Christmas 2013 Level 3

To All of my level 3 students of 2013.
I really hope that your results exceed your expectations.
I would like to wish all of you a Christmas filled with the love of Jesus
To those of you who were successful in 2013, may hard work during 2014 bring you the results you long for.
You are in my thoughts
Naas Breytenbach

Christmas 2013 Level 4

To All of my level 4 students of 2013.
I really hope that your results exceed your expectations.
I would like to wish all of you a Christmas filled with the love of Jesus
To those of you who were successful in 2013, may you follow your dreams and become the best in whatever you are going to do with the rest of your lives.
The few unlucky ones who must still work on a subject or two, may hard work during 2014 bring you the results you long for.
You are in my thoughts
Naas Breytenbach

Urgent Note to all Engineering Students.

This time of the year is called spring. It put sparkles in the eyes of lovers and make the hearts beat faster. The days became longer and the beaches call.
But!
Please!
Remember that this time of the year is also the time when students must apply their new found knowledge to impress the lecturers in order to be promoted to the next level or, to earn a Certificate that will determine their futures.
You are one of those students. You and me both know that you have worked hard during the year in order to pass your tests. Completed your tasks in order to obtain good ISAT marks.
Please do not throw away all your hard work during the year by falling into the Spring-trap.
Now is the time for you to have self-discipline. To stay off the beaches and study.
A little bit of discipline and hard work now can prevent tears and a bad holiday later.
Please guys, make use of the Question papers on the log to study. Remember that, although I expect a lot from you, you are still doing this for yourself and YOUR OWN future.  

Milling Level 4 Indexing

Fitting and Turning Level 4

Milling machine – Indexing calculations

INDEXING EQUIPMENT:

Indexing is done on the milling machine using a dividing head. The dividing head is a very important tool used to divide the circumference of a work piece into equally spaced divisions. This is important when milling gears, splines, hexagons and so on. The dividing headset consists of the headstock with footstock, chuck, center rest, index plates and change gears.

The chuck clamps the work piece when milling while the footstock supports the work piece on the opposite side of the dividing head when milling between centers. 

The center rest supports long work pieces when milling between centers.

SIMPLE INDEXING:

Simple indexing is performed in the following manner.

Have the worm and worm gear engaged.

Calculate the indexing

Place the adjustable plunger into the required hole on the chosen index plate.

Adjust the sector arms to count the required number of holes.

Turn the index crank handle the number of full turns and part of a turn determined by the sector arms and put into the set hole

Move the sector arms and repeat the procedure until the required number of divisions or sides have been cut.

Two types of dividing heads have been developed namely Brown and Sharp as well as the Cincinnati.

Brown and Sharp: The dividing head id supplied with three index plates:-

Plate 1:  15, 16, 17, 18, 19 and 20 holes

Plate 2:   21, 23, 27, 29, 31 and 33 holes

Plate 3:   37, 39, 41, 43, 47 and 49 holes

The Cincinnati dividing head is supplied with only one indexing plate that is reversible:

Side 1:   24, 25, 28, 30, 34, 37, 38, 39, 41, 42 and 43 holes

Side 2:   46, 47, 49, 51, 53, 54, 57, 58, 59, 62 and 66 holes

It is also important to note that the crank handle must turn through 40 full revolutions before the work piece and worm wheel is turned through one revolution.

Out of this information we use the following formula for indexing.  

        Formula  =40/N      where N = the number of divisions or sides to be machined.

Let us do two examples. In one example the divisions is more than 40 (in which case there will be no full turns of the handle) and in the next the divisions is less than forty (in which case there will be some full turns of the handle.)

Example 1

We want to cut a gear with 44 teeth. In our formula N will be equal to 44 and we are using the Cincinnati dividing head.

               Formula  =40/N   

=40/44   We can simplify this  

=10/11  ×  66/1    (on the Cincinnati plate 66 is the first number of holes dividable by 11)

= 60

Our full answer will now be: 0 full turns of the crank handle, 60 holes on a 66-hole circle plate.

