3.15 - Tool and Machine Safety

Employees in Stanford's mechanical trades are subject to greaterimmediate hazards than other non-laboratory employees. Electricians,plumbers, grounds keepers, carpenters, HVAC technicians, and others workin a wide variety of environments-and face hazards from just as manytools. Further, injuries resulting from heavy machines and tools aregenerally more severe than office-type injuries; consequently, eachemployee must evaluate the potential hazards of each machine or tool andeliminate or minimize those hazards before beginning a job. Often thissimply means thinking through the consequences of one's actions beforedoing something needlessly risky. If necessary, contact the EH&S'sSafety Engineering Office (725-1472) for a safety analysis of the job tobe undertaken.

--PERSONAL PROTECTIVE EQUIPMENT

* Safety glasses should be worn at all times when in the shop.

* Hearing protection should be used in a noisy environment. If you are unsure whether hearing protection is needed, check with your supervisor.

* When handling rough stock, gloves should be worn. However, when performing any machining operations, gloves become a hazard because they can be caught in rotating parts.

* Sturdy, thick, slip-proof shoes should be worn.

* Wear short-sleeved shirts whenever possible. If long-sleeved shirts are necessary, make sure that they are not loose fitting.

* Always tie the strings on your work apron in the back and keep the strings as short as possible.

--GENERAL OPERATING PROCEDURES

* Perform all lifting operations in a correct manner to avoid back injuries.

* Proper lighting at all workstations should be supplied.

* The floor should be in place to protect the user from any of the four mechanical hazards that are present in many shops: points of operation, shear points, nip points, and power transmission points.

* All work should be ceased when any sign of electrical danger is perceived: shock or tingling sensation during operation, exposed wiring, excessively hot motors, erratic switches, funny odors, sparks, or smoke.

* Thoroughly wash any skin area that has been in contact with any lubricant, coolant, or solvent.

* Any tool that is found to be defective or in need of repair should be set aside, marked clearly, and not put back into service until properly repaired.

* Never leave a chuck key in the chuck.

* Never use a machine until you have received formal training on the safe use of that machine.

* Read and become familiar with the operator's manual for the machine that you are using.

* Never reach around or over a guard until the machine has come to a complete stop.

* Check the condition of the blades, bits, and cutters before any operation.

* Do not start a machine when the cutting tool is already in contact with the work piece.

* Never touch chips with your bare hands.

* Avoid any type of distractions. Do not operate any machinery if you are angry or upset.

* Clean up the work area when your job is finished.

* Develop a regular inspection routine for your shop to insure proper functioning of all machines.

--HAND TOOLS

Hand tools are non-powered. They include anything from axes to wrenches.The greatest hazards posed by hand tools result from misuse and impropermaintenance. If a tool is not maintained properly it should be removedfrom service and reported to your supervisor.

* Hammers or mallets with broken handles or loose heads should not be used.

* Mushroom heads on chisels and punches should be "dressed" properly or the tool should be discarded.

* While chipping, use prescribed type of goggles and chip in a direction where flying chips can do no harm. Use a screen if necessary.

* When cutting with pliers, be sure cuttings do not fly.

* A wood saw or hacksaw should be started by drawing the saw blade backward if fingers are used to guide it at the cutting edge.

* All files should be equipped with handles.

* Use wrenches properly sized for the job. Be sure wrench jaws are not sprung, chipped, or have worn teeth. Never use a wrench as a hammer.

--MACHINE TOOLS

* Do not remove or make ineffective any safeguards unless authorized. Guards removed for repairs should be replaced promptly.

* Machinery should be inspected regularly to insure cleanliness and proper operation.

* Machinery should be placed and anchored securely to prevent tipping or other movement.

* There should be a power shut-off switch within reach of the operator at each machine.

* Machinery should be equipped with an emergency stop button that is colored red.

* Manually-operated valves and switches controlling the operation of machines should be identified and readily accessible.

* Machines must be shut down before cleaning, repairing, or oiling. Disconnect or use Lock Out techniques.

* Keys or adjusting tools must never be left so that they may creep, be thrown, or fall when a machine is started.

* When drilling or tapping material see that it is securely fastened by blocks or clamps so that it cannot spin or climb the drill. In no case should the operator rely on his hands to secure the material from turning.

* Use a brush, special tool, or hook to remove chips, shavings, or other material from work.

* Transparent guards should be kept clean.

