Identifying and analyzing the interactions of factors affecting Just-in-time in a supply chain using DEMATEL and ISM methods (Case study of Iran Khodro Binalood)

Nowadays, due to highly competitive markets, meeting customer demand, quickly with the best quality and lowest cost, has become inevitable and achievable with the optimal utilization of resources and facilities. Just in Time (JIT) production system is an effective strategy to that end. Various measures and factors are involved in implementing JIT in the supply chain. The identification and analysis can give managers a clear vision of the supply chain and JIT so that this system can be implemented with the best performance in organizations. In this study, the most significant and effective measures involved in JIT were identified. Then the importance and priority of these measures were determined in terms of impact on JIT's performance. Moreover, the relationship between measures and their effectiveness was determined. The research results can be applied for the efficient implementation of JIT.

Following the literature review and receiving expert opinions by statistical analysis (Friedman test), the factors affecting JIT were classified into six key measures: i) information–feedback; ii) manufacturing unit; iii) purchase unit; iv) sales unit; v) customers; and vi) suppliers, which were the foundation for designing the questionnaire as the primary research tool in the field study. A questionnaire was designed based on the DEMATEL-Dalalah technique. It was used for quantitative analysis of relationships and interactions between factors and Interpretive Structural Modeling (ISM) to prioritize the measures. In a case study using a questionnaire, the opinions of 25 experts from the production line planning unit of the Iran Khodro Binalood Car Assembly Plant were collected and analyzed.

The information-feedback and purchasing unit factors were correlated to all other factors, indicating that such factors require special attention in organizations. It was also found that customers had the most negligible impact on JIT. In general, three factors of purchasing unit, information-feedback, and sales unit were considered as independent factors, and the other three factors – including manufacturing unit, suppliers, and customers – were dependent. Also, the ISM approach categorized the factors into three levels. The purchasing unit directly affected information feedback and sales unit factors. Then these two factors affected the factors at level 1, i.e., the manufacturing unit, customers, and suppliers; hence, these three factors had the most impressibility. Research limitations/implications: There are different methods for data collection and analysis and accordingly, through various data collection and analyses, the assessment can be performed from different aspects. It is suggested to researchers evaluate various factors affecting JIT in different industries. If more statistical data are available from experts in various industries, this subject can be explored from different aspects. The concept of JIT implementation in the country was not concentrated in this study. The involvement of different companies in such a system could be a great help in collecting more data for further research. Practical implications: The improvement of the purchasing unit positively affects the entire system due to its high importance and impact on JIT. Moreover, the information-feedback factor is always part of the infrastructure of any organization that other units can use to interact with each other; thus, facilitating communication is very significant. Also, the sales unit can predict the level of demand for the future due to being in touch directly with customers and receiving the demand, which, if correctly predicted, will put JIT in the right direction. Another factor is the manufacturing unit, which is the primary basis of any manufacturing firm. Its interruption, as it is affected by many factors, can challenge the performance of JIT. Its constant improvement should not be neglected. Since customers and suppliers on both sides of the supply chain are typically dependent factors, it is crucial to consider other measures for ensuring the satisfaction of such factors, which in turn leads to optimal circulation and performance of the whole system.

The main originality/value of this study is the analysis and identification of critical measures affecting JIT in the supply chain. Considering crucial quality factors to enhance the organization's productivity in using JIT, and the application of the DEMATEL-Dalalah technique as well as ISM to analyze the collected data are other aspects of the research innovation. The identification and evaluation of the positive and significant relationships among influential and impressible factors on JIT, and a real case study in a car manufacturing company distinguish this study from previous studies.