Occupational Health and Safety in Metal Products Manufacturing

General Provisions and Regulatory Framework for Occupational Health and Safety

The operation of any modern enterprise whose technological cycle is associated with metal processing, protective coatings application, or mechanical forming of metal products is accompanied by the complex impact of hazardous and harmful production factors. Effective risk management requires not only a deep understanding of physicochemical processes and human biomechanics, but also strict compliance with a developed regulatory framework. The fundamental document regulating this area in Ukraine is the Rules for Occupational Health and Safety during Cold Metal Processing, approved by the order of the Ministry of Energy and Coal Industry (NPAOP 0.00-1.68-13). These rules apply to all business entities regardless of ownership forms and establish mandatory requirements for such processes as metal cutting (turning, milling, drilling, planing), bending, drawing, pressing, cold stamping, and grinding.

Historically, the regulatory framework in this area has undergone significant transformations. For example, previous Soviet standards, such as NPAOP 28.0-1.02-83 (Rules on Safety and Industrial Sanitation in Cold Metal Processing), were officially canceled by the order of the Ministry of Social Policy in 2017 (Order No. 592), which became a step toward harmonizing Ukrainian legislation with international standards. The modern paradigm of industrial safety is moving away from reactive response to incidents, shifting focus to proactive risk assessment and engineering control.

According to current legislation, the employer bears full, unquestionable responsibility for creating safe working conditions. This responsibility is realized through a series of organizational measures. First, the employer is obliged to create a specialized occupational health and safety service in accordance with the requirements of the Standard Regulation (NPAOP 0.00-4.21-04). Second, it is necessary to develop and approve lists of jobs with increased danger, as well as jobs the execution of which requires strict professional selection. This means that only persons who have undergone appropriate medical examinations, special training, and briefings are allowed to perform certain technological operations.

The design of metalworking equipment, in turn, must comply with general technical safety requirements (DSTU 2807-94). This standard applies to all groups of metal- and woodworking equipment and requires that machine design exclude the hazardous impact of electric current, electromagnetic fields, and kinetic energy of moving parts on personnel. Equipment must have an appropriate degree of shell protection (IP), and the temperature of its external surfaces is strictly regulated by the standard DSTU EN 563-2001 to prevent thermal burns. Only the synergy of administrative control, high-quality personnel training on the use of personal protective equipment, and a reliable engineering base can ensure a zero level of occupational injuries.

Safety during Mechanical Metal Cutting

Mechanical metal processing is a fundamental process in mechanical engineering, which involves the use of equipment generating enormous kinetic energy. This energy is transmitted to the cutting tool and the workpiece, causing plastic deformation of the metal, chip formation, intensive local heating, and the occurrence of significant mechanical stresses. Each group of metalworking machines has a specific risk profile, requiring the application of specialized safety measures.

The specifics of working on drilling and boring machines dictate strict limitations on the use of hand protection equipment. Hole processing is associated with tool rotation, which creates an extremely high risk of entanglement and winding of fibers. That is why the rules categorically prohibit performing work on drilling machines using mittens, textile gloves, or with bandaged hands, as this inevitably leads to severe injuries, bone fragmentation, and amputations. It is also strictly forbidden to check the sharpness of cutting edges, the exit of the drill from the workpiece, or hole depth by hand while the spindle is rotating. It is unacceptable to use wet rags to cool the tool; instead, standard coolant supply systems must be used.

Working on metalworking machines of the milling group requires exceptional attention to the condition of the cutting tool and its correct positioning. The milling process is characterized by an intermittent cutting process, which creates shock loads.

When replacing a tool on a milling machine, the milling arbor or cutter must be secured in the spindle with a wrench only after engaging the gearbox to prevent sudden spindle rotation. Elastic pads are used to support the cutter during its knocking out, protecting the worker’s hands and the tool from damage. It is forbidden to leave the wrench on the clamping bolt head or use the electric motor to clamp the cutter.

For the turning group of machines, a critical factor is the management of chip formation dynamics. When turning viscous metals (e.g., low-carbon steels), continuous ribbon chips are formed. They have razor-sharp edges and can curl unpredictably, posing a threat of deep cuts to the face and neck. To prevent this, it is necessary to use cutting tools with grooves, overlay chip breakers, or chip curlers that forcibly break chips into small fragments. Conversely, when processing brittle metals (cast iron, bronze), finely divided chips (dust-like) are formed, which fly off at high speed. In this case, the use of transparent protective shields and special chip deflectors is mandatory.

