All tools are dangerous if used improperly or carelessly. Working safely is the first thing the user or operator should learn because the safe way is the correct way. A person learning to operate machine tools must first learn the safety regulations and precautions for each tool or machine. Most accidents are caused by not following prescribed procedures. Develop safe work habits rather than suffer the consequences of an accident.

Most of the safety practices mentioned in this section are general in nature. Safety precautions for specific tools and machines are described in detail in the chapters along with the description of the equipment. Study these carefully and be on the alert to apply them.


Using eye protection in the machine shop is the most important safety rule of all. Metal chips and shavings can fly at great speeds and distances and cause serious eye injury. Safety glasses must be worn when working with handcutting tools, since most handcutting tools are made of hardened steel and can break or shatter when used improperly.

There are many different types of safety glasses available in the supply system; however, the ones that offer the best protection are the safety glasses with side shields. Safety goggles should be worn over prescription glasses. For specific information about eye protection, contact the Occupational Health Clinic or refer to TB MED 586.


Noise hazards are very common in the machine shop. High intensity noise can cause permanent loss of hearing. Although noise hazards cannot always be eliminated, hearing loss is avoidable with ear muffs, ear plugs, or both. These are available through the local supply system or from the Occupational Health Clinic. Ear plugs must be properly fitted by qualified personnel. For specific information on hearing protection, refer to TB MED 501.


The floor in a machine shop is often covered with razor-sharp metal chips, and heavy stock may be dropped on the feet. Therefore, safety shoes or a solid leather shoe must be worn at all times. Safety shoes are available in the supply system. These have a steel plate located over the toe and are designed to resist impact. Some safety shoes also have an instep guard.


Grinding dust from abrasive wheels is made up of extremely fine particles of the metal and the wheel. Some grinding machines are equipped with a vacuum dust collector. When operating a grinder without a vacuum, wear an approved respirator to avoid inhaling the dust. Whenever possible, use coolant when grinding. This will aid in dust control. Grinding dust can be very dangerous to your health, especially beryllium or parts used in nuclear systems. These materials require careful control of grinding dust.

Metals such as zinc give off toxic fumes when heated above their boiling point. Inhaling these fumes may cause temporary sickness, or death. The fumes produced from lead and mercury are very harmful, as their effect is cumulative in the body and can cause irreversible damage. When unsure of the materials being machined, it is advisable to wear a respirator. For more specific information on respirator safety, refer to TB MED 502.


Using improper lifting procedures may result in a permanent back injury. Back injury can be avoided if the correct lifting procedures are followed. When lifting heavy or large objects, get some assistance or use a hoist or forklift.

Objects within your ability can be lifted safely as long as the following procedures are followed:

* Keep your back straight.
* Squat down, bending at the knees.
* Use the leg muscles to do the work and lift slowly. Do not bend over the load as this will put excessive strain on your spine.
* Carry the object where it is comfortable, and pay close attention to where you are walking and objects around you.
* When placing the object back on the floor, use the same procedures as when it was lifted.


Exposure to electrical hazard will be minimal unless the operator becomes involved with machine repair. The machine operator is mostly concerned with the on and off switch on the machine tool. However, if adjustments or repairs must be made, the power source should be disconnected. If the machine tool is wired permanently, the circuit breaker should be switched off and tagged with an appropriate warning statement. Most often the power source will not be disconnected for routine adjustment such as changing machine speeds. However, if a speed change involves a belt change, make sure that no other person is likely to turn on the machine while the operator’s hands are in contact with belts and pulleys.


Since different cutting tools and machining procedures are used on various machine tools, the safety precautions for each may vary. The following are general safety rules for any machine tool:

* Gears, pulleys, belts, couplings, ends of shafts having keyways, and other revolving or reciprocating parts should be guarded to a height of 6 feet above the floor. The guards should be removed only for repairing or adjusting the machine and must be replaced before operating it.

* Safety setscrews should be used in collars and on all revolving or reciprocating members of the machine tool or its equipment.* Do not support the workplaces by hand. Use a holding device to prevent the workpiece from being tom from the operator’s hand.
* Do not operate any machine tool without proper lighting.
* Never attempt to operate any machine tool until you fully understand how it works and know how to stop it quickly.
* Never wear loose or torn clothing and secure long hair, since these items can become caught in revolving machine parts. Ties should be removed and shirt sleeves should be rolled up above the elbow.
* Gloves should never be worn when operating machinery except when absolutely necessary.
* Always stop the machine before cleaning it or taking measurements of the workpiece.
* Do not lubricate a machine while it is in motion. Injury to the operator and damage to the machine may result from this practice.

