LAB 1: SAFETY

LABORATORY 1: SAFETY
Western Carolina University
Department of Engineering & Technology
MACHINING LAB SAFETY RULES

1. EYE PROTECTION IS REQUIRED WHEN YOU ENTER THE LAB. WEAR YOUR SAFETY GLASSES!
You are required to obtain your own safety glasses. A limited number is available in the shop.

2. All injuries must be reported to the supervising instructor immediately.

3. NO BARE FEET OR OPEN-TOED SANDALS ALLOWED IN THE SHOP. Long hair must be tied back, long
sleeves must be cuffed or rolled up, and jewelry removed when working on machinery.

4. NO FOOD OR DRINK ALLOWED IN THE MACHINE SHOP AREA.

5. DO NOT WORK ALONE. Use the “buddy” or “two-man” system in order to have someone present in the shop
to summon help in case of an accident. IN CASE OF AN ACCIDENT OR EMERGENCY, CALL 911 !

6. ENSURE THE SAFETY OF YOURSELF AND OTHERS by being aware of your surroundings. If you see someone
     committing an unsafe act, report it to the supervisor immediately. As the machine operator you are responsible for the
     safety of the people in your immediate area. It is your responsibility to look around and be sure that everyone within
     your range is wearing safety glasses.

7. IF YOU BREAK A PIECE OF TOOLING, discover broken tooling or machinery that is not operating correctly; notify
     the shop supervisor immediately. Everyone must comply with this rule in order to prevent injuries caused by broken or
     malfunctioning equipment. Hiding or concealing broken tooling only slows the replacement of that piece of tooling, so it
     won’t be there next time you need it if you didn’t tell the supervisor that you broke it.

8. YOU MAY NOT WEAR GLOVES while operating machinery. Holding objects with a rag near moving machinery is
also not permitted. Gloves, rags, etc. can be easily caught in machines that are in motion, pulling the operator into the
equipment.

9.   SECURELY CLAMP DOWN ALL WORK PIECES IN DRILL PRESS AND MILLING MACHINES. This will
      prevent work from being lifted up or spun around with the cutters. Use all guards that are available and be wary of points
      of contact with rotating cutters and chucks.

10. USE PUSH STICKS or some other approved method for keeping fingers away from moving blades on bandsaws.

11. USE A VACUUM CLEANER after machining non-metallic substances (e.g. acetyl, acrylics, phenolics, etc.) This will help
control coolant contamination on machines with coolant systems.

12. DO NOT MACHINE, GRIND, or CUT ANY RADIOACTIVE OR OTHER SOLID TOXICS (Beryllium, asbestos) in
the shop.

13. DO NOT LEAVE KEYS ON CHUCKS OF LATHES, DRILL PRESSES, AND MILLING MACHINES. The key can
be thrown out with GREAT force when machinery is turned on. This also applies to wrenches used to tighten the cutting
tools into the spindles of the milling machines.

14. USE A BRUSH OR WOODEN DOWEL TO REMOVE CHIPS FROM THE MACHINING AREA. Chips can be very
sharp and often very hot.

15. CLEAN UP THE WORK AREA. Part of your grade will be based on good safety and housekeeping.

16. DO NOT USE COMPRESSED AIR to blow chips off machinery. It drives chips between the machine ways and scatters
them about the shop. Vacuum the machine and sweep the floor area of any remaining chips.

17. CLEAN AND REPLACE TOOLS WHERE YOU FOUND THEM. The toolboxes and cabinets are organized according
to the character of their contents. People expect to find tools in their ‘usual’ locations, so clean and replace everything
where it belongs when you’re finished.

18. DO NOT ATTEMPT ANY UNFAMILIAR OPERATIONS. When in doubt, seek advice and help from those more
experienced in the operation.

19. FOLLOW GUIDELINES POSTED ON THE INDIVIDUAL PIECES OF EQUIPMENT.

20. In order to prevent injury to you and damage to the equipment, DO NOT ATTEMPT TO OVERLOAD THE
CAPABILITIES OF THE MACHINERY.

I have read, understood, and agree to abide by the above Machining Lab Safety Rules. I accept responsibility for following good safety practices when
working in the Machining Lab and for reporting any unsafe conditions therein.

