Defect reduction using DMAIC and Lean Six Sigma: a case study in a manufacturing car parts supplier

Abstract

PurposeCompetitive pressures force companies to seek solutions to eliminate wastes while improving product quality. Lean Six Sigma (LSS) has been considered one of the most effective approaches for business transformation. This article aims to present an empirical case study where LSS and Define, Measure–Analyze–Improve–Control (DMAIC) methodologies are applied to reduce defects in a car parts manufacturer.Design/methodology/approachThe study follows the DMAIC methodology. Design of experiments and hypothesis testing were applied in a single case study.FindingsThe main defects and the main factors that cause defective parts were indicated for die-casting and machining processes. Solutions implemented reduced the defect incidence from a chronically high level to an acceptable one. The sigma level rose from 3.4 s to 4 s sustainably.Research limitations/implicationsThe study is limited to a single case study, without intention of generalizing the results to other types of industries.Practical implicationsThis paper can be a useful guide of how to use DMAIC Six Sigma approach to defect reduction and can be applied in many sectors.Social implicationsThis study offers the knowledge on how to apply the Six Sigma DMAIC methodology, reducing the dependence on specialization courses.Originality/valueThis study describes in detail the process used in a structured improvement exercise including sigma-level calculation, factorial experiments and hypothesis tests – a set of techniques still poorly combined in the literature.

Operational excellence of the steel industry using the Lean Six Sigma approach: a case study

“…The voice of the customer is integrated into the definition of lean value. Lean manufacturing reduces work in process, cycle time, lead time, conversion costs, space requirements, equipment downtime, waste and overall costs (Adeinat et al, 2022;Cond e et al, 2023;Hariyani and Mishra, 2022). It offers benefits such as increased inventory turnover, capacity, customer satisfaction, sales, return on assets, labor productivity, product quality, on-time delivery, overall productivity, financial performance, market performance, competitive market position and various intangible advantages (Gijo et al, 2018;Panayiotou et al, 2022).…”

“…Lean manufacturing reduces work in process, cycle time, lead time, conversion costs, space requirements, equipment downtime, waste and overall costs (Adeinat et al. , 2022; Condé et al. , 2023; Hariyani and Mishra, 2022).…”

“…Reducing process variations is another critical aspect of LSS implementation, as variations can lead to inefficiencies, defects and customer dissatisfaction (Cond e et al, 2023;Costa et al, 2021;Ricciardi et al, 2020). LSS employs statistical tools and techniques such as Design of Experiments (DoE), control charts and Failure Mode and Effects Analysis (FMEA) to measure, analyze and mitigate process variations, ensuring consistent and predictable outcomes (Murmura et al, 2021;Noronha et al, 2022;Pereira et al, 2019;Svensson et al, 2015;Tannady et al, 2019).…”

“…Reducing process variations is another critical aspect of LSS implementation, as variations can lead to inefficiencies, defects and customer dissatisfaction (Condé et al. , 2023; Costa et al.…”

A Novelty Procedure to Identify Critical Causes of Materials Incompatibility

“…It refers to the processing and production of products compatible with quality [ 3 , 4 ], in order for special processes to be realised based on the validated algorithm or method [ 5 , 6 ]. The companies are taking different actions in this area [ 7 ]. One of the basic actions is the investigation of the quality of materials and processes according to the qualitative analysis method for materials, products, or production processes [ 8 , 9 ].…”