Research On Quality Cost Of Garment Production Line &Nbsp And "Single Piece Flow" Transformation

　　 Aiming at the problems existing in the production quality and production efficiency of garments, a Shirt manufacturer As an empirical research object, through the "single piece flow" transformation of its sewing production line, the balanced production is realized, the quality cost is reduced, and the production efficiency and product quality are greatly improved.

Based on the results of empirical research, the author analyzes the changing trend of quality cost and establishes the trend of quality cost. Production mode After changing the quality cost model, the concept of "quality opportunity cost" is put forward and its function is expounded.

In the process of garment production, production efficiency and product quality is a difficult problem that puzzles business managers for a long time. Sewing process is a bottleneck process, and it is also the main process determining the output and quality of clothing. The balance of sewing production line is the key content of garment production research.

One piece flow (OPF) is also called unit synchronous flow. "Single piece flow" is an organic combination of personnel, processes and equipment. Each production unit is produced and transmitted by a minimum quantity (ideally one) as a unit, and there is no stagnant production mode between the front and rear processes.

The production of "single piece flow" was first put forward by Japanese enterprises on the basis of JIT production mode in 1970s, and it is a fundamental change in traditional production concept. Garment "single piece flow" operation system is the application of lean production theory in garment production. Lean production originated in Japan's Toyota Auto Body Co in 1950s, and was adopted by European and American enterprises in the middle of 1980s. "Jing" means excellent, precise and exquisite; "interest" means interest and benefit.

　　 one piece flow The essence is to reduce the waste of resources for the purpose of reducing the process or actions that can not create value in the production process as far as possible, and optimize the production elements in the production process so as to enhance the production efficiency and production quality.

Compared with the "single piece flow", it is the production mode of "bundled" traditional clothes. This mode decomposes the production of clothing into trunk processes, and each process is completed by one or more workers, that is, each employee holds a certain number of semi-finished products, and when they are completed, they are sent to the next process through the transceiver. The advantage of this method is that personal efficiency is high, but the shortcoming is the overall efficiency is low. The greater the number of semi-finished products held by employees, the longer the semi finished products stay between the production processes, and the more prone to idle time between processes.

In accordance with the plan agreed with the enterprise, the "single piece flow" transformation in the sewing production line has no change in the personnel and equipment in the original production team. Only according to the needs of production and the ability of the staff, the adjustment of personnel and process is organically adjusted, so that the number and difficulty of the workers on the production line are different, but the production time is the same, and the product flows smoothly at the same rhythm on the production line, so as to achieve the goal of balancing production and resource saving.

The comparison of data before and after the "single piece flow" transformation of the sewing production line is analyzed. The efficiency and quality comparison data before and after transformation are shown in Table 1. We can see that the production efficiency and quality level have been greatly improved, both in practice and in theory.

Significance --

Three important references to clothing industry

Achieving win-win between employees and enterprises

At present, the difficulty of recruitment and the mobility of workers are closely related to wage income. Generally speaking, piecework wage is widely adopted in processing enterprises, and a substantial increase in production efficiency means a substantial increase in wages. The average income of the employees has risen from 1400 yuan to 2000 yuan, which has effectively stabilized the workforce for enterprises. While the workers are benefiting, the profits of the enterprises have also been greatly improved. Suppose that the company made 1 million shirts in 2009 with a profit of zero. After calculation, the unit price of processing fee is 10 yuan. This year, the enterprise should have a profit of about 1 million 500 thousand. If we add the factors such as the increase of processing fee this year, we will gain considerable profits.

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Adapting to small batch quantitative trend of clothing production

Usually, small batch orders have the characteristics of high price, short delivery time and so on. Nowadays, the development trend of garment orders is "multi variety, small batch, fast delivery", and the original single variety and mass production mode is far from meeting customer requirements. Nowadays, the general product transformation in the garment sewing workshop takes 2 days for -3 days to complete the finished product offline. This determines that the traditional production mode can not adapt to the development trend of small batch, multi variety and fast delivery date due to the lack of quick response capability.

The modified "one piece flow" sewing production line has a very strong adaptability to small batch orders. The author has observed the whole process of three production changes in a production line for four orders a day. Among them, the loss of working hours per time is less than 1 hours.

Easy to control production schedule

The "one-piece flow" makes the production cycle greatly shortened, and it can be solved quickly when various problems occur in the production process. It will not generate a large number of semi-finished products backlog situation, and is easy to control the production schedule. In addition, the output of the finished product can have clear objectives and plans, and better meet customer's timely delivery requirements.

Analysis -

Two factors to increase production efficiency

After analysis, the promotion of efficiency comes mainly from:

Equipment comprehensive operation rate increased

The sewing process is mainly done by means of industrial sewing machines. In the sewing process of main garment varieties, it is often necessary to cooperate with a variety of equipment, but the sewing machine is the absolute main type in quantity. Therefore, the operation efficiency and running time of the sewing machine are decisive for the output. As can be seen from table 1, the average daily running rate of the sewing machine in April (after reconstruction) increased by 21.90% compared with that in March of this year. Therefore, the improvement of equipment operation rate directly improves the production efficiency.

