OPSI
Vol 18 No 2 (2025): OPSI - December 2025

Enhancing quality in plastic manufacturing: Six sigma application to polybox containers

Priyanti, Nadia Nabila (Unknown)
Saragih, Johnson (Unknown)
Mayusda, Idriwal (Unknown)



Article Info

Publish Date
30 Dec 2025

Abstract

Historical production data from November 2021 to February 2022 revealed that polybox plastic containers suffered from a 2.84% defect rate, exceeding the company’s 2% threshold. This study applies the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology to enhance product quality. The Define phase utilized SIPOC and Critical to Quality (CTQ) diagrams to outline quality characteristics. In the Measure phase, P and U Control Charts established a baseline performance with a Defect Per Million Opportunities (DPMO) of 8,420 and a sigma level of 3.89. The Analyze phase employed Fishbone diagrams and Failure Mode and Effects Analysis (FMEA) to isolate root causes. High Risk Priority Numbers (RPN) highlighted worker carelessness (294), welding inaccuracies (252), and manual handling issues (210). Consequently, the Improve phase implemented new Standard Operating Procedures (SOPs), welding guidelines, and hand-truck trolleys. Post-implementation monitoring during the Control phase showed immediate improvements: the DPMO dropped to 6,305, and the sigma level increased to 3.99. These findings confirm the efficacy of Six Sigma interventions in reducing manufacturing defects and aligning production with quality standards.

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Journal Info

Abbrev

opsi

Publisher

Subject

Industrial & Manufacturing Engineering

Description

Jurnal OPSI adalah Jurnal Optimasi Sistem Industri yang diterbitkan oleh Jurusan Teknik Industri UPN “Veteran” Yogyakarta sebagai wahana publikasi hasil karya ilmiah, penelitian rekayasa teknologi di bidang Teknik Industri, Sistem Industri, Manajemen Industri dan Teknologi ...