CHESS has a variety of equipment
in its machine shop, each with potential hazards. Before using any
equipment in the shop, you must be trained to use it and checked out by
the Machine Shop Supervisor.
General Guidelines for Shop Safety:
• Eye Protection: grinding, cutting and drilling of metal and wood
generate airborne particles. Always wear safety glasses, goggles, or
shields.
• Foot Protection: always wear sturdy, closed-toed shoes to protect your feet from wood and metal wastes on shop floors, and from heavy objects that can crush feet and toes. A safety shoe and boot truck visits CHESS regularly - check with your supervisor or the Shop Supervisor for information on where to buy safety shoes. CHESS personnel are allowed to purchase one pair of safety shoes annually.
• Hand Protection: to prevent cuts, burns, sprains and repetitive motion injuries, be proactive about protecting yourself. Wear appropriate gloves (unless you are using equipment with unforgiving rotating parts), and remove watches and jewelry before you start work. Don't handle shop chemicals or operate machinery with your bare hands, and don't ignore safety guards on machinery. Always inspect equipment and machinery for wear, dull cutting blades, or broken parts before you begin work. Use the correct tool for the job. If you are lifting and carrying heavy objects, be aware of narrow doorways where your hands can get caught and crushed: when stacking heavy objects, keep your hands on either side, not underneath, to avoid crushing your fingers.
• Clothing: be aware, especially when working with equipment with moving parts, of hair and clothing that could become trapped in machinery. Tie back long hair, remove neckties, and roll up long sleeves. Wear a safety apron to protect your body from flying particles of metal or wood.
• Housekeeping: clean up after yourself. Put away materials when you are
finished with them. Roll up power cords and return them to their
appropriate storage places. Do not leave machines running unattended.
Think ahead before you begin any project: What are the steps necessary
to complete it and what are the potential hazards? Consider other people
working in your area and let them know if you are doing work that may
create a potential safety hazard for them.
Basics of Machine Safeguarding
Crushed hands and arms, severed fingers, blindness - the list of
possible machinery related injuries is a long as it is horrifying. There
seems to be as many hazards created by moving machine parts as there are
types of machines. Safeguards are essential for protecting workers form
needless and preventable injuries.
A good rule to remember is: Any machine part, function, or process which
may cause injury must be safeguarded. Where the operation of a machine
or accidental contact with it can injure the operator or others in the
vicinity, the hazard must be either controlled or eliminated.
This section describes the various hazards of mechanical motion and
action and presents some techniques for protecting workers from these
hazards.
Where Mechanical Hazard Occur
Dangerous moving parts in these three basic areas need safeguarding:
1.
The point of operation: that point where work is performed on the
material, such as cutting, shaping, boring, or forming of stock.
2. Power transmission apparatus: all components of the mechanical system which transmit energy to the part of the machine performing work. These components include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears.
3.
Other moving parts: all parts of the machine which move while the
machine is working. These can include reciprocating, rotating, and
transverse moving parts, as well as feed mechanisms and auxiliary parts
of the machine.
Hazardous Mechanical Motions and Actions
A wide variety of mechanical motions and actions may present hazards to
the worker. These can include the movement of rotating members,
reciprocating arms, moving belts, meshing gears, cutting teeth, and any
parts that impact or shear. These different types of hazardous
mechanical motions and actions are basic to nearly all machines, and
recognizing them is the first step toward protecting workers from the
danger they present. The basic types of hazardous mechanical motions and
actions are:
Motions
•
rotating (including in-running nip points)
•
reciprocating
•
transverse
Actions
•
cutting
•
punching
•
shearing
•
bending
Brief examination of each of these basic types:
Motions:
Rotating motion can be dangerous; even smooth, slowly rotating shafts
can grip clothing, and through mere skin contact force an arm or hand
into a dangerous position. Injuries due to contact with rotating parts
can be severe.
Collars, couplings, cams, clutches, flywheels, shaft ends, spindles, and
horizontal or vertical shafting are some examples of common rotating
mechanisms which may be hazardous. The danger increases when bolts,
nicks, abrasions, and projecting keys or set screws are exposed on
rotating parts.
In-running nip point hazards are caused by rotating parts on machinery.
There are three main types of in-running nips.
1.
Parts can rotate in opposite directions while their axes are parallel to
each other. These parts may be in contact (producing a nip point) or in
close proximity to each other. In the latter case the stock fed between
the rolls produces the nip points. This danger is common on machinery
with intermeshing gears, rolling mills, and calendars.
2. Another nip point is created between rotating and tangentially moving parts. Some examples would be: the point of contact between a power transmission belt and its pulley, a chain and a sprocket, or a rack and pinion.
3.
Nip points can occur between rotating and fixed parts which create a
shearing, crushing, or abrading action. Examples are: spoked handwheels
or flywheels, screw conveyors, or the periphery of an abrasive wheel and
an incorrectly adjusted work rest.
Reciprocating motions may be hazardous because, during the
back-and-forth or up-and-down motion, a worker may be struck by or
caught between a moving and a stationary part.
