PUTRI, Icha Ayu Azzara; SITANIA, Farida Djumiati; SUKMONO, Yudi. Preventive Maintenance Analysis to Improve the Readiness of Heavy Equipment Hydraulic Excavator Liebherr R9250 & R9350 with Six Sigma Method at PT. XYZ. IJIEM - Indonesian Journal of Industrial Engineering and Management, Jakarta, Indonesia, v. 5, n. 3, p. 701–711, 2025. DOI: 10.22441/ijiem.v5i3.22917. Disponível em: https://training-ojs3-publikasi.mercubuana.ac.id/index.php/ijiem/article/view/22917. Acesso em: 28 may. 2026.