The system includes not only the machine and the operator; It includes everything from the initial design of the machine to the training of all those responsible for any aspect, to documentation of all changes, to regular security audits and finally a corporate culture of security.
Design is the part of the life of a machine where you can make the greatest impact in avoiding accidents. The designer must ensure that the machine is safe to set up and operate, safe to install, safe to maintain, safe to repair and safe to dismantle.
Although safe operation is usually at the forefront of a designer's mind, maintenance insurance and repair should also be a high priority. About 50% of fatal accidents involving industrial equipment are associated with maintenance activities, and design contributes to about 32% of these deaths.
In our project Accident Avoiding System for Punching Machine the IR sensors are used to avoid the accident. The system stops automatically when the IR sensor detects the operator parts inside the machine.
The designer must make the machine as reliable as is reasonably possible to minimize the maintenance requirement and allow long intervals between routine maintenance tasks. It is also important to design the machine and its control system so that maintenance can be carried out safely.
For example, retention controls can be installed to allow a machine to operate at a reduced speed, or removable tool holders can be used so that sharp blades can be replaced on a workbench rather than in a difficult position within a Machine. In addition, safety equipment should be avoided by operators and maintenance technicians.
Safety components are often designed to interrupt processes in the event of a failure and will have an impact on the availability of the machine. In order to minimize this effect - and the temptation to interfere with safety circuits - highly reliable safety components must be specified to keep the number of nuisance failures to a minimum.
It is important to design safety in a new machine, but remember that the vast majority of machines do not remain unchanged, with operating procedures unchanged, throughout their life.
NEED OF MACHINERY SAFETY SYSTEM
Modifications are almost inevitable and work practices may evolve or be deliberately reviewed by managers in an attempt to improve performance. Any changes made to the machine or its operation also modify the original risk assessment. Research has shown that a significant number of industrial accidents result from uncontrolled changes. It is usually through a complex sequence of events that a change leads to an accident.
It is clear that there is a need to ensure that machinery and operating procedures are fully documented. Even if a machine and its associated safety systems are properly designed and documented, it is vital that the machine is monitored during installation, commissioning and first production. Often it is necessary to make small changes during any or all of these stages.
It is imperative that any proposed change is first subjected to a rigorous risk assessment, and any changes that are implemented must be fully documented. Once production has commenced, a further review should be performed to ensure that no additional changes have been made. Also note that "no further change" also refers to the raw materials or components being processed by the machine. Audits should be conducted regularly to verify that the machine and operating procedures are still in the documented state.
In addition, functional audits should also be carried out in machinery safety systems. Often the components of a safety control system are only used in case of an emergency, which can make them very difficult to test. However, these systems should be tested at regular intervals.
Security buses such as AS-i Safety At Work and Profisafe can support intelligent field devices capable of performing self-monitoring functions and transmitting diagnostic data to a central controller that can alert the operator of the machine before the fault Becomes an unacceptable risk.