Basic Safety Knowledge for Mechanical Operations

1. What are the main causes and types of injuries caused by mechanical accidents?
Injuries caused by mechanical accidents primarily include the following types:
1. Injuries caused by rotating parts and components of machinery and equipment. For example, gears, pulleys, sheaves, chucks, shafts, lead screws, spindle assemblies, and other components in machines and equipment are all designed to rotate. The primary ways these rotating parts can injure workers are through entanglement and being struck by flying objects.
2. Injuries caused by the linear motion of machine components and parts. For example, the ram of forging hammers, punching machines, shearing equipment, the pressing elements in plate-cutting machines, the headstock of horizontal shapers, the bed surface of gantry cutting machines, as well as the trolleys and lifting mechanisms of overhead cranes—these all move in straight lines. Accidents resulting from the linear motion of such components typically involve crushing, impact, and pinching injuries.
3. Injuries caused by cutting tools. For example, lathe tools on lathes, milling cutters on milling machines, drill bits on drilling machines, grinding wheels on grinders, saw blades on sawing machines—and many others—are all types of cutting tools used in machining parts. The primary injuries these tools can cause during the machining process include burns, punctures, and cuts.
4. Injuries Caused by Machined Parts: During the machining process, mechanical equipment can pose a risk of injury to personnel. The most common types of accidents include: ① Machined parts that are not securely fixed may fly off unexpectedly and strike workers—such as when a workpiece slips out of a lathe chuck during rotation, potentially causing serious harm. ② Machined parts could fall or drop during lifting, handling, or loading/unloading, leading to crushing injuries.
5. Injuries Caused by Electrical Systems. Most of the machinery used in factories is powered by electricity, meaning each piece of equipment comes equipped with its own electrical system. Key components typically include electric motors, distribution boxes, switches, buttons, local lighting fixtures, as well as proper grounding (earthing) and power supply cables. The primary risk to workers from electrical systems is electric shock.
6. Injuries caused by hand tools.
7. Other types of injuries: In addition to the various hazards mentioned above, machinery and equipment can also cause other kinds of harm. For instance, some machines generate intense light or high temperatures during operation, while others emit chemical energy, radiation, or even release hazardous substances like toxic dust—each of which poses potential risks to human health.

2. What are the basic safety requirements for mechanical equipment?
The basic safety requirements for mechanical equipment are primarily:
1. The layout of mechanical equipment should be well-organized, ensuring ease of operation for workers when loading and unloading workpieces, monitoring the machining process, and removing debris—while also facilitating convenient access for maintenance personnel to inspect and repair the machinery.
2. The strength and rigidity of mechanical equipment's components must meet safety requirements, and they should be securely installed to prevent frequent malfunctions.
3. Mechanical equipment must be equipped with safe devices that are reasonable, reliable, and do not interfere with operation, in accordance with relevant safety requirements.
For example:
(1) Rotating parts and components must be equipped with safety guards, protective barriers, guardrails, or other similar protective devices to prevent entanglement injuries.
(2) For components and parts that may lead to hazardous accidents due to overpressure, overload, overtemperature, overtravel, or other similar conditions, safety devices should be installed—such as overload limiters, travel limiters, safety valves, temperature relays, time relays, and more. These devices are designed to detect dangerous situations and automatically activate, mitigating risks and preventing accidents from occurring.
(3) When certain actions require warning or alerting people, appropriate signaling devices or warning signs should be installed. These may include audible signals such as electric bells, horns, and buzzers, as well as various visual signals like lights and different types of warning signs—all of which qualify as safety devices in this context.
(4) Interlocking devices should be installed for components and parts whose sequence of operations cannot be reversed. Specifically, a particular action can only proceed after the previous one has been completed; otherwise, the action simply cannot occur. This ensures that accidents are prevented due to incorrect sequencing of operations.

4. The electrical installations of mechanical equipment must meet electrical safety requirements, primarily including the following points:
(1) The power supply wires must be installed correctly, with no damage or exposed copper areas.
(2) The motor insulation should be in good condition, and its terminal block must be covered with a protective cover to prevent direct contact.
(3) Switches, buttons, and similar components should be intact and undamaged, with no live parts exposed.
(4) It should be equipped with proper grounding or earthing systems, and the connecting wires must be securely fastened without any breaks.
(5) Local lighting fixtures should use a 36V voltage; the use of 110V or 220V voltages is strictly prohibited.