PRINT NAME:_______________________________

SIGN NAME : ________________________________ Date:______________________

Western Carolina University

Engineering and Technology Department

Machine Shop and Fabrication Shop

Safety Guidelines

January 2009

Table of Contents

Page

Definition of Machine Tools …………………………………………. 4

Specialized Machine Tools …………………………………………… 4

Manual Machine Tools and Equipment ……………………………… 5

Risk …………………………………………………………………... 6

Risk Management Program ………………………………………….. 7

General Shop Safety

Eye Protection …………………………………………………11

Hazardous Noise Protection …………………………………...12

Foot Protection ………………………………………………...12

Grinding Dust and Hazardous Fumes …………………………12

Clean up ……………………………………………………….12

Proper Lifting Procedures ……………………………………..12

Electrical Safety ……………………………………………… 13

Safety Rules for Machine Tools ……………………………….13

Portable Machine Tools

General Information ………………………………………….. 15

Pneumatic and Electrical Tool Safety ………………………... 16

Electrical Extension Cords …………………………………… 16

Drilling Machines

General Information ………………………………………….. 17

Drilling Machine Safety ……………………………………… 17

Grinding Machines

General Information ………………………………………….. 18

Grinding Machine Safety …………………………………….. 18

Sawing Machines

General Information ………………………………………….. 19

Sawing Machine Safety ……………………………………… 19

Lathe Machines

General Information ………………………………………….. 20

Lathe Machine Safety …………………………………………20

Milling Machines

General Information ………………………………………….. 21

Milling Machine Safety ………………………………………..21

Welding

General Information ………………………………………….. 22

Welding Safety ……………………………………………….. 22

Acknowledgements …………………………………………………..23

GENERAL INFORMATION

DEFINITION OF MACHINE TOOLS

Machine tools are power-driven equipment designed to drill, bore, grind, or cut metal or other material.

SPECIALIZED MACHINE TOOLS

In view of the different design and operating features incorporated in specialized machine tools by various manufacturers, no attempt has been made to include information pertinent to them in this guide. For complete information on these tools see pertinent technical manuals published by the manufactures covering their specific machines. The machining facilities available for students to learn Computer Numerical Control (CNC) problem solving as well as manual machining techniques primarily consist of state-of-the-art Haas machines. A summary of machining capability includes:

Haas VF-3 with TR-160 Trunnion Table: The Haas VF-3 vertical machining center has 1016 x 508 x 635 mm of x-y-z travel and is built utilizing cast-iron components. The VF-3 produces 75 ft-lb of torque at a low 1400 rpm, and will run up to 7500 rpm in 1.2 seconds for finishing aluminum. This machine is equipped with a dual-spindle trunnion table for machining helical parts, giving the machine 5-axes of motion.

Haas TM-1 Toolroom Mill - The Haas Toolroom Mill combines the ease and simplicity of a manual machine with the power and flexibility of full CNC. The instrument has x-y-z travels of 762 x 305 x 406 mm. It is easily moved with a pallet jack and takes up very little floor space. The instrument is considered an open machine. It may be run in the CNC or manual mode and is intended to handle small parts.

Haas Mini Mill – The Haas Mini Mill is a compact machine which features a 40-taper spindle, speeds to 6000 rpm, 600-ipm rapids and a 10-pocket automatic tool changer. The Mini Mill handles small-parts manufacturing – it is ideal for finishing work and cutting aluminum, yet also provides enough low-end torque to cut steel.

Haas TL-1 Toolroom Lathe - The TL-1 operates in four modes, ranging from fully-manual to fully-automatic. In all modes, the Haas control provides extremely accurate digital read-out of position, displayed to 0.0005" when using the manual hand wheels or to 0.0001" when using the electronic jog handle.

Haas SL-10 CNC Lathe - The SL-10 takes up only 6.5' x 4.5' of floor space, yet provides an 11" turning diameter, 14" turning length and a 16.25" swing over the front apron. This compact machine is well-suited as a “second-op” machine. It is also ideal for start-up shops, or as a first step into CNC turning. Tailstock provides rigid support between centers.

Haas SL-20 CHC Lathe - Haas SL Series offers a wide range of capacities, and the SL-20 increases capacity further while retaining the original footprint. The SL-20, with a max turning capacity of 10.3" x 20" and an 8.3" chuck, has a bar capacity of up to 2.0".

Haas VF-1 with HRT-210 rotary table: The Haas VF-1 machining center has 508 x 406 x 508 mm x-y-z travel and is built utilizing cast-iron components. This machine employs a 20-position tool changer and has 4^th-axis capability provided by an HRT-210 rotary table.

