Example of how to perform the risk assessment for a product covered by

Machinery directive

Göran Lundmark

Machinery Directive 2006/42/EC, ANNEX I

Essential health and safety requirements relating to the design and construction of machinery

GENERAL PRINCIPLES

The manufacturer must ensure that a risk assessment is carried out

and determine the health and safety requirements which apply.

The machinery must then be designed and constructed taking into account the results of the risk assessment.

2006/42/EC, ANNEX I

Iterative process of risk assessment and risk reduction:

— determine the limits of the machinery

— identify the hazards

— estimate the risks

— evaluate the risks,

— eliminate the hazards or reduce the risks

EN ISO 14121-1, Safety of machinery – Risk assessment – Part 1:Principles

Determination of limits of machinery• Use limits. Example of aspects to take into account:

• Different operating modes and intervention procedures

• Intended use and user population (industrial – domestic, sex, age, limiting physical abilities etc.)

• Anticipated levels of training, experience or ability of users

• Exposure of other persons

Determination of limits of machinery• Space limits. Example of aspects to take into account:

• Range of movement

• Space requirements for persons

• Human interaction

• “Machine-power supply” interface

Determination of limits of machinery•Time limits. Example of aspects to take into account:

• “Life limit” of machinery and components

• Recommended service intervals

• Other limits. Examples

• Environmental limits (min – max temperature, indoors – outdoors, dry – wet, etc.)• Housekeeping – level of cleanliness required• Properties of processed materials

Hazard identificationImportant to regard hazards during all phases of the machine life cycle (e.g. transport, assembly and installation, commissioning, use, de-commissioning, dismantling and disposal).

Task identification (setting, start-up, feeding, stop, emergency stop, operator intervention, cleaning etc.)

Various methods for structured hazard identification are available.

Two basic approaches.

Top-down approach: Starts with a check-list of potential consequences and establishes what could cause harm.

E.g. Potential consequence = crushingWhat could cause harm = moving elements, loss of stability, falling objects etc.

Disadvantage: Checklists are not exhaustive and requires experience and creative thinking to “see beyond the list”.

Hazard identification

Bottom-up approach: Starts with examining all the hazards and considering all possible ways that something can go wrong. Is more comprehensive and thorough.

E.g. Origin of hazard = moving element nr 1.Potential consequences = crushing, cutting, abrasion, impact, shearing etc.

Disadvantage: More time-consuming

Hazard identification

Risk is a function of • severity of harm and• probability of occurrence.

The probability of occurrence is a function of • the exposure of persons to the hazard• the occurrence of a hazardous event• the technical and human possibilities of avoiding or limiting the harm

Risk estimation

Risk estimation tools

Available tools normally uses• a risk matrix

Risk estimation

Risk estimation tools

Available tools normally uses• a risk matrix• a risk graph

Risk estimation

Risk estimation tools

Available tools normally uses• a risk matrix• a risk graph

Risk estimation

Risk estimation tools

Available tools normally uses• a risk matrix• a risk graph• numerical scoring• quantified risk estimation• combinations of the above

Risk estimation

The objectives of risk evaluation are• to decide which hazardous situations require further risk reduction, and

• to determine whether required risk reduction has been achieved without introducing further hazards or increased other risks

Risk evaluation

Risk reduction is achieved by implementing protective measures.

Priority order of protective measures:

1.Elimination of hazard

2.Elimination of hazardous situation, i.e. limit exposure

3.Elimination of possible hazardous events

4.Implementation of means to avoid harm

Risk reduction

Example

Use limits:……….. ………….Occasional need for intervention procedure of the operator by malfunction of machine…………

Example

Hazard identification:

Example

Risk estimationCrushing

Example

Risk evaluation: Risk reduction necessaryCrushing

Example

Risk reduction

1. Elimination of hazard2. Elimination of hazardous

situation, i.e. limit exposure

3. Elimination of possible hazardous events

4. Implementation of means to avoid harm

1. Increase distance2. ……..3. ……..

Example

Risk reductiona

Action: Extend frame of machine to implement a safety gap between frame and moving part.Specification according to EN 349 – Safety of machinery – Minimum gaps to avoid crushing of parts of the human body.

Example

Risk estimationCrushing

a

Example

Risk evaluation: No further risk reduction required

Crushing

Further guidance can be found in:

EN ISO 14121-1Safety of machinery – Risk assessment – Part 1: Principles

ISO/TR 14121-2Safety of machinery – Risk assessment – Part 2: Practical guidance and examples of methods