UNESCO-NIGERIA TECHNICAL & VOCATIONAL EDUCATION REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN MECHANICAL ENGINEERING TECHNOLOGY
BASIC WORKSHOP TECHNOLOGY AND PRACTICE COURSE CODE: MEC113 YEAR I- SE MESTER I PRACTICAL Version 1: December 2008
BASIC WORKSHOP PRACTICE COURSE CONTENT
Subject
Basic Workshop Practice
Year
1
Semester
1
Course Code
MEC 113
Credit Hours
3
Theoretical
1
Practical
2
CHAPTER
1
: Workshop Safety
CHAPTER 2 : Classification of Machine shop Marking out tools • Assessment 1 CHAPTER •
5
6
Week 5 – 6
Week 7 – 8
3
: Metal Joining Processes.
Week 9 – 12
4
: The Use Of Machining Processes.
Assessment
Week 3 – 4
2
: Use of drilling Machine.
Assessment
CHAPTER •
4
Assessment
CHAPTER •
: Machine Shop Measurement Tools And Type.
Assessment
CHAPTER •
3
Week 1 – 2
5
Week 13 -15
Table of Contents: CHAPTER 1 : WORKSHOP SAFETY
WEEK
1 machine gurad:....................................................................................................................................... safe lifting heavy materials .................................................................................................................... Safe use of machines and tools ..............................................................................................................
WEEK 2 Safety in the Workshop ......................................................................................................................... Wearing a safety dress ........................................................................................................................... Safety shoes .......................................................................................................................................... Safety goggles ........................................................................................................................................ Correct behavior ....................................................................................................................................
CHAPTER 2 : CLASSIFICATION OF MACHINE SHOP MARKING OUT TOOLS
WEEK
3 Learning outcomes: ............................................................................................................................... Introduction: .......................................................................................................................................... Use of marking out tools: ...................................................................................................................... Production of Simple objects using bench/hand tools .......................................................................... Maintenance of hand tools: ....................................................................................................................
WEEK 4 Use of simple measuring and testing equipments:........ ……….……………………………..…….. Perform simple measuring exercises ................................................................................................................... Use of Dail Indicator: ............................................................................................................................ Carry out exercises involving flatness, squareness straithness e.t.c .....................................................
CHAPTER 3 : AND TYPES
MACHINE SHOP MEASUREMENT TOOLS WEEK 5
Learning outcomes: ............................................................................................................................... Introduction............................................................................................................................................ Practical use of different types of drilling machine ............................................................................... Carry out drilling operatio such as Counter-sink, Counter Boring ........................................................ Grinding Drill Bits ................................................................................................................................ Select Correct Drilling Speed ................................................................................................................ WEEK 6 Demonstrate the use of Grinding Machine ........................................................................................... Calculate Drill Speed .............................................................................................................................
CHAPTER 4 : USE OF DRILLING MACHINES
WEEK
Learning out comes : ............................................................................................................................. Demonstrate use of Reamer ................................................................................................................... Select correct Speed for Reaming Operation ........................................................................................
WEEK 8 Select Correct Tapping Drill Size .......................................................................................................... Select Correct Taps ................................................................................................................................
7
Carry Out Tapping operation on the bench,on drilling and Lathe Machine ......................................... Student results........................................................................................................................................
CHAPTER 5 : THE USE OF FITTING TOOLS
WEEK
9
Learning out comes ............................................................................................................................... Fabrication Of Metal Container ........................................................................................................... Joining of Metals by the grooving technique......................................................................................... Carry Out soft Soldering ....................................................................................................................... WEEK 10
Assembling of Oxy-acetylene Plant …...……………………………………..…… … Selection of various welding Regulators .............................................................................................. Perform Gas welding by various Welding Technique ........................................................................... WEEK 11 Regulate Current And Determine Polarity for Metal Arc Welding l ..................................................... Determine Polarity and select Current .................................................................................................. Perform Various Arc Welding Joints by Down and up Hand Operation .............................................. WEEK 12 Threading .............................................................................................................................................. Tapping ................................................................................................................................................. Practical use of taps ............................................................................................................................... Dieing .................................................................................................................................................... Care of dies ............................................................................................................................................ Practical application of die ....................................................................................................................