MANUAL MACHINE TOOLS AND EQUIPMENT

Not as high-tech but equally important are various machine-tools that are not controlled using CNC. They are able to be operated manually without a lot of training or skill to perform certain operations related to materials processing. They include:

Horizontal Band Saw: Used to cut bulk materials into appropriate sizes for further processing. This machine is equipped with coolant that can be applied to lubricate, cool, and manage chip accumulation.

Vertical Band Saw: There are two of these machines available, one for processing bulk metal materials and the other for processing plastics and wood. Neither of these machines have coolant capability.

Index Turret Drill Press: Vertical drill press with a turret that can support a series of drills, reams, or tap in one setup.

Pedestal Grinder: Used for manual griding of FERROUS MATERIALS ONLY!. Can be setup with two grinding wheels or with one grinding wheel and one wire wheel.

Heat-treating Oven: For heating metal materials in order to change the characteristics of the material to suit a specific product requirement.

Tensile Testing Machine: For conducting destructive testing on materials to determine the materials stress-strain relationship and other factors of tensile strength.

Metal Inert Gas (MIG) Welder: For fabrication of products or prototypes that require the joining of steel components into one structure.

Oxygen Acetylene Gas: For fabrication of products or prototypes that require the joining of steel components through gas welding into one structure or for the separation of components or bulk materials through a gas cutting process.

Plasma Cutter: For the separation of metal components or bulk materials using a plasma arc process.

RISK

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.

A Risk Assessment for the Engineering Technology Department Machine Shop and Fabrication Shop is described below and is matched to the diagram that follows:

The Probability of an accident occurring is assessed among five categories: Frequent-occurs often, Likely-occurs several times a career, Occasional-occurs sometimes, Remote-possible to occur, and Unlikely-can assume will not occur. Since all students participating in the Engineering and Technology Curriculum are exposed to the hazards involved with operating the equipment listed above during their tenure at WCU, this exposure to the materials and processes involved in ET 349, ET 449, ET 461, and ET 479 put students into the Remote category of being involved with an accident.

After determining the probability of an accident occurring, the Severity of an accident is accessed along the following levels: worse case, an accident could be Catastrophic-resulting in death or permanent total disability, Critical-resulting in permanent partial disability or temporary total disability in excess of three months, Marginal-resulting in a minor injury with lost school days, or Negligible-requiring first aid or minor medical treatment. An accident involving any one of the Haas machining centers or manually operated equipment could fall into any one of the Critical to Negligible categories.

Risk is determined along four levels. Extremely High Risk signifies a student could lose his ability to complete school, High Risk signifies he could be significantly degraded in his ability to complete school, Moderate Risk signifies a student could be hindered in school, and Low Risk means there could be little to no impact on the student. Since the probability of an accident is Remote but the severity of a accident could be anywhere from Critical, Marginal, to Negligible, the Risk Level accessed for the Machine and Fabrication Shop is Moderate, meaning that there is a remote probability of a student sustaining an injury that could result in a permanent partial disability

RISK-MANAGEMENT PROGRAM

In order to manage the risk level assessed in the Machine and Fabrication Shop and to assure a high degree of safety, no machine tool is to be used unless the risk management program outlined below is understood and adhered to by the user.

Lab Supervisors: Lab Supervisors are ET Department Faculty and Staff plus selected Graduate Students and qualified individual Undergraduate Students. Lab Supervisors are in the lab to ensure the safe and efficient operation of all lab equipment. Graduate and selected Undergraduate students are assigned to these positions semi-annually or annually depending on the graduation status of these students.

Lab Trustees: Lab Trustees are Graduate Students and individual Undergraduate Students who are able to pass the department safety test and demonstrate their ability to operate specific pieces of equipment and machinery. They are able to operate machinery according to a strict classification system explained below. These individuals are able to work in the lab without a Lab Supervisor being present as long as there is another trustee present to assist in case of an accident or emergency.

Certification Procedures:

Beginning with ET 141, students will be given a safety presentation and lab orientation. They will be required to sign a form signifying their understanding of a number of department safety rules. Following this initial introduction to department lab safety, they will go to One Stop and have their Class I badge created. These badges must be worn in the Machine and Fabrication labs at all times.

