In the process of deep transformation of automobile manufacturing towards Industry 4.0, the efficiency, flexibility, and quality controllability of production lines have become key indicators of the core competitiveness of enterprises. As a benchmark for digital transformation in the industry, GAC Motor Yichang Factory has achieved industry-leading efficiency of producing a new car in 52 seconds with Siemens' fully integrated automation (TIA) solution, and Siemens PLC is the core control center supporting this breakthrough. From 100% automated welding in the welding workshop to flexible switching of multiple vehicle models in the final assembly workshop, the PLC system runs through the entire production process, solving many pain points in traditional manufacturing.
- Welding workshop: AI+PLC realizes full process control of solder joint quality
The welding quality of the white body directly determines the safety performance of the car. The main structure of each car's "white body" contains 2000-3000 different types of welding points, and the traditional sampling mode is difficult to eliminate quality hazards. The welding and assembly workshop of Guangzhou Automobile Yichang Factory adopts Siemens S7-1500 PLC as the main control core, and has built a fully automated control system covering more than 60 welding robots, achieving precise control and quality traceability of the welding process.
In terms of system architecture design, the technical team adopts a "master-slave collaboration" mode: S7-1500 PLC serves as the IO controller, and multiple S7-1200 intelligent devices are connected through PROFINET bus as distributed control nodes, forming a circular redundant topology network. This architecture not only controls the network interruption recovery time within 200ms, but also optimizes data exchange through GET/PUT instructions, reducing robot response delay from 15ms to 3ms, ensuring synchronous welding accuracy among multiple robots. In response to the cross system integration requirements of ABB welding robots, the GSDML file of the robot was imported to complete the configuration of 64 byte solder joint coordinate input and 32 byte status signal output in TIA Portal, and the ProfiSafe protocol was enabled to achieve fast response of emergency stop signal<10ms, completely solving the compatibility problem of different brand equipment collaboration.
In terms of quality control, the deep integration of Siemens PLC and industrial artificial intelligence software has become a key breakthrough. PLC collects 12 process parameters such as welding current, voltage and pressure in real time, analyzes them in real time through edge computing module, and predicts the quality of each welding spot based on machine learning algorithm. When the current fluctuation of a certain welding point exceeds the threshold of ± 5%, the PLC immediately triggers an alarm and records abnormal data, while suspending the operation of the workstation and waiting for manual review. This "real-time monitoring intelligent prediction precise intervention" mode reduces the welding defect rate by 60% and increases the quality inspection efficiency by three times, completely replacing traditional destructive testing methods.
- Final assembly workshop: flexible control and fast switching support for multi vehicle hybrid production
Faced with the demand for mixed production of multiple vehicle models such as SUVs and sedans, the final assembly workshop of GAC Yichang factory utilizes the flexible control function of Siemens PLC to achieve rapid switching of production processes and efficient scheduling of equipment. The workshop control system adopts Siemens S7-1500 PLC combined with distributed IO module ET200SP, which connects more than 300 execution devices through PROFINET bus, covering the entire process of vehicle body transportation, component assembly, inspection, etc.
In response to the pain points of switching between multiple vehicle models, the technical team utilizes the formula management function of PLC to preset the assembly process parameters (such as tightening torque, assembly sequence, detection threshold, etc.) of different vehicle models as independent formulas. When the production plan changes, the operator issues a switching command through the HMI interface, and the PLC can reset all equipment parameters within 10 minutes, improving production line compatibility by 80%. This capability enables the factory to flexibly respond to changes in market orders, and a single production line can achieve mixed production of four vehicle models.
In the logistics transportation process, the factory uses Siemens AGV cars instead of traditional conveyor belts, and achieves intelligent scheduling of vehicle transportation through PLC. S7-1500 PLC real-time collects AGV position, battery level, vehicle model and other data, dynamically adjusts transportation path based on production rhythm. When there is a shortage of materials at a certain workstation, the PLC immediately dispatches the nearest AGV for priority delivery, reducing the waiting time at the workstation by 40%. At the same time, the PLC controlled heavy-duty tilting EMS lifting device achieves 110 degree rotation in both directions of the vehicle body, greatly improving the operational convenience of interior assembly and increasing the per capita assembly efficiency by 25%.
- Whole workshop collaboration: digital control achieves maximum production efficiency
In order to achieve data interoperability and global optimization among various workshops, Siemens PLC has been deeply integrated with the manufacturing operation management platform Opcenter to build a digital control system for the entire process from order issuance to finished product delivery. S7-1500 PLC real-time collects equipment OEE (comprehensive efficiency), energy consumption, faults and other data, and uploads them to the management platform through OPC UA protocol. Management personnel can monitor the operation status of each production line through a visual interface.
In terms of equipment maintenance, the diagnostic buffer of PLC and the OB82 interrupt organization block play a key role. When an IO module fault is detected, the PLC immediately records the fault code, occurrence time, and associated equipment, and pushes it to the maintenance personnel's mobile phone through the WeChat alarm module. By combining the temperature and torque data of robot joint motors collected by PLC, the system can predict potential equipment failures and reduce unplanned downtime by 40%. Through these intelligent control measures, the welding cycle of the final assembly line at GAC Yichang factory has been shortened from 120 seconds per unit to 98 seconds per unit, ultimately achieving industry-leading efficiency of producing a new car in 52 seconds.
- Application effectiveness: Data witnesses the value of upgrading intelligent manufacturing
The comprehensive application of Siemens PLC system in Guangzhou Yichang factory has achieved multiple breakthroughs in production efficiency, quality control, and operating costs: the automation rate of the production line has reached 100%, and the single shift production capacity has increased by 50%; The welding defect rate decreased from 0.8% to 0.32%, and the first pass rate increased to 99.2%; Through predictive maintenance and energy optimization, equipment maintenance costs have been reduced by 35%, and unit product energy consumption has been reduced by 18%. As Zhang Shaowei, Deputy General Manager of GAC Motor Yichang Branch, said, the digital solution with Siemens PLC as the core truly transforms the "Industry 4.0" concept into actual production efficiency.
This case fully demonstrates that Siemens PLC, with its core advantages of precise control, flexible adaptation, and intelligent interconnection, can not only solve specific process pain points in automotive manufacturing, but also build a full process digital production system, providing solid technical support for the intelligent manufacturing transformation of the automotive industry.
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