Example 2

We want to cut a gear with 12 teeth on a Brown and Sharp dividing head. 

               Formula   =40/N   

=40/12   We can simplify this  

=3 1/3   ×  15/1    (on the Brown and Sharp plates 15 is the first number of holes dividable by 3)

      =1/3   ×  15/1    (we ignore the three and calculate only the fraction)

Type equation here.

=   5

Our full answer will now be: 3 full turns of the crank handle, 5 holes on a 15-hole circle plate.

ANGULAR INDEXING:

If we want to cut grooves or slots at an angle in a work piece. If we are working with angles it is important to remember that 40 full turns of the crank handle will0 rotate the work piece through only one full turn. (360°) To work out how many degrees the crank handle will turn the work piece in one full turn of the handle, we must divide 360° by 40. This will give us 9°. 

The formula for indexing when working with degrees will therefore be  N/(9°)   

For example:- Using the Cincinnati head, calculate the indexing to cut a gear with 38° teeth. 

Our Formula =N/(9°)   

=38/9   

=4 2/9   

=2/9  ×  54/1   (we ignore the 4 and 54 is the first number of holes dividable by 9)

= 12

 Our full answer will now be: 4 full turns of the crank handle, 12 holes on a 54-hole circle plate.

DIFFERENTIAL INDEXING:

Sometimes it is impossible to calculate the indexing because the plates do not provide a number of holes that are divisible by the number of teeth or divisions. To overcome this the headstock can be attached to a number of interchangeable gears. The gears will in fact slightly change the number of turns the crank handle make for one full revolution of the work piece. 

How do we do these calculations? 

Step 1: Round of the divisions either up or down.

Step 2: make a note that, if you have rounded up, the plate must turn the same direction as the crank handle and if you have rounded down, the plate must turn in the opposite direction as the crank handle. (make use of an idler gear to change direction.)

Step 3: Use the following formulae: Indexing =40/n   and Gear Ratio (n-N)  ×  40/n   (Where N = Real number of divisions and n = rounded number of divisions.

The change gears supplied are the following: 2 of each 24, 28, 32, 40, 44, 48, 56, 64, 72, 86, 100

EXAMPLE:

Using the Cincinnati dividing head calculate the indexing for 99 divisions.

Round the divisions to 100

Indexing =40/n     

=40/100   

=4/10  ×  20/1   (20 is the first divisible number of holes on Cincinnati plate)

= 8

  Gear Ratio =(n-N) ×40/n

=(100-99) ×40/100

=1×40/100

=40/100

=4/10  ×10/10     

=40/100

Our full answer will be: Indexing = 0 full turns of the crank handle, eight holes on a 20-hole circle plate with a gear ratio of   40/100  and the index plate turning in the same direction as the crank handle.

RAPIT INDEXING:

No difficult calculations needed. You want to cut a hexagon or a square

EXAMPLE:

Determine the indexing to complete six sides on you work piece.

For rapid indexing follow these steps:

Using the handle on the dividing head, disengage the worm from the worm wheel.

On the 12 slot plate, mark every second slot with chalk.

Place the plunger in the first marked slot and cut the first division.

Remove the plunger from the slot, turn the spindle by hand to the next marked

        slot. 

        Engage the plunger and cut the next division.

Repeat the proses until all six divisions have been cut.

AET Level 4 Beams

Applied Engineering Technology – Level 4

A look at simple beams

A possible question on beams can be as follows:

Use the following information and draw the beam to the scale 1 meter = 1 cm.

A beam of 12 meter is supported at L and R. Point L is 3 meter from the left end of the beam and point R is 2 meter from the right end of the beam. There is a point load of 40N on the left end of the beam and a point load of 20N on the right end of the beam. There is another point load of 50N, 3 meter from the right end of the beam. A uniformly distributed load of 10N/meter starts at L and end at the point load of 5N. Ignore the mass of the beam.

Draw a simplified diagram to scale to solve the reactions at L and R

At first glance this problem seem to be massive because of all the confusing information, but remember that you can eat a big elephant one bite at a time. So let us attack this problem one step at a time.