CHAPTER 6 : THE USE OF MACHINING PROCESS WEEK 13 ............................................................................................................... Controling Distursion in Welding Operation : ...................................................................................... Controling Distursion by Stop Back method ........................................................................................
Controling Distursion by Skipping ....................................................................................... Apply Pre and Post Heating Technique ................................................................................................ WEEK 14 WEEK 15
Basic Turning Operations ..................................................................................................... Practical work .......................................................................................................................
WEEK 1: WORKSHOP SAFETY AND PERSONAL PROTECTIVE EQUIPMENT
Learning outcomes: The student should be able to: 1.
Observe safety precaution in the workshop.
2.
Operate safety equipment e.g. fire extinguisher, safety water hose etc.
3.
Use of protective wear.
4.
Observe al l safety rules and regulations.
All tools are dangerous if used improperly or carelessly. Working safely is the first thing the student should learn because the safe way is the correct way.
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.
Basics
Always listen carefully to the teacher and follow instructions.
Do not run in the workshop, you could cause an accident.
Know where the emergency stop buttons are positioned in the workshop.
Always wear an apron as it will protect your clothes and hold loose clothing such as ties in place.
Wear good strong shoes. Training shoes are not suitable.
When attempting practical work all stools should be put away.
Bags should not be brought into a workshop as people can trip over them.
When learning how to use a machine, listen very carefully to all the instructions given by the teacher. Ask questions, if you do not understand.
Do not use a machine if you have not been shown how to operate it safely.
Always be patient, never rush in the workshop.
Always use a guard when working on a machine.
Keep hands away from moving/rotating machinery.
Use hand tools carefully, keeping both hands behind the cutting edge.
Report any damage to machines/equipment as this could cause an accident.
Personal Protective Equipment Personal protective equipment (PPE) includes all types of equipment used to increase
individual
performing
safety
potentially
while
hazardous
tasks. This may include safety glasses,
hard
hats, gloves, lab coats, respirators, or
any
equipment used to protect against injury or illness. Fig (1.1)
Eye Protection Eye protection is required when there is a possibility of injury from chemicals or flying particles. Examples of operation requiring the use of eye protection include, but are not limited to:
Chipping, grinding, and impact drilling.
Welding or helping in welding of any type.
Riveting, grinding, or burning metals.
Foot Protection Non-skid shoes shall be worn where floors may be wet or greasy. Where there is reasonable probability of foot or toe injury from impact and compression forces, safety footwear shall be worn.
Body Protection Loose fitting clothing, neckties, rings, bracelets, or other apparel that may become entangled in moving machinery will not be worn by machine operators or their helpers.
Hand Protection Multi-use gloves shall be worn to protect the hands from injuries caused by handling sharp or jagged objects, wood, or similar hazard-producing materials.
Head Protection Hard hats shall be worn by all personnel working below other workers and in areas where sharp projections or other head hazards exist.
Hearing Protection Appropriate hearing protection shall be used where employees are in designated hazardous noise areas with operating noise sources, or using tools or equipment which are labeled as hazardous noise producers.
Proper Lifting Techniques Before lifting, take a moment to think about what you're about to do. Examine the object for sharp corners, slippery spots or other potential hazards. Know your limit and don't try to exceed it. Ask for help if needed, or if possible, divide the load to make it lighter. Know where you are going to set the item down and make sure it and your path are free of obstructions. Then follow these steps.
1. Stand close to the load with your feet spread apart about shoulder width, with one foot slightly in front of the other for balance.