The rules strictly prohibit working with a non-rotating tailstock center during high-speed cutting due to the risk of thermal welding of the center to the workpiece, as well as using clamping chucks with worn-out cam working surfaces (which can lead to the workpiece flying out under centrifugal force). When working with highly toxic alloys (beryllium, magnesium), workpiece loading must be performed using automatic manipulators or industrial robots, and for small parts — bunkers or mechanical hands.

Planing, slotting, and broaching machine groups require retracting the table or slide to the maximum distance from the support during workpiece installation. Cutting equipment (guillotine shears, saws) must be equipped with protective guards overlapping the danger zone by at least 100 mm, and doors for replacing saws must be electromechanically interlocked with the machine’s starting device.

Thermal Processes: Welding, Laser Cutting, and Protection against Toxic and Optical Impact

The application of high-energy processing methods, such as arc welding, plasma cutting, and laser cutting, generates the most aggressive spectrum of hazardous factors in metalworking. These include intense electromagnetic radiation in a wide range (from ultraviolet to infrared spectrum), extremely high temperatures, and the emission of highly toxic aerosols.

Toxicology of Welding and Laser Aerosols

During arc welding (MIG, MAG, TIG) and laser cutting of alloyed metals, the material does not simply melt, but evaporates. The resulting smoke is an aerosol of ultrafine particles, the diameter of which is often less than 0.1 micron. Due to such sizes, they bypass the natural protective barriers of the human respiratory system, penetrating deep into the alveoli and even directly into the bloodstream.

The greatest danger is posed by the processing of stainless steel and chromium-alloyed metals. As a result of thermal oxidation, hexavalent chromium (Cr VI) is formed. This compound is a highly aggressive technogenic toxin and a recognized carcinogen. Prolonged exposure to hexavalent chromium causes lung cancer, chronic asthma, severe irritation of mucous membranes, and even irreversible perforation of the nasal septum. Welding with coated electrodes is one of the most active sources of its formation. Emission levels are also affected by operating modes: for example, during MAG welding of stainless steel, the concentration of hexavalent chromium is lower when using the spray transfer mode than during short-circuit welding.

In addition to chromium, welding fumes contain nickel and copper oxides. Inhaling copper vapors causes the so-called “metal fume fever” and a specific lung disease — mederosis. Manganese exposure can have a neurotoxic effect, causing symptoms that mimic Parkinson’s disease. The use of inert and active shielding gases (argon, oxygen, carbon dioxide) additionally initiates the formation of toxic gases such as nitrogen oxides (NOx) and highly reactive ozone (O3). Accordingly, occupational health and safety standards, in particular OSHA and COSHH directives, establish strict permissible exposure limits (PEL) for these substances. Respiratory protection requires the use of N95-type respirators or powered air-purifying systems (PAPR), as well as powerful local exhaust ventilation directly in the cutting or welding zone.

Vision Protection: “Chameleon” Technology and Laser Safety

Intense ultraviolet (UV) and infrared (IR) radiation from the welding arc can cause photokeratitis (electro-ophthalmia) — a painful burn of the cornea. For effective protection, modern manufacturing is massively switching to welding masks with automatic darkening filters of the “Chameleon” type.

The operating principle of such filters is based on the use of liquid crystal matrices and highly sensitive optical sensors (from 2 to 4 arc sensors) that continuously analyze the illumination level of the working area.

Laser cutting and welding constitute a special class of hazard. Industrial laser systems (in particular, fiber lasers) belong to the most dangerous Class 4. A laser beam is focused energy with a power of thousands of watts, concentrated in a point with a diameter of fractions of a millimeter. Unlike arc welding, a laser emits coherent light that often lies in the invisible infrared range. This means that if the beam enters the eye or reflects diffusely from a metal surface (especially copper or aluminum), the natural blink reflex is not triggered, leading to instant burning of the retina.

