Mechanical Machinery Hazards
Most machinery has the potential to cause injury to people, and machinery accidents figure prominently in official accident statistics. These injuries may range in severity from a minor cut or bruise, through various degrees of wounding and disabling mutilation, to crushing, decapitation or another fatal injury.
It is not solely powered machinery that is hazardous, for many manually operated machines (e.g. hand-operated guillotines and fly presses) can still cause injury if not properly safeguarded. Machinery movement basically consists of rotary, sliding or reciprocating action, or a combination of these.
These movements may cause injury by entanglement, friction or abrasion, cutting, shearing, stabbing or puncture, impact, crushing, or by drawing a person into a position where one or more of these types of injury can occur. The hazards of machinery are set out in BS EN ISO 12100 – Part 2: 2003, which covers the classification of machinery hazards and how harm may occur.
A person may be injured by machinery as a result of:
A crushing hazard through being trapped between a moving part of a machine and a fixed structure, such as a wall or any material in a machine;
A shearing hazard which traps part of the body, typically a hand or fingers, between moving and fixed parts of the machine;
A cutting or severing hazard through contact with a cutting edge, such as a band saw or rotating cutting disc;
An entanglement hazard with the machinery which grips loose clothing, hair or working material, such as emery paper, around revolving exposed parts of the machinery. The smaller the diameter of the revolving part the easier it is to get a wrap or entanglement;
A drawing-in or trapping hazard such as between in-running gear wheels or rollers or between belts and pulley drives;
An impact hazard when a moving part directly strikes a person, such as with the accidental movement of a robot’s working arm when maintenance is taking place;
A stabbing or puncture hazard through ejection of particles from a machine or a sharp operating component like a needle on a sewing machine;
Contact with a friction or abrasion hazard, for example, on grinding wheels or sanding machines; a high-pressure fluid injection (ejection hazard), for example, from a hydraulic system leak.
In practice, the injury may involve several of these at once, for example, contact, followed by entanglement of clothing, followed by trapping.