Transverse motion (movement in a straight, continuous line) creates a
hazard because a worker may be struck or caught in a pinch or shear
point by the moving part.
Actions
Cutting action involves rotating, reciprocating, or transverse motion.
The danger of cutting action exists at the point of operation where
finger, head, and arm injuries can occur and where flying chips or scrap
material can strike the eyes or face. Such hazards are present at the
point of operation in cutting wood, metal, or other materials. Typical
examples of mechanisms involving cutting hazards include bandsaws,
circular saws, boring or drilling machines, turning machines (lathes),
or milling machines.
Punching action results when power is applied to a slide (ram) for the
purpose of blanking, drawing, or stamping metal or other materials. The
danger of this type of action occurs at the point of operant where stock
is inserted, held, and withdrawn by hand. Typical machinery used for
punching operations are power presses and iron workers.
Shearing action involves applying power to a slide or knife in order to
trim or shear metal or other materials. A hazard occurs at the point of
operation where stock is actually inserted, held, and withdrawn. Typical
examples of machinery used for shearing operations are mechanically,
hydraulically, or pneumatically powered shears.
Bending action results when power is applied to a slide in order to draw
or stamp metal or other materials, and a hazard occurs at the point of
operation where stock is inserted, held, and withdrawn. Equipment that
uses bending action includes power presses, press brakes, and tubing
benders.
Requirements for Safeguards
What must a safeguard do to protect workers against mechanical hazards?
Safeguards must meet these minimum general requirements:
Prevent contact: The safeguard must prevent hands, arms, or any other
part of a worker's body from making contact with dangerous moving parts.
A good safeguarding system eliminates the possibility of the operator or
another worker placing their hands near hazardous moving parts.
Secure: Workers should not be able to easily remove or tamper with the
safeguard, because a safeguard that can easily be made ineffective is no
safeguard at all. Guards and safety devices should be made of durable
material that will withstand the conditions of normal use. They must be
secured to the machine.
Protect from falling objects: The safeguard should ensure that no
objects can fall into moving parts. A small tool which is dropped into a
cycling machine could easily become a projectile that could strike and
injure someone.
Create no new hazards: A safeguard defeats its own purpose if it creates
a hazard of its own such as a shear point, a jagged edge, or an
unfinished surface which can cause a laceration. The edges of guards,
for instance, should be rolled or bolted in such a way that they
eliminate sharp edges.
Allow safe lubrication: If possible, one should be able to lubricate the
machine without removing the safeguards. Locating oil reservoirs outside
the guard, with a line leading to the lubrication point, will reduce the
need for the operator or maintenance worker to enter the hazardous area.
Non-mechanical Hazards
All power sources for machinery are potential sources of danger. When
using electrically powered or controlled machines, for instance, the
equipment as well as the electrical system itself must be properly
grounded. Replacing frayed, exposed, or old wiring will also help to
protect the operator and others from electrical shocks or electrocution.
High pressure systems, too, need careful inspection and maintenance to
prevent possible failure from pulsation, vibration, or leaks. Such a
failure could cause explosions or flying objects.
Machines often produce noise (unwanted sound) and this can result in a
number of hazards to workers. Not only can it startle and disrupt
concentration, but it can interfere with communications, thus hindering
the worker's safe job performance. Research has linked noise to a whole
range of harmful health effects, from hearing loss and aural pain to
nausea, fatigue, reduced muscle control, and emotional disturbances.
Engineering controls such as the use of sound- dampening materials, as
well as less sophisticated hearing protection, such as ear plugs and
muffs, have been suggested as ways of controlling the harmful effects of
noise. Vibration, a related hazard which can cause noise and thus result
in fatigue and illness for the worker, may be avoided if machines are
properly aligned, supported, and, if necessary, anchored.
Because some machines require the use of cutting fluids, coolants, and
other potentially harmful substances, operators, maintenance workers,
and others in the vicinity may need protection. These substances can
cause ailments ranging from dermatitis to serious illnesses and disease.
Specially constructed safeguards, ventilation and protective equipment
and clothing are possible temporary solutions to the problem of
machinery-related chemical hazards until these hazards can be better
controlled or eliminated form the workplace.
Training
Even the most elaborate safeguarding system cannot offer effective
protection unless the worker knows how to use it and why. Specific and
detailed training is therefore a crucial part of any effort to provide
safeguarding against machine-related hazards. Thorough operator training
should involve instruction or hands-on training in the following:
1.
a description and identification of the hazards associated with
particular machines;
2. the safeguards themselves, how they provide protection, and the hazards for which they are intended;
3. how to use the safeguards and why;
4. how and under what circumstances safeguards can be removed, and by whom (in most cases, repair or maintenance personnel only; and
5.
what to do (e.g., contact supervisor) if a safeguard is damaged,
missing, or unable to provide adequate protection.
This kind of safety training is necessary for new operators and
maintenance or setup personnel, when any new or altered safeguards are
put in service, or when workers are assigned to a new machine or
operation.
