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Manufacturing
Engineering
MMG150S
Notes
Part 1
Compiled by
W. Alexander
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TABLE OF CONTENTS
1.
SAFETY
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2.
OHSACT LEGISLATION
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3.
MARKING OUT
4.
HAND TOOLS
5.
CUTTING THEORY
6.
MEASURING INSTRUMENTS
7.
CENTRE LATHE
8.
DRILLING
9.
MECHANICAL FASTENERS
10. WELDING
11. PLASTICS
12. POWDER METALLURGY
13. MILLING
14. HEAT TREATMENT
15. PRESSES AND DIES
16. GRINDING
17. HOT STEEL PROCESSES
18. COLD STEEL PROCESSES
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Cape Peninsula University of Technology
DEPARTMENT OF MECHANICAL ENGINEERING
Manufacturing Engineering
Safety
It’s my responsibility
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1. SAFETY MEASURES
1.1 INTRODUCTION
The tools and machinery that you are going to use are very dangerous if you do not know how to use then
properly. Before you attempt to do any work, make sure that you know the safety measures specified
for each tool and machine. These safety measures are designed to protect you, your fellow workers and
the equipment you use.
Most accidents happen because people are negligent and do not know how to prevent accidents, so you
must develop safe-working habits very soon. You prevent most accidents if you are responsible and
always consider the well-being of the people you work with. Be aware of your fellow workers and their
safety as well as your own and remember that it is important for you to have a professional attitude
towards your job and working environment. We will now discuss some of the safety measures that will
help you develop safe working habits.
1.2 What is an Accident?
It is an unplanned and uncontrolled event caused by unsafe acts or unsafe conditions and can be traced to
carelessness or negligence on someone's part. Accidents do not happen; they are caused. Accidents occur
because people do not know how to prevent them.
There are six factors involved in the sequence of events which lead to and follow an accident:
 Lack of control
 Personal and work factors
 Careless acts and unsafe conditions
 The accident itself
 Costs involved
 Injury and damage to property and interruptions to production
1.3 General duties of employees
Subject to the provisions of section 14(1) of the Act, and without derogating from any other specific
duty imposed on an employee by the Act or the regulation, every employee shall(a) Take reasonable care for his own health and safety as well as those who may be affected by
his actions.
(b) Carry out any lawful order given to him and shall obey the safety rules and procedures laid
down by his employer or by anyone authorized thereto by his employer, in accordance with or
for the proper observance of the provisions of the Act or the regulations or in the interest
of safety.
(c) Where a situation that is unsafe at or near his workplace comes to his attention, as soon as
possible report such situation to a safety representative or to his employer.
(d) Report any incident, which has affected his health or safety or has caused injury to himself,
to his employer or H & S not later than the end of the shift in which the incident occurred
1.4 Accident prevention
Accidents in the workshop can be prevented by paying particular attention to the following:
 Unsuitable clothing
 Unsafe conditions
 Unsafe acts
 Notices and safety signs
 Hand tools
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Machines
Electricity
Eye protection and other equipment
1.5 Personal safeguarding
An overall is the most practical, as well as the safest form of clothing for general workshop purposes or
when working on site. However, to be completely effective, further precautions must be taken as shown
in the next table:
1.6 GENERAL HEALTH AND SAFETY PRECAUTIONS
As already stated you must adopt a positive attitude and approach to health and safety. Your training is
an important way of achieving competence and helps to convert information into healthy and safe working
practices. Act responsibly and always consider the well being of other people working with you.
Remember to observe the following precautions.
• Horseplay
 work is not the place for horseplay, practical jokes, or silly tricks.
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• Hygiene
 Never eat or drink in a workshop
 always wash your hands using suitable hand cleaners and warm water before meals, before and after
going to the toilet, and at the end of each shift;
 dry your hands carefully on the clean towels or driers provided – don’t wipe them on old rags;
 paraffin, petrol or similar solvents should never be used for skin cleaning purposes;
 use appropriate barrier cream to protect your skin;
 conditioning cream may be needed after washing to replace fatty matter and prevent dryness;
 take care when working with metalworking fluids.