5. The control handles and foot switches of mechanical equipment, among other components, shall meet the following requirements:
(1) Important handles should have reliable positioning and locking mechanisms. Coaxial handles must have a clear distinction in length.
(2) The handwheel can disengage from the rotating shaft during operation, preventing it from turning along with the shaft and potentially injuring personnel.
(3) The foot switch should be equipped with a protective cover or recessed into a hollowed-out section of the machine bed to prevent dropped parts from landing on the switch and inadvertently activating the machinery, which could lead to injury. (4) The work area for mechanical equipment must maintain an optimal environment—specifically, adequate lighting, moderate humidity and temperature levels, minimal noise and vibration, and neatly arranged components, tools, and fixtures. Such conditions help ensure the operator remains comfortable and focused, enabling precise and error-free performance.
(5) Each piece of machinery should have safety operating procedures, as well as systems for inspection, lubrication, maintenance, and more, tailored to its specific performance and operational sequence, ensuring operators follow these guidelines.
3. What are the common protective devices found in mechanical processing workshops, and what are their primary functions?
Common protective devices found in machining workshops include guards, guard panels, guardrails, and safety nets. Protective equipment must be installed on hazardous components of machinery, such as drive belts, open gears, ground-level couplings, rotating shafts, pulleys, flywheels, grinding wheels, and circular saws. Additionally, safety devices are essential for the rotating parts of press machines, rolling mills, calendering machines, electric planers, and shearing machines—types of pressure equipment. Guard shields are specifically designed to isolate exposed rotating elements like pulleys, gears, sprockets, and rotating shafts. Guard panels and safety nets come in both fixed and movable versions, serving to block or contain flying metal chips. Guardrails, meanwhile, are used to prevent workers from falling during high-altitude tasks or to clearly mark off safe working areas. In general, protective devices can be categorized into three main types: fixed guards, interlocked guards, and automatic guards.

4. What are the safety management regulations for operators of mechanical equipment?
To ensure that machinery-related workplace accidents do not occur, it’s not only essential for the equipment itself to meet safety standards—but even more critical that operators strictly adhere to safe operating procedures. Of course, the specific safety guidelines for operating machinery vary depending on the type of equipment; however, the fundamental safety rules remain consistent across the board:
1. Ensure you properly wear all required personal protective equipment. Always put on what’s necessary and avoid wearing anything that isn’t needed. For instance, during mechanical processing, female workers are required to wear protective headgear—failure to do so could result in their hair getting caught in the machinery. Additionally, gloves are strictly prohibited; if worn, the rotating parts of the machine could easily pull the gloves—and potentially your hands—inward, causing serious injury.
2. Before operation, conduct a safety inspection of the mechanical equipment and run it on idle to ensure everything is functioning properly before putting it into actual operation.
3. Machinery and equipment must undergo regular safety inspections during operation, as required by regulations. In particular, check whether fastened components have loosened due to vibration, and retighten them if necessary.
4. Equipment must never be operated while faulty—absolutely avoid making do with it to prevent accidents.
5. Mechanical safety devices must be used correctly as specified—under no circumstances should they be removed or left unused.
6. Cutting tools, workholding devices, and processed parts used in machinery must be securely clamped and fastened—looseness is strictly prohibited.
7. When machinery is running, it is strictly prohibited to adjust it by hand. Likewise, never use your hands to measure parts, lubricate components, or remove debris and other materials. If such tasks are absolutely necessary, first ensure the machinery is turned off before proceeding.
8. When machinery is in operation, operators must not leave their workstations to ensure that someone is available to handle any issues that may arise.
9. After finishing work, turn off the power switch, remove the cutting tools and workpieces from the machine, and thoroughly clean the workspace. Arrange parts, fixtures, and other items neatly, and ensure the machinery is properly sanitized.

