Hazard Identification and Analysis for Machinery Design and Safety

Effective machinery safety begins with the systematic identification of all hazards that could arise during the machine’s life. Hazard identification is the first stage of risk assessment, required by international standards, and involves cataloguing any situation or condition that could lead to harm. ISO 12100 (Safety of machinery – General principles for design – Risk assessment and risk reduction) establishes the framework for this process. It mandates that designers recognise “reasonably foreseeable hazards” in every life-cycle phase of the machine (transport, assembly, installation, commissioning, operation, maintenance, and disposal). Complementary European standards address specific hazard categories. For example, EN ISO 13857 (safety distances) requires identifying zones where moving parts pose entrapment risks, EN 60204-1 (electrical equipment) requires identification of electrical shock and fire hazards, and EN 12198 addresses radiation hazards. These standards and the Machinery Directive’s Annex I safety objectives collectively guide the analysis of hazards that are specific to machinery design, distinct from broader risk evaluation.

ISO 12100 and related standards emphasise that hazard identification must be structured, methodical and exhaustive. Designers must consider all normal and abnormal operating modes (including start-up, normal cycle, manual operation, maintenance, and emergency stop), and all reasonably foreseeable misuse. The process involves multiple complementary techniques to ensure no hazard is overlooked. In practice, a combination of checklists, task and function analyses, design reviews, energy tracing, expert workshops, and historical data review is used. Each method contributes a different perspective: checklists ensure known hazards are not missed, task analysis examines hazards in each operation, design reviews scrutinise the machine’s structure and control logic, energy tracing identifies all sources of stored or transmitted energy, expert brainstorming can uncover unexpected issues, and historical data highlights failures observed in similar machines.

Hazard Identification Techniques: Multiple techniques should be employed in combination to achieve completeness. Key methods include:

• Checklists: These are systematic lists of potential hazards drawn from standards (for example, ISO 12100 Annex B provides examples of hazard types and hazardous events), regulations, and past experience. A checklist may include mechanical hazards (pinch, shear, draw-in), electrical hazards (shock, arc flash), thermal hazards (hot surfaces, steam), ergonomic issues (awkward postures, repetitive tasks), radiation (optical or electromagnetic sources), and environmental factors (noise, dust, lighting). Engineers review the machinery design against each checklist item to confirm presence or absence of each hazard. Checklists are updated and customised for each machine type. For instance, a press machine checklist would include presence of a flywheel or clutch, whereas a robot checklist would include moving arm reach hazards. Using checklists helps ensure that routine hazards (such as unstable loads, sharp edges, pinch points, or exposed live parts) are systematically considered.
• Task Analysis: This method breaks down the operator’s and maintainer’s activities into step-by-step sequences (often via Hierarchical Task Analysis). Each task or sub-task (for example, start-up, normal cycle operation, tool change, cleaning, and maintenance) is examined to identify where hazards may occur. For each step, the analysis asks what could go wrong: e.g. during maintenance could residual energy cause an unexpected motion? Are emergency stops accessible during that task? Task analysis ensures that hazards arising in each working mode (normal production, set-up, cleaning, etc.) are captured. For example, setting up a power press includes placing material and removing dies, which introduces pinch or crush risks; a task analysis would explicitly identify those. It also covers infrequent modes: e.g. fault conditions, emergency procedures, or shutdown tasks.
• Design Reviews (Preliminary Hazard Analysis): Formal design review meetings with multidisciplinary stakeholders (design engineers, safety experts, end-users, maintenance staff) are essential. At each major design stage (concept, detailed design, prototype), the team examines drawings, layouts, control schematics, and 3D models to identify hazards. Methods like Preliminary Hazard Analysis (PHA) or design Failure Mode and Effects Analysis (FMEA) can structure these reviews: each component or subsystem is considered for potential failure or misuse that leads to a hazard. For example, a design review of a conveyor would highlight risks from exposed belt drives or lacking emergency stops. Early design reviews allow hazards to be eliminated by design changes (e.g. arranging that pinch points are inherently inaccessible) rather than relying solely on guarding later.
• Energy Tracing (Hazardous Energy Identification): This technique systematically identifies all forms of energy present in the machine that could cause harm if released or contacted. Sources include mechanical (kinetic energy of moving parts, potential energy in springs or raised loads), hydraulic or pneumatic pressure, electrical energy, thermal energy, stored chemical energy, and gravitational energy (e.g. suspended loads). By tracing each source to where it is used or stored, one can spot where uncontrolled release could occur. For instance, tracing the pneumatic system of a robot shows pressurised air in actuators, alerting to the hazard of sudden motion or ruptured lines. Energy tracing is akin to a Lockout/Tagout analysis: it ensures that even hidden or secondary energy (e.g. residual charge in capacitors, or tension in elastic components) is noted as a hazard source.
• Expert Workshops: Structured brainstorming sessions (sometimes called HAZID studies) bring together experts from design, production, maintenance, and safety to pool knowledge. These workshops may use guides such as the “What-If” technique or fault-tree thinking to question every aspect of the system. For example, a HAZOP-style examination might query deviations in robot arm speed or conveyor belt alignment to find hazards. The diversity of expertise helps reveal subtle issues, such as unusual misuse patterns or operator shortcuts that a checklist might not cover. Because participants include those with field experience, they often recall incidents from similar machines that highlight hard-to-see hazards.
• Historical Data and Incident Analysis: Past accident records, near-miss reports, warranty claims, maintenance logs, and industry safety bulletins are reviewed. This data highlights hazards that have actually led to harm or disruption. For machinery of similar type, common failure modes (e.g. broken tool pieces, controller faults, fall of unsecured loads) are learned from history. This often involves checking databases such as the European MAHB or ENISA (for electrical incidents), or internal company archives. Historical analysis may reveal, for instance, that a certain model of press tended to have clutch engagement faults that cause unexpected strokes – a hazard to identify in new designs. Using real-world data helps prioritise obscure hazards that theoretical analysis alone might miss.