* Keep fingers clear of a machine's point-of-operation by using special tools or devices, such as push sticks, hooks, or pliers.

* Stand to one side-never directly in line-with work being fed through machines such as circular saws, jointers, or wood shapers.

* Revolving shafts, although apparently smooth, will catch loose or ragged clothing, gloves, jewelry, hair, or wiping rags. Proper clothes and caution are always necessary when working around any revolving machinery. Shirt sleeves should be rolled up. Neckties should not be worn.

* Goggles must be worn whenever flying chips, particles of material, liquids, chemicals, or sparks may cause eye injury.

* Whenever possible, ground all power tools.

--ABRASIVE WHEELS

* Grinding wheels should be equipped with tool rests that hold the work firmly. The tool rest should be kept adjusted close to the wheel with a maximum opening of 1/8". Adjust the tongue to no more than 1/4" of the wheel.

* Bench and pedestal grinders should be permanently mounted or secured.

* Face shields should always be used when grinding.

* The maximum RPM rating of each abrasive wheel must be compatible with the RPM rating of the grinder motor.

* Each electrically operated grinder should be effectively grounded.

* Each grinder should have an individual "On" and "Off" control switch.

* Abrasive wheels must not be stored where they would be exposed to high temperature or humidity, water or other liquids, freezing temperatures or any temperature low enough to cause condensation on the wheels when moved from the storage area to an area of higher temperature, or where they would be subjected to physical damage from falling tools or materials.

* Before new abrasive wheels are used they should be visually inspected and ring tested.

* Safety guards used on machines known as "right angle head" or "vertical portable" grinders must not have an exposure angle greater than 180 degrees, and the guard must be located so that it is between the operator and the wheel during use. The guard should be adjusted so that pieces of an accidentally broken wheel will be deflected away from the operator.

* The side of an energy wheel should not be used for grinding, unless it is a special type of wheel designed for that purpose.

* Grinding of large parts, prolonged grinding, grinding of potentially toxic materials, and cutting of wheels all require mechanical exhaust ventilation.

* Defective abrasive wheels (cracked, broken, out of balance) should not be used.

* Abrasive wheels which have been discarded should not be re-used.

* Flanges should be of such design as to satisfactorily transmit the driving torque from the spindle to the grinding wheel.

* Flanges may be made of steel, cast iron, or other material of equal or greater strength and rigidity.

* Flanges shall be designed with respect to rigidity so that when tightened, the radial width of bearing surface of contact on the wheel is maintained.

* Abrasive wheels must have cover guards.

--LATHES

* Make sure that all gear and belt guards are in place.

* Never leave a chuck wrench in a chuck.

* Keep your hands off chuck rims when a lathe is in operation.

* Do not attempt to screw the chuck onto the lathe spindle with the power on, as it may get cross-threaded and cause injury. Stop the machine, place a board under the chuck, and then screw on by hand.

* Steady rests should be properly adjusted to conform with the material being worked on.

* When filing work in a lathe, file with the right hand over lathe instead of left hand, and face the head stock. If left-handed, reverse lathe and file from back side of lathe.

* See that tailstock, toolholder, and work are properly clamped before turning on power.

* Never attempt to adjust a tool while the lathe is running.

* Never apply a wrench to revolving work or parts.

* Always use a brush to remove chips--never your hands.

* When possible, use pipe sleeves to cover work protruding from the end of the lathe.

* Before removing your work from the lathe, remove the tool bit.

--WELDING, CUTTING, AND BRAZING

* Signs reading "DANGER--NO SMOKING, MATCHES, OR OPEN FLAMES" or the equivalent should be posted.

* Grounding of the machine frame and safety ground connections of portable machines should be checked periodically.

* Electrical power to the welder should be shut off when no one is present.

* Welding is to be done only by those employees who are qualified as welders.

* Red should be used to identify acetylene (and other fuel-gas) hoses, green for oxygen hoses, and black for inert gases and air hoses.

* Always stand to one side and away from the gauge faces and front of the regulator when opening the cylinder valve. In case of an explosion, you will not be cut by flying glass.

* Never open an acetylene cylinder valve more than one-half (1/2) turn. Always keep the key on the acetylene cylinder valve. In case of a flashback or fire from a leaky cylinder connection, a gloved hand can withstand the heat long enough to close the valve.

