Glossary · Risk assessment and risk reduction
Machine limits
In machine safety, machine limits are the use, space, time, environmental and other boundaries considered in risk assessment. Determining them is the first step of risk analysis under ISO 12100.
- Machine safety
- Risk assessment
In one sentence
Machine limits define the use, space, time and environment a risk assessment covers; anything outside them is not assessed, so they must be explicit.
Example
For a CNC machining center, the limits include the intended workpieces and operating modes, the required floor space and access for maintenance, tool life and service intervals, and a shop-floor temperature range.
How it applies
- Risk assessment: ISO 12100 distinguishes use limits (intended use, operating modes, users, foreseeable misuse), space limits (range of movement, installation and maintenance space, interfaces), time limits (life limit of the machine and its components, service intervals) and other limits such as environment, materials and cleanliness.
- Integrated systems: When machines are combined into a line, the limits of each machine meet at interfaces. Document the system boundary and who assesses the hazards at each interface.
- Technical documentation: Many limits reappear in the operating manual as technical data, permitted materials and environmental conditions. Keep both sources consistent.
- Evidence: Limits are operating assumptions. If operation leaves them, for example a higher throughput or a different material, the risk assessment must be reviewed.
Machine limits vs. system boundary
Machine limits describe the conditions a single machine's risk assessment covers. A system boundary in systems engineering defines what belongs to a system and what is its environment. On integrated lines, both need to be aligned.