Chapter 2.1
Risk Assessment
We guide you in assessing potential risks and how to navigate the legal requirements on what measures should be taken in each situation. Risk assessment or its documentation is often missing when companies are asked to present their conformity documents to a customer – or worse – the authorities. Many consider it a type of “secret art” or even a waste of time.
Why should you do risk assessment?
There are at least three good reasons:
- In most industrialized countries it is required by law. In the EU, the Machinery Directive 2006/42/EC and its successor the Machinery Regulation 2023/1230 require it.
- It is almost impossible to design machinery with a sufficient degree of safety without following a systematic approach.
- We all want to avoid learning the hard way: through accidents which may cause injury to people and incur liability for the manufacture
The key faults in risk assessment are the following:
- It is done with a needlessly cumbersome approach.
- It is done too late, when product design is more or less completed or the machine/ system already built.
Consider two things that will help you
Follow the task-based approach, this is also required by (EN) ISO 12100.
Step 1/2
Follow a targeted, uncomplicated approach
- Identify the relevant phases of life
Identify the relevant phases of life. Transport, installation, operation, maintenance, troubleshooting... - Define operations and tasks
An "operation" is an automatic process inside the machine. A "task" is an action taken by an operator. Typical operations and tasks in the operation phase for instance are: insert work piece (manually), start process, punch/mill/ grind/weld automatically, remove finished part from machine. - Identify hazards
Look for hazards in each defined operation and task. Punching automatically in a press for instance causes crushing/shearing and noise. - Estimate risk
Crushing in a press can cost a hand or arm. Large presses can kill a person. Since parts need to be inserted often, the hazard occurs frequently. Since presses move fast, people can hardly escape the hazard. (To standardize risk estimation, you should use a method from one of the international standards). - Select a safety measure
Select a safety measure. - Check directives/standards
Check how the measure is to be designed (measures must be state of the art according to laws and standards). This last step is the most difficult, as it involves researching standards (more about this see under “Researching standards”).
Step 2/2
Do it with time to spare
Conduct the risk assessment in good time
Performing the risk assessment while the product is still “on paper" can help you detect hazards at an early stage. Although the very early design stages might be too soon, once you have a clear idea of how the machine will function and what moving parts are required, it's time to begin. The later you assess the risk, the more challenging, time-consuming, and less effective it will be.
Starting early will also help you avoid two common consequences of faulty risk assessment:
- Costly, late design changes
- Unsafe machinery that leads to accidents, complaints by authorities or even legal prosecution.
Follow a live risk assessment now
Define task to be assessed
Task:
Operator brings pallet into the machine and checks it.
Find the hazards and describe the hazardous event
Hazard
Approach of a moving element to a fixed part:
- Crushing, shearing
- Impact
Hazardous event
Operator may be crushed between moving robot and pallet or machine parts.
Select a safety measure
Type of measure:
Combination of guards and protective devices (llc).
- The hazard zone is enclosed by a guard fence that prevents intentional and unintentional access.
- A door is provided for access, which serves as a movable guard.
- The movable guard is provided with interlocking and guard locking that holds the door closed until robot and machine movements in the hazard zone have stopped.
- The machine cannot start as long as the door is still open or not locked.
- The door switch must be provided with an escape release lock.
Allocate requirements from directives/standards
Machinery directive:
- 1.3.7 – Risk related to moving parts
- 1.4.2.1 – Fixed guards
- 1.4.2.2 – Interlocking movable guards
EN ISO 12100: 2010: sections 6.3.3.2.2 and 6.3.3.2.3
Do a risk estimation to find the PL for the interlocking function
Do a risk estimation to find the PL for the interlocking function
S – Severity of injury: 2
Operator could be seriously injured by the robot, fatal injury possible.
F – Frequency and duration: 1
The pallet must be replaced approximately once per hour.
P – Prevention of harm: 2
The robot moves at speeds of up to 10 m/s, avoidance hardly possible.
O – Probability of occurrence: 2
No evidence available.
PLr: d
The most vital parts of an risk assessment
Risk assessment is useful or even indispensable for a number of other processes in the development, manufacture, testing, and aftersales services.
Information on directives and standards applied
Drafting of declaration of conformity, or declaration of incorporation.
Description of limits of machinery
Drafting of “Safety Notes” in operating instructions.
List of the phases of life, the operations and tasks
Design of control system operating modesand procedures. Structuring of operating instructions.
Description of guards and safety devices
Drafting of acceptance checklist for test field. Design of warning signs on the machine. Drafting list of protection measures in operating instructions. Drafting warning messages in operating instructions.
Description of control system safety functions
Design of safety-related parts of control system.
Learn more in our webinar on risk assessment