*   Never make any adjustments while the machine is operating.
* Never remove metal chips, turnings, or shavings with your hands; they may cause a serious cut. If the shavings are long, stop the machine and break them with pliers or a bent rod, and then brush chips off the machine. Remove cast-iron chips, which break into small pieces, with a brush. Never wipe away chips when the machine is operating.
* Always wear safety glasses or goggles while operating machine tools. Also, wear respiratory protection if operation creates hazardous dust. All persons in the area where power tools are being operated should also wear safety eye protection and respirators as needed.
* Know where fire extinguishers are located in the shop area and how to use them.
* Never wear jewelry while working around machine tools. Rings, watches, or bracelets may be caught in a revolving part which could result in the hand being pulled into the machine.
* Avoid horseplay. Tools are very sharp and machines are made of hard steel. An accidental slip or fall may cause a serious injury.
* Never use compressed air without a safety nozzle to clean machines or clothing. It will blow sharp, dangerous metal chips a long distance.
* Keep the floor around machines free of tools, stock, oil, grease, and metal chips. Tripping over metal on the floor, especially round bars, can cause dangerous falls. Wipe up all oil, grease, and cutting fluid spills on the floor as soon as possible to prevent a fall. Metal chips are very sharp and can easily become embedded in the soles of shoes, making them very slippery, especially when walking on a concrete floor.
* Never place tools or other materials on the machine table. Cluttering up a machine with tools or materials creates unsafe working conditions. Use a bench or table near the machine for this purpose.
* Always use a rag when handling sharp cutters such as milling cutters and end mills.
* Do not expose power tools to rain or use in damp or wet locations.
* Always secure the workpiece. Use clamps or a vise. It is safer than using your hands, and it frees both hands to operate the tool
* Do not abuse electrical cords. Never carry a tool by its cord or yank it to disconnect it from a receptacle. Keep electrical cords away from heat, oil, and sharp edges. Have damaged or worn power cords and strain relievers repaired or replaced immediately.
* Remove adjusting keys and wrenches. Form a habit of checking to see that keys and wrenches are removed from tools before turning them on.
* Do not operate any machine tool while under the influence of drugs, alcohol, or any medication that could cause drowsiness.



All maintenance shops and work areas should be marked with the correct colors to identify hazards, exits, safe walkways, and first-aid stations. It is acceptable to use material other than paint, such as decals and tapes, in the appropriate, similar colors. Listed below are the main colors authorized for use in maintenance shops.

Red color markings should be used to identify the following equipment or locations:

* Fire alarm boxes (pull boxes).
* Fire blanket boxes.
* Fire extinguishing containers.
* Fire extinguishers, unless painting is unnecessary. For large areas and when the extinguisher is not readily visible to the area occupants, use red on the housing wall or support above the extinguisher to show its location.

* Fire hose locations.
* Fire pumps.
* Fire sirens.
* Sprinkler piping.
* Fire buckets.
* Fire reporting telephone stations.
* Store all idle tools in a safe, dry place.
* Provide visitors to the work area required personnel protection equipment.
* An exception may be made to comply with local laws or when current facilities provide green exit signs.
* Emergency stop buttons for electrical machinery.
* Emergency stop bars on hazardous machines.
* Yellow color markings should be used to identify the following equipment or locations:
* Industrial areas where particular caution is needed, such as handrails, guardrails, bottom edge of overhead doors, or top and bottom treads of stairways.
* Fire hydrant barrels.
* Caution signs.
* Piping systems containing flammable material.
* Waste containers for highly combustible material.
* A hazardous area or a safe aisle within a hazardous area.
* Lower pulley blocks and cranes.
* Coverings and guards for guy wires.
* Pillars, posts, or columns that are physical or shop hazards.
* Fixtures suspended from ceilings or walls that extend into normal operating areas.
* Corner markings for storage piles.
* Exposed and unguarded edges of platforms, pits, and wells.

Green color markings normally on a white color background should be used for the following equipment or locations:

* First-aid equipment.
* First-aid dispensaries.
* Stretchers.
* Safety starting buttons on machinery.
* Safety instruction signs.

Black and white are the basic colors for designating housekeeping and interior traffic markings. The following are examples of where solid white, solid black, single-color striping, alternate stripes of black and white, or black and white squares will be used.

* Locations and width of aisles in nonhazardous areas.
* Dead ends of aisles or passageways.
* Directional signs.
* Locations of refuse cans.
* White corners of rooms or passageways.
* Clear floor area around first-aid, fire-fighting, and their emergency equipment.

Blue color markings are used on the outside of switch boxes electrical controls that are the starting point or power source for hazardous electrical machinery or equipment.

Orange markings are used to designate dangerous parts of machines or energized equipment, including electrical conduits, which may cut, crush, shock, or injure.


Signs are placed in categories according to their purpose. Use the examples in the following paragraphs as guides when choosing the correct sign design to display a message. In overseas commands, the use of International Standard Safety Signs is encouraged and authorized.


Ensure that the wording of any sign-

* Is concise and easy to read.
* Contains enough information to be easily understood.
* Is designed for the message to be carried in a picture when appropriate.
* Is a positive rather than a negative statement when appropriate.
* Is bilingual with the second language common to the local personnel when appropriate.


Signs should be inspected regularly and maintained in good condition. They should be kept clean, well illuminated, and legible. Replace or repair damaged or broken signs. All signs will be designed with rounded or blunt corners and with no sharp projections. Put the ends or heads of bolts or other fastening devices where they will not cause a hazard.

When choosing a sign, consider dimensions that will permit economical use of standard size material. Base the size of the sign on the following:

* Location at which the sign will be placed.
* Character of the hazard involved.
* Purpose of the sign.
* Distance from which the sign should be legible.


All signs require a predominant color based on the sign’s purpose. Below are the five types of signs and their predominant color.

* Danger signs: RED.
* Caution signs: YELLOW.
* Safety instruction signs: GREEN.
* Directional signs: BLACK.
* Informational signs: A variety of colors may be used, except for red, yellow, or magenta (purple).


Danger signs should only be used when immediate hazard exists. There will be no variations in the type or design of signs posted to warn of specific danger. All personnel will be instructed that danger signs indicate immediate danger and that special precautions are necessary.


Caution signs should be used only to warn against potential hazards or to caution against unsafe practices. All personnel will be instructed that a caution sign indicates a possible hazard against which proper precautions will be taken.