That is why ordinary welding masks or anti-spatter glasses are completely ineffective against lasers. Operators are required to use special certified goggles (standard PN-EN 207), the lenses of which are selected to absorb radiation of a specific wavelength. The modern concept of laser safety is based on complete physical isolation: the machine is designed as an enclosed cabin, the doors of which are equipped with optical and mechanical interlocking systems (interlocks). Opening the doors instantly stops beam generation. Every enterprise must appoint a Laser Safety Officer (LSO) who evaluates the Maximum Permissible Exposure (MPE) and develops accident response protocols.

Chemical Factors: Galvanizing Processes, Hot-Dip Galvanizing, and Coolant Management

The production of metal products is not limited to mechanical processing; chemical and electrochemical surface treatment processes are used to impart anti-corrosion properties and wear resistance to parts. These processes impose a significant toxic load on the production environment and personnel.

In electroplating shops, extremely aggressive reagents are used during pickling, degreasing, and coating. For example, cyanides used as an electrolyte are potent cellular respiration poisons; their maximum allowable concentration (MAC) in the working area air is only 0.3 mg/m³. Inhaling even minuscule doses of cyanide vapor causes dizziness and nausea. Another reagent — silver nitrate — has the property of accumulating in the body during years of work. It is deposited in the connective tissues of capillary walls, kidneys, bone marrow, and especially in the stellate cells of the liver as pure metal (MAC 0.01 mg/m³). Hot concentrated sulfuric acid (MAC 1 mg/m³) releases vapors that severely damage mucous membranes and lungs, and upon skin contact cause instant deep chemical burns. Storage and transportation of toxic technical liquids require the use of sealed containers, clear labeling, and compliance with strict rules for joint storage with other petroleum products.

The process of hot-dip galvanizing requires special attention. It consists of immersing prepared steel structures in a bath of molten zinc, the temperature of which reaches 450-460°C. This method provides not only barrier but also cathodic (sacrificial) protection of steel against corrosion. However, the process poses a serious explosion hazard if hollow structures (pipes, box profiles, reservoirs) are improperly prepared.

Any sealed cavity before immersion in molten zinc must have drainage and ventilation openings. If the part is sealed or openings are insufficient, residual moisture and air inside the cavity are instantly heated to 450°C. An avalanche-like expansion of gases and conversion of water into steam occurs, the pressure in the cavity rises rapidly, which inevitably leads to a catastrophic rupture (explosion) of the metal structure directly in the bath. This is accompanied by a large-scale release of molten zinc, posing a mortal danger to personnel and destroying equipment. According to standards (specifically DSTU EN ISO 1461:2024), in square and rectangular profiles, openings should be located diagonally at both ends. For large closed volumes, the total area of ventilation openings should be 25–50% of the cross-sectional area of the product. Ventilation openings ensure air escape (preventing the formation of unprotected air pockets), and drainage openings ensure free flow of zinc, which also saves up to 10-20% of material.

During metal cutting and drilling, metalworking fluids (coolants) are massively used. Prolonged skin contact with these substances is the main cause of occupational contact and atopic dermatitis. To prevent diseases, sanitary standards must be strictly observed: use oil-resistant gloves, apply barrier creams. It is strictly forbidden to use aggressive solvents (petroleum, gasoline, kerosene) for hand washing. Instead, daily showers with warm (not hot, 37-38°C) water without rough washcloths that traumatize the epidermis are indicated, followed by the application of softening medical-cosmetic products (emollients) to damp skin.

Disposal of spent coolants, as well as drilling muds (containing oil-bearing clay slurries, surfactants, and metals), must be carried out by specialized enterprises. The entry of these wastes into soil or water bodies fatally disrupts the nitrogen balance and leads to ecosystem degradation.

Fire and Explosion Safety: Metal Dust Risk Management

Metal processing, in particular grinding, polishing, and cutting of aluminum, magnesium, titanium, and their alloys, is accompanied by the formation of finely dispersed metal dust. Metal dust is characterized by extremely high reactivity. The physics of the process is that the smaller the dust particle, the greater the total surface area of the substance relative to its mass. This radically increases its chemical and physical activity, accelerating oxidation and reducing the ability to settle under gravity.

