In today's world, automobiles, as one of the most important means of transportation, occupy a vital position in people's lives and work. Since the birth of the first automobile at Ford in the 19th century, cars have begun to change people's lifestyles and pace of life. The automotive manufacturing industry has evolved from manual to mechanized to automated processes, with continuous improvement and enhancement of manufacturing technology, making automobiles a reliable and safe mode of transportation. It can be said that advanced and safe manufacturing technologies have played an indispensable role, serving as a solid foundation for people's continued acceptance of new automotive products and technologies. The automotive manufacturing industry, in particular, requires safe production . Currently, automotive production lines can be divided into four main stages based on major processes: stamping, welding, final assembly/painting, and engine manufacturing. Firstly, the use of robots greatly improves productivity, but it also makes the production environment more dangerous. The complex pre-programmed movements of robots and the great strength of their robotic arms pose a relatively high safety threat to people in the vicinity. Secondly, most of the metal shells of automobiles, such as the body and chassis, are formed by machine stamping. Currently, the most common method is the use of hydraulic press automated production lines, and the extent of injuries caused by danger around these machines is very serious. In welding environments, whether using welding robots or manual welding, visual fatigue and prolonged repetitive labor can easily increase the risk of production accidents. The squeaking and whooshing sounds of robots moving around also create psychological stress. On assembly and painting lines, the risk of bumps, cuts, and crushing injuries is high. In engine manufacturing, the use of CNC machine tools and milling machines, driven by the pursuit of efficiency and production costs, along with high-speed cutting tools, tool changers, and high-acceleration machine equipment, poses an increasing threat to operators. Advanced production equipment and processes have fueled the prosperity and complexity of the automotive manufacturing industry, but this also increases the risks for workers and necessitates advanced safety protection technologies to ensure their personal safety and protect the company's production safety and interests. Increased competition and cost reduction demands higher levels of automation in the automotive manufacturing industry, but this does not mean that human intervention can be completely eliminated. For production technology, process monitoring, and timely adjustments, the experience and flexibility of humans are unmatched by machines. Therefore, in the highly automated environment of automotive manufacturing, the safety of personnel is particularly important. Safety Protection Technical Standards The technical foundation of safety protection comes from advanced European safety protection technologies. Machines originated in Europe, and after more than 200 years of continuous development and improvement, numerous standards have been established, divided into three different hierarchical structures: Class A, Class B, and Class C standards. Class A standards specify the basic standards that all machines must meet. Class B standards define the commonalities across the entire category of machines. Class B standards can be further subdivided into B1 and B2 standards. B1 standards specify parameters related to safety protection, such as safety distances, surface temperature, and noise; B2 standards specify specific requirements for safety protection devices, such as two-hand buttons, safety door switches, and safety mats. Within the numerous Class C standards, each standard provides detailed specifications for a specific machine device. The most common safety-related standards include EN292, EN1050 Hazard Assessment, and EN954-1 Safety Classification and Use Standards. Regardless of the level of automation, the automotive manufacturing industry is built upon a vast array of machines and production lines of all sizes. All equipment must comply with the corresponding safety standards to ensure the safety of production personnel and machinery. According to the Machine Directive 98/37/EC, the principles of machine safety protection are as follows: 1) Wherever there is danger, protection is required. 2) Protection must be based on the level of danger, analyzed, and appropriate safety protection levels and measures selected accordingly. 3) Safety protection design must follow a specific design sequence and cannot be reversed. Safety should be implemented throughout the entire process from machine design, assembly, and commissioning to manufacturing completion. If the first step cannot completely avoid danger, safety protection measures must be taken. For remaining dangers that cannot be avoided by the above measures, prominent warning signs should be affixed. The instruction manual should provide information on the correct operating methods and warnings for machine safety protection products. Examples of safety protection products used in the automotive industry illustrate the various ways to achieve safety protection for machinery and equipment, such as electromechanical, electronic, hydraulic, and pneumatic methods. The most widely used and technologically mature method is electromechanical. Based on the characteristics and specific safety requirements of the automotive manufacturing industry, appropriate safety standards and product technologies are generally determined in the automotive manufacturing industry based on the required processes, technologies, protected environments, and economic and cost budgets. The main methods that can be adopted are shown in Figure 1. Safety Protection Technology (Safety Protection Against Hazards) Separable Protection Devices Non-Separable Protection Devices Fixed Devices Mobile Devices Fences, Doors, Covers, etc. Position Constraints Position Unconstrained Proximity Functions Contact Switches Electronic Sensing Devices - Position Switches - Door Lock Switches - Carpet Switches - Edge Switches - Light Curtain Switches - Laser Scanning Two-Handed Button Confirmation Switches - Relays - Monitoring Modules - Bus Emergency Stop Switches Figure 1. Common Safety Protection Devices and Products Safety protection devices can be divided into two types: separable protection devices and non-separable