When students take ET 349 or when individual students want to earn the ability to use the Machine Shop and Fabrication Lab, they will be required to take a written safety exam based on the information in this guideline. They will also be required to perform a hands-on demonstration of their ability to safely use various specialized and manual machine tools and equipment. The student’s level of certification and ability to safely operate the machines and equipment in the two labs will be represented by the badge system explained below. Generally, students should be able to move from a Class I to a Class II certification without too much trouble. Achieving a higher certification will involve a significant investment in time and effort by individual students. Successful completion of a three-part Final Exam could elevate the student to a Class IIIA and IIIB level.

During ET 449, students will be pushed to raise their certification levels to Class IIIA and IIIB in preparation for ET 461 and ET 479.

Badge Identification System:

Class I: Badge is Red in color with the individual’s picture, name, and department embossed on it. Individuals issued this badge must be supervised at all times while working in the Machine and Fabrication Labs.

Class II: Badge is Yellow in color. To qualify for this badge the individual must pass a written safety test and be able to demonstrate the ability to use the machine tools listed above and available hand tools such as hand grinders and drills. They are not authorized to work without a supervisor being present.

Class IIIA: Badge is Dark Green in color. To qualify for this badge the individual must pass a written safety test and be able to demonstrate the ability to use the Haas Mill. Students will graduate from Class II to Class IIIA so they will not have to retest on the manual machine and hand tools. They are not authorized to work without a supervisor being present.

Class IIIB: Badge is Blue in color. To qualify for this badge the individual must pass a written safety test and be able to demonstrate the ability to use the Haas Lathe. They are not authorized to work without a supervisor being present.

Safety Violators: Students who fail to follow the safety rules and policies established by the department are subject to loosing their ability to work in the Machine Shop and Fabrication Lab and thus be unable to satisfy the requirements of a number of ET curriculum courses. Safety violations are serious and punishment will match the offense. For example, failure to support the Badge Identification System or coming to lab without the proper safety clothes may earn a suspension from the lab for several days. Fighting or horse play that results in an injury would probably draw permanent suspension.

Lab Management: Lab Supervisors, Trustees, and Safety Violators will be identified on a Lab Management Board.

Their positions and pictures will be displayed in a prominent place in the Machine Shop so outside observers and people not normally associated with lab activities, may readily identify those persons responsible for safety and the people trusted to work without supervision in the lab. ET Faculty and Staff are too numerous to be placed on this board but they are assumed to be responsible anytime they are in the lab. Taken together with another sign that shows outside observers the certification levels,

anyone should be able to recognize whether students are qualified to use the equipment they are on. Safety Violators can be quickly identified and dealt with prior to an accident occurring.

GENERAL SHOP SAFETY

Develop safe work habits rather than suffer the consequences of an accident. Most of the safety practices mentioned in this first safety section are general in nature. Safety precautions for specific tools and machines are described in more detail in the following sections along with a general description of the equipment. Study these carefully and be on the alert to apply them.

EYE PROTECTION

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 hand cutting tools, since most hand cutting tools are made of hardened steel and can break or shatter when used improperly. There are many different types of safety glasses available however, the ones that offer the best protection are the safety glasses with side shields. Safety goggles should be worn over prescription glasses if the oversize safety glasses are unavailable.

HAZARDOUS NOISE AND HEARING PROTECTION

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. Wear hearing protection when appropriate. A good rule of thumb to follow is; if one must considerably raise his/her voice to be heard over the noise, wear hearing protection.

FOOT PROTECTION

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 should be worn at all times. Safety shoes have a steel plate located over the toe and are designed to resist impact. Some safety shoes also have an instep guard. Running and tennis shoes will reluctantly be allowed while flip-flops or sandals will not.

GRINDING DUST AND HAZARDOUS FUMES

Grinding dust from abrasive wheels is made up of extremely fine particles of the metal being processed 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.

CLEAN UP

A clean lab is a safer lab. Students who use Specialized and Manual Machine Tools are responsible for cleaning those tools and the surrounding area where they are used, when they are finished using them. Tools and materials will be put away every day either in the tool room or in designated project storage areas. Cleanup after course lab sessions will be determined by the instructor or lab supervisor in charge of the class. Generally, a major cleaning of the entire lab will occur twice a semester, around Mid-term and during Final Exam Week. There will also be specific maintenance related tasks to be performs during the Final Exam Week in preparation for the following semester.