* Oxygen is not a substitute for compressed air. Never use oxygen equipment around oily gloves, clothes or oily surfaces. Oil or grease in presence of oxygen, under pressure, will ignite violently.

* Suitable fire extinguishing equipment should be available for instant use.

* Fire watchers should be assigned when welding or cutting is performed in locations where a serious fire might develop.

* A lighted torch should not be turned on concrete. Concrete always contains some moisture which may cause the concrete to explode.

* Cylinders have exploded from what seemed to be slight jars. Be sure your cylinders are chained or strapped securely.

* Never use acetylene from a cylinder in a horizontal position. In this position, the acetone is drawn out of the cylinder with the acetylene.

* Use the cylinder valve--not the regulator--to turn the gas off. The regulator is not designed to be used as a shut-off valve.

* Do not watch the electric arc without welding lenses. Ultra- violet and infra-red rays are thrown off in concentrated form and can burn unprotected eyes.

* Eye protection helmets, hand shields, and goggles meeting the appropriate standards are required.

* Local exhaust ventilation is recommended for most welding, cutting, and brazing. It is required when the following base metals, fluxes, coatings, platings, or filler metals are used:

- beryllium

- cadmium

- chromium

- fluorides

- lead

- mercury

- zinc

- inert gas welding

- oxygen cutting of stainless steel

Silver soldering requires local exhaust ventilation due to cadmium inthe solder.

* When working in confined spaces, environmental monitoring tests should be taken and means provided for quick removal of welders in case of an emergency (see section on confined space safety).

--DRILL PRESSES

* Clamp material to be drilled securely to the drill-table before starting the machine.

* Tighten the chuck of the drill press and remove the release key before starting the machine or your arm may be twisted around the spindle. Never leave the key in the chuck.

* Use drills properly sharpened to cut the right size.

* Run drills only at the correct speed and do not force or feed too fast. Broken drills can cause serious injury.

* If your work should slip from the clamp, never attempt to stop it with your hands. Stop machine to make any adjustment or repair.

* Drill presses should never be forced by exerting excess pressure on the feed lever.

* Drive belts should be covered.

--LADDERS & SCAFFOLDS

* Use care in placing a ladder. A ladder's feet should be one- fourth of its length away from the wall against which it is leaning.

* Be sure your ladder is long enough for the job. A ladder's overall length is different than its usable length. The top three rungs of a ladder are not meant to be stood upon.

* Do not leave tools on top of a stepladder or on any other elevated place from which they may fall. Effective toolholders should be used.

* Place ladders only against solid footing and stationary backing.

* Always face the ladder when ascending or descending. Use both hands when going up or down a ladder.

* Use only ladders in good repair. Never use a broken or weak ladder or one with missing rungs.

* Metal ladders conduct electricity! If you plan to use a ladder near power lines, with electrical equipment, or to change a bulb, use a wooden or fiberglass ladder if at all possible.

* No uprights, braces, or supporting members of a scaffold should be removed, loosened, or weakened while any of the scaffold planking or flooring is in place.

* Do not work on a double extension ladder unless someone is holding the bottom.

* Do not use ladders in a strong wind.

* If you must set up a ladder in a traffic area, use a barricade or guard to prevent unexpected collisions.

* When using a step ladder, make sure it is fully open and its spreader is locked.

* To avoid shifting, tie down straight ladders as close to the support point as possible.

* If you need tools, carry them in a tool belt or raise and lower them with a hand line.

* Never reach or lean too far to one side--keep your belt buckle between the ladder rails to maintain your balance.

* Don't climb higher than the second tread from the top on a step ladder.

* Scaffolds and their components must be capable of supporting without failure at least 4 times the maximum intended load.

* An access ladder or equivalent safe access must be provided to all scaffolds.

* Slippery conditions on scaffolds should be eliminated once discovered.

--WOODWORKING MACHINES

* Saws used for ripping should be equipped with anti-kick back devices and spreaders.

* A dull saw is dangerous. It retards speed and may break.

* A ripsaw should not be used for crosscutting, nor should a crosscutting saw be used for ripping.

* Woodworking machinery must be frequently checked by the Shop Foreman for defects.

* Saws must be sharp (not cracked), properly mounted, and have a blade guard.

* Check planer, shaper, jointer, knives, bolts, nuts, clamps, and guards.

* Stop a machine before leaving it. Another person may be injured by it.

* Radial arm saws should be arranged so that the cutting head will gently return to the back of the table when released.