The use of machinery can present hazards that may result in serious injuries, such as crushed fingers or hands, lacerations, abrasions ,amputations, burns, or blindness. It is important to safeguard workers and others who may be present during the operation of dangerous machinery. Machines or any of it’s functions that could become a hazard by making contact with people in the area must be safeguarded. Safeguards range from fixed barrier guards (most effective) and safeguarding devices to safe work procedures and personal protective equipment. A comprehensive risk assessment will determine which safeguards are most effective.
Properly designed and installed barrier guards, are an effective way to protect workers. To keep workers from being hurt by moving parts, harmful fluids or projectiles, fixed barrier guards should be locked by a fastener in the front. This way its impossible for the worker to access danger areas during normal operation without a tool. When a barrier guard must be moved aside to enable a worker to access a point of operation or feed point, the guard must be interlocked to disable the control system until the guard is put back in place and the control system is reset. Some material processor barriers are adjustable to allow for differences in thicknesses of materials to enter a machine. Other barriers attach onto dies that go inside of a machine. A common requirement of all barriers is to prevent people from reaching around or through them into the danger area.
Safe Guarding Devices
Access to different points of the machine is often required during normal operation. This may make the use of a fixed barrier guard types, impracticable. Fortunately there are a number of other safeguarding devices that can provide a high level of protection to workers.
These devices generally operate in one or more of the following ways:
- Requiring the operator to remove hands or body from the danger area before the machine can begin to operate. Two-hand controls and interlocked gate guards function this way.
- Having the machine stop if the operator or other worker enters the danger area while the machine is running. Presence-sensing devices such as light curtains and photoelectric devices and pressure sensitive mats function this way. These devices depend for their effectiveness on a very reliable braking system and associated control system.
- Restraints such as a safety belt and lanyard to prevent the operator from reaching into the danger area of the machine.
- Emergency stop device if all or some of a worker’s body approaches the danger area. Examples include a “belly bar” or “crash bar” in front of a trim saw in-feed lug chain; the emergency trip wire installed along a conveyor system; and the emergency contact bar in front of the in running feed rolls of a flatwork ironer
- Limiting machine movement to a safe range or speed. Examples include operating the machine in a “jog,” “inch,” or “setup” mode, activated by special control buttons (printing presses); limiting die movement to 6 mm (¼ inch) or less before a piece can be inserted into the dies; an anti-repeat device that prevents a machine from performing more than one cycle (single stroke mode).
- Locating the worker in a safe place before the machine can be started using a foot control fastened to the floor a safe distance from the machine (called “captive” or “hostage” control); the activating control for an X-ray machine located in an isolated room.
- “Hold-to-run controls,” which require the operator to keep the control activated in order for the machine to continue to operate (also known as “deadman” or “operator-maintained” controls).
- “Captive key systems,” which use a series of keys and locks to start or shut down a hazardous operation in a prescribed and safe sequence.
All safeguarding devices must be designed, constructed, installed, used and maintained according to CSA Standard Z432, Safeguarding of Machinery. All safeguarding devices should be inspected on a regular basis by a qualified, competent person, and by the machine operator as part of a pre start-up checklist.