Other Safeguarding Methods | Machine Guarding

Other methods for safeguarding machines include guarding by location or distance and by feeding methods that prevent operator access to the point of operation.

Add a Note HereGuarding by location
Add a Note HereSafeguarding by location involves positioning or designing a machine so that the hazardous parts are away from areas where employees work or walk, or alternatively, installing enclosure walls or fences that restrict access to machines.

Add a Note HereGuarding by feeding methods
Add a Note HereThe feeding process can be safeguarded by distance if the operators maintain a safe distance between their hands and the point of operation. For instance, if the stock is several feet long and only one end of the stock is being worked on, the operator may be able to hold the opposite end while performing the work. Safeguarding by distance is sometimes used during power press brake operations to ensure its effectiveness. This method of safeguarding requires close supervision and training.
Add a Note HereAutomatic and semiautomatic feeding and ejection methods can protect the worker by minimizing or eliminating direct contact with machinery. These methods typically require frequent maintenance, however, and are only protective for normal machine operation. Examples of semiautomatic feeding methods include:
§  Add a Note HereGravity feeds, where the part slides down a chute into the point of operation, and
§  Add a Note HereMagazine feeding, where the worker places the part in a magazine which is then fed into the point of operation.
Add a Note HereAutomatic and semiautomatic ejection methods include pneumatic (jet of air), magnetic, mechanical (such as an arm), or vacuum.

Add a Note HereHand-feeding tools
Add a Note HereOperators can use tools to feed work pieces into equipment to keep their hands away from the point of operation, but this should be done only in conjunction with the guards and devices described previously. Using hand tools requires close supervision to ensure that the operator does not bypass their use to increase production. Tools should be stored near the operation to encourage their use. To prevent repetitive trauma disorders, hand-feeding tools should be ergonomically designed for the specific task being performed.

Add a Note HereFoot controls
Add a Note HereFoot controls are not safeguards because they do not keep the operator’s hands out of the danger area. If you use them, they will need some type of guard or device, such as barriers or pullouts with interlocks capable of controlling the start up of the machine cycle. Using foot controls may increase productivity, but the freedom of hand movement allowed while the machine is operating increases the risk of a point of operation injury.
Add a Note HereFoot controls must be guarded to prevent accidental activation by another worker or by falling material and not allow continuous cycling. They work best when the operator is in a sitting position. Always avoid the hazard of riding the pedal (keeping the foot on the pedal while not actively depressing it.)

Add a Note HereMachines with clutches
Add a Note HereCertain machines can be categorized based on the type of clutch they use — full-revolution or part-revolution. Differing modes of operation for these two clutches determine the type of guarding that can be used.
Add a Note HereOnce activated, full-revolution clutches complete a full cycle of the slide (lowering and raising of the slide) and cannot be disengaged until the cycle is complete. So, presence-sensing devices may not work and a worker must maintain a safe distance when using two-hand trips. Machines incorporating full-revolution clutches, such as power presses, must also incorporate a single-stroke device and anti-repeat feature.
Add a Note HereThe part-revolution clutch can be disengaged at any time during the cycle to stop the cycle before it completes the down stroke. For example, part-revolution presses can be equipped with presence-sensing devices, but full-revolution presses cannot. Likewise, hydraulic presses can be stopped at any point in the cycle, and their safeguarding is similar to guarding for part-revolution clutch presses.
Add a Note HereSpecial hand tools may be used to place or remove stock, particularly from or into the point of operation of a machine. A typical use would be for reaching into the danger area of a press or press brake. Figure 1 shows an assortment of tools for this purpose. Holding tools should not be used instead of other machine safeguards; they are merely a supplement to the protection that other guards provide.

Figure 1: Holding tools
Add a Note Here
Add a Note HereA push stick or block, such as those in Figure 2, may be used when feeding stock into a saw blade. When it becomes necessary for hands to be in close proximity to the blade, the push stick or block may provide a few inches of safety and prevent a severe injury. In the illustration, the push block fits over the fence.

Figure 2: Use of push stick or push block
Add a Note Here

No comments:

Popular Posts