Why does the "single piece flow" increase the operation rate of the equipment? After the author's on-site observation and understanding, the following two main factors are summed up:

Synergistic effect enhancement. The production mode of "one piece flow" is much more balanced than the previous "bundled" production mode. Through scientific arrangement, each production line is responsible for the number and difficulty of the process, though it is different, but it can produce and transmit at the same time. This avoids the influence of the bottleneck process in the past, and greatly reduces the waiting and handling time caused by the unequal busy time, so that people can do their best and make the best use of it.

The pace of production is accelerating. The "single piece flow" is a "push back pull" production mode. It promotes the entire production line's rapid flow through healthy competition and orderly cooperation between the preceding and the subsequent processes. The "one-piece flow" production mode enhances the sense of urgency of employees, accelerates the pace of work, deepens the sense of teamwork and team spirit, and is conducive to the improvement of the comprehensive operation rate of the machine.

Quality cost reduction to achieve unity of quality and output

The reduction of quality cost is mainly reflected in the reduction of the unqualified rate of the first inspection in the sewing process. It is the key factor to ensure the final product quality. Since the first product is not more than two hours from the open line to the offline, the number of online products is greatly reduced. If the quality problem of the first product occurs, it can prompt and correct the parties in time, thus effectively reducing the number of rework. There is another advantage of the "one piece flow" mode of operation. If employees are wrong, employees in the next process will find it convenient and timely to correct. The "single piece flow" can basically eliminate the systematic defects of the whole batch due to factors such as unclear process and so on, which greatly reduces the waste of working hours and improves the effective operation rate of the equipment. It can be seen that the improvement of quality can not only reduce output but also increase output effectively.

Discussion --

3 understandings of quality cost

As for the definition and composition of quality cost, scholars and organizations at home and abroad have different discussions. The quality cost concept defined by ISO8402:1994 is the cost incurred to ensure and guarantee satisfactory quality, and the loss caused by satisfactory quality. According to the 1994 edition of ISO9004-1 issued by the international standardization organization, "quality cost can be generally divided into quality costs incurred by internal operation and quality costs incurred by external activities".

Quality cost is not the manufacturing cost of the product, but the cost of ensuring the quality of the product. Quality cost is the concept of management accounting, which is allocated to many different cost and expense items under the current financial accounting.

Traditional quality cost model

The world's first application of the concept of quality cost in practice is the A.V. Feigenbaum of the United States. At the beginning of 1960s, A.V. Fagin, in the book "total quality management", put forward that the scope of quality cost involved the whole product life cycle, and divided the quality cost into four categories, namely, preventive cost, identification cost, internal failure cost and external failure cost, which laid a theoretical foundation for the application of quality cost in total quality management.

According to the internal relationship between quality cost and total cost of quality and the economic benefits of enterprises, and for the convenience of quantitative research, we should appropriately merge quality cost items. Because the internal fault cost and external fault cost are all caused by the quality problems of the products, the two quality costs can be combined into one item, which is called "quality failure cost". The prevention cost and appraisal cost are to prevent product accidents and ensure that the products meet certain quality standards. Therefore, the two quality costs can be combined into one item, which is called "quality control cost".

Traditional quality cost theory holds that there is a relationship between control cost and failure cost. The control cost is generally low at the beginning and increases with the quality requirements. When the quality reaches a certain level, if the quality is demanded again, the cost will rise sharply. At the beginning of the failure cost, due to the low rate of qualified products and the high cost of loss, the cost of failure will gradually decrease with the increase of control cost. When the quality reaches a certain level, even if the control cost is substantially increased, the rate of failure cost will gradually slow down. Only when the failure cost falls faster than the growth rate of the control cost, that is, the reduction of the failure cost is greater than the investment cost of control cost, then the enterprise can further expand the profit space. Until the amount of the cost of the failure is equal to the investment amount of the control cost, the enterprise will stop investing in controlling the cost. Therefore, in the product quality cost model, there must be an ideal cost lowest point, which can maximize the profit of the enterprise. This point is the best quality level of the traditional quality cost theory, and the corresponding quality cost is the best quality cost. (as shown in Figure 1)

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Defects in traditional quality cost models

According to the traditional quality cost, the total cost of quality can be controlled in a suitable area by reasonably controlling the proportion structure and cost distribution of quality cost, so that the quality cost can be balanced with the product conformance quality, so that the enterprise can effectively reduce the total quality cost and guarantee the product quality to meet the design requirements, so as to lay the foundation for improving the economy and rationality of the quality cost investment and achieving good economic benefits. Therefore, for an enterprise, there is a lowest quality cost, the most suitable quality level, any effort to get a higher level of quality than this level is not worth the candle. When the quality level tends to zero defect, the cost of quality control tends to infinity, so there is no need to further improve the quality level.