Step 1: A beam of 12 meter – We stop here and draw a line 12 cm long (scale 1meter = 1 cm.)

   ________________________________________________________________________________

Step 2: Point L is 3 meter from the left end of the beam. We measure 3 cm from the left end to find L

 Step 3: Point R is 2 meter from the right end of the beam. We measure 2 cm from the right end to find R

Step 4: There is a point load of 40N on the left end of the beam.

Step 5: There is a point load of 20N on the right end of the beam.

Step 6: There is another point load of 50N, 3 meter from the right end of the beam.

Step 7: A uniformly distributed load of 10N/meter starts at L and end at the point load of 5N.

And that is your final drawing, your first elephant has been eaten. Now we must start to work out the forces at L and R.

First we need to transform the UDL (uniformly distributed load) of 10N/m to a point load. It is important to work out the length over which the load is distributed. The load starts 3 meter from the one end of the 12 meter beam and ends 3 meter from the other end. Therefore we are going to take the length of the beam and subtrack the the two 3 meter ends. The calculation will look like this. 12-(3+3) = 12-6 = 6 meters.

Now we know that the UDL is distributed over 6 meters at a load of 10N/m (given) The pointload will thus be 6 X 10 = 60N and it will be in the centre of the UDL. Let’s make it part of our drawing:

 The next step is to work out the values of L and R in Newton.

Let us start with the value of L. – To work out the value of L we must determine the movements around the centre point R. remember that the whole beam can now rotate around the point of R. If we count all the forces we find the following from left to right: 40N ,  L , 60N , 50N and 20N. Note that we do not count R. So there are 5 forces and we must make sure that we take all of them into account.

Now we must decide which of these five forces will work clockwise around R and which of them will work counter-clockwise. This is easy if we follow the following rule of thumb:

All downward forces to the left of the point R will move counter-clockwise.

All downward forces to the right of the point R will move clockwise.

The opposite is true for the upward forces.

All upward forces to the left of the point R will move clockwise.

All upward forces to the right of the point R will move counter clockwise.

Let us start with the force at L because we want L to be on the left hand side of our equation.

You will find that L is an upward force on the lefthand side of the centre at R and moves the beam in a clockwise direction around R. To find the downward forces that will move the beam clockwise around R (the same direction as L) we must look for downward forces to the right of R. There is only one downward force to the right of R and that is the 20N force ar the end of the beam. Logic now dictate that the remaining three forces wil be counter-clocwice around R because they are downward and to the left of R.

Each force stand in relation to the distance from R and the clokcwise forces must be equel to the counter-clockwise forces. We have two clockwise forces = three counter-clockwise forces. The Equation wil be:

(force X distance)+ (force X distance) = (force X distance)+ (force X distance)+ (force X distance)

(L X 7m)+(20N X 2m) = (40N X 10m)+(60N X 4m)+(50N X 1m) Make sure your distances from R is correct.

(L X 7m)+ 40 = 400 + 240 + 50

(L X 7) = 690 – 40

L = 650 ÷ 7

L = 92.86N

We worked out L. Now we must do the same for R. To work out the value of R we must determine the movements around the centre point L. Remember that the whole beam can now rotate around the point of L. If we count all the forces we find the following from left to right: 40N ,  60N , 50N , R and 20N. Note that we do not count L. So there are 5 forces and we must make sure that we take all of them into account.

Now we must decide which of these five forces will work clockwise around L and which of them will work counter-clockwise. This is easy if we follow the following rule of thumb:

All downward forces to the left of the point L will move counter-clockwise.

All downward forces to the right of the point L will move clockwise.

The opposite is true for the upward forces.

All upward forces to the left of the point L will move clockwise.

All upward forces to the right of the point L will move counter clockwise.

Let us start with the force at R because we now want R to be on the left hand side of our equation.