For a catastrophic dust explosion to occur, the simultaneous presence of five factors is necessary (the so-called “explosion pentagon”):

1. Presence of combustible dust (fuel material).
2. Presence of an oxidizer (oxygen in the working area air).
3. Ignition source (spark from grinding, static electricity, hot surface).
4. Suspended state of dust (formation of a dust-air cloud).
5. Enclosed or semi-enclosed space (shop, ventilation duct).

The degree of explosion hazard is determined by the lower explosion limit (LEL) and auto-ignition temperature. Spherical dust particles oxidize more slowly, whereas irregular particles significantly increase the reaction rate.

The greatest threat in industry is posed by secondary explosions. A local flash in a small dust cloud (primary explosion) generates an intense shock wave. This wave propagates through the shop and disturbs dust layers that have settled for years on beams, pipelines, light fixtures, and equipment housings. A new, giant dust-air cloud is formed, which instantly ignites from the flame of the primary explosion. A secondary explosion is always much more powerful and destructive, capable of destroying the entire building.

Risk management is based on preventing the formation of the “explosion pentagon”:

1. Prevention of accumulation: Regular cleaning of settled dust. It is strictly forbidden to blow off dust with a jet of compressed air, as this artificially creates an explosive cloud. Cleaning must be carried out using special explosion-proof industrial vacuums.
2. Ignition source control: Use of non-sparking tools, strict grounding of equipment to dissipate static voltage.
3. Engineering systems (ATEX): Installation of aspiration systems (local exhaust ventilation) designed in accordance with explosion protection standards. Such systems are equipped with special rupture membranes or panels for directional release of explosion pressure outside the building.

Lifting Operations, Logistics, and Manual Material Handling

Intra-shop logistics involving the movement of raw materials (rolled metal), blanks, and heavy finished products poses a significant trauma risk. This risk is caused by the use of large-sized hoisting machines as well as intensive manual labor.

Hoisting cranes (overhead, gantry) are classified as high-hazard machinery and mechanisms. According to legislation, their operation is permitted only after a full technical inspection, expert assessment, and obtaining a declaration of conformity of the material and technical base with occupational health and safety requirements (in accordance with CMU Resolution No. 1107). Commissioning a crane is prohibited if the mechanisms have exhausted their ultimate service life and have not undergone proper expert diagnostics.

Special attention is paid to the electrical safety of crane facilities. Crane tracks are subject to mandatory grounding. After grounding is installed, an instrumental check is carried out: current spreading resistance must not exceed 4 ohms for cranes with an isolated neutral and 10 ohms for cranes with a solidly grounded neutral. During operation, the mass of the lifted load must not exceed the nominal lifting capacity of the crane. Importantly, the total mass of the load obligatorily includes the weight of all load-gripping devices (slings, traverses) and containers. Performing loading and unloading operations during vehicle maneuvers is prohibited. The maximum speed of material-handling vehicles (e.g., forklift trucks) inside production premises is strictly limited to 5 km/h. When forklifts operate in enclosed warehouses, they must be equipped with exhaust gas neutralizers. Aisles between material stacks must be from 0.8 to 1.2 meters.

Despite global mechanization, manual material handling remains common in metalworking enterprises. This activity conceals high risks of cumulative musculoskeletal trauma — ligament strains, spinal injuries, fractures, and the development of chronic back conditions. Physiological standards strictly regulate these processes:

1. Maximum single weight: For men over 18 years of age, the limit for carrying loads on a flat and horizontal surface is 50 kg. Loads weighing over 50 kg, as well as lifting any loads to a height of more than 3 meters, are subject to mandatory mechanization.
2. Regular handling: If loads are moved continuously throughout the work shift, their single mass must not exceed 7 kg. The total mass of loads moved per hour is limited to 350 kg (when lifting from the work surface level) and 175 kg (when lifting directly from the floor).
3. Long-length loads: Rolled metal, reinforcement, or pipes must be carried by a team of workers synchronously on the same shoulder. Dropping the load is performed exclusively on a clear command, and all workers must be on one side of the load to avoid leg injury from metal rebound.
4. Use of rollers: When moving heavy boxes or machines on supports (rollers), the ends of the latter must not protrude from under the load by more than 0.4 meters. Guiding rollers with feet is strictly prohibited. When moving along an inclined plane, braking winches must be used.

