liquid level detection machine
1.Using graphical man-machine interface , intuitive and concrete
2.The processing speed is fast, the inspection accuracy is high, the fastest speed can reach 50000 BPH
3.Simple operation, easy to production line staff
4.Multi angle inspection, no dead angle, less manual intervention, low false tick rate
5.Using high brightness LED light source, adjustable brightness, long lfe, energy saving,maintenance free
I. Project Equipment Overview
Project Name: PET Bottle Cap, Anti-theft Ring, Liquid Level, and Inkjet Printing Inspection System
Project Description: This system is designed to inspect PET bottles for defects related to caps, anti-theft rings, liquid levels, and inkjet printing, and to automatically remove non-conforming bottles from the production line.
Maximum Throughput: 60,000 bottles/hour
Applicable Container: PET bottles
Product Capacity Range: 200 ml – 2 L
II. Environmental Conditions
Operating Altitude: 5–3000 meters above sea level
Operating Temperature: 5°C – 40°C
Relative Humidity: 50% – 65% RH
Factory Requirements: The production site must comply with national standards regarding floor levelness, load-bearing capacity, and other conditions to ensure stable equipment operation.
Storage Conditions: After delivery, components and equipment must be stored in facilities that meet relevant standards. Proper lubrication and regular maintenance should be performed during storage to prevent surface damage, corrosion, or deformation that could impact installation, commissioning, or operation.
III. Equipment Operating Conditions
Power Supply: 220V, 50Hz, single-phase (to be provided by the customer; non-standard voltages must be confirmed in advance as they may affect specifications, delivery time, and pricing).
Total Power Consumption: Approx. 2.4 kW
Control Voltage: 24 VDC
Compressed Air: 4–12 Pa (customer must supply the pipeline connection from the air source to the main unit).
IV. Equipment Description
Installation Location
Installed on the production line at the designated inspection point.Inspection Scope
Missing cap
Over-height cap
Tilted cap
Broken or damaged anti-theft ring
Low liquid level
Missing inkjet code
Excessive inkjet printing
Detection Principle
As each PET bottle passes the positioning sensor, the control unit records the bottle’s ID along with the corresponding encoder signal.
The positioning sensor triggers the camera system to capture images of the cap, liquid level, and inkjet printing. These images are processed by the image processor, with the results displayed in real-time on the HMI and simultaneously transmitted to the PLC for defect evaluation.
If a defect is detected, the control unit issues a command to the rejector, which removes the identified bottle from the line according to its ID.
4. Equipment mechanical components
model
| Name | Components | Functional Description | Remark
|
1 | Distribution cabinet | Composed of an image processor, an interface processor, a strobe controller, and a PLC. | Provides power to the entire system, processes images, and controls the rejection of defective products. | |
2 | Detection module | LED light source, industrial CCD camera, and sensor. | Dynamically captures images of PET bottles. | |
3 | Rejection device | Main components include solenoid valves and mechanical components. | Receives signals and controls the rejection of defective products. |
5. Electrical composition of the equipment
model
| Name | Unit | Brand Notes | Quantity |
1 | Embedded imaging industrial computer (4 Ethernet ports) i5+4G+120G | Unit | Taiwan Chaoen, dust-proof, fast processing speed, and excellent stability | 1 |
2 | DAHUA high-speed gigabit digital camera | Unit | Resolution 680x480, imported from Canada, industry-leading brand | 4 |
3 | Camera I/O module | Set | Made-in-China | 4 |
4 | Lens | Piece | COMPUTAR 6MP, 12mm | 4 |
5 | Camera-50/30line cable | Piece | Made-in-China, 5m | 4 |