You will find that R is an upward force on the righthand side of the centre at L and moves the beam in a counter-clockwise direction around L. To find the downward forces that will move the beam Counter-clockwise around L (the same direction as R) we must look for downward forces to the left of L. There is only one downward force to the left of L and that is the 40N force ar the end of the beam. Logic now dictate that the remaining three forces wil be clocwice around L because they are downward and to the right of L.

Each force stand in relation to the distance from L and the clokcwise forces must be equel to the counter-clockwise forces. We have two counter-clockwise forces = three clockwise forces. The Equation wil be:

(force X distance)+ (force X distance) = (force X distance)+ (force X distance)+ (force X distance)

(R X 7m)+(40N X 3m) = (60N X 3m)+(50N X 6m)+(20N X 9m) Make sure your distances from L is correct.

(R X 7m)+ 120 = 180 + 300 + 180

(R X 7) = 660 – 120

R = 540 ÷ 7

R = 77.14N

Well done! We have calculated the forces at L and R. Now to make sure thet we have done so correctly. If the forces at L and R is correct the sum of the two upward forces should be equal to the sum of all the downward forces.

L + R = F1 + F2 + F3 + F4

92.86 + 77.14 =  40 + 60 + 50 + 20

170 = 170  And they balance so our calculations were correct.

Now, let us work out the Shear force diagram: We do this directly underneathour drawing that we started with. Draw very light construction lines down from every force (up or down force) and then draw a zero line.

Our Shear force diagram must now be build around the zero line. We will work from left to right and start on the left side of the zero line. Our first force is 40N downward. Strarting from zero we go four centimeter down to A.

For the next three meters there are no force on the beam. We can therefore draw a line straight across to B.

At B we find an upward force of 92.86N (Force at L) Starting at B we draw a line of 9.3cm straight up to C.

From here we find a downward UDL (Unifomed Distributed Load) of 60N over the next 6 meters. We measure 6cm across to D (6 meters) and 6cm down to E (60N). Now we draw a diagonal line from C to E. A UDL will always form a diagonal line.

At point E there is another downward force of 5N so from E we draw a 5cm line down to F.

From F to G there is no force. We draw a 1cm line from F to G.

At G we find that the upward force at R apply. That tells to draw a line of 7.7cm straight up from G to H.

From H to I there is no force. We draw a 2cm line from H to I.

The downward force of 20N at I turn into a 2 cm line that will end on the zero l

Work according to schedules

Schedules are plans to describe what needs to be done and in what order.

A production schedule:

The different stages that a work piece goes through in the production process. This is usually compiled in the job card and/or the engineering drawings and will include the following information.

·         When will the job start

·         The number of hours that each stage will take to complete

·         The order in which the stages should be done

·         The deadline by which the job should be completed

A production schedule is useful for the following reasons.

·         It helps to plan the work flow. During the planning process jobs can be scheduled for specific machines that are best suited for the job. This will improve sufficiency in the workplace and will safe time and money.

·         The schedule will help to cost the job more accurately.

·         The schedule informs you of how many items or components must be made. This is called a production target.

·         The schedule allows the stages to be monitored. This means that any problems with equipment or the production process is picked up early, easily and solved quickly saving time and money.

·         The production schedule also give an indication of which machines and employees will be needed to complete the work piece or project

·         The schedule also give an indication of how busy the work place will be and if other work can be done at the same time as the project

 A maintenance schedule:

All machines needs regular maintenance to keep them working properly and sufficiently. A maintenance schedule is necessary for the following reasons.

·         Keep machines running smoothly and sufficiently

·         Prevent machines from breaking down unexpectedly and losing production time

·         Pick up problems before they become serious and, therefore more costly

·         Keeping a record of work done on the machine and, parts that has been replaced so that everyone who uses the machine in future knows what has been done to the machine

Follow the manufacturer’s specifications when you work.

The manufacturer’s specifications or instructions are given in manuals that come with the machine. This includes the following types of information.

·         The types and sizes of the parts, like drill bits or grinding wheels that fit into the machine.

·         The speed at which to set the machine

·         The revolutions per minute (rpm) at which to operate the machine

·         The level of the voltage and the current needed to operate the machine.

