Utilizing Lean Six Sigma and Waste Assessment Model to Reduce Waste in the Hot Rolled Coil Production

Industrial and Systems Engineering Department, Institut Teknologi Sepuluh Nopember, Surabaya

^* Corresponding author: rindi@its.ac.id

Abstract

The global steel industry is pivotal, driven by substantial demand. In Indonesia, a leading steel manufacturing company, boasting significant production capacities for Hot Rolled Coil (HRC) and Cold Rolled Coil (CRC) products, with capacities of 2,400,000 and 850,000 tons per year. However, current production lags at 1,500,000 and 500,000 tons annually for HRC and CRC. Notably, the production process recorded defect ratios of 15.85%, 15.65%, and 15.56% from 2020 to 2022, with waste waiting accounting for a breakdown time and operating time ratio of ±40%. The study employs Lean Six Sigma to analyze and mitigate waste during HRC production, aiming to augment product value, production efficiency, and cost reduction. Through Value Stream Mapping and Process Activity Mapping, 44.93% of Necessary Not Value- Added Activities (NNVA). In the next stage, critical wastes including waste defects, overproduction, and waiting are selected using the Waste Assessment Model. The Analysis stage employs fishbone diagrams and Failure Mode and Effect Analysis to determine root causes and assess risk. Proposed improvements include toolbox meetings, maintenance scheduling, check sheets, a work roll replacement algorithm, and sensor adjustments, projected to raise sigma values significantly for waste defects, overproduction, and waiting.