Vibropac Machinery Co.,Ltd , https://www.vibropac-power.com
Application of QR code technology in engine parts processing line
In 2012, Nanjing Automobile Group Co., Ltd. introduced Direct Part Marking (DPM) technology into its production process, marking a significant step toward achieving precise traceability for key engine components. The system first enabled accurate tracking of the engine block, cylinder head, and crankshaft. However, due to limited space on parts like the connecting rod and camshaft, it was not feasible to print QR codes on them, so only batch-level traceability was possible for these components.
The implementation involved setting up nine two-dimensional code marking and scanning stations along the cylinder line, cylinder head line, and crankshaft line. These stations were responsible for printing the QR code directly onto the workpieces. The code included essential information such as the part identification code, part number, and blank supplier code. After printing, the QR code was scanned using a dedicated scanner, and the data—along with measurement results—were uploaded via the PT-MES system to the Q-DAS database. This integration allowed for real-time tracking and quality control throughout the assembly process.
DPM, or Direct Part Marking, is a specialized marking technology that enables direct labeling on component surfaces without the need for labels or tags. It’s often referred to as “direct part identification†and is particularly useful in industrial environments where durability and accuracy are critical.
In our factory, the use of QR codes for marking is primarily automated. Once a workpiece is positioned and clamped, a proximity sensor sends a signal to the PLC controller. Based on pre-set logic, the controller transmits the necessary data—such as the component identification code, part number, and supplier code—via an RS232 interface to the marking machine. The machine then prints the QR code on the surface of the workpiece. A scanner later reads the code, ensuring that all data is captured accurately.
As shown in Figure 1, pneumatic marking is used on the upper line of the cylinder and cylinder head lines, while laser marking is applied at the discharge point of the final inspection equipment on the crankshaft line.
Figure 1: Two-dimensional code practical application
At the cylinder head line, two-dimensional code marking and scanning stations are strategically placed at different stages of the production process. For example, the upper-line marking station is located at OP10, the lower-line scanning station is at the quality gate (OP150), and a middle scanning station is set at OP50. Similar setups are also found in other lines.
The on-line marking and scanning process involves several steps:
1. The operator clicks the "Cycle Start" button on the HMI interface.
2. The sensor detects the workpiece, and the spacer mechanism separates the next piece.
3. The clamping mechanism positions and secures the workpiece.
4. The system checks if the supplier model matches the one stored on the panel. If not, an alarm is triggered.
5. The marking machine moves into position.
6. The system sends the serial number to the marking machine, which prints the QR code.
7. After printing, the marking machine returns to its initial position, and the scanner takes over.
8. The QR code is scanned and decoded.
9. If decoding fails, the system alerts the operator, who can retry or manually input the code.
10. If the same code is repeated, the system warns the operator.
11. If successful, the workpiece is released.
For offline scanning stations, the process is similar but more manual. When a workpiece reaches the scanning station, the system automatically captures and decodes the QR code. If the scan fails, the operator can manually enter the data or use the rescan function. In extreme cases, the bypass button allows the workpiece to be released regardless of the scan result.
To achieve full product traceability, the PT-MES and Q-DAS systems play a crucial role. Through PT-MES, users can query product information by selecting criteria such as product, time, or location. Each entry includes details like the serial number, steel stamp number, status, workstation, and operation code.
Q-DAS is used for measuring data queries. For instance, when checking the leakage measurement of a cylinder cover at OP50, the software connects to the database, retrieves the measured value, and displays it alongside traceability information like the measurement date and time.
Common issues with the QR code traceability system include low scanning rates, inconsistent reading between lines, and incorrect Andon counts. Solutions such as adjusting lighting, camera angles, and print depth have improved the success rate to over 99.9%. Ensuring consistent settings across all scanners has also resolved issues with mismatched readings.
In conclusion, two-dimensional code technology has proven invaluable in engine manufacturing, offering a reliable and efficient method for traceability and quality control. While implementing such a system requires careful coordination of processes, equipment, and data integration, the benefits make it a powerful tool for modern production management. With continuous refinement, this technology will continue to drive improvements in efficiency and product quality.