·         Safety information about the machine. How to use the machine without getting an electrical shock and what protective equipment to use

Fitting and Turning – Worksite health and safety practices

Health and safety practices are the rules that you need to follow on a worksite to make sure that your workplace is healthy and safe. In South Africa these rules are described in the Occupational Health and Safety (OHS) act 85 of 1993. All employers and employees in South Africa must follow these rules. It is therefore important that you know the rules and understand what they mean.

The responsibility of the Employer:

The employer is the person or company that pays people to work for them. The employer must:-

·         Make sure that employees have all the right equipment and machinery, and that this equipment and machinery is working properly and is safe to use.

·         Make sure that there are no dangers at the worksite that can affect the health and safety of employees.

·         Take all safety steps needed to protect the health and safety of employees at the worksite.

·         Take care and train the employees to make sure they are healthy and safe at the worksite.

·         Make sure that no employee operates machinery or equipment or does any task without taking the right safety steps.

·         Make sure that all employees follow the rules in the OHS Act.

·         Make sure that all the required safety signs are put up in the right areas at the worksite.

·         Stop people from entering the worksite unless they have received permission from the employer or user of the machinery.

·         Make sure that no one who is under the influence of drugs or alcohol enters or stay on the worksite or operate any machinery on the worksite.

·         Make sure that the employee can get first aid treatment for any injuries that might happen at the worksite.

·         The employee must supply a first aid where everybody can see it if there are more than 5 employees on the worksite. In addition, if there are more than ten employees on the worksite the employer must make sure that at least one person at the worksite is trained in first aid, has a first aid certificate and get first aid training every year.

 The responsibility of the employee:

 The employee is a person that works for the employer. The employer must:-

·         Look after his or her own safety, as well as the safety of of others in the worksite.

·         Obey the health and safety rules, and follow orders given by the employer regarding health and safety I n the worksite.

·         Report any unsafe conditions or situations in the worksite to the employer or the safety representative.

·         Report any incidents, accidents or injuries as soon as possible

·         Wear the required safety equipment at all times.

Applicable environmental procedures

Lighting:  How light or dark is it where you work. The lighting in the worksite should be sufficient to allow you to see properly so that you can work efficiently, effectively and safely. If there are not enough windows to let in natural light, you need to make sure that lamps or lights are put into the worksite in such a way that everybody can see properly. Lights should not shine directly into your eyes.

Ventilation:  ventilation should be enough so that the air is kept fresh and safe to breath in the worksite. All work sites should be properly ventilated by either open windows or air conditioning. If areas contain dangerous gases or dust the employer must provide every employee with respiratory equipment.

Areas that have large amounts of dust must also have a dust extraction system. Welding bays should also be equipped with an extraction system because of the dangerous gases.

Noise levels:  Noise levels mean how loud the noise from all the machines in the workplace is. Noise levels louder than 85 decibels can damage your ears. If the noise levels are higher than 85 decibels, signs must be put up to worn employers and visitors to wear ear protection supplied by the employer. The employer must train the employees to make sure they know how to use the ear protection properly.

Fire exits:  A fire exit, or emergency exit, is a safe open passage or staircase that you can use to exit the building in case of a fire or other emergency. All workplaces must have a fire exit and it must be kept open and clean. It must also open easily to the outside of the building and be made of non-combustible material.

General rules for working safely:

·         Don’t wear loose-fitting clothing or jewelry, as this can get caught in the moving parts of equipment and can cause serious injury.

·         Make sure that long hair is tied back, as it can get caught in the moving parts of equipment and can cause serious injury.

·         Make sure the work area is suitably ventilated when working with dangerous gases. Flammable gases can ignite and start a fire while poisonous gases can make you sick or kill you if breathed in.

·         Make sure that all equipment is kept in good condition. Report any faulty equipment to your supervisor so that accidents can be prevented.

·         Put enough fire-fighting equipment where people can see them.

·         Fire-fighting equipment should be inspected regularly by safety inspectors to make sure they are in good working condition.

