Glossary · Risk assessment and risk reduction
Risk estimation
German: Risikoeinschätzung
In machine safety, risk estimation is the process of assigning values to the probability and severity components of risk. The values can be qualitative, semi-quantitative or quantitative.
- Machine safety
- Risk assessment
In one sentence
Risk estimation rates severity and probability of harm for each hazardous situation, often with a risk graph or risk matrix, to rank and evaluate risks.
Example
For a light curtain–guarded press, the team rates crushing of fingers as serious and irreversible, exposure as frequent and avoidance as scarcely possible, which leads to a high required Performance Level.
How it applies
- Parameters: ISO 12100 uses severity and the probability of harm, which depends on exposure, the occurrence of the hazardous event and the possibility to avoid or limit harm.
- Functional safety: ISO 13849-1 uses a risk graph with severity, frequency or duration of exposure and possibility of avoidance to determine the required Performance Level. IEC 62061 uses a comparable scheme to assign a SIL.
- Technical documentation: Record the parameter values and the reasoning for each. A bare result such as “medium” cannot be reviewed.
- Consistency: Use one documented method across a project, with defined categories, so that different engineers reach comparable results.
Risk estimation vs. risk evaluation
Risk estimation assigns values. Risk evaluation judges whether those values call for risk reduction. Keeping them separate prevents the judgment from influencing the estimate.