Mechanical hazards and safety precautions

Mechanical risk can give rise to an injury due to the mechanical action of machine elements, tools, workpieces or projected materials, solid or fluid. The concept of the machine includes all those sets of elements or installations that transform forms of energy (electrical, pneumatic, etc.).

The mechanical risk generated by parts or pieces of their shape (cutting edges, sharp parts), their relative position (since when the pieces or parts of machines are in motion, they can cause trapping, crushing, shear, etc.

The types of mechanical hazards (moving parts) produced by machines are the danger of cutting or sectioning, snagging, impact, piercing or puncturing, entanglement, drawing in or trapping, high-pressure fluid injection, and friction or abrasion.

The non-mechanical hazards of power sources) produced by machinery is the danger of noise, vibration, hazardous substance, radiation, fire, explosion, slip trip and fall, ergonomics, electrical and temperature etc.

What are the five major types of mechanical hazards?

Shear Hazard: 

This hazard is located at the points where the edges of two objects move close enough or one moving past the other with the same speed. Many of these points cannot be protected, so you have to be especially careful when it is in operation because on many occasions the movement of these objects is not visible due to their high speed causing the amputation of a limb. 

The danger of entrapment or dragging: 

It is due to areas formed by two objects that move together, of which at least one rotates, as is the case with feed cylinders, gears, transmission belts, etc. The parts of the body most at risk of being trapped are the hands and hair, the work clothes used are also a cause of trapping and dragging, so to avoid this, tight clothing should be worn to prevent it from being caught and protect areas near rotating elements and hair must be tied up.

Crushing Hazard: 

Crush hazard zones are mainly present when two objects move over each other, or when one is moving and the other is static. This risk mainly affects people who help with hitching operations, being trapped between the machine and the implement or wall. The fingers and hands are also often injured.

Stabbing and puncture: 

Sharp and small ejected material from the machine penetrate into the body. Many machines in normal operation expel particles, the foreign objects such as stones, branches, and others can enter, which are thrown at high speed and could hit the operators. This risk can be reduced or avoided with the use of guards. The machines can also project liquids such as hydraulic systems capable of causing burns and reaching the eyes. To avoid this, hydraulic systems must have adequate preventive maintenance.

Cutting or severing, 

Contact with moving sharp edges such as a blade.

Other Hazards

Entanglement: 

The operator caught on a rotating machine part due to loose clothing or long hair.

Drawing or trapping: 

The body parts caught between two moving parts are drawn into the machine.

Impact: 

The body is struck by the projecting part of the machine.

Safety measures for mechanical hazards

Types of safeguards:

A guard is an element of a machine used for protection utilizing a material barrier. 

Fixed guard: They are kept in position permanently. They completely enclose the dangerous zone due to its dimensions and distance from the dangerous zone, they make it inaccessible.

Mobile guard with interlocking: Guard is associated with an interlocking device so that the dangerous machine functions covered by the guard cannot be performed until the guard is closed. Opening the guard, while performing the dangerous functions of the machine, gives rise to a stop order. Closing the guard does not in itself cause it to start up.

Adjustable guard: It is a fixed or mobile guard that is fully adjustable or that incorporates adjustable parts.  A protection device that prevents a dangerous phase of the machine from being started or maintained, while the human is present in the dangerous zone.

Sensitive command: A command device that starts and maintains the elements of a machine only while the actuator remains associated.

Two-hand control: Control that requires at least the simultaneous actuation of two actuation organs to start and maintain the operation of a machine or its elements.

Sensitive device: A device that causes a machine or its elements to stop when a person or part of their body exceeds a safety limit.

Limiting device: A device that prevents a machine or its elements from exceeding a set limit.

Pulse start control: Control device whose actuation allows only a limited movement of one element of the machine.

Protection measures are to be taken by the user.

The user of a machine, for his part, must adopt the necessary measures so that, the work equipment is kept safe during the entire time of use. This maintenance will be carried out taking into account the manufacturer's instructions,

The use of personal protective equipment

• Personal protective equipment (PPE) is those intended to be carried or held by the worker to protect him from one or several risks;  

• The regulations in force classify PPE into three categories, according to the level of severity of the risks against which they protect:

• The PPE must have the CE conformity marking, which guarantees that the manufacturer complies with the required conformity tests and quality controls. This marking depends on the category of the PPE:

Head protectors: Head protection helmets are intended to protect the upper part of the user's head against falling objects, and must be made up of at least two parts: a frame and a harness. For good protection, the helmet must be adjusted to the size of the wearer's head, it is designed to absorb the energy of the impact through partial destruction or through damage to the frame and harness, therefore, even if these damages are not apparent, any helmet that has suffered a severe impact must be replaced. 

Eye protectors: All eye protectors that are intended to protect in work with ionizing radiation, electrical risks or for work in hot environments. They should be used whenever mechanical work (grinding machines) is being carried out, in drilling work, in material cutting operations with saws and in welding operations

Hand protection: Protective gloves protect against resistance to abrasion, resistance to blade cutting, and resistance to tearing. As additional requirements, they may present resistance to impact cutting and for handling hot or cold.

Foot protection: Protective footwear should be worn in all operations to protect against foot injuries, such as falling objects, rolling objects, slip trip hazards, etc. 

Trunk protection: Personnel exposed to welding work must wear anti-flammable protective clothing and leather aprons. It also applies to personnel who carry out oxyfuel operations. This protects the user against small projections of molten metal and short-term contact with a flame.

Hearing protectors: Hearing plugs are noise protectors worn inside the ear canal or at the ear canal entrance. There are several different models of earplugs, and the user chooses the type that is most comfortable for him. Its use is recommended in those operations due to noise levels throughout the working day that can cause discomfort or hearing disorders; for example, operations with grinding, drilling, hammering, etc.