Jul 16, 2026
A machinery risk matrix is a tool used during machine risk assessments to evaluate the level of risk associated with a particular hazard. It helps safety professionals, engineers and machinery users determine whether additional control measures are required and prioritise actions based on the severity and likelihood of potential harm.
Risk matrices are commonly used as part of machinery risk assessments conducted in accordance with ISO 12100 and can play an important role in helping organisations make consistent and justifiable decisions about machinery safety.
While the exact format may vary between organisations, the purpose remains the same: to provide a structured method for assessing risk and determining whether it has been reduced to an acceptable level.
Industrial machinery can present a wide range of hazards, from moving mechanical parts and electrical systems to stored energy and automated processes. Not all hazards present the same level of risk, so organisations need a way of evaluating which issues require immediate attention and which may already be adequately controlled.
A risk matrix provides a simple visual framework for assessing hazards based on factors such as:
By considering these factors together, a risk matrix helps assessors prioritise risks and focus resources where they will have the greatest impact.
Most risk matrices combine two primary factors: severity and likelihood.
Severity considers the potential consequences if an incident were to occur. For example, a minor cut may be considered a low-severity outcome, whereas an amputation or fatality would be categorised as high severity.
Likelihood considers how probable it is that the hazardous event will occur. This may take into account factors such as frequency of exposure, reliability of safety systems and the opportunities for human error.
When these two factors are combined, the result is a risk rating that typically falls into categories such as:
| Risk Rating | Typical Action |
|---|---|
| Low | Risk may be acceptable with existing controls |
| Medium | Review controls and consider improvements |
| High | Additional risk reduction measures required |
| Very High | Immediate action required before operation continues |
The purpose of the matrix is not to generate a definitive answer but to support a consistent and documented decision-making process.
One of the most common misconceptions is that ISO 12100 requires a specific risk matrix.
In reality, the standard does not prescribe a particular matrix or scoring system. Instead, it requires organisations to estimate and evaluate risk using a structured methodology.
ISO 12100 identifies several factors that should be considered when estimating risk, including:
Many organisations use risk matrices because they provide a practical way of incorporating these factors into the assessment process.
However, it is important to remember that the matrix itself is only one part of the overall risk assessment. The quality of the assessment depends on the competence of the assessor and their understanding of the machinery being evaluated.
Consider a packaging machine with exposed moving components that operators access during routine cleaning activities.
An assessment may identify the potential for entanglement injuries if cleaning is carried out while the machine is energised.
The assessor might determine that:
Based on these factors, the hazard may receive a high-risk rating, indicating that additional controls are required.
Risk reduction measures could include improved guarding, interlocked access doors, isolation procedures or changes to the machine's control system.
Once these measures have been implemented, the risk would be reassessed to determine whether it has been reduced to an acceptable level.
Risk matrices can be valuable tools, but they are often misused.
One common mistake is focusing solely on the numerical score rather than understanding the actual hazard. A low score does not automatically mean a risk is acceptable, particularly if the potential consequences are severe.
Other common issues include:
A risk matrix should support professional judgement, not replace it.
Although risk matrices are widely used, they have limitations.
Two assessors may assign different scores to the same hazard based on their experience, understanding of the machine or interpretation of the scoring criteria. This can lead to inconsistent results if a robust methodology is not followed.
Risk matrices can also oversimplify complex machinery hazards. A numerical score cannot always capture the full range of factors that influence machinery safety.
For this reason, risk matrices should always be used alongside a thorough hazard identification process and an understanding of applicable machinery safety standards.
The purpose of a machinery risk assessment is not simply to assign scores to hazards. The ultimate goal is to reduce risk.
Once hazards have been identified and evaluated, organisations should follow the hierarchy of risk reduction outlined in ISO 12100.
This generally involves:
A risk matrix helps determine where action is needed, but effective risk reduction is what ultimately improves machinery safety.
A machinery risk matrix is a structured tool used to evaluate hazards and determine the level of risk associated with machinery. By considering factors such as severity, likelihood and exposure, organisations can prioritise safety improvements and make informed decisions about risk reduction.
While risk matrices are widely used during machine risk assessments, they should not be viewed as a substitute for competent assessment or professional judgement. When combined with a thorough understanding of machinery hazards and the principles of ISO 12100, a risk matrix can form an important part of an effective machinery safety programme.