6 | MW.24v DC power supply 75/120W (DRP-75/120-24) | Piece | Taiwan Mean Well | 2 |
7 | PLC | Piece | Maotong independently developed | 1 |
8 | Touchscreen display | Piece | Taiwan IEI 15-inch | 1 |
9 | Light source controller | Unit | Customized in China, 4-way asynchronous triggering, screen flicker control technology, significantly extending light source life | 1 |
10 | Photo light source | Unit | Customized surface lighting, infrared, and blue | 4 |
11 | Power distribution cabinet | Piece | Made-in-China, 304 material, brushed, pickled, oxidized, and brushed finishes | 1 |
12 | Single-stage rejector Mono | Piece | Customized, air-push type, 304 material | 1 |
13 | Reject unit cylinder | Piece | Norgren high-speed cylinder, UK | 1 |
14 | Reject unit solenoid valve | Piece | MAC high-speed solenoid valve, US, 4.9ms response speed | 1 |
15 | Encoder | Piece | Made-in-China, Hode, incremental type | 1 |
16 | Low-voltage electrical components | Piece | Schneider, France | Several |
17 | Image processing system | Piece | Maotong independently developed, can develop V3.0 according to customer needs | 1 |
18 | Special equipment refrigeration unit - industrial air conditioner | Piece | Shanghai Highly Special, cooling capacity 320W | 1 |
19 | Terminal blocks | Piece | Honeywell, USA | Several |
20 | Photoelectric sensor | Piece | Leuze, Aurora PNP | 1 |
21 | Other electrical components | Piece | - | Several |
22 | Cabinet material and surface treatment | Piece | 304 material, igus® mechanical parts, brushed, pickled, oxidized, and brushed finishes. | 1 |
23 | Alarm light | - | Several | |
24 | Oil-water separator | - | Schneider tri-color tower light | Several |
25 | Relay | Piece | 1 | |
26 | Glass material | Piece | AirTac | 1 |
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)
This module employs three CCD cameras positioned at different angles to capture bottle images, minimizing blind spots. Equipped with specialized optical lenses, it filters incoming light from all directions to achieve high-quality imaging. The system is primarily used to identify cap defects, including missing caps, misaligned caps, tilted caps, and damaged caps.
PET bottle capping images captured by CCD camera
8. Liquid Level Detection
This module employs a CCD camera to capture frontal images of the liquid level, ensuring that the liquid surface appears nearly horizontal when the bottle is at rest. Through image processing techniques, the section below the liquid level is displayed as black, while the empty portion above appears white. A dedicated algorithm is applied to reliably differentiate whether the liquid level is above or below the preset threshold.
9. Inkjet Printing Inspection
This module utilizes a CCD camera to capture front-facing images of the inkjet codes on both bottles and caps. The acquired images are digitally processed and analyzed to identify any defects in the print quality. Bottles with non-compliant inkjet markings are automatically and accurately rejected. The system supports inspection for both yellow caps with black ink and black caps with white ink.
Sample image recognition processing effect
10. Detection accuracy
Inspection Items | Inspection Contents | Detection accuracy
| Rejection rate
|
| No cap | —— | ≥99.99% |
High cap | ＞0.8 mm | ≥99.98% | |
Crooked cap | ＞0.8 mm | ≥99.5% | |
Safety ring 100% disconnected | ＞1mm gap | ≥99.99% | |
Safety ring >70% broken | ＞1mm gap | ≥98.32% | |
Safety ring >50% broken | ＞1mm gap | ≥95.78% | |
Safety ring 100% missing | —— | ≥99.99% | |
Safety ring 70% missing | —— | ≥98.21% | |
Safety ring 50% missing | —— | ≥95.78% | |
Inspection Items | Liquid level detection (high and low) | 3mm below (or above) the standard
| ≥99.92% |
Bottle Cap Inspection | No inkjet print | ≥99.99% | |
Overall inkjet print 50% missing | ≥99.95% | ||
Overall inkjet print 30% missing | ≥99.9% | ||
Overall inkjet print 20% missing | ≥99.8% | ||
Inkjet print is blurred enough to remove the inkjet characters after processing | ≥99.99% |
