Six sigma in controlling and improving crop quality

Quality is one of the most important issues of the times, so the quality of clothing products must be paid attention to by producers and researchers in the field of production and manufacturing of ready-made clothes. The cutting process in the ready-made garment industry is of particular importance as it represents the first step in the basic stages of production in the garment factory. It has become necessary to perform it with a great degree of accuracy and control in order to obtain healthy cuts and pieces of a high degree of accuracy and quality that can be sewn and assembled as required.

In order to improve quality, there must be a good understanding and awareness of the requirements of customers and consumers. Therefore, modern systems of quality are based on preventing the occurrence of defects instead of discovering them. In order for us to be able to prevent the occurrence of defects in manufacturing processes, there must be a clear methodology that leads to achieving tangible improvements in performance, and these improvements can be applied through what It is called the Six Sigma methodology, and this study is an attempt to apply it in the various technical stages, especially the cutting process in the garment industry.

The results of the study indicated:

. 1 The mechanical measurements errors when cutting jeans fabric to make trousers (470 g/m2) using rectangular scissors are less than those using a circular knife, as indicated by the measurement error analysis method:

(Repeatability – Reprodcibility – Fabric Variation – R & R Tools).

2. It has been established that ideal shear conditions are met when:

The speed of the rectangular scissors is 3500 rpm/min.
The coefficient of tightness of the fabric is 100.
Weapon length 29.4 cm.
The height of the fabric layers is 7 cm, in agreement with the results of experiments known as Design Analyses Factorial

3. There was a sharp decrease in the number of shear defects after applying the quality improvement system according to the results of (DPMO).

The importance of treating defects in the shearing process:

The importance of performing the shearing process becomes clear by analyzing the common and recurring defects that result from simply increasing or decreasing the length of the shear line. Also, the angle of inclination of any line when shearing changes from its origin, which causes many technical problems that appear clearly during the knitting process. There is also another type of shearing defect. The resulting small weave marks on the flat cloth, which makes it difficult for the cutter to complete the cutting process with the required quality.

The process of matching the parts of the pattern to the parts of the cut-outs is one of the most cuts in the industry, where the part of the pattern is placed above or below the cut-out part of the fabric, and the match or mismatch between them appears, and thus the cut is reviewed, and accordingly, we find that the quality of the cut is directly affected by three factors:

The quality and error of the machine is called Equipment Variation (EV).
Errors of the same cutter or the so-called Variation Operator (AV).
The randomness of the properties of the fabric itself, or what is called Fabric Variation (FV).

Accordingly, the total differences that determine the quality of clippings are estimated by calculating what is called (Total Variation) or (TV), and then this output is compared with standard values for it to know the severity of the decision regarding the quality of clippings.

And if the process of matching the clippings on the parts of the pattern is common in the industry today, it describes one part of three parts that represent the differences expected to occur, in addition to that it is done in a descriptive rather than quantitative way, and this indicates the urgent need for a new system and a proposal for the quality of the clippings because of its negative effects on each From the quality of knitting and the wearing comfort of the costumes, and this is the aim of this study, and this can be done through the following monitoring system:

Monitor the regularity and cleanliness of the cut line.
Commitment to pattern cutting lines and internal and external sewing marks.
Exact assembly of size, color and use of assembly tact.
Review the dimensions, sizes and number of pieces of each size.

This is done by continuous monitoring and making observations that take place immediately with random review on the cutting and assembly processes, and then making a daily report on the level of quality of the scraps.

The study is also interested, perhaps for the first time, in correcting the following measurement errors:

( Repeatability Part Variation – Reproducibility )

R & R Tools)) in both descriptive estimates.

The modified and proposed application in the cutting phase and the quantitative measurements reached by this study in one of the most important garment manufacturing processes, which is the cutting process, with its clear impact on the quality of the product.

Terminology of study:

What is Sigma:

Sigma is used to express the standard deviation of any production or service process, meaning that it is a measure of the dispersion of the process from its arithmetic mean. Therefore, if the facility can measure the number of defects in a process, it can scientifically remove those defects.

What is Six Sigma?

The concept of Six Sigma is one of the most famous management concepts in the world of total quality management. This concept appeared in the American Motorola company in the early eighties of the last century and achieved wide spread, and major international companies began to adopt it and apply it to their various procedures.

It is an integrated system used to improve the performance of the process and it does so by observing and understanding the nature of variation (Variation).
It is a very accurate measure, as it is a new method of management, and this measure leads us to an actual system for working in institutions and factories without a high cost.
It is an activity that stems directly from Total Quality Management and has its own alphabet, basics and fixed stages based on two important principles:
Good and continuous training to improve quality.
Reducing the output differences of any process to the lowest level.

The goal of using Six Sigma

The main objective of using the Six Sigma program is to reduce diversity and difference in production. The Six Sigma level, which is estimated at about 3.4 defects per million, provides the highest level of quality, as it seeks to try to reach production to the immortality of defects. Working at the level of 6 sigma, the first one has 308,537 defects, while the second one has 3.4 defects per million control points.At sigma level, defects are reduced and costs are reduced