Methods of Machine Guarding
There are various ways to design and implement machine safeguarding. The type of operation, size or shape of stock, method of handling, physical layout of the work area, type of material, and production requirements or limitations will determine the appropriate machine safeguarding method for the individual machine.
As a general rule, a power transmission apparatus is best protected by fixed guards that enclose the danger areas. For hazards at the point of operation, where moving parts perform work on stock, several types of machine safeguarding may be possible. You must always choose the most effective and practical means available.
Five General Classifications of Machine Safeguards
We can group machine safeguards under five general classifications.
- Guards: Guards are barriers that prevent access to danger areas. There are four general types of guards and we'll discuss them in the next section.
- Devices: A safety device may perform one of several functions. It may stop the machine if a hand or any part of the body is inadvertently placed in the danger area; restrain or withdraw the operator's hands from the danger area during operation; require the operator to use both hands on machine controls, thus keeping both hands and body out of danger; or provide a barrier which is synchronized with the operating cycle of the machine in order to prevent entry to the danger area during the hazardous part of the cycle.
- Location/Distance: To consider a part of a machine to be machine guarded by location, the dangerous moving part of a machine must be positioned so that those areas are not accessible or do not present a hazard to a worker during the normal operation of the machine. This may be accomplished by locating a machine so that the hazardous parts of the machine are located away from operator work stations or other areas where employees walk or work.
- Potential Feeding and Ejection Methods: Feeding and ejection methods generally do not require the operator to place his or her hands in the danger area. In some cases, no operator involvement is necessary after the machine is set up. In other situations, operators can manually feed the stock with the assistance of a feeding mechanism. Properly designed ejection methods do not require any operator involvement after the machine starts to function.
- Miscellaneous Aids: While these aids do not give complete protection from machine hazards, they may provide the operator with an extra margin of safety. Sound judgment is needed in their application and usage. Below are several examples of possible applications.
Knowledge Check Choose the best answer for the question.
2-1. Which classification of machine safeguards use a physical barrier to prevent access to the danger areas?
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