Quality Improvement in Meranti Plywood Manufacturing Using Six Sigma DMAIC and the Seven Basic Quality Tools

Abstract

The plywood industry must maintain strict standards of quality if it is to survive the global market competition and be sustainable in terms of resources. In this paper, a quality assessment of meranti (Shorea spp.) plywood in Indonesia is reported, based on QC records from January–December 2024 covering 188,015 panels, which employs the integrated Six Sigma DMAIC and the Seven Quality Tools. The study highlights the major defects responsible for production losses, including insufficient core, thinness, blistering, press marks, and brittleness. An assessment of the performance through Sigma level calculation showed a value of 3.1, computed from the DPMO using five defect opportunities per panel and the conventional 1.5 sigma shift. The use of Fishbone Diagrams and P charts (included in the Results) helped identify process instability and highlight root cause patterns related to machine calibration, operator performance, and thermal variation. Proposed improvements include a proactive maintenance schedule and standardized SOPs for adhesive application and pressing. This approach can be used to scale up yield and quality in the wood-based industry.