5. How can metal cold-working workshops prevent workplace injuries?

The metal cold-working workshop is equipped with a wide variety of machine tools. However, as long as the workplace is properly arranged, essential protective and safety devices are installed, and safety operating procedures are strictly followed, industrial accidents can be effectively prevented.
Machine tool layout requirements:
1. Prevent parts or chips from flying out and causing injury.
2. Operators are shielded from direct sunlight to prevent glare.
3. Convenient handling of finished and semi-finished products, as well as easy cleanup of metal chips.
4. The workshop should be equipped with safety passages to ensure unobstructed movement for both personnel and vehicles.
Protection device requirements:
1. Guard: Shields exposed rotating parts from contact.
2. Guardrails: Machine tool sections that pose a risk of injury during operation, as well as machine tools not operated directly on the floor, must be equipped with guardrails standing at least 1 meter in height.
3. Protective shields: Prevent chips, swarf, and coolant from splashing.
Insurance device requirements:
1. Overload Protection Device: Automatically disengages or stops the machine when overloaded.
2. Travel Limit Switch: The moving parts automatically stop or return to the designated position upon reaching their target location.
3. Sequential Action Interlock Device: The next action cannot proceed until the current one is completed.
4. Emergency Interlock Device: In the event of a sudden power failure, the compensation mechanism will immediately activate or bring the machine tool to a stop.
5. Braking System: Prevents the loading or unloading of workpieces while the machine tool is rotating; ensures immediate shutdown of the machine in case of sudden emergencies.

6. What safety precautions should machinists keep in mind?
Safety precautions that machinists should observe include:
1. Wear tight-fitting protective clothing, ensuring sleeves are not left open; long hair must be covered with a protective cap; gloves are prohibited during operation.
2. When mounting or removing the chuck on the machine tool spindle, always stop the machine first—never use the motor's power to take off the chuck.
3. It is best to use protective guards on the protruding parts of chucks, dividing heads, and collet chucks that hold workpieces, to prevent them from catching clothing or other body parts. If no guard is available, be sure to keep a safe distance and avoid standing too close while operating these tools.
4. When clamping a workpiece with a center, ensure that the center aligns perfectly with the center hole. Never use a damaged or bent center; before use, thoroughly clean both the center and the center hole. Additionally, make sure the tailstock center is securely tightened.
5. When turning slender workpieces, use a steady rest or follow rest to ensure safety, and clearly mark the portion extending beyond the lathe.
6. When turning workpieces with irregular shapes, balance blocks should be installed, and the setup should be test-turned for balance before proceeding with cutting.
7. Ensure the cutting tool is securely clamped; the portion of the blade extending beyond the tool body should not exceed 1.5 times the height of the tool body. Additionally, the shape and dimensions of any shims placed beneath the blade must match those of the tool body, and the number of shims should be minimized while maintaining stability.
8. For strip-shaped and long, spiral chips generated during cutting, use a hook to remove them promptly—never pull them out by hand.
9. To prevent flying chip fragments from causing injury, transparent guards should be installed in appropriate locations.
10. Except for lathes equipped with measuring instruments that automatically perform measurements during operation, all workpieces should be measured while the machine is stopped, and the tool post must be moved to a safe position.
11. When sanding the surface of a workpiece, move the tool to a safe position and ensure your hands and clothing do not come into contact with the workpiece surface.
12. When grinding internal holes, never support the abrasive cloth with your fingers—use a wooden stick instead—and ensure the lathe speed isn’t too high.
13. Tools, fixtures, or workpieces must not be placed on the lathe bed or the spindle gearbox.

7. Safety precautions that milling operators should observe include:
1. When starting the cutting process, the milling cutter must be fed into the workpiece slowly—never with any impact—to avoid compromising the machine tool’s precision or damaging the tool’s cutting edge.
2. Workpieces must be properly supported and securely clamped to prevent loosening during operation, which could lead to accidents.
3. Speed adjustments, directional changes, and any corrections to workpieces or tools must be performed only after the machine has been stopped.
4. Gloves should not be worn during work.
5. Always use a brush to remove chips from the bed surface, and stop the machine before clearing chips off the milling cutter.
6. When the milling cutter becomes dull, stop the machine to sharpen the cutting edge or replace the tool. Before stopping, retract the tool first; never stop the machine while the cutter is still partially engaged with the workpiece.