·         Make sure you know where the fire-fighting equipment is kept and that you know how to operate them.

·         Make sure that you know how to use each piece of equipment in the workshop correctly. If you are not sure how to use something, ask for training.

·         Check that you use the correct safety clothing and safety equipment for the job.

·         Check that the safety equipment is in good working condition and not damaged or faulty.

Working safely with tools:

·         Make sure you are using the right tool for the job. Using the wrong tools can damage the job as well as the tool.

·         Don’t carry sharp tools in your pocket.

·         Only keep the tools you need for the job close at hand. Pack the other tools away so that they don’ get in the way.

·         Make sure the handle of the hammer is fixed to the head. If the head flies of while you use the hammer it can seriously injure you or a fellow worker.

·         Don’t use a file without a handle.

·         Don’t use a chisel with a mushroom head. A small piece of metal can break off and seriously damage your eyes if you are not wearing safety goggles.

·         Don’t leave tools with sharp edges sticking out over the edge of the work bench, as it can cut you or some-one else.

Working safely with machines:

·         Check that all the moving parts of the machinery are covered and protected by the correct safety guards or devices.

·         Check that all safety equipment is in good working condition.

·         Never lean against a machine or sit on it, because the moving parts can injure you.

·         Make sure that you know the dangers of using the machine and that you follow the safety precausions.

·         Don’t leave a machine running unattended

·         Do not let anyone else operate the machine you are working on without the permission of your supervisor.

·         If a machine looks unsafe to use, switch it off and inform your supervisor immediately before someone gets hurt.

·         Don’t do maintenance or repairs to a machine while it is operating.

·         Check that no one is working close to the machine before you turn it on.

·         Make sure all work pieces are clamped firmly in position.

·         Don’t touch the work piece while the machine is operating.

·         Don’t try to stop the machine with your hands.

·         Check the floor for oil or grease. Slippery floors can lead to serious injury.

·         Don’t wear open-toed shoes or sandals in the workshop. Wear safety boots.

Maintaining Lubrication systems (Fitting and Turning Level 3)

1)      Understanding the system

2)      Safety procedures

3)      Planning Maintenance

4)      Prepare the site for maintenance

5)      Inspect and assess the system

6)      Fix the faults

7)      Check that system operates correctly

8)      Record information on work completed

Understanding the system.

The principles of lubrication systems (How does it work?)

A lubrication system applies oil or grease to parts of a machine to reduce friction between the parts and to keep them moving smoothly. It keeps the machine in good working condition and reduces wear and tear on the moving parts. Parts that needs lubrication are bushing slides, bearings and gears.

Lubrication systems can be:

                Manual – Works with a spot lubrication gun and needs a person to operate it or

                Automatic – This system is built into a machine and work as part of the machine based on the requirements of the machine. Although the work without an operator they still need to be maintained.

A lubrication system consists of the following main parts.

a.       A reservoir or container to store the lubricant.

b.      A pump, to force the lubricant through pipes to the parts that need to lubricated. 

c.       A filter to ensure that the lubricant is kept clean.

In addition to reducing friction, lubrication has the following functions.

v  They prevent corrosion

v  They cover dirt and/or dust particles to prevent the moving parts from seizing

v  They reduce the operating temperature by reducing friction

v  They provide insulation in electrical systems such as oil cooled transformers

v  They transmit power in hydraulic systems. (hydraulic fluid, brake and clutch fluid)

The characteristics of a lubricant:

v  It will stay viscous (fluid) and will not become solid

v  It is not acidic

v  It is not abrasive

v  It keeps it film thickness

v  It is very slippery.

There are four main types of lubrication systems:

·         The gravity feed oil lubrication system

·         The grease lubrication system

·         The oil splash lubrication system

·         The forced oil and grease lubrication system.

The gravity feed oil lubrication system:

This system uses the force of gravity to feed the oil into the system. This method is usually used in parts requiring a small amount of oil. Two types of lubricators using this system are:

The siphon-wick lubricator: This lubricator consist of a container filled with oil. A pipe is positioned in the middle of the container ending above the level of the oil. A wick is placed in the oil and fed down the pipe. The wick soaks up the oil in the container and gravity makes it flow down the wick in the pipe delivering it as drops at the end of the wick. The amount of oil delivered depends on the thickness of the wick.