Each of these methods contributes to a comprehensive hazard list. In practice, a design team will use checklists as a baseline and fill in gaps via workshops and data analysis. Design reviews and task analyses focus on the specific machine, while energy tracing ensures no source of harm is omitted. Together, they form an exhaustive search for hazards.

Organisation by Life-Cycle, Mode and Category

Hazard identification must be organised systematically in three dimensions: life-cycle phase, operational mode, and hazard category.

• Life-Cycle Phases: Hazards can vary across the machine’s life. ISO 12100 explicitly calls for consideration of all relevant phases, including transport, assembly and installation, commissioning, normal operation, adjustment or set-up, cleaning, maintenance and servicing, and end-of-life (decommissioning and disposal). For each phase, different hazards may emerge. For example, during transportation and installation, hazards include manual handling injuries, falling loads, or impacts; during normal operation, hazards involve the main production cycle (e.g. moving tooling, material ejection); during maintenance, hazards include unexpected start-ups, trapped energy, or exposure to hazardous substances (lubricants, cooling fluids). A comprehensive hazard identification process will list hazards specific to each phase. Typically, a table or matrix is used in risk documentation that crosses life-cycle phases against hazard types to ensure completeness.
• Operational Modes: Within normal life phases (especially operation and maintenance), the machine may operate in multiple modes: for instance, automatic production mode, manual mode (e.g. manual feed or program teaching), setup/adjustment mode, maintenance mode, and fault/emergency mode. Each mode can introduce unique hazards. For example, a conveyor in automatic mode presents pinch hazards at rollers, but in maintenance mode the main drive may be deactivated and new hazards appear (such as dislodged inertia). Robots in “teach mode” may allow a human to be within the cell while moving, creating a high collision risk if a program error occurs. Thus, hazard identification must explicitly consider what happens in each mode. Common practice is to list modes and identify hazards under each (for example, one might enumerate: (a) automatic processing, (b) manual feeding/teaching, (c) cleaning and maintenance, (d) emergency shutdown, etc.). Certain standards (such as ISO 12100 and ISO 13849) note that hazards in foreseeable misuse or unusual modes must also be included.
• Hazard Categories: In parallel with phases and modes, hazards are categorised by their origin or nature. The principal categories are: Mechanical hazards (moving or fixed parts causing impact, crushing, entanglement, shearing, cutting or drawing-in), Electrical hazards (electric shock, arc flash, fire from wiring faults), Thermal hazards (burns from hot surfaces, scald from steam or hot fluids), Ergonomic hazards (cumulative trauma from posture, vibration, repetitive motions or manual handling), Radiation hazards (ionising radiation, laser or UV exposure), and Environmental or Ambient hazards (noise, dust, lighting, weather conditions, or unguarded terrain). Each category is evaluated by inspecting the design and operation of the machine for that type of risk. For example, mechanical hazards are found by identifying all moving parts and potential release of stored energy; electrical hazards by tracing all live circuits and fault scenarios; thermal hazards by checking for contact with heat sources; ergonomic hazards by analysing control panel layout and task demands; radiation hazards by identifying any sources of optical or electromagnetic emissions. Hazard checklists typically separate these categories so that each is considered. Often a cross-disciplinary hazard list will note mechanical, electrical etc. In practice, any identified hazard is assigned a category to ensure appropriate expertise is applied (e.g. electrical engineers assess shock hazards, human factors experts assess ergonomics).

