Root cause analysis of production defects in a foundry using lean tools

Abstract

Inlcudes bibliographical references.Lean manufacturing is one of the philosophies that many major businesses have been trying to adopt in order to remain competitive in an increasingly global market. This research project focuses on the implementation of lean principles, standardizing operations in the production line and thereby improving productivity. The study is conducted in a large-scale metal casting company, Atlantis Foundries which manufactures cylinder blocks and gear box castings. At present scrap and rework rate of heavy duty, cores exceed set targets; this is a major quality concern for the company. From literature, it is known that the introduction of standardized work is one of the best practices in building the quality of products. Therefore, project focuses on introduction of standardised work at the core shop heavy duty flow line for reducing scrap rate, reducing rework rate and for increasing the production of heavy-duty cores. To know how the employees accept standardised work, it is essential to diagnose the employee behaviour. The project analyses the behaviour of core shop heavy duty flow line employees towards the introduction of standardised work. Moreover, this project analyses the personal and training development of employees, whether employees structure their work environment (5S) and existence of the seven wastes at core shop heavy duty flow line by means of a structured standardized questionnaire. At the end, this project uses A3 Practical problem solving report (PPS) for analysing the root cause of production defects for reducing the increase in rework occurred at the core shop heavy duty flow line after the introduction of standardised work. Standardised work was introduced with the generation of standard work instruction, job element sheet, skills training matrix and layered process audit prepared in consultation with the operators. On analysis of production figures, it was known that the introduction of standardised work reduced scrap rate, reduced rework rate and increased production. Analysis of employee behaviour, personal and training development of employees, structuring of work environment (5S) and the existence of the seven wastes with questionnaire resulted in the respective conclusion that the employees are satisfied with standardised work, personal and training development of employees increased, employees structure their work environment and lesser existence of the seven wastes at core shop heavy duty flow line. Analysis with PPS resulted that increase in rework was due to the worn bushes of Machine 150. Hence, the checks for worn bushes of Machine 150 were included in change over procedures and total productive maintenance activities. The project suggests that lean tools like standard work instruction, job element sheet, skills training matrix and layered process audits need to be introduced at each department of the company. Standard work instructions need to be introduced for changeover as well as for total productive maintenance checks. TPM checks must be done regularly at all stations of core shop heavy-duty flow line