1- General
1-1- Introduction
Quality can be defined in different ways, most people only have a conceptual understanding of quality, or in other words, an understanding of one or more specific features in a product or service. Conceptual understanding is a useful starting point, but a more accurate and useful definition is needed.
Quality has become one of the most important factors in customer decision-making in choosing between existing products and services. This attitude, regardless of whether the consumer is a person, an industrial organization, a retailer, a bank, a financial institution, or even a military program, has gone beyond and has become almost universal in society. Therefore, understanding and improving quality as key factors for business success and growth is considered a competitive advantage. A significant return on investment should be expected in the case of improved quality, as well as the successful application of quality as part of the macro business strategy (Garvin, 1987).
In today's industrial world under the influence of tight industrial competition, the justified necessity of quality, attention to quality and continuous improvement in quality has become of special importance for the managers of any production organization. In other words, the desirability of the quality of the final product is no longer the only essential factor for success in the competition and a superior and continuous presence in the market, but many other effective factors have been proposed, among the most important of which is the confidence of customers in the ability of organizations to maintain the level of quality for the products they produce and supply. Based on this, it can be said that the main attention has shifted from the desirability of product quality to the quality of all functions and processes that affect quality (Qabachi, 2013).
Today, quality control is one of the most important issues in industrial units. Quality control is the representative of the customer in the production process, and its use makes the manufacturer aware of sudden or minor changes in product quality and prevents defective production and imposing heavy costs. Quality as an important business strategy in It is considered that organizations can increase their productivity, market share, profit and popularity if they have successful quality improvement programs. On the other hand, the development of technology in the fields of measurement and calculation has made it possible to use statistical process control in various industries as a daily activity (Qabachi, 2013).
Control means taking the necessary measures to create and maintain specifications and standards. identify and take the necessary measures to eliminate these causes (Nakhandarian, 2013). Quality control and improvement has become a basic strategy in most organizations, and quality is considered a competitive advantage in today's competitive world, and organizations that can improve quality and keep their customers satisfied through quality improvement and control will have an advantage over their competitors (Montgomery, 2013). Also, from statistical methods. It can also be used to improve the quality of products and services. Quality is an important issue in today's world and it is investigated in all fields and it is one of the most important factors in the customer's decision in choosing between products and services. There are many tools to implement and realize quality. In the last decade, the conclusion of the World Trade Agreement led to the breaking down of commercial and customs barriers and borders, and the creation of large arteries of goods exchange and the flooding of products and services to different countries. In such circumstances, naturally, developing countries are also at the center of gravity of the entry of products and goods produced by more advanced countries. Because these countries also have to open their gates to these products and services in order not to be isolated and stay away from international trade. The existence of this phenomenon in developing countries can be the source of conflicting and different effects:
The prosperity, growth and dynamism of their economy, which is the result of the collision and competition between domestic production and imported products. Also, the level of their expectations will increase. Because they can easily recognize the difference between a quality product and a poor product, and this is the responsibility of domestic producers in production.. Because they can easily recognize the difference between a quality product and a poor product, and this makes the responsibility of domestic producers heavier in producing with higher quality and lower cost. Of course, in such a flow and direction, domestic organizations and institutions are forced to produce with maximum quality and improve the quality level of their products, on the one hand, with a more accurate attitude and attention to the demands and opinions of customers, and on the other hand, they should pay attention to reducing the costs of their products and services. in such a way that while producing quality products and services, the cost price is also reduced so that these two things together lead to an increase in sales and finally reach an acceptable level of profitability. Achieving this goal requires the application and use of all management tools and goals, in this way two of the most effective cases are the use and implementation of modern and efficient quality and productivity systems. Quality management and productivity management as two basic and important pillars have a significant role and impact and deserve attention in developing the competitiveness and continuity of organizations, and perhaps neglecting them can lead to negative consequences and results. bring pleasure to an organization. Every organization can be sure that by producing quality products and services, as well as observing the principles of productivity, it is not only able to stabilize its position in the market, but also to look at distant horizons (Montgomery, 1383). There are many tools to implement and realize quality, the most famous of these tools; There are seven tools of quality. Today, the necessity of statistical quality control has been emphasized in most production and service organizations. Control charts are one of these tools that actually determine the deviation of the process. Considering that the main topic of this research is the design and implementation of control charts to improve the quality of detergent products, in this project, the data is controlled by these charts, and process fluctuations are checked, and we examine the out-of-control points, the cause of problems, and the description of corrective action. And we also examine the change points and examine the changeability. As we know, in any production process, there is always a certain amount of variability inherent despite good design or proper maintenance. This variability or disorder is caused by the accumulation of a large set of small and unavoidable deviations.
If the differences in a process are small, then the performance of the process will be acceptable in terms of variability. In the structure of statistical quality control, this inherent variability is usually called "random deviations". is known A process that operates only in the presence of random deviations is called a process under statistical control. Other types of variability may also occasionally be observed in the production process. Variability in quality specifications usually originates from three sources: misadjustment of the device - operator error - faulty raw materials.
In general, such variability is larger compared to the inherent disturbances in the process, and usually indicates an unacceptable level of process performance. These sources of variability, which are not part of random deviations, are called deviations with a reason. A process that operates slowly in the presence of deviations with a reason is called an out-of-control process.
One of the main goals of statistical process control is to quickly find out the existence of deviations with a reason or changes in the process, before a large number of defective products are produced, and investigate the causes of such deviations and take corrective measures. The control chart is one of the methods of controlling the process during production, which is suitable for this purpose (Mirkhahan, 2013). Recently, a lot of research has been done on control charts and their use to improve and control quality, in various fields and for various industries and services in the fields of medicine and health, construction, banking and finance, manufacturing industries, etc. Since no research has been done in the field of designing a control chart for detergents, we consider it necessary to raise this issue and improve the health of users by controlling the quality of detergents.