Ergonomics, Vibration, and Noise: Prevention of Irreversible Occupational Diseases

Technological processes of cutting, stamping, riveting, and working with pneumatic tools are sources of intense industrial noise and vibration. Prolonged exposure to these physical factors leads to the development of specific occupational pathologies that are cumulative and often irreversible in nature.

Vibration disease (“white finger” syndrome, angiotrophoneurosis) develops as a result of long-term exposure to local or general vibration on the worker’s body. The pathogenesis of this disease is extremely complex and is based on reflex disorders of the central and autonomic nervous systems. Vibration destructively affects the skin mechanoreceptors (specifically, Vater-Pacini corpuscles), leading to the formation of stagnant excitation foci in the spinal cord. This, in turn, causes persistent spasm of the peripheral blood vessels of the hands. The first clinical symptoms usually appear after 5–7 years of continuous work with the tool. Patients complain of hand numbness, decreased muscle strength, sharp pallor and cyanosis (bluish discoloration) of the fingers, especially under the influence of cold, as well as deformation of the terminal phalanges resembling “clubbed fingers”. Local vibration is typical for working with grinding machines and chipping hammers, whereas general vibration is transmitted through vibrating floor surfaces.

Intense industrial noise is a trigger for the development of sensorineural hearing loss. This is a disease of the inner ear in which the auditory nerve and sensitive hair cells of the cochlea, which transform mechanical sound waves into nerve impulses, are directly damaged. In the early stages, the disease manifests as constant ringing or noise in the ears (tinnitus) and a decrease in sensitivity to high-frequency sounds. Depending on the duration of exposure, acute (up to 1 month, changes still reversible), subacute (1–3 months), and chronic hearing loss (over 3 months) are distinguished. Continuous industrial noise exhausts the adaptive mechanisms of the auditory analyzer, which eventually leads to permanent and complete hearing loss.

Minimizing these risks requires a comprehensive approach. In addition to personal protective equipment (anti-vibration gloves, certified hearing protection earmuffs and earplugs), the primary task is engineering noise reduction at the shop design stage. In accordance with building codes (DBN V.1.2-10:2021 “Protection against noise and vibration”), it provides for the use of structural and vibration-isolating materials (rubber and polymer dampers), sound-absorbing wall linings, and acoustic screens that dissipate the kinetic energy of sound waves. Heavy metalworking machines and stamping presses must be installed on strong, carefully calibrated vibration-isolated foundations, which prevents the transmission of low-frequency vibrations to the building structures.

Electrical Safety and Modern Optoelectronic Equipment Protection Systems (LOTO)

Reliable energy management is a critical aspect of safety in any metalworking production. During maintenance, setup, repair, or cleaning of machines, the key task is to prevent their accidental or unauthorized startup. To achieve this goal, the global standard has become the introduction of a lockout/tagout system (known as the Lockout/Tagout or LOTO system).

The essence of the lockout procedure is the physical disconnection of the machine from all possible energy sources (electrical, pneumatic, hydraulic, or mechanical). Special mechanical blockers are installed on switching devices (circuit breakers, valves, latches) that make their switching impossible. A personal dielectric padlock is attached to this blocker, the key to which is held exclusively by the worker performing the repair work. The use of coded secret locks in the LOTO system is strictly prohibited, as the code can be transferred to another person or guessed, which nullifies personal responsibility. When performing collective work by several specialists simultaneously, lockout hasps are used, which allow each member of the repair crew to attach their individual padlock to a single switch, guaranteeing that the equipment will not be turned on until the last worker removes their lock.

To protect the working zones of modern equipment (stamping presses, robotic welding complexes, guillotines) during their standard operation, advanced optoelectronic devices are used:

1. Safety light curtains: These devices create an invisible plane of multiple infrared beams between the transmitter and receiver. If an operator’s hand or body crosses even a single beam, breaking the optical connection, the curtain instantly sends an electronic signal to the machine controller to stop moving parts. Depending on the beam spacing (resolution), curtains are classified into devices for finger protection (14 mm resolution), hand protection (30 mm), and body protection. Type 4 curtains are used for equipment with the highest risk level.
2. Safety laser scanners: Unlike flat curtains, scanners use time-of-flight measurement technology to form a two-dimensional detection zone. They allow engineers to virtually “draw” complex protection and warning zones (for example, for concealed CANBO M-901 sensors with a 10 cm spot diameter and an operating range from 0.8 to 10 meters, IP67 waterproof rating) without the need to mount physical guards.