PROPER LIFTING PROCEDURES

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 the object was lifted.

ELECTRICAL SAFETY

Exposure to electrical hazards 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.

SAFETY RULES FOR MACHINE TOOLS

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 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 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 the 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 maybe caught in a revolving part which could result in the hand being pulled into the machine. Exceptions will be made for wedding bands that cannot be removed. Recognize that you are at a higher risk for injury

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 the cord 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.

PORTABLE MACHINE TOOLS

GENERAL INFORMATION

The portable machine tools identified and described in this section are intended for use in a shop or field environment. These lightweight, transportable machine tools can quickly and easily be moved to the workplace to accomplish machining operations. The accuracy of work performed by portable machine tools is dependent upon the user’s skill and experience.

Portable machine tools are powered by self-contained electric motors or compressed air (pneumatic) from an outside source. They are classified as either cutting tools (straight and angle hand drills, metal sawing machines, and metal cutting shears) or finishing tools (sanders, grinders, and polishers).

PNEUMATIC AND ELECTRIC TOOL SAFETY

Here are some safety precautions to follow:

Never use electric equipment (such as drills, sanders, and saws) in wet or damp conditions.

Properly ground all electric tools prior to use.

Do not use electric tools near flammable liquids or gases.

Do not use electrical tools while standing in water.

Inspect all pneumatic hose lines and connections prior to use.

Keep constant watch on air pressure to stay within specified limits.

Keep all equipment in proper working order, and use the equipment according to the manufacturer’s instructions.

Remove chuck keys from drills prior to use.

Hold tools firmly and maintain good balance.

Secure the work in a holding device, not in your hands.

Wear eye protection while operating these machines.

Ensure that all lock buttons or switches are off before plugging the machine tool into the power source.

Never leave a portable pneumatic hammer with a chisel, star drill, rivet set, or other tool in its nozzle.

ELECTRIC EXTENSION CORDS

Use the right wire gage for the length of the cord. As the length of the extension cord increases, heavier gage wire must be used. Lengthening extension cords by connecting several small gage cords together causes a serious drop in voltage. This results in the cord overheating. Extension cords that overheat will bum away the insulation, creating a potential electric shock and fire hazard.

DRILLING MACHINES

GENERAL INFORMATION

A drilling machine comes in many shapes and sizes, from small hand-held power drills to bench mounted and finally floor-mounted models. They can perform operations other than drilling, such as counter sinking, counter boring, reaming, and tapping large or small holes. Because the drilling machines can perform all of these operations, this chapter will also cover the types of drill bits, took, and shop formulas for setting up each operation.

A drilling machine, called a drill press, is used to cut holes into or through metal, wood, or other materials. Drilling machines use a drilling tool that has cutting edges at its point. This cutting tool is held in the drill press by a chuck or Morse taper and is rotated and fed into the work at variable speeds. Drilling machines may be used to perform other operations. They can perform countersinking, boring, counter boring, spot facing, reaming, and tapping. Drill press operators must know how to set up the work, set speed and feed, and provide for coolant to get an acceptable finished product. The size or capacity of the drilling machine is usually determined by the largest piece of stock that can be center-drilled. For instance, a 15-inch drilling machine can center-drill a 30-inch-diameter piece of stock. Other ways to determine the size of the drill press are by the largest hole that can be drilled, the distance between the spindle and column, and the vertical distance between the worktable and spindle.

DRILLING MACHINE SAFETY

Drilling machines are one of the most dangerous hand operated pieces of equipment in the shop area. Following safety procedures during drilling operations will help eliminate accidents, loss of time, and materials. Listed below are safety procedures common to most types of drilling machines found in the machine shop.

Do not support the workpiece by hand. Use a holding device to prevent the workpiece from being tom from the operator’s hand.

Never make any adjustments while the machine is operating.

Never clean away chips with your hand. Use a brush.

Keep all loose clothing away from turning tools.

Make sure that the cutting tools are running straight before starting the operation.

Never place tools or equipment on the drilling tables.

Keep all guards in place while operating.

Ease up on the feed as the drill breaks through the work to avoid damaged tools or workplaces.

Remove all chuck keys and wrenches before operating.

Always wear eye protection while operating any drilling machines.

