Inkjet defect detection machine

I. Project Equipment Overview

1. Project Name: Inkjet Printing, Liquid Level, and Anti-Theft Ring Inspection System

2. Project Description: This system inspects PET bottles for cap integrity, anti-theft ring condition, liquid level accuracy, and inkjet print quality, with automatic rejection of defective products.

3. Maximum Throughput: Up to 60,000 bottles per hour

4. Applicable Bottle Type: PET bottles

5. Product Capacity Range: 200 ml – 2 L

II. Environmental Conditions

1. Altitude Range: 5–3000 meters above sea level

2. Ambient Temperature: 5°C – 40°C

3. Ambient Humidity: 50–65% RH

4. Factory Requirements: Floor levelness, load-bearing capacity, and other site conditions must comply with relevant national standards to ensure stable operation of the equipment.

5. Storage Conditions: Upon delivery, equipment and components must be stored in facilities that meet national standards. During storage, proper lubrication and preventive maintenance must be performed to avoid surface damage or deformation that could affect future installation, commissioning, and operation.

III. Equipment Operating Requirements

1. Power Supply: 220V, 50Hz, single-phase (special voltages must be confirmed in advance; variations may affect equipment specifications, delivery schedule, and pricing).

2. Total Power Consumption: Approx. 2.4 kW

3. Control Voltage: 24 VDC

4. Compressed Air Supply: 4–12 Pa (customer to provide air pipeline from the source to the equipment main unit).

IV. Equipment Overview

1. Installation Location: To be positioned according to production line layout.

2. Inspection Parameters:

• Missing cap

• Raised cap

• Misaligned cap

• Broken anti-theft ring

• Low liquid level

• Missing inkjet code

• Excessive or misprinted inkjet code

1. As a PET bottle passes the positioning sensor, the sensor identifies its presence and sends a signal to the control unit. The control unit assigns a unique ID to the bottle and synchronizes it with the encoder’s real-time position data.

2. The sensor then triggers the camera system to capture images at three key inspection points: bottle cap, liquid level, and inkjet marking (inspection targets the print itself, not the printer). The captured images are analyzed by the image processor, with results simultaneously displayed on the HMI (Human-Machine Interface) and sent to the PLC (Programmable Logic Controller) for decision-making.

3. If defects are detected, the PLC correlates the rejection signal with the bottle’s unique ID and instructs the rejector to remove the identified non-conforming bottle from the production line.

4. Equipment mechanical components

5. Electrical composition of the equipment

6. Testing cabinet structure diagram

Capping liquid level detection (capping liquid level detection at stations one and three)

Inkjet printing inspection (station 2, single-camera inkjet printing inspection)

7. Cap Inspection

This module employs three CCD cameras positioned at different angles to capture images of each bottle, effectively minimizing blind spots. Equipped with specialized optical lenses, it filters light from multiple directions to enhance image clarity and acquisition efficiency. The system is designed to identify cap-related defects, including missing caps, raised caps, tilted caps, and damaged caps.

PET bottle capping images captured by CCD camera

8. Liquid Level Detection

This module uses a CCD camera to capture a frontal image of the bottle’s liquid level. It ensures that the liquid surface inside the container appears horizontally aligned when the bottle is at rest. Through image processing, the region below the liquid level is rendered black, while the upper portion representing the empty space of the bottle is shown in white. A specialized algorithm is then applied to distinguish whether the liquid level is above or below the preset threshold.

             PET bottle image captured by the camera         Processed liquid level detection image

9. Inkjet Printing Inspection

This module uses a CCD camera to capture images of the inkjet printing on bottles and caps from the front. It then digitally analyzes the captured images and automatically and accurately rejects bottles with unqualified inkjet printing. It is compatible with both yellow caps with black ink and black caps with white ink.

Sample image recognition processing effect

10. Detection accuracy