2. Squat down bending at the knees (not your waist). Tuck your chin while keeping your back as vertical as possible.
3. Get a firm grasp of the object before beginning the lift.
4. Begin slowly lifting with your LEGS by straightening them. Never twist your body during this step.
5. Once the lift is complete, keep the object as close to the body as possible. As the load's center of gravity moves away from the body, there is a dramatic increase in stress to the lumbar region of the back.
Hand and Power Tools Tools are such a common part of our lives that it is difficult to remember that they may pose hazards. All tools are manufactured with safety in mind but, tragically, a serious accident often occurs before steps are taken to search out and avoid or eliminate tool-related hazards.
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 improper maintenance.
Basic Rules for Hand tool Safety
Safety is a state of mind. Always think when using a tool:
Is it in good condition?
Is it sized right for the job?
Is it in the proper working condition?
Every tool was designed to do a certain job. Use it for its intended purpose.
Tools subject to impact (chisels, star drill, punches, etc.) tend to "mushroom". Keep them dressed (sharpened) to avoid flying spalls. Use tool holders.
Secure your work in a vise whenever possible. Never hold small work in your hand when using a screwdriver. Fig (1.2 )
Hammers should have heads ground properly. Should not have broken claws or handles.
Cutting tools should be kept sharp to ensure good smooth cutting. Always use proper handles.
Screwdriver points should not be badly worn and handles should be in good condition. Use the proper size and type of screwdriver for the job.
Appropriate personal protective equipment, e.g., safety goggles, gloves, etc., should be worn due to hazards that may be encountered while using portable power tools and hand tools.
Power Tools Power tools can be extremely dangerous if they are used improperly. Each year, thousands of people are injured or killed by power tool accidents. Common accidents associated with power tools include abrasions, cuts, lacerations, amputations, burns, electrocution, and broken bones. These accidents are often caused by the following:
Touching the cutting, drilling, or grinding components
Getting caught in moving parts
Suffering electrical shock due to improper grounding, equipment defects, or operator misuse
Being struck by particles that normally eject during operation
Touching hot tools or work pieces
Falling in the work area
Being struck by falling tools
fig ( 1.3 )
When working around power tools, you must wear personal protective equipment and avoid wearing loose clothing or jewelry that could catch in moving machinery. In additional to general shop guidelines, follow these guidelines for working with power tools:
Use the correct tool for the job. Do not use a tool or attachment for something it was not designed to do.
Select the correct bit, blade, cutter, or grinder wheel for the material at hand. This precaution will reduce the chance for an accident and improve the quality of your work.
Always operate tools at the correct speed for the job at hand. Working too slowly can cause an accident just as easily as working too fast.
Watch your work when operating power tools. Stop working if something distracts you.
Before clearing jams or blockages on power tools, disconnect from power source. Do not use your hand to clear jams or blockages, use an appropriate tool.
Never reach over equipment while it is running.
When the chance for operator injury is great, use a push stick to move material through a machine.
Disconnect power tools before performing maintenance or changing components.
Remove chuck keys or adjusting tools prior to operation.
Keep all guards in place. Cover exposed belts, pulleys, gears, and shafts that could cause injury.
WEEK 2 : WORKSHOP SAFETY AND PPE Guards Moving machine parts must be safeguarded to protect operators from serious injury. Belts, gears, shafts, pulleys, fly wheels, chains, and other moving parts must be guarded if there is a chance they could contact an employee. Fig ( 1.4 ) As mentioned before, the hazards associated with moving machinery can be deadly. There are three types of barrier guards that protect people from moving machinery. They consist of the following:
Fixed guards
Interlocked guards
Adjustable guards
Safety guards must never be removed when a tool is being used. For example, portable circular saws must be equipped with guards. An upper guard must cover the entire blade of the saw. A retractable lower guard must cover the teeth of the saw, except when it makes contact with the work material. The lower guard must automatically return to the covering position when the tool is withdrawn from the work.
Housekeeping Good housekeeping shall be maintained in all shops, yards, buildings, and mobile equipment. Supervisors are responsible for good housekeeping in or around the work they are supervising. As a minimum, the following requirements shall be adhered to: 1.