By organising hazard identification in this way – along life-cycle stages, operational modes, and hazard types – no aspect of the machine’s use is overlooked. It ensures that, for instance, an ergonomic issue during maintenance or a mechanical pinch hazard in emergency stop mode will receive attention.

Hazard Origins and Evaluation

The origin of a hazard refers to the source of potential harm in the machine. Each origin must be examined and evaluated as follows:

• Mechanical Hazards: These arise from the physical movement or configuration of machine parts. Examples include crushing (between a moving press ram and the bed), shearing (the cutting action of a power press), entanglement (clothing or hair caught in a rotating drive belt), trapping or drawing-in (hands pulled into nip points), impact (collision with a swinging arm), cutting or stabbing (sharp edges), and projection (parts or material being thrown). Mechanical hazards are identified by reviewing all moving parts (gears, cams, belts, slides, chutes) and any fixed structures that could trap or impale. Designers evaluate them by determining the type of injury (e.g. amputation, fracture) possible and ensuring guards or design changes eliminate or protect the danger zone. Standards such as ISO 12100 Annex B list typical mechanical hazards to prompt this analysis.
• Electrical Hazards: These originate from electrical energy in the machine. The most obvious is electric shock from contact with live parts (supply conductors, exposed components of motors or control circuits). Other electrical hazards include arc flashes or blasts (short-circuit events), fires caused by overload or insulation failure, and hazards from electromagnetic fields. The evaluation involves identifying all voltages present, both primary (mains supply, motor drives) and residual (capacitor charge, stored static). Designers check compliance with EN 60204-1, which demands e.g. that circuits be guarded or insulated, that no hazardous voltages are accessible without interlock, and that emergency stops cut power effectively. Electrical schematic reviews during hazard identification ensure any potential contact or fault is spotted. For example, if a robot cell has a high-voltage weld torch, the shock and UV hazards from the torch must be identified.
• Thermal Hazards: These come from heat sources. Hot surfaces (exhausts, motors, furnaces), steam or hot fluids, and even cryogenic sources (coolants) present burn or scald risks. In hazard identification, one notes components that reach elevated temperature during normal or fault conditions. A press working metal will heat its tooling and chips; a conveyor may have hot bearings; a robot welding arm produces intense heat. Ergonomic considerations include guarding these surfaces or warning operators. The evaluation process might use EN 1040/ISO 12100 advice to label or guard surfaces over a certain temperature. Thermal hazards also include fires from flammable materials (e.g. oil leaks on hot parts). Identification ensures such sources are listed so that the risk assessment can later estimate burn severity.
• Ergonomic Hazards: These involve the human-machine interface rather than the machine itself. Examples include awkward postures required to reach controls or load parts, excessive force or repetition needed in manual tasks, whole-body vibration from large moving platforms, or poorly designed displays causing visual strain. Ergonomic hazard identification reviews the operator’s tasks and environment. For instance, repetitively feeding a heavy metal sheet into a press can cause strain – the hazard is musculoskeletal injury. Standards like EN ISO 12100 note consideration of human capabilities and limitations. Evaluating ergonomic hazards may involve simulating tasks or measuring reach distances (referencing standards like ISO 13857 for reach), and identifying tasks with high manual handling or awkward postures.
• Radiation Hazards: These originate from energy emitted by machinery, such as ionising radiation (X-rays, radioactive sources in specialized equipment) or non-ionising radiation (lasers, intense UV from welding, infrared heat, microwave, or even static discharge). EN 12198 specifically covers radiation safety in machines. Identifying radiation hazards means listing any processes that emit hazardous radiation: laser cutters, arc welders, UV lamps, laser sensors, etc. The evaluation includes checking applicable exposure limits and considering shielding, interlocks or warnings. For instance, a robotic welder must have analysis of UV and IR exposure to operators, and the hazard identification will note the need for protective barriers or PPE.
• Environmental Hazards: These arise from the operating environment or byproducts the machine generates. This category includes: noise (continuous or impact, leading to hearing loss risk), vibration (whole-body or hand-arm vibration), dust or fumes (generated by the process, e.g. metal shavings, chemical vapours), poor lighting, or slippery surfaces around the machine. Environmental hazards are identified by considering both the machine’s emissions and the workplace conditions required. For example, a conveyor in a dusty grain elevator creates grain dust (an explosion and inhalation hazard); a machine in outdoor use may expose workers to weather effects. Evaluation involves recognizing these factors and planning controls (such as enclosures, ventilation, dampening mounts, or PPE) in later risk reduction. Environmental factors are often overlooked, so explicit consideration in hazard identification is critical.