8. Safety precautions that planers should observe include:
1. The planer blade must be securely clamped, and there should be a slight gap between the blade and the workpiece before starting. When making the first cut, avoid cutting too deep to prevent damaging the blade or injuring yourself.
2. Do not stand directly in front of the shaper during operation, and certainly do not lean over to inspect the workpiece in front of the machine.
3. Adjust the machine tool stroke and tighten the bolts that control the stroke.
4. Around the surface of the planer, install a vertical, hinged cylindrical guard shield.
5. Collect the swarf neatly in a specially designed chip collector to prevent cutting debris from injuring your feet.

9. Safety precautions that grinding machine operators should observe include:
1. Before starting the machine, you must check whether the workpiece fixture is properly installed, securely fastened, and if the magnetic chuck is functioning correctly. If not, operating the machine is strictly prohibited.
2. When operating the machine, use manual adjustment to maintain an appropriate gap between the grinding wheel and the workpiece, starting with a small feed rate to prevent the grinding wheel from cracking or breaking.
3. All measurements of workpieces, machine tool adjustments, and cleaning tasks must be performed only after the machine has been stopped.
4. To prevent injury from flying fragments in case the grinding wheel breaks, the grinder must be equipped with a protective guard. Grinding operations using wheels without a guard are strictly prohibited.

10. Safety precautions that drill press operators should observe include:
1. Gloves are not permitted during operation, and it is strictly forbidden to remove metal chips by hand.
2. Keep your head away from the drill press—wear a cap while working.
3. Before drilling, first secure the worktable tightly; for radial drilling machines, also ensure the arm is securely locked in place before starting the drill.
4. When starting the drilling process and as the workpiece is nearly pierced through, never apply excessive force.

11. When operating stamping equipment, operators must follow these safety procedures:
1. Before starting operation, carefully inspect whether the protective devices are intact and ensure that the clutch-brake mechanism functions smoothly and remains safe and reliable. Additionally, clear the workbench of all unnecessary items to prevent them from vibrating and accidentally landing on the foot switch during operation, which could trigger a sudden start of the press and lead to an accident.
2. When machining small workpieces, never use your hands—always rely on dedicated tools, and ideally, install an automatic feeding device.
3. Operators must exercise careful and cautious control over the foot pedal switch; when loading or unloading workpieces, keep your foot off the pedal. Unauthorized personnel are strictly prohibited from lingering near the foot pedal switch. 4. If a workpiece becomes stuck in the mold, use a dedicated tool to remove it—never grab it with your hands—and be sure to move your foot away from the pedal.

12. Safety precautions that fitters should observe include:
1. Tools used by machinists must be inspected before use.
2. An iron wire safety net should be installed on the bench used by fitters, and care must be taken to ensure the safety of personnel working directly opposite during chiseling. High-speed steel chisels are strictly prohibited. 3. When sawing workpieces with a hand saw, the saw blade should be properly tightened to prevent it from snapping and causing injury.
4. When using a sledgehammer, always pay close attention to the surroundings—front, back, left, right, and overhead—and strictly prohibit anyone from standing within the hammer's swinging radius. Additionally, never use a sledgehammer to strike a smaller hammer, nor should you use a smaller hammer to tap a larger one.
5. When working on multiple levels or in intersecting operations, ensure you wear a safety helmet and carefully follow unified instructions.
6. After completing equipment maintenance, ensure that all safety guards, safety valves, and various audible and visual signals are restored to their normal operating conditions.