Material shall not be placed where anyone might stumble over it, where it might fall on someone, or on or against any support unless the support can withstand the additional weight.
2.
Aisles and passageways shall be kept clear of tripping hazards.
3.
Nails shall be removed from loose lumber or the points turned down.
4.
Ice shall be removed from all walkways and work areas where it may create a hazard or interfere with work to be done. If ice cannot be removed readily, sand or other approved materials shall be applied.
5.
Trash and other waste materials shall be kept in approved receptacles. Trash shall not be allowed to accumulate and shall be removed and disposed of as soon as practicable, at least once per shift (or more often if needed).
6.
Disconnect switches, distribution panels, or alarm supply boxes shall not be blocked by any obstruction which may prevent ready access.
7.
Machinery and equipment shall be kept clean of excess grease and oil and (operating conditions permitting) free of excessive dust. Pressure gauges and visual displays shall be kept clean, visible, and serviceable at all times. Drip pans and wheeled or stationary containers shall be cleaned and emptied at the end of each shift.
Tutorial 1
(1) Look at figure (1.5) and write the correct number beside each statement: ( ( ( ( ( ( ( ( ( ( ( ( ( (
) Loose tools carried while mounting a ladder. ) Badly arranged tools. ) Climbing up on unstable supports. ) Carrying things that limit the vision ahead. ) Throughing tools. ) Lift wood pieces with nails. ) Uncleaned workshop floor. ) Pointing compressed air on others. ) Broken bottles on the ground. ) Lift pipes in the middle of the workshop. ) Standing bellow lifted materials. ) Carrying long bars. ) Carrying heavy loads. ) Uncovered pits.
(2) Which of the four sketches bellow shows the correct way to lift a heavy load?
(3) What special precautions should be taken with regard to the storage of flammable substances?
WEEK 4: MEASUREMENT AND TESTING Objective The student should be able to: 1. Perform simple measuring exercise using steel rules, vernier calipers and micrometers. 2. Use dial indicators to (i) set up jobs on the lathe (ii) Roundness testing etc 3. Carry out exercise involving flatness squareness, straightness and surface finish test.
Tools and material Steel rule Venier caliper Micrometer Dial indicators Screw gauge
Procedures 1. 2. 3.
Prepare and mark out the sheet using steel rule and scriber as shown. Prepare and measure as shown. Prepare and check measurement as shown
WEEK 5&6 DRILLING AND DRILLING OPERATION OBJECTIVE The student should be able to:1 Operates different types of drilling machine. 2 Carry out drilling operations such as Counter boring and Counter-sinking. 3 Grind Drill bits accurately. 4 Select correct drilling speeds. PROCEDURE Mark out the centre Use centre punch to find the centre of the hole as shown. Set up the work piece on the vice Hold the sheet metal in a hand vice as shown.
Marking out for Drilling operation
Drills and drilling operation
Drilling and reaming operation
Speed and drills selection for drilling different materials
WEEK 7: DATUM POINTS Datum's Before marking out any part it is necessary to establish a datum from which measurements can be made. The type of datum depends on the part to be marked out and the material to be used.
Datum face: Used when marking out from face of the work piece.
Datum edge: The edge of the work piece is used for measuring and marking out.
Datum line: Used in sheet metal work when marking out irregular shape (centre line).
Datum point: The centre of the circle or round object is used for measuring and marking out.
Fig (4.1)
WEEK 8:- TAPPING OPERATION OBJECTIVES The student should be able to 1. Select correct tapping drill size. 2. Select correct taps. 3. Carry out tapping operation. I) On the work bench II) On the drilling machine III) On the lathe
PROCEDURE 1. Prepare a hole to the tapping drill size by drilling to the size of the hole . 2. Place the work piece on the vice or position it on the lathe. 3. Set the tap as shown.
