1. Project Overview

This solution applies a machine vision inspection system in the post-printing stage for finished social packaging products. High-speed industrial cameras conduct real-time image capture together with intelligent inspection software to deliver comprehensive inspection covering printing defects, barcode quality, variable data, label stains, missing prints, die-cut misalignment, gold & silver hot stamping flaws, mixed serial numbers and other issues. It realizes automatic identification and effective rejection of wrong, missing and defective labels to guarantee factory pass rate, control finished product quality and satisfy quality inspection requirements for mass label production.

2. Inspection Requirements and Performance Indicators

To meet full-dimensional inspection demands, the system is designed with the following core indicators:

Inspection Mode: Offline inspection after printing

Applicable Materials: Coated art paper, white cardboard, grey cardboard, gold and silver cardboard

Inspection Width: 300~350 mm

Operating Speed: Stable inspection speed with a maximum of 120 m/min Inspection Precision:

① Minimum detectable area for defects including missing prints and dirt spots: Front side ≥0.2 mm²;

② Overprint deviation inspection: ≥0.2 mm

③ Die-cut deviation inspection: ≥0.2 mm

④ Scratches: Horizontal or vertical scratches with vertical width over 0.2 mm, horizontal width over 0.15 mm, length over 15 mm and contrast above Grade 20 can be detected;

⑤ Partial color difference inspection ΔE≥2.5 ΔELab

3. Full-Dimensional Core Inspection Functions

3.1 Printing and Appearance Defect Inspection (Standard Fixed Content Labels)

The system compares samples with templates to identify surface physical and printing flaws in real time:

Printed Texts & Patterns: Missing print, blocked plates, dirt spots, ink specks, streaks, ink splashes, knife lines.

Color Control: Supports online color difference monitoring and quantitative inspection of overall or local printing color deviation.

Post-Processing Structures: Die-cut misalignment, glue overflow, missing labels (broken strips).

Special Processes: Misaligned or missing gold & silver hot stamping, uneven varnish coating or surface scratches.

3.2 Variable Data and Barcode Compliance Inspection (Intelligent Variable Content Labels)

Carry out information comparison for high-standard labels used in pharmaceutical, food, electronics and other industries:

First-level quality grading for barcodes and QR codes.

Real-time reading of 1D barcodes and 2D QR codes.

Real-time online quality grading of barcode indicators including contrast, modulation ratio and decodeability. Automatic rejection and alarm will be triggered if the grading result falls below the preset standard.

3.3 Text Inspection

Automatically identify and match template text contents including production date, batch number, shelf life and serial number.

Verify text integrity and readability to avoid incomplete or broken characters.

Duplicate & Missing Code Prevention Control: The system dynamically compares code packages and code pool databases. Interception will be activated once duplicate printed serial numbers or skipped serial numbers are detected.

4. Hardware System Architecture

Top-tier industrial cameras and light sources are deployed for the inspection system to cope with harsh high-reflection and high-speed working environments. Custom hardware configurations are available to satisfy diverse customer demands.

4.1 Industrial Cameras

① Line Scan Camera: Suitable for high-speed wide-width label inspection with continuous scanning imaging.

② Area Scan Camera: Suitable for single-piece label inspection or low-speed fixed-station inspection. Color / Monochrome Cameras: Color cameras are mandatory for color difference and colored pattern inspection; monochrome cameras deliver higher resolution for structural and barcode-only inspection.

4.2 Light Source System

Labels are made of various materials. Dome shadowless lights are adopted for high-reflective materials to eliminate surface reflection; strip lights or ring lights are used for ordinary materials.

4.3 Image Capture Card and Processing Host

Ensure real-time data transmission and processing under high-speed printing conditions.

5. Closed-Loop Control and Defective Product Disposal Mechanism

Defect detection is only the preliminary step, while effective interception serves as the core of post-print inspection.

The inspection machine adopts a high-speed rejection mode. For inspected cut single-piece labels, the system links pneumatic blow-off valves or mechanical push rods to eject defective labels to waste collection areas.

6. Data Management and Upstream Process Tracing

Automatic Defect Classification & Statistics: The system automatically categorizes detected defects (e.g. 30% missing prints, 50% dirt spots, 20% low-grade barcodes) and generates pie charts and trend graphs.