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• Housekeeping
Make sure that there are no liquids or scrap materials on the floor around your workplace.
Always have rubbish bins in particular places of the scrap materials you collect when you sweep the
floors and machines.
never throw rubbish on the floor;
keep gangways and work area free of metal bars, components, etc.;
if oil, or grease is spilled, wipe it up immediately or someone might slip and fall;
never put oily rags in overall or trouser pockets.
• Moving about
always walk – never run;
keep to gangways – never take shortcuts;
look out for and obey warning notices and safety signs;
never ride on a vehicle not made to carry passengers, e.g. fork-lift trucks.
Personal protective equipment
use all personal protective clothing and equipment, such as ear and eye protectors, dust masks,
overalls, gloves, safety shoes and safety helmets;
get replacements if damaged or worn.
Always wear protective footwear to prevent heavy objects injuring your feet when you work.
Ordinary shoes do not provide enough protection.
Wear a shop coat or overalls. Make sure that you roll your sleeves up or that you fasten the cuffs
because loose clothing can get caught in moving work pieces or machines.
Wear safety glasses when you use machines, portable power tools and when there is possible danger
to your eyes. Safety glasses will stop pieces of metal or liquids from harming your eyes.
Wear a hard safety hat when you work in an area where there are overhead cranes.
Wear gloves when you move large work pieces with sharp or rough edges, or when you handle liquids
that can harm your skin.
• Ladders
do not use ladders with damaged, missing or loose rungs;
always position ladders on a firm base and at the correct angle – the height of the top support should
be four times the distance out from the base;
ensure the ladder is long enough – at least one metre above the landing place;
make sure the ladder is tied at the top or secured at the bottom;
never over-reach from a ladder – be safe, get down and move it;
take all necessary precautions to avoid vehicles or people hitting the bottom of the ladder.
• Harmful substances
When you work with flammable gas or liquids, make sure that there is enough ventilation in the
workshop or around your workplace.
learn to recognise hazard warning signs and labels;
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follow all instructions;
before you use a substance find out what to do if it spills onto your hand or clothes;
never eat or drink in the near vicinity;
do not take home any clothes which have become soaked or stained with harmful substances;
do not put liquids or substances into unlabelled or wrongly labelled bottles or containers.
• Electricity
Make sure that regular maintenance is carried out on all electrical equipment. Immediately report
any faulty equipment to your supervisor.
make sure you understand all instructions before using electrical equipment;
do not use electrical equipment for any purpose other than, nor in the area other than the intended
one;
always switch off or isolate before connecting or disconnecting any electrical equipment.
• Compressed air
only use compressed air if allowed to do so;
never use compressed air to clean a machine – it may blow in your face or someone else’s and cause an
injury.
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• Fire
Do not block access to fire-fighting equipment
know the location of fire extinguishers;
Make sure that you have fire-fighting equipment readily available for emergencies. Check that:
 The expiry date on the fire-fighting equipment has not lapsed; and
 The safety seal is not broken.
take care when using flammable substances;
know the correct fire drill. If you hear the fire alarm, move to the assembly area as quickly as
possible.
• Smoking
Never smoke in the workshop. There are usually fumes of spilt liquids and gases in workshops and
smoking can start a fire or an explosion. This can then cause serious injuries or death.
it is against the law to smoke in enclosed or substantially enclosed workplaces.
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• First aid
Make sure that you know where the first-aid kit is kept.
have first aid treatment for every injury however trivial;
know the first aid arrangements for your workplace.
Never lock emergency exits
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1.7
SAFETY MEASURES WHEN USING HAND TOOLS / MACHINERY
Each different machine has particular safety measures, which you must know. These
are the following general rules that you must follow when you work with machinery:
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Use each tool to do the task it is meant for.
