Just in time manufacturing
|Just in time manufacturing|
|Methods and techniques|
Just In Time (JIT) - one of the techniques used in quality management related to production. It includes the complete elimination of waste by providing every production process with all the necessary elements at the required time and quantity required. The main benefit associated with JIT is to reduce the time to completion to a minimum, which brings significant savings associated with the reduction of stocks.
The effectiveness of implementing the JIT method depends on finding a balance between the flexibility of suppliers and the stability of users, with the proper involvement of management, employees and the use of the advantages of teamwork.
Taiichi Ohno is recognized as the creator of the just in time method, who developed his concept based on the premises of the Ford system and the American retail trade (J. Morris, B. Wilkinson 1995, p. 722). It was first used by Kiichiro Toyoda in Toyota's plants in the 1950s, and implementation in all branches of the group ended in 1962. Then it was gradually recommended to suppliers. The method assumes the organization of production on the basis of drawing raw materials and semi-finished products from previous links of the process, which allows minimizing stocks. At a time when companies were focusing on sales development, Ohno claimed that they would gain an advantage over them using Toyota's just-in-time production system. Ohno believed that the improvement never ends, therefore, for many years he did not write anything about his concept, in order not to allow the process to stop at a certain stage. According to him, "just-in-time system makes the factory become for the company what the body is for a human being".
Just In time, which assumes the delivery of components exactly at the time when they are needed, has evolved over time to even more precise deliveries, with time corresponding to the precise production needs of the assembly line - Just In Sequence, i.e. exactly on the sequence of the production line. Both concepts, Just-In-Time and Just-In-sequence, significantly shorten the delivery cycle. In addition, thanks to their efficiency, they build a strong position among advanced, carefully planned, and most importantly, effective logistics operations.
Basic activities are applied to ensure the smooth flow of materials (J. Witkowski 1998, p. 49):
- organization of the production space in such a way as to minimize the distance between the links of the process,
- implementation of the product using the most effective tools, regardless of their level of technological advancement,
- creation of small production sockets,
- minimizing the time of retooling machines,
- far-reaching standardization of products and processes,
- constant improvement of employees' qualifications,
- elimination of half-storage,
- location of suppliers near the plant,
- improving the flow of information.
The full JIT functionality can be achieved using auxiliary methods such as Total Productive Maintenance, 5xS and QFD.
The JIT concept has been transferred to American and European enterprises. Many years of research conducted by a number of scientists have shown that in a large part of the organization, even after many years of implementation, it has failed to achieve such good results as in Japanese companies. The biggest deficiencies concerned (Morris J., Wilkinson B. 1995, p. 722):
- significant limitation of decision-making autonomy postulated in JIT through the use of standards and instructions and increasing dependencies between cells of the production process as a result of liquidation of storage areas,
- lack of willingness to use autonomous groups of their rights to organize work,
- much smaller effects of elimination of waste,
- lower work discipline.
The reasons for this state of affairs are seen in a different culture and way of organizing the economy. In Japan, keiretsu - the largest organizations of enterprises and banks - is standing above most of the business organizations. Within them, exchange of experience, knowledge and technology is carried out, which is to result in better cooperation and understanding between contractors. Under such conditions, it is much easier to build long-term favorable relations with suppliers or to synchronize production (RL Cutts 1992, p. 48 et seq.).
Also, the manner of personnel management has an impact on the effects of JIT. In Japan, there is a tradition of employing certain employees in one establishment from the end of the period of education up to retirement. Trade unions not only care about the interests of their members, but also about the company and the entire economy. Relations between employees and superiors are based on the Confucian principles of responsibility, loyalty, trust and harmony. Wages are related to employee qualifications and seniority in the organization, and less to the position in the hierarchy. Patterns present in the educational system in Japan favor the cultivation of group work traditions, which also translates into much greater acceptance for showing the group's achievements, not individuals (T. Tachibanaki 1982, p. 447). The European and American style of personnel management takes into account completely different preferences of employees who individually seek promotion and change their job many times over their lives. The rapid development of information technology has allowed the development of new methods of production planning and control, such as MRP. Their implementation is much faster than the full just in time implementation, and in the short term gives similar results. Even in Japan, many companies are moving away from JIT to MRP, especially where there are very complex products and manufacturing processes. However, a comparison of both concepts in the long run may indicate an advantage of the Japanese concept, due to the continuous improvement of each element of the production process in it, while it does not occur in the MRP (J. Witkowski 1998, p. 52).
Rules for the implementation of the Just in time concept
The following principles of JIT functioning in an organization can be distinguished (RT Greene, 1993):
- Each process is a supplier of a different process; every process is a client of another process,
- Management should not exert pressure on production; the activities carried out should be aimed at supporting development and stimulating the production process,
- Individual customer needs should be met through mass production,
- The production process must be free from defects:
- The exchange of products, services and information within the enterprise and with external co-operators should be carried out in the shortest possible time,
- Information on management decisions, sizes and results of production, inventory, etc. should be clearly and clearly presented,
- Only what you need, when it is needed and exactly where it is needed, should be delivered to the enterprise,
- The transport should be adapted for delivery and unloading directly to the production line,
- To ensure the universality of work cell activities, employees who create them should be trained in many areas,
- The company should strive for continuous reduction of production costs,
- Suppliers must be involved in product and process design,
- It is advisable to undertake long-term joint investments with suppliers,
- Continuous transfer of new technologies to suppliers is recommended,
- The expedition of goods ordered by the recipients should be carried out bypassing the earlier storage,
- Each worker can stop the production line, causing the problem to be resolved immediately and on site,
- Management inspections of new workplaces should be performed with particular accuracy; inspections should aim to support activities that improve the place and scope of work,
- Activities that eliminate employee shifts, errors, fatigue and stress should be taken in a creative way,
- Purchases should be made taking into account quality, not price, limiting the number of suppliers to a minimum, including long-term contracts with suppliers.
- The JIT principles presented above are considered to be the conditions for precise and immediate implementation of the client's needs with the minimum amount of losses.
The introduction of the JIT program requires building long-term producer-supplier relationships aimed at limiting the number of the latter. Using one full source of supply of a specific component guarantees the possibility of small orders being executed at short intervals.
The basic aims of the Just-in-time system are:
- achieving the highest customer satisfaction
- continuous improvement of the supply chain
- cost reduction
- improving the timeliness of deliveries
- improvement of the quality of deliveries
The effects of implementation
Just-in-Time is not a strategy that can be implemented "just like that". This system requires appropriate preparatory work before its implementation. It can meet workers' resistance and complications from suppliers. In addition, it can cause problems in the inventory management and control system. However, it complicates the functioning of the company for a certain period of time, overcoming difficulties related to the implementation of the JIT system, is equal to obtaining a number of benefits. Such advantages include reducing inventory levels, reducing expenditures, improving the quality of products and minimizing the costs associated with their control, higher standard of services provided to customers, no need to organize and maintain warehouses, reducing the time in the order execution cycle, increasing the potential of employees and their development as well as maximizing production efficiency.
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