0,12 minutes.

4. REFERENCES

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

Springer L. (2003), Optimisation of Apparel Manufacturing Resource Allocation Using a Generic Optimised Table-Planning Model, The International Journal of Advanced Manufacturing Technology, Volume 21, Number 12 / September, 2003, page numbers 935-944, ISBN 0268-3768

Wong, W.K. Chan, C.K. & Ip, W.H. (2001), Application of fuzzy concept in the apparel industry, IFSA World Congress and 20th Nafips International Conference, 2001. Joint 9th, page numbers 2547-2550 vol.5, ISBN: 0-7803-7078-3, Vancouver, Canada.

Hui Patrick, Ng Frency, C.L., Chan Keith & S.F., C.C. (2000), A study of the roll planning of fabric spreading using genetic algorithms, International Journal of Clothing Science and Technology, Volume: 12 Issue: 1, Year: 2000 Page: 50 - 62, ISSN: 0955-6222.

Table 1. Average values for the constant times (tk1 / tk11)

 Work
 time
No. Work phase (min)

1 Selecting the necessary framing 1,14
2 Selecting, placing the bales on the rack 1,31
3 Cutting paper for the layering support 0,12
4 Superimposing sections of the layering 0,86
5 Writing labels for the layering 0,91
6 Cutting the end of the layering sheet 0,51
7 Fixing the end of the layering sheet 0,13
8 Changing 1 bale 0,07
9 Sectioning the layering 1,03
10 Changing the second bale 0,66
11 Changing the third bale 1,5

Table 2. The average values of the variable times (tv1 / tv8)

 Length of the layering

No. Phase 1,8 3,5 5,4 6,8

1 Establish the length of the 1,02 1,14 1,23 1,25
 layering
2 Remove framing 0,41 0,59 0,78 0,84
3 Place the paper sheet under the 0,18 0,23 0,27 0,30
 layering
4 Shift in opposite way 0,18 0,23 0,27 0,30
5 Place layering 0,23 0,27 0,32 0,34
6 Adjust edge of layering 0,19 0,26 0,32 0,34
7 Superimposing the framing over the 0,51 0,74 0,97 1,03
 layering
8 Gluing the framing over the 1,28 1,86 2,41 2,57
 layering

Table 3. Calculating the time needed to accomplish a layering

 Length of the
 layering (m)/
 Symbol *
No. variable 1,8 3,5 5,4 6,8

1 tk1 1,14
2 tv1 1.02 1,14 1,23 1,25
3 tv2 0,41 0,59 0,78 0,84
4 tv3 0,18 0,23 0,27 0,30
5 tv4 0,18 0,23 0,27 0,30
6 tk3 0,12
7 tk2 1,31
8 tv5 x n 4,6 5,4 6,4 6,8
9 tv8 x n 1,4
10 tv6 x n 3,8 5,2 6,4 6,8
11 tk7 x n 2,6
12 tk9 x m 3,09
13 tv7 0,51 0,74 0,97 1,03
14 tv8 1,28 1,96 2,41 2,57
15 tk10 x p 0,66 1,98 3,96 5,28
16 tk4 0,86
17 tk5 0,91
18 tk6 0,51
19 tk11 x m 9,0
Time norm (min/piece) 33,58 38,41 43,63 46,11