Be aware of your work area.
Always look for the “Emergency Stop” button on the machine before working on any power driven
machine
keep your concentration while the machine is in motion;
never leave your machine unattended while it is in motion;
take care not to distract other machine operators;
never clean a machine while it is in motion – always isolate it from the power supply first;
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never clean swarf away with your bare hands – always use a suitable brush;
keep your hair short or under a cap or hairnet – it can become tangled in drills or rotating shafts;
avoid loose clothing – wear a snug-fitting boiler suit, done up, and ensure that any neckwear is tucked
in and secure;
do not wear rings, chains or watches at work – they have caused serious injury when caught
accidentally on projections;
do not allow unguarded bar to protrude beyond the end of a machine, e.g. in a centre lathe;
Replace the machine guards before you switch the power on if the guards were removed to repair or
adjust the machine.
always ensure that all guards are correctly fitted and in position – remember, guards are fitted on
machines to protect you and others from accidentally coming in contact with dangerous moving parts.
Never carry tools, which have sharp edges in your pockets.
Keep the sharp edges of tools pointed away from you, towards the back of you workbench.
Keep your tools clean, dry and free of oil.
Take care of your tools, for example have a storage place for each tool and service them regularly.
Do not use your tools incorrectly or carelessly.
Make sure that you know how to operate the machine and how to stop the machine in an emergency.
Clean up excess oil or grease on or near bearings and grease caps.
Keep the floors; passageways and space around machines clear of small objects and machine
accessories.
Work inside the marked boundaries of the passageways and walkways between machines and
equipment.
Make sure that there is a place for each machine tool; accessory or attachments that you use so that
you can store them after you use them.
Make sure that your work piece is properly secured before you switch the machine on.
Never leave tools on machines – if they get caught in the machine they can damage the machine and
the work piece.
Do not sit on, or lean against, a machine.
Do not leave a machine unattended while it is operating.
Do not touch the work piece or take measurements while the machine is operating.
Lock-out electrically before doing any repairs on a machine
Ensure in-running nip-points on rotating/reciprocating machines are guarded to prevent objects from
being pulled into the machine
Do not wear gloves when performing machining operations
Keep long sleeves away from rotating/moving machine parts- roll them up
Keep long hair tied behind the head or wear a hair net or cap
Never leave the chuck key in the chuck (on the lathe)
If you suspect electrical trouble with a machine, turn it off immediately
Do not keep a liquid gas cigarette lighter in your pocket when welding
Make sure there are no flammable liquids or oily rags nearby when you are welding
Never weld in an enclosed area without proper ventilation - you could be overcome by the fumes
Never wear clothes made from flammable synthetic material in a workshop – sparks may ignite the
clothing that may burn rapidly, causing serious burns on the body.
1.8 What are unsafe acts
Unsafe acts can be described as follows:
 Working at dangerous speeds
 Working without authority
 Failing to secure machinery and materials
 Rendering safety devices inoperative
 Arranging or placing objects in unsafe positions
 Fooling around with, teasing or abusing work mates
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Using equipment carelessly or failing to use the correct equipment
Adjusting or working on equipment which is moving
Taking chances
Standing too close to moving machinery
Not using safety equipment
Not wearing protective clothing
1.9 What are unsafe conditions
Unsafe conditions are any departure from accepted standards which, if not rectified, may cause
accidents resulting in injury or damage. The following can be considered unsafe conditions bearing in
mind that unsafe conditions are caused and can be traced to carelessness or negligence on
someone's part:
 Unsafe construction
 Disorderly and haphazard planning
 Inadequate guarding
 Lack of machine and other guards
 Defective working conditions such as rough sharp or slippery surfaces
 Bad factory layout with inadequate or badly marked walkways and exits
 Overcrowding in workshops
 No personal protective policy
 Unsafe ventilation and lighting
 Unsafe storage of hazardous liquids and materials
1.10 Types of machine guards
Injuries caused by machines are usually severe and permanent, but such accidents can generally be
prevented. Machine guards are most important because the danger posed by the machines can often be
reduced or removed altogether by mechanical safeguards.