8.1
Thread produces using stock and dies
8.2
Internal thread produces using taps
8.3
Selection of taping drills size
WEEK 9:- METAL JOINING OPERATION OBJECTIVE 1. Fabricate metal container by knock-up joining 2. Join metals by the grooving technique. 3. Carry out soft soldering.
PROCEDURE 1. 2. 3. 4. 5.
9.1
Mark out the lap Close down over scribe metal Inscribe the wire Tuck in the edges Form up the box and solder the edges or corners flaps
LAYOUT FOR FORMING A BOX
9.2
Fabrication of metal box by knock-up joint
Week 10: Oxyacetylene Welding Learning outcomes: The student should be able to:
1. Follow and recognize all safety methods and precautions when oxy-acetylene welding in the flat position. 2. Identify the equipments used in oxyacetylene welding. 3. Carry out the oxy-acetylene welding of various joints in the flat position correctly.
Storage and Handling of Cylinders •
Keep cylinders away from physical damage, heat, and tampering.
•
Securely chain equipment to prevent falling.
•
Store away from flammable and combustible materials.
•
Store extra gas and oxygen cylinders separately.
•
Store in an upright position.
•
Close cylinder valves before moving.
•
Protective caps or regulators should be kept in place.
•
Roll cylinders on bottom edges to move--Do not drag.
•
Allow very little movement when transporting.
Safety Clothing The figure below show the welding safety clothing.
General Gas Welding Safety Tips •
Inspect equipment for leaks at all connections using approved leak-test solution.
•
Inspect hoses for leaks and worn places.
•
Replace bad hoses.
•
Protect hoses and cylinders from sparks, flames and hot metal.
•
Use a flint lighter to ignite the flame.
•
Stand to the side (away from the regulators) when opening cylinder valves.
•
Open cylinder valves very slowly to keep sudden high pressures from exploding the regulators.
•
Only open the acetylene cylinder valve 1/4 - 3/4 turn; leave wrench in place so the cylinder can be quickly closed in an emergency.
•
Open and light acetylene first, then open and adjust oxygen to a neutral flame.
•
Close the acetylene torch valve first when shutting off the torch ( a "pop" might occur as the oxygen "blows out" the flame, but this eliminates the possibility of the flame burning up the acetylene line).
•
When finished, close cylinder valves, bleed the lines to take pressure off regulators, neatly coil hoses and replace equipment.
•
Have a fire extinguisher easily accessible at the welding site.
Personal Protective Equipment:
•
Infrared radiation is a cause of retinal burning and cataracts. Protect your eyes with safety glasses.
•
Protect your body from welding with protective clothing Such as: o
Woolen clothing
o
Flame-proof apron
o
Gloves
o
Properly fitted clothing that is not frayed or worn.
o
Shirts should have long sleeves.
o
Trousers should be straight-legged and covering shoes when arc welding.
o
Fire resistant cape or shoulder covers are needed for overhead work.
•
Check protective clothing equipment before each use to make sure it is in good condition.
•
Keep clothes free of grease and oil.
Proper Ventilation
Be sure there is adequate ventilation available when welding in confined areas or where there are barriers to air movement. Natural drafts, fans and positioning of the head can help keep fumes away from the welder's face.
Week 11:Running continuous weld bead with filler rod Objective -The student should be able to use the filler rod to produce continuous runs.
Tools and materials - Oxy-acetylene welding station, filler rod, scriber, steel rule, carbon steel
Procedures 1- Mark the layout as shown in fig (a)
Fig (a)
2- Set the flame to neutral.
3- Concentrate heat on the sheet and wait till the metal starts to melt thus creating a molten pool.
4- While keeping the pool moving, start applying the rod to the pool in a continuous
Producing Runs using a filler rod : Objective -The student should be able to use the filler rod to produce continuous runs.
Tools and materials - Oxy-acetylene welding station, filler rod, scriber, steel rule, carbon steel.