The baseline foundation for the reliable operation of all electrical equipment is compliance with electrical safety standards (DSTU B V.2.5-82:2016). In accordance with these standards, all metal non-current-carrying parts of equipment (frames, housings) that may accidentally become energized due to insulation failure are subject to mandatory protective grounding (or zeroing, depending on the system — TN, TT, or IT). Grounding provides the path of least resistance for leakage current, diverting it into the ground. Additionally, for instant response to current leakage exceeding a safe threshold (differential current), residual current devices (RCDs) are used. An RCD continuously compares the current flowing into the phase with the current returning through the neutral; any imbalance indicates leakage (e.g., through a human body), causing contact separation in milliseconds, saving a life. Building grounding and lightning protection systems are designed in accordance with the requirements of international standards of the IEC 62305 and IEC 61140 series.

First Aid for Occupational Injuries

Despite multi-level protection systems, automation, and organizational measures, emergency situations in the production of metal products are possible. The speed, adequacy, and correctness of the first aid algorithm are critical factors for saving the victim’s life and minimizing the consequences of the injury. The main types of injuries in metalworking are mechanical wounds, thermal and chemical burns, and electric shock.

When receiving deep cuts, lacerations, or partial amputations, the absolute priority is the immediate stoppage of bleeding. Minor venous bleeding is effectively stopped by direct pressure on the wound with hands (mandatory use of medical gloves to prevent infection) and subsequent application of a tight compression bandage. The rules strictly prohibit independently washing deep wounds, removing foreign objects (metal chips, tool fragments), or pouring iodine or alcohol into the wound, as this causes pain shock and chemical burns to damaged tissues. In case of massive arterial bleeding (pulsating jet of bright red blood) that cannot be controlled by pressure, a tourniquet is applied. It should be applied 5-7 cm above the wound site, necessarily over fabric or clothing (to protect the skin from pinching), and tightened until bleeding completely stops and the pulse below the application site disappears.

Thermal burns resulting from contact with hot metal, hot chips, molten zinc, or from exposure to the welding arc require immediate removal of thermal energy from tissues. The affected area must be cooled with cool running water for 15-20 minutes. It is strictly forbidden to apply ice to a burn, as sharp vasospasm leads to local hypothermia and tissue necrosis. It is also strictly forbidden to puncture burn blisters and apply any fats, oils, sour cream, ointments, or plant juices (e.g., aloe) to the damaged skin before medics arrive. The best solution in the production first-aid kit is the use of a special hydrogel burn dressing, which effectively cools the wound, does not stick to it, and reliably protects against infection.

Chemical burns (e.g., from contact with electrolytes or acids in an electroplating shop) require prolonged rinsing with a stream of cool water (about 20 minutes) to mechanically wash away and dilute the reagent. However, there is a critical exception: burns from quicklime are strictly prohibited from being washed with water. The interaction of lime with water causes a violent exothermic reaction with the release of a large amount of heat, turning a chemical burn into a severe thermal one. In such a case, the lime powder is removed by dry mechanical means, and the affected area is treated with animal or vegetable oils.

Electric shock requires the highest level of caution from the rescuer. The first step is the immediate cessation of current flow (turning off the switch, pulling the plug from the outlet). If this is technically impossible, the rescuer is obliged to insulate themselves (put on rubber dielectric gloves, stand on a rubber mat or dry board) and knock the wire away with a dry stick or pull the victim away exclusively by dry clothing, avoiding contact with their body. After release from the current, the presence of breathing and consciousness is checked. If breathing is absent, cardiopulmonary resuscitation (artificial ventilation and closed chest compressions) is immediately started and continued until vital functions are restored or an emergency medical team arrives. In case of eye injuries (getting scale in the eye), do not rub the eyes; a protective shield (e.g., from a paper cup) should be applied and both eyes covered, as their movements are synchronized.

When working in open areas (e.g., during the installation of metal structures in winter), frostbite is possible. In such cases, the affected area is warmed with body heat; it is strictly forbidden to rub frostbitten skin with snow or fabric, as this leads to microtraumas and infection.