There are three basic types of machine guards:
 Fixed
 Interlocking
 automatic
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1.10.1 Characteristics of an effective guard
 It must provide maximum protection
 It must block access to the danger zone during operation
 It must be corrosion and fire resistant as well as repairable
 It should not create hazards such as splinters and pinch points
 It should comply with the requirements of the department of labour
 It should be a permanent part of the machinery without weakening its structure
 The guard should not affect the efficient operation of the machine
 It should be strong enough to withstand wear and tear
1.14
COLOUR CODING
This is the exercise where objects are painted a certain colour. They are important to identify certain
safety features in a factory environment.
Colour codes identify:
 Dangerous parts of machines
 Areas where it is safe to walk / work
 Danger zones
 Fire-fighting equipment
 Contents of Pipelines
 Electrical equipment
1.15
EXAMPLES HOW COLOUR CODING ARE PRACTISED.
Contents of pipeline / feature
Colour code
Air……………………………………….
Arctic blue
Acids……………………………………..
Jacaranda
Alkalis…………………………………
Dove grey
Oils………………………………………
Golden brown
Gases other than air…………
Light stone
Steam……………………………………
Silver or Aluminium
Water……………………………………
Brilliant green
Fire-fighting………………………
Signal red
Walkways……………………………
Yellow
Danger zones……………………….
Red and white tape
Electrical equipment………..
Orange
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1.16
ESSENTIAL ELEMENTS OF A FIRE
There are 3 essential elements needed to start a fire or keep it going.
HEAT
FUEL
Flammable
material
Removing one of these elements will extinguish the fire.
Once a fire has started, it produces sufficient heat to maintain its own
combustion reaction and sufficient heat to spread itself.
1.17
OXYGEN
MAIN CLASSES OF FIRE AND COMMONLY USED EXTINGUISHERS
A fire extinguisher is a piece of equipment used for putting out fires. Different types of fires need to
be dealt with in different ways.
There are various types of fire extinguishers namely: Fire hoses with pressurised water
 Fire hydrants
 Foam extinguishers for fighting oil and chemical fires
 Carbon Dioxide extinguishers used on burning gasses and vapours
 Dry Powder extinguishers used for small fires involving flammable liquids.
Class
A
B
C
1.18
Fire
Wood, paper grass, tobacco and
other organic materials
Flammable liquids & greases e.g.
alcohol, benzene, oil, paraffin,
petrol etc.
Electrical fires
Type of extinguisher
Water, foam, dry powder, Halotron
ordinary foam, Halotron, CO2, dry powder,
Halotron, carbon dioxide, dry powder
FIRE PREVENTION AND PROTECTION
Prevention is always better than cure and fire prevention is better than fire fighting. Fires are caused
by:
 Rubbish left lying about that may catch alight.
 Unwanted materials such as wood shavings, off-cuts left lying around.
 Highly flammable materials left open and on floors.
 Bad electrical fittings and joints.
 Do not drape clothing or other materials over heaters.
 Ensure that there are no flammable liquids or other materials around when using welding
equipment.
 Keep exits and stairways clear and unobstructed.
 Dispose of cigarette butts carefully.
 Keep flammable liquids stored in closed metal containers.
 Keep matches away from children.
 Ensure that the correct type of fire extinguishers is available and accessible.
 Familiarise yourself with fire fighting equipment.
 Water is a good conductor of electricity and therefore should never be brought into contact with
live wires.
 Flammable liquids float on water; therefore water should not be used to extinguish burning
flammable liquids as it can only spread the fire to other areas. It can also increase the intensity
of the fire.