protection devices. The former is a more economical approach, requiring mechanical fencing to isolate hazards from people, thus ensuring people stay away from danger. However, it requires a relatively large production area. Access doors are installed where people need to enter and exit, with separable safety door switches and/or safety door lock switches installed on the doors, forming a safety monitoring and protection circuit with safety relays. For example, in the most common automotive production sites: welding robots, assembly robots, etc., are all protected by iron mechanical fences, and door lock switches are installed on the access doors that are not frequently used (Figure 2). The most significant characteristic of safety door switches and door locks is their separate operating mechanism. Using safety door switches and electromagnetic locks requires ensuring that the machinery does not perform dangerous actions when the safety door is open. This is achieved through the definitely-breaking safety contacts inside the door switch and lock. When the safety door is closed, the machine will not be accidentally started. Installing a door switch during machine operation stops any dangerous actions of the machine once the safety door is opened. Using a safety door lock generally ensures the safety door remains locked at all times; entry is only permitted after the machine has stopped and there is no danger. Besides robots used in welding and final assembly processes, safety doors and door locks are also widely used in CNC machine tools and milling machines in engine manufacturing. Safety limit switches can also be installed on the safety door devices of some CNC machine tools, but definitely-breaking safety contacts must be used. The symbol for a definitely-breaking safety contact is: [symbol missing]. Figure 2. Robot on-site diagram. Figure 3. Light curtain/grating application. In the automotive manufacturing industry, characterized by high automation, high integration, and rapid material consumption, frequent entry and exit from hazardous areas are necessary. Light curtains and gratings are often chosen at the entrances to these areas (Figure 3). For example, in the stamping process, there is a need for continuous feeding and picking of materials on stamping equipment. On the final assembly line, when robots are picking up and assembling materials on one side while replenishing production materials on the other, it is undesirable to stop the entire production line, only temporarily halting the picking robot at that station. In such cases, light curtains/gratings become the best choice. Safety light curtains/gratings with shielding functions are even more widely used in the automotive manufacturing industry. Through configuration, these gratings can intelligently determine whether the light is blocked by a product or a person, and accordingly stop the machine or ignore it. Moreover, this design protection principle is replicated as much as possible throughout the entire production line. This is why photoelectric gratings and light curtains are most widely used on automotive lines (Figure 4). After designing and installing light curtains and gratings, it is essential that people cannot bypass them to enter hazardous areas. Furthermore, excessively strong ambient light can interfere with the reliability of robot movements. Therefore, safety doors and locks are widely used in welding processes. Figure 4. Shielded light curtain/grating; Figure 5. Safety mat; Figure 6. Safety module . Contact-type safety mats are also widely used. Safety mats must comply with the European Community standard EN1760-1 (Figure 5). Typically, safety mats are used to protect hazardous areas with frequent foot traffic. When someone passes by or stands on the safety mat, it detects the pressure and outputs a disconnect signal via a matching detection relay. Safety mats are very robust, even withstanding vehicle traffic. The outer layer of the safety mat is made of a special rubber material with high abrasion resistance and water resistance, and can withstand corrosion from various chemicals. In the safety protection of machinery and equipment, to improve reliability, especially for highly dangerous machinery and equipment, safety monitoring modules are used to enhance the level of safety protection. In addition to detecting the activation of safety switches and the operation of emergency stop switches, safety monitoring modules, depending on their design, can also detect other faults in the safety circuit: switch/sensor failure; circuit open circuit; circuit short circuit; ground short circuit; soldering of output contactor contacts; relay failure of the module; detection circuit fault; insufficient operating voltage, etc. (Figure 6). All machinery and equipment must have an emergency stop function (with only a few exceptions). Emergency stop switches can only be used as an additional hazard prevention measure for machinery and equipment, and cannot replace necessary safety protection devices, nor can they be used as automatic safety devices. On automotive assembly lines, emergency safety pull-cord switches are the most common emergency stop devices; in an emergency, pulling the cord at any point will stop the machine. One pull-cord switch is equivalent to several emergency stop buttons. All safety protection products are manufactured in accordance with certain safety standards. In addition, there are two-hand protection devices, safety edge switches, complex area protection laser scanners, etc., which will not be described in detail here. Conclusion With the development of economic globalization, the standards selected by the International Organization for Standardization for machine safety protection are mostly based on relevant European/German standards. The development and naming of these standards will subsequently appear in the form of ISO EN XXX or EN ISO XXXX. In contrast, my country's national standards are mainly derived from ISO international standards, but currently, there are no complete corresponding standards for machine safety protection. Following European standards is currently the best choice. There is reason to believe that with the rapid development of the automotive manufacturing industry, safety technology will also develop significantly along with advanced automotive manufacturing technologies. As automotive manufacturing and processing technologies are promoted, safety protection technologies will inevitably be applied to a wider range of fields.