GRINDING MACHINES

GENERAL INFORMATION

Grinding is the process of removing metal by the application of abrasives which are bonded to form a rotating wheel. When the moving abrasive particles contact the workpiece, they act as tiny cutting tools, each particle cutting a tiny chip from the workpiece. It is a common error to believe that grinding abrasive wheels remove material by a rubbing action; actually, the process is as much a cutting action as drilling, milling, and lathe turning.

The grinding machine supports and rotates the grinding abrasive wheel and often supports and positions the workpiece in proper relation to the wheel. The grinding machine is used for roughing and finishing flat, cylindrical, and conical surfaces; finishing internal cylinders or bores; forming and sharpening cutting tools; snagging or removing rough projections from castings and stampings; and cleaning, polishing, and buffing surfaces. Once strictly a finishing machine, modern production grinding machines are used for complete roughing and finishing of certain classes of work.

GRINDING MACHINE SAFETY

Grinding machines are used daily in a machine shop. Grinding is to be performed only on ferrous materials. DO NOT ATTEMPT TO GRIND ALUMINUM OR ANY OTHER NON-FERROUS MATERIALS. To avoid injuries follow the safety precautions listed below.

Wear goggles for all grinding machine operations.

Check grinding wheels for cracks before mounting.

Never operate grinding wheels at speeds in excess of the recommended speed.

Never adjust the workpiece or work mounting devices when the machine is operating

Do not exceed recommended depth of cut for the grinding wheel or machine.

Remove workpiece from grinding wheel before turning machine off.

Use proper wheel guards on all grinding machines.

On bench grinders, adjust tool rest 1/16 to 1/8 inch from the wheel.

SAWING MACHINES

GENERAL INFORMATION

The sawing machine is a machine tool designed to cut material to a desired length or contour. It functions by drawing a blade containing cutting teeth through the workpiece. The sawing machine is faster and easier than hand sawing and is used principally to produce an accurate square or mitered cut on the workpiece.

The power hacksaw and the band saw are two common types of sawing machines used to cut metal in the machine shop. The power hacksaw uses a reciprocating (back and forth) cutting action similar to the one used in a hand hacksaw. The power hacksaw is used for square or angle cutting of stock. The band saw uses a continuous band blade. A drive wheel and an idler wheel support and drive the blade. When using the horizontal band saw one should apply firm, controlled pressure on the handle of the saw to move the saw through the material.

SAWING MACHINE SAFETY

Sawing machines have some special safety precautions that must be observed. Here are some safety precautions that must be followed:

Keep hands away from the saw blade of the hack sawing machine or band sawing machine when in operation.

Ensure the power supply is disconnected prior to removal or installation of saw blades.

Use a miter guide attachment, work-holding jaw device, or a wooden block for pushing metal work pieces into the blade of the band saw wherever possible. Keep fingers well clear of the blade at all times.

Do not hang on the handle or apply one’s full body weight to the saw handle in order to move the saw blade through the material being cut.

When removing and installing band saw blades, handle the blades carefully. A large springy blade can be dangerous if the operator does not exercise caution.

LATHE MACHINES

GENERAL INFORMATION

The lathe is a machine tool used principally for shaping articles of metal (and sometimes wood or other materials) by causing the workpiece to be held and rotated by the lathe while a tool bit is advanced into the work causing the cutting action. The basic lathe that was designed to cut cylindrical metal stock has been developed further to produce screw threads, tapered work, drilled holes, knurled surfaces, and crankshafts. The typical lathe provides a variety of rotating speeds and a means to manually and automatically move the cutting tool into the workpiece. Machinists must be thoroughly familiar with the lathe and its operations to accomplish the repair and fabrication of needed parts.

LATHE MACHINE SAFETY

All lathe operators must be constantly aware of the safety hazards that are associated with using the lathe and must know all safety precautions to avoid accidents and injuries. Carelessness and ignorance are two great menaces to personal safety. Other hazards can be mechanically related to working with the lathe, such as proper machine maintenance and setup. Some important safety precautions to follow when using lathes are:

Correct dress is important, remove rings and watches, roll sleeves above elbows.

Always stop the lathe before making adjustments.

Do not change spindle speeds until the lathe comes to a complete stop.

Handle sharp cutters, centers, and drills with care.

Remove chuck keys and wrenches before operating

Always wear protective eye protection.

Handle heavy chucks with care and protect the lathe ways with a block of wood when installing a chuck.

Know where the emergency stop is before operating the lathe.

Use pliers or a brush to remove chips. Never use your hands.

Never lean on the lathe.