Each identified hazard origin is marked for later risk estimation. While the risk estimation step (severity and probability) comes afterwards, during identification the designer notes the severity of potential harm implicit in each origin (for example, mechanical pinch points imply likely injury severity is high). This ensures that later risk analysis will address the correct magnitude of risk. In summary, all sources of potential injury – whether from machine parts, energy sources, human factors, or environment – are catalogued and categorized during hazard identification.

Case Study: Power Press Machine

Consider a mechanical power press used for stamping metal.

Hazard identification for a press starts by examining the basic press operation and structure. Mechanical hazards are foremost: the press ram (sliding platen) can crush or shear workpieces and hands. The machine has large moving parts (ram, adjustable slides, flywheels, clutch/brake) and stored energy (in flywheel momentum and springs). Checklists would note typical press hazards: crushing/shearing between the ram and bolster, drawing-in at in-running nip points (if material is pulled into the die), and impact from dropped tooling. The inspector would verify that safety distances (per EN ISO 13857) between guards and moving parts are adequate and that fixed guards or light curtains are planned.

Next, electrical hazards are identified: the press motor and controls may carry hundreds of volts. Hazards include shock from exposed wiring or control panels and arc flash if a short occurs. EN 60204-1 guides checking that electrical enclosures, emergency stops, and control circuits are correctly specified. For example, emergency buttons should de-energise the ram drive immediately.

Thermal hazards in a press arise mainly from continuous operation: motors and power electronics heat up, and lubricating oil can become hot. If an older press uses hydraulic clutch/brakes, residual hot oil might contact maintainers. Identification would note all hot surfaces (>60°C) and require guarding or insulation.

Ergonomic hazards appear in tasks like loading heavy dies or handling workpieces. Manual handling checklists would record tasks where operators lift or twist, suggesting the need for hoists or mechanical assist. Sitting or standing at an awkward height to operate pedals can cause strain; hazard identification might involve measuring reach and posture.

Radiation hazards are minimal for a press, except possibly welding stations on or near the press. However, if the press has laser alignment devices or uses arc welding for fabrication, those sources are noted.

Environmental hazards include noise (metal stamping is very loud) and vibration (operator stands on a vibrating floor). Hazard identification notes that noise levels are high enough to require hearing protection and acoustic enclosures.

To systematically find these hazards, engineers would use multiple methods: a checklist of common press hazards, a task analysis of the press cycle (e.g. clamp dies, cycle ram, unload part), and an energy trace (identifying stored kinetic energy in the flywheel and potential energy in flyweights/springs). A design review might reveal, for instance, that the old “banjo” cam plate (one-piece cam) is a known failure point; historical incident data shows wear can cause unintended presses. Thus a new “full-ring knockout” cam (as per best practice) is specified. An expert workshop with maintenance personnel would highlight the hazard of failed clutch brakes causing creep. All these identified hazards are then documented for risk estimation.

Case Study: Industrial Robot

An industrial 6-axis articulated robot presents a different hazard profile.

Mechanical hazards dominate: the robot arm can move very fast along complex trajectories with high force. Hazards include collision and impact (between the arm or end-effector and a person or object), pinch points at moving joints, and entrapment (an operator trapped between the robot and a fixed structure). Hazard identification begins by mapping the robot’s envelope of motion and noting reachable zones. Safety distance checklists (from ISO 13857/10218) ensure that during operation, humans cannot intrude into that space. In task analysis, one considers both automatic production mode and “teaching mode” (manual control), noting that hazards are higher during programming because a person may share the workspace.

Electrical hazards include the high-voltage drives and control cabinet. The robot has large power supplies (often 380–480 VAC three-phase) and capacitors, so shock and arc risks are present. Hazard identification flags all access panels, e-stops, and programmable limit switches. EN 60204-1 compliance ensures safe disconnects.

Thermal hazards might come from servo motors that heat up or if the robot carries heated tools (like a welding torch). Identification means noting any hot surface or hot work process.

