Statistical Process Control Fundamentals in Packaging Substrate Converting
Statistical process control in substrate converting relies on sub-grouping across machine direction variance and isolating non-normal barrier defects.
Roll Mapping
Quality Tracking
Digital records link the exact spatial position of physical defects to their corresponding location on a wound roll of paperboard. In modern paper mill operations, roll mapping compiles sensor data from the scanning frame to build a two-dimensional layout of the paper web’s quality. This file travels with the roll to the slitter and the printing press, allowing automated systems to remove defective material before it enters the production stream.
System Integration
As the paper web is wound, scanners detect and record any occurrences of holes, streaks, or wet spots along the length and width of the sheet. The roll mapping software indexes these anomalies to the reel’s linear footage, generating a digital map that details where each defect resides. When the roll is mounted on the high-speed slitter or the printing press, the machine reads the map and can slow down or stop to allow the operator to splice out the bad section.
This prevents defective board from reaching the die-cutter, where a major flaw could damage the expensive steel rules or the counter plates.
Waste Reduction
Automating the rejection of defective segments reduces the volume of hand-sorted waste and increases the yield of first-quality cartons. This tracking boosts the productivity of both the mill and the converter.