13. How can metal hot-working workshops prevent industrial accidents?
The production in a metal hot-working workshop is characterized by numerous processing steps and heavy lifting and transportation activities, which often generate high temperatures, toxic gases, and dust during operations—conditions that can severely degrade the working environment and increase the risk of industrial accidents. Therefore, it is essential for metal hot-working workshops to implement effective safety measures:
1. Carefully select furnace materials to prevent the inclusion of explosives, and ensure that all materials added are thoroughly dried. Additionally, preheat any alloys before adding them to the mix.
2. When tapping molten metal, an electric, pneumatic, or hydraulic eye-plugging mechanism—or a rotary front furnace—should be used.
3. Strict measures must be implemented to prevent both groundwater and surface water from seeping into the pit.
4. Containers for molten metal must meet manufacturing quality standards; the metal liquid inside the ladle should not be overfilled.
5. The forging hammer should be operated using a manipulator or robotic arm to prevent hot forged pieces, such as oxide scale, from flying out and causing injury. Additionally, an isolation protective shield must be installed between operators and the air hammer operator’s seat to prevent burns and provide thermal insulation.
6. Tools and workpieces must be preheated before being placed into the heat treatment salt furnace, and railings or protective shields should be installed around the quenching oil tank.
7. Welding operations areas should be isolated or equipped with appropriate shielding; however, metal surfaces are not recommended as shielding materials.
Additionally, the workshop should have safe passageways, with floors that are flat, non-slip, and kept clear at all times. The workshop must also maintain adequate daylighting, and the building design should facilitate both mechanical and natural ventilation. Wherever possible, workstations and processes should be separated from one another without compromising production or material handling. Equipment that poses potential safety risks should be isolated as needed, equipped with safety barriers or protective netting. Workers in metal hot-working workshops are required to wear essential protective gear, including hard hats, safety goggles, and sturdy footwear.

14. Safety precautions steelworkers should keep in mind include:
1. Do not add damp raw materials or scrapped weapons into the furnace as scrap steel to prevent explosions. Additionally, molten steel and red slag must never be poured into wet steel containers, slag ladles, or onto damp ground.
2. To prevent splashing and explosion accidents during melting, avoid adding excessive oxidizers and refrain from vigorously stirring the molten steel.
3. Do not overfill the molten steel ladle, and strictly follow operational procedures when lifting it with the crane to prevent any tipping accidents.
4. If a furnace leak, ladle leakage, interruption of circulating water, or water leakage inside the furnace is detected, immediate and appropriate safety measures must be taken.
5. Employees must regularly wear personal protective equipment; anyone failing to do so will be prohibited from operating machinery or performing their duties.

15. Safety precautions that casting operators should pay attention to include:
1. The casting area and pits must be kept dry and free of water to prevent molten iron from splashing and causing injury.
2. All tools used, such as fire tongs, fire rods, hooks, and others, should be preheated.
3. The molten iron in the ladle should not be filled too full. When lifting the ladle, avoid tilting it or stopping abruptly—instead, work together smoothly and in sync.
4. Before casting, the chills on the upper and lower molds should be securely pressed in place or fastened tightly with screws, and the risers should be checked while ensuring proper venting channels are opened.
5. Do not look directly at the riser during pouring; instead, promptly vent the air to prevent gas explosions inside the mold.
6. During casting, unauthorized personnel must stay away. Always wear safety goggles when observing the freshly poured molten metal outlet.

16. Safety precautions that forging operators should pay attention to include:
1. When retrieving molds, punches, shims, and other tools from the workbench, always use tongs—never your hands.
2. When performing manual operations, ensure proper coordination when swinging the sledgehammer; it is strictly prohibited to walk or work within 2 to 5 meters behind the person swinging the hammer.
3. When cutting metal stock, be sure to tap gently to prevent the severed piece from flying off and causing injury. The handle of the pliers held by the person guiding the material should never point directly toward the abdomen.
4. When the steam hammer is in operation, do not strike empty blows, measure the workpiece dimensions, or allow any part of the human body to enter the hammerhead’s stroke area. Before inspection or repair, the hammerhead must be securely locked in place. Additionally, ensure that no flammable materials are stored near the heating furnace.

17. What types of injuries can occur during welding production? During the welding process, welders frequently come into contact with flammable and explosive gases, and sometimes they must work at heights, underwater, or in confined spaces. Additionally, welding generates toxic gases, harmful dust, arc radiation, noise, and high-frequency electromagnetic fields—all of which can pose significant health risks to workers. Welding sites also carry the potential for serious workplace accidents, such as explosions, fires, burns, poisoning, electric shocks, and falls from heights. Moreover, welders may suffer various injuries on the job, potentially leading to occupational diseases affecting the blood, eyes, skin, lungs, and other body systems. As welding operators are classified as specialized personnel, they must undergo comprehensive safety training and pass a qualifying examination before being authorized to work independently.