But from the actual situation of enterprise development, the best value of quality cost in theory is not the goal pursued by enterprises. In general, enterprises always improve their quality level through various methods, while reducing the quality cost. This conclusion is obviously contrary to the results of the practice of Six Sigma management implemented by international big enterprises, and is also negated by the author's empirical research conclusion.

Taking this case as an example, compared with March (before transformation), the production efficiency of the assembly line in April (after transformation) increased by 34.68%, but the quality cost had the opposite change (see Table 2, figure 2) - the unit failure cost decreased by 12.32%; the control cost remained unchanged, and the output increased by 34.68%; the unit control cost dropped by 25.75%; (1-1 (1+34.68%) * 100%): the total quality cost of the unit decreased by 38.07%.

With the continuous improvement of production efficiency and the decrease of an unqualified rate, both the failure cost and the control cost are decreasing. When both of them reach a stable state, both the failure cost and the control cost will become a constant and a straight line is shown in the graph.

The traditional quality cost model looks at the problem from the standpoint of isolation and static. It does not take into account the great impact of technological progress and management innovation. It can not explain the continuous improvement of the quality level of production process and the decrease of quality cost in empirical research.

Quality cost and opportunity cost

In order to quantitatively determine the role of quality cost in quality sewing process, we must rely on the operation time of the equipment. Under ideal production condition, the output is always proportional to the running time of the equipment. Due to the defects of the communication between the relevant departments within the enterprise and the technical level of the operator, the failure rate of the sewing process of the traditional sewing production line is usually around 20%, which results in a lot of rework. It is precisely because of the large number of rework that the operation time of equipment is consumed in large quantities, and the loss of working hours consumed by rework is the quality cost, but it is difficult to directly and accurately measure in practice.

Opportunity cost, also known as alternative cost, refers to the cost or loss of potential benefits from abandoning another option in the economic decision-making process. If we make use of some kind of resources in the best way, the value it can produce is the opportunity cost, also known as the "choice cost". According to the explanation issued by the national science and technology terminology examination committee, the opportunity cost refers to the cost brought about by the profit opportunities abandoned by a resource that has not been fully utilized.

From the standpoint of traditional sewing line, the loss caused by working hours consumed by rework is both quality and opportunity cost. Here we can define it as "quality opportunity cost", which means "the quality cost brought about by the profit opportunities that a resource has not been fully utilized and abandoned." In this case, it is generated by the choice of different modes of production. The concept of quality opportunity cost provides us with a way to quantitatively measure and evaluate the defects of the existing traditional sewing line, so that managers can have the opportunity to reduce the quality cost through management innovation. Reducing the quality cost can improve product quality and production efficiency in reducing labor intensity.

In view of the fact that the running time of the sewing machine in the same period of 2009 has been unable to obtain, in order to facilitate the research, we measured the daily average running time of the sewing machine in March this year and in April. From table 3, we can see that in April compared with March, the per capita daily production increased by 34.68%, and the average running time of the sewing machine increased by only 21.90%. The difference between 12.78% and 12.78% is due to the reduction of quality cost. This part of the quality gains account for 1/3 of the increments, and the enterprises think there is still a great potential to tap. We can also see that even in the traditional sewing line, if other factors remain unchanged, as long as the rework rate can be reduced to 7.80%, the output will increase by 12.78%. It is only in that mode that the control factors are more complex and difficult to achieve.

The above results also confirm the view of quality management master Crosby: quality is free. Although it is not a gift, it does not cost money. What we need to spend is Unquality. That is all the remedial measures that must be taken at the beginning when we do not do the work right. Quality is not only free, it is also a real rocking Qian Shu. As the work is right at the beginning, every penny saved without rework will be included in the column "profit" in the accounting statement.

Conclusion -

The effect of single flow is obvious and needs appropriate conditions.

The best way to solve the plight of garment processing enterprises is to improve production efficiency. Practice has proved that the use of "one-piece flow" production will shorten the production cycle and increase production. "Single piece flow" provides an effective way for enterprises to improve production efficiency at low cost, and has important guiding significance for improving the management level of traditional garment enterprises.

Although the effect of the "single flow" production mode is very attractive, the successful implementation of the "one-piece flow" also requires some conditions, such as the reasonable remuneration policy of the enterprise, the higher quality of the production management personnel, and the sufficient preparation for the production.

At present, the research articles on "single piece flow" mainly focus on its implementation methods.

For a long time, quantitative research on quality cost of production process has always been a difficult problem. By comparing the data before and after the production line transformation, we can quantitatively analyze the quality cost structure quantitatively. This empirical study is limited by time and product variety, and can only do some preliminary exploration. If we can find suitable cooperative enterprises in the future, we need further verification and in-depth and long-term research.