A machine manufacturer in Australia has a legal responsibility to conduct a hazard identification and risk assessment of the machine. Risk levels must be determined at design stages to avoid as many hazards as possible. The completed machine must conform to AS4024 (Safe Guarding of Machinery) and any other standards that may apply to that particular type of machine.
This involves the consideration of the following aspects.
Guarding of moving
components (mechanical or light curtain guarding)
Fitting an emergency stop switch to stop moving parts quickly (eg. normally closed red mushroom switch)
Calculation of safe operating distance from moving components
Audible and visual alarms
Electrical protection of mains power supply
Disconnection of energy source to motors and solenoids in event of emergency
Installation of safety relays
Failsafe emergency stopping (failure within machine does not prevent emergency stopping occuring)
Documentation of risk assessment and operator instructions
Self testing of safety components
Compliance to European directives if exporting
Safe removal of heat generated by drives and electronic controllers
Two handed controls in hazardous situations
Earthing and earth leakage protection
Labelling of controls
Possible fire risks
A machine with a complex control systems will require a thorough analysis, more than can be achieved here.
Further information can be found on the Pilz Australia web site.
An automated machine
must also be fitted with emergency stop switches to prevent injury
to operators. This may also be used to prevent mechanical damage
to the machine, however the priority is on operator safety. Emergency
stop switches must have at least the following characteristics,
although other conditions may also apply depending on the machine.
Must be colored red. The background as far as practically possible should be colored yellow.
Shall be suitably marked and prominently located and readily accessible from all operator positions.
Shall overide all other machine functions in all operating modes.
Shall remain active at all times.
Shall not be used for normal stopping functions.
Must be failsafe, i.e. normally closed switches where mechanical forces opens the contacts.
Must be a mushroom head, pushbutton, latching switch.
Must require manual resetting or unlocking before the machine can be operated again.
Must override all other functions of the machine in all operating modes.
Must be located at each operator control station and be easily accessible to all operators.
Must not increase risk of injury by presing the switch.