Never lay tools directly on the lathe ways. If a separate table is not available, use a wide board with a cleat on each side to lay on the ways.

Keep tool overhang as short as possible.

Never attempt to measure work while it is turning.

Never file lathe work unless the file has a handle.

File left-handed if possible.

Protect the lathe ways when grinding or filing.

Use two hands when sanding the workpiece. Do not wrap sand paper or emery cloth around the workpiece.

MILLING MACHINES

GENERAL INFORMATION

Milling is the process of machining flat, curved, or irregular surfaces by feeding the workpiece against a rotating cutter containing a number of cutting edges. The milling machine consists basically of a motor driven spindle, which mounts and revolves the milling cutter, and a reciprocating adjustable worktable, which mounts and feeds the workpiece.

Milling machines are basically classified as vertical or horizontal. These machines are also classified as knee-type, ram-type, manufacturing or bed type, and planer-type. Most milling machines have self-contained electric drive motors, coolant systems, variable spindle speeds, and power-operated table feeds.

MILLING MACHINE SAFETY

Milling machines require special safety precautions while being used. They are:

Do not make contact with the revolving cutter.

Place a wooden pad or suitable cover over the table surface to protect it from possible damage.

Use the buddy system when moving heavy attachments.

Do not attempt to tighten arbor nuts using machine power.

When installing or removing milling cutters, always hold them with a rag to prevent cutting your hands.

While setting up work, install the cutter last to avoid being cut.

Never adjust the workpiece or work mounting devices when the machine is operating.

Chips should be removed from the workpiece with an appropriate rake and a brush.

Shut the machine off before making any adjustments or measurements.

When using cutting oil, prevent splashing by using appropriate splash guards. Cutting oil on the floor can cause a slippery condition that could result in operator injury.

WELDING

GENERAL INFORMATION

Welding includes jobs involved in welding metals and alloys. The work requires knowledge of electric, gas, and other welding processes, and the skill to apply these processes in manufacturing, repairing, modifying, rebuilding, and assembling various types of metal and alloy parts, equipment, systems, and structures such as buildings, aircraft, and ships.

WELDING SAFETY

Welders, assistants, and anyone else in the welding area shall wear glasses or shields of recommended shades during welding operations.

A screen shall be erected around the welding area to protect other personnel in the shop from injury.

Inspect all welding equipment to be used for possible damage prior to each use.

Avoid handling oxygen bottles with greasy hands, gloves or rags.

Always strap tanks to a welding cart or a fixed object. Never allow a gas cylinder to be free standing. Replace the safety cap on all cylinders when not in use.

When welding make sure the work and/or work table is properly grounded.

Do not weld in a wet area.

Be alert to possible fire hazards. Move the object to be welded to a safe location, or, remove all flammable materials from the work area.

Never weld in the same area where degreasing or other cleaning operations are performed.

Keep suitable fire extinguishing equipment nearby and know how to operate it.

Shut off the cylinder valves when the job is completed, release pressure from the regulators by opening the torch valves momentarily and back out regulator adjusting valves. Never leave the torch unattended with pressure in the hoses.

Utilize all protective equipment and clothing. Do not weld with any part of the body uncovered, the arc is actinic light (excessive ultraviolet) and will cause burns similar to severe sunburn.

Never weld inside drums or enclosed spaces without adequate ventilation, or, the use of airline respirators or self-contained breathing apparatus.

Check the ventilation system before starting to weld and periodically thereafter to insure adequate performance. Welding fumes should not be allowed to get into the rest of the shop working areas.

Never cut or weld any container that has held explosive or flammable materials. Use prescribed methods for cleaning or flooding.

Never use wrenches or tools except those provided or approved by the gas cylinder manufacturer to open valves. Never use a hammer to open or close valves.

Allow for proper ventilation when brazing or soldering. The fluxes are acidic and toxic.

Do not weld on painted, galvanized or greasy, oily metals. Not only can the fumes be toxic, but the welds will not be satisfactory and will fail in use.

When arc welding, make sure welding rods are dry and have been stored in a proper moisture proof container. Do not use old welding rods that have been exposed to high humidity.

Acknowledgements

Many sections of this manual are pulled directly from Training Circular No. 9-524, Fundamentals of Machine Tools , Headquarters, Department of the Army, Washington, DC, 29 October 1996. Distribution of the manual is “Approved for public release; distribution is unlimited”.