Procedures 1- Mark the layout as shown in fig (b)
Fig (b) 2- Set the flame to neutral. 3- Concentrate heat on the sheet and wait till the metal starts to melt thus creating a molten pool. 4- While keeping the pool moving, start applying the rod to the pool in a continuous manner. fig.(c)
Fig (c)
Week 12: Welding an outside corner using filler rod Objective -The student should be able to produce an acceptable outside corner joint using a filler rod.
Tools and materials - Oxy-acetylene welding station, filler rod, jig, 2 sheets of carbon steel.
Procedures 1- set the sheets in a jig as shown in fig (a)
Fig (a)
Note: When setting up, the sheets should have a gap between them. This gap should equal the size of the filler rod. 2- Adjust the oxy-acetylene torch to neutral. 3- Tack weld the end opposite to the welding direction. 4- Concentrate heat till you get a small molten pool 5- Move your hand in a weaving manner to create a weld run.
6- Start applying the filler rod to the molten pool in a continuous manner.
Penetration at root
Student’s Record of Achievement Practical Skills
PC No 1 2 3
Competency Student’s Performance Criteria
Comp
Not comp
Retrail Comp
Follow safety rules during work Identify the tools and equipment of oxyacetylene welding Select the appropriate tools and equipment for various processes
4
Running weld pool correctly
5
Welding of a flanged joint correctly
6
Running weld bead with filler rod
7
Welding an outside corner joint with filler rod
Total PC =7
Not comp
Date
Week 13: Braze welding of a T joint Objective: The student should be able to braze weld a T joint of 1.6 mm thick mild steel sheet in the horizontal/vertical position.
Tools and material: • 2 pieces of 120x50x 1.6 mm of mild steel plate. • Filler rod 2.5 mm dia. Brazing filler wire • Flux
Flame: Slightly oxidizing
Procedure: 1. Clean the plates and form a T shape using the plates.
(Braze welding of a T joint )
2. Adjust the torch to a slightly oxidizing flame and tack the plates. 3. Heat the joint at the right end, dip heated rod in the flux and melt some of it into the corner. 4. Adjust the flame angle to deposit an equal amount of filler alloy on each leg of the joint
5. Let the finished joint cool. Don’t move the parts until the temperature has dropped enough. 6. Clean the flux from the joint
WEEK 14 : METAL MACHINING PROCESS (TURNING) Turning The lathe is a machine tool used for shaping metal (and sometimes wood or other materials) by causing the work piece 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
Fig (6.8)
move the cutting tool into the work piece. Turning is the machining operation that produces cylindrical parts. In its basic form, it can be defined as the machining of an external surface:
with the work piece rotating,
with a single-point cutting tool, and
with the cutting tool feeding parallel to the axis of the work piece and at a distance that will remove the outer surface of the work.
Fig ( 6.9)
A basic manual centre lathe is shown below. This type of lathe is controlled by a person turning the various handles on the top slide and cross slide in order to make a product / part.
Center Lathe Main Parts
Fig ( 6.10)
Head Stock: Produce the main motion and houses the main spindle and its driving arrangement. The gear trains give different revolution to the main spindle.
Lathe Bed: it carries the lathe parts and guides the carriage and tailstock. The Carriage: Transmits the adjusting and feed motions to the tool and moves the tool over the different surfaces of the work piece.
Tail Stock: It can be moved along the lathe bed and locked in any position to support the long work pieces. Also, it can be used for centering, drilling, and taper operations.
WEEK 15: METAL MACHINE PROCESS Objective The student should be able to use the lathe machine to produce par t.
Tools and material 1.
Three jaw chuck
2.
Turning tool
3.
Catch plate
4.
Carrier
5.
Life center
6.
Dead center
7.
Vernier caliper
8.
Drill chuck
9.
Round bar
Procedure 1.
Hold the work on the three jaw chuck as shown in the figure below.
2.
Surface the two end of the bar to the required length.
3.
Center drills the two end of the bar.
4.
Mount the work piece on the catch plate.
5.
Set the parameters of the accessories
6.
Test runs all the parameters
7.
Start the operation
