Hollie Dixon from leading machinery safety specialist Euchner UK highlights some of the often–overlooked aspects of machinery risk assessments.
Did you know that it is a legal requirement for every machinery manufacturer to carry out a risk assessment before anything is placed on the market? However, even when risk assessments are undertaken, they are often not of a suitable standard. Guidelines on risk assessments can be found in EN ISO 12100, a standard that describes basic risks that can occur and identifies steps with which a risk assessment can be carried out.
Content of a risk assessment
The risk assessment itself consists of the sections:
Risk assessment using EN ISO 12100
One of the central points of the standard is a general strategy on how to reduce the risk on a machine and here, the following three-stage process must be applied:
Step 1: The risk of injury must be reduced as far as possible by means of a suitable design. For example, spoked wheels and pulleys can be designed with a solid infill to the prevent trapping and shearing fingers and limbs.
Step 2: If all hazards cannot be eliminated or adequately minimised with Step 1, technical measures for risk reduction must be applied where applicable. Generally, these measures involve physical guarding with control system interlocking to suit the risk/hazard involved. The safety related control functions also require an assessment to determine safety integrity. EN ISO 13849-1 gives further information on this aspect.
Step 3: Additional protective measures are the last option within the hierarchy requiring users of the equipment to protect themselves from harm through the use of PPE, training and warning signs. Unfortunately, there are too many instances where designers of equipment jump straight to this step without safeguarding or considering designing the hazard out.
This process should be well documented and included as part of the Technical Construction File (TCF) for all manufacturers of machinery and equipment covered under the Machinery Directive.
Machinery Lifecyle
EN ISO 12100 also provides guidance on which phases of the life of a machine must be considered and which of the various hazards must be assessed. These phases of life include transport, assembly and installation; commissioning; use; and dismantling, disabling and scrapping.
The erection and dismantling of a machine are included in the phases of life but often overlooked by many machine manufacturers, despite there being significant hazards during these phases, including:
During all these tasks, hazards in the risk assessment must be taken into account and, if there is a danger, itmust be reduced in accordance to the risk assessment. An additional point to the risk assessment that is frequently overlooked is the unintentional behaviour of an operator or the reasonably foreseeable misuse of a machine. Malfunctions on a machine, due to the failure of a component for example, are also to be considered.
It is not uncommon for hazards originating from a machine or installation to be missed during the risk assessment. For this reason, there are also examples for the various possible hazards in the Annex to the standard, including (but not limited to):
Taken altogether, this can be a very complex task for the design engineer although there is wide range of external support available including training, risk assessments and safety concept design services from companies like Euchner.
Methodology for risk estimation
There are various factors that define the risk in a danger zone on a machine. Primarily, there is of course the possible extent of the harm. However, a risk is lower if the exposure to a hazard is only infrequent or brief, for example with fully automated machinery. The second factor is the frequency and duration of usage. The third factor is whether the person can avoid the hazard because, for example, the motion that causes the hazard is so slow that it is possible to leave the danger zone by simply moving away. A fourth factor is the probability of the hazard actually occurring.
In summary, EN ISO 12100 provides guidelines for the safety of machinery. It is intended to help manufacturers design safe machinery and to assist in the creation of national regulations for the safety of machinery. The standard covers a wide range of topics, including risk assessment, and is meant to help ensure the safety of machinery by reducing the risk of accidents and injuries to workers and other people who may come into contact with machinery.
For further information on Euchner’s portfolio of safety services for machinery manufacturers visit https://bit.ly/3tMKflc, email services@euchner.co.uk or call the Safety Technology Centre on +44 (0)114 256 0123.
This article appeared in the Dec/Jan issue of Design Solutions magazine.