Ergonomic hazards in robots are mainly in the programming and maintenance tasks. Writing robot programs via a teach pendant often requires awkward positions near the running cell. Task analysis of maintenance might reveal repeated bending to access base screws, prompting a mention of potential overexertion.

Radiation hazards can be significant: for instance, welding robots emit bright arc light (UV and infrared), and laser-cutting robots emit laser radiation. These are identified as radiation sources requiring shields or interlocks (per EN 12198 for laser safety). For a robot with a welding gun, the identification would include PPE for arc rays.

Environmental hazards: Robots can generate electrical noise (EMI) and require secure grounding. They may be installed in areas with slippery floors (e.g. spilled lubricant), so surrounding environment factors are noted in hazard identification.

In practice, a robot’s hazard identification might use a process-safety style workshop (HAZOP) examining each move and sensor fault. Energy tracing identifies sources: electric energy for the motors, compressed air if present, and stored energy in brakes or springs. Previous incident records (e.g. collisions due to sensor failure or programming error) inform the case. The output is a comprehensive hazard list: high-speed collision (with possible crushing injury), accidental start during maintenance, falls of unsecured fixtures, etc. These then lead to design of safety fencing, pressure-sensitive mats, rated load limits, and so on.

Case Study: Conveyor System

For a conveyor belt system, the hazard identification starts with the belt and rollers.

Mechanical hazards include pinch and nip points where the belt passes over rollers or pulleys, which can pull in fingers, hair or clothing. An identification task would list every exposed roller and drive pulley. Shear points at belt take-ups or transfers (where materials pass between rollers or between roller and guard) are noted. The hazard identification process would follow guidance (similar to ISO 13857) to ensure guards or covers over these points. Entanglement hazards also exist with chain or sprocket drives, and these are checked as well. The conveyor’s loading and discharge points may create crush hazards (e.g. material pile-up).

Electrical hazards: the conveyor drive motor and its control panel (frequency converter, etc.) are sources of shock. Hazard identification will note exposed wiring or inadequate grounding. EN 60204-1 requires that control circuits include emergency stops and interlocks, which must be identified.

Thermal hazards: normally conveyors have low thermal issues, but if they carry hot materials (e.g. a heating tunnel conveyor), hot surfaces must be recognised. Bearings and motors can also become warm; hazard identification would require the review of motor nameplate temperatures.

Ergonomic hazards: conveyors often involve repeated material loading/unloading by operators. Manual handling of heavy packages or repetitive movements (such as twisting to sort materials on a moving belt) are noted. Identification might use an ergonomic checklist to find awkward reaches along the belt or standing postures.

Radiation hazards: conveyors themselves rarely emit radiation, but if integrated with processes (e.g. metal detectors with X-rays), these sources are identified.

Environmental hazards: noise is common (belt drive noise, motor hum), so a noise hazard is recorded. Dust may accumulate around some conveyors (e.g. grain or cement conveyors); hazard identification would note respiratory risks. Slips/trips around the conveyor (leading/trailing rollers) are also environmental hazards to identify.

Typical hazard identification methods include walking the conveyor’s layout to spot any unguarded moving parts, consulting conveyor-specific checklists (e.g. ASME B20.1 or EN 619 series), and reviewing past conveyor incidents (like nip point amputations). Energy tracing would identify the electrical drive, any stored energy in tensioned springs (like self-tensioning take-ups), and potential gravitational hazards (if the conveyor is inclined, falling objects). After identification, the hazards guide choices like installing pull-cord emergency stops along the conveyor and providing knee-high mesh guarding around rollers, all of which would be documented in the safety plan.

Conclusion

Hazard identification in machinery design is a rigorous, systematic process guided by standards such as ISO 12100 and specific EN standards. It requires the use of multiple, structured methods – from checklists and task analyses to design reviews and data mining – to ensure all potential sources of harm are found. The process must span every phase of the machine’s life and every mode of operation, and must consider all categories of hazard (mechanical, electrical, thermal, ergonomic, radiation and environmental). Through an exhaustive combination of methods, designers produce a comprehensive list of hazards (illustrated above in case studies of a press, robot, and conveyor). This list becomes the foundation for risk estimation and the subsequent selection of safety measures. By embedding hazard identification into the early stages of design and development, engineers ensure that machinery can be operated safely, compliant with legislation, and protected against foreseeable misuse and failure. The result is safer machinery and protection of operators through design-informed prevention of hazards, rather than ad hoc fixes.