Sight-feed lubricator: This lubricator is a container mounted on a metal base with a hole in the center. The container has a metal cap fitted with a tapered needle valve that extends to the hole at the bottom. A lever connected to the needle lifts the needle when oil flow is needed and lowers the needle when no oil is required.

The grease lubrication system:

This system is only used for plain bearings that carries small loads at low speeds. There are three types of lubricators that use this lubrication system:

The Stauffer grease cup: This lubricator consist of a closed container filled with grease and screwed down onto a base with a tapered hole in it. The grease is forced through this hole onto the surface of the bearing.

The telltale grease cup: This lubricator has a fluted upper container filled with grease. The bottom part of the container narrows to a very thin pipe. The top part has a spring-loaded piston that is smaller than the cup. This prevents the piston from forcing all the grease from the cup. The piston forces the grease through the narrow opening at the bottom of the cup onto the surface of the bearing.

The hand grease gun: The hand grease gun has a cylinder filled with grease. A spring loaded piston connected to a handle provide mechanical advantage to assist in forcing the grease through a bendable pipe into a grease nipple. The grease nipple is positioned on the bearing surface where the grease is then delivered. Modern grease pumps works with rechargeable batteries.

The splash lubrication system:

this system is designed into the machine when it is manufactured. It consist of a reservoir or sump, filled with oil or lubricant through which one or more of the moving parts will operate. As these parts move through the lubricant, pick up the lubricant and splashes it onto the rest of the parts. There are two types of splash systems in operation:

The scoop system used in machines that run at high revolutions. The scoop picks up the oil and splashes it onto the parts.

The ring oiler system used in machines that run at low revolutions has an oil ring that dips into the oil and scoops it up to lubricate the applicable parts.

The forced lubrication system:

This system uses a pump to deliver the lubricant (mostly oil) under pressure onto the part(s) that need it. The oil is drawn from the sump through a filter and discharged through pipes and channels to be delivered onto the parts that need lubrication. This system forms part of the machine and is fully automatic. It starts when the machine starts and stop when the machine stops.

The correct sequence of activities to follow:

Step 1.           Study and understand the instructions and information on the job card, previous reports and engineering drawings to determine the service history of the lubrication system.

Step 2.           Study the records and manufacturers manual to determine the correct lubricants to be used.

Step 3.           Find out which filtration parts you need to use.

Step 4.           Identify the tools and equipment you will need to complete the maintenance.

Step 5.           Check the worksite and make sure it is safe to work in.

Step 6.           Isolate the equipment and make sure that the system is safe to work on.

Step 7.           Inspect the lubrication system while in operation.

Step 8.           Diagnose the system faults.

Step 9.           Identify the parts to be serviced and the parts to be replaced.

Step 10.       Remove the parts and service or replace them.

Step 11.       Fit the serviced and replaced parts.

Step 12.       Select the testing tools and equipment.

Step 13.       Run a full operational test to check that the system is working properly and without leaks.

Step 14.       Write a report on your work.

The implications of not following this sequence of activities:

Ø  You will contaminate the workshop floor with oil if you do not drain the oil from the system first.

Ø  You will damage the lubrication system and the machine if you use the wrong lubricant.

Ø  You will waste time if you realise halfway through the job that you don’t have the right tools, equipment or spares to continue.

Ø  You will damage parts, have breakdowns or cause leaks if you fit the parts in the wrong order.

Ø  You will get an electrical shock if you haven’t isolated the equipment before you start working on it. 

Safety procedures.

Safety in the workshop is very important. Failing to comply to safety measures can lead to injury or even death to yourself or someone else.

Safety rules to follow while working on lubrication systems:

o   Check that the machine you are working on is disconnected from the power supply or you will get an electrical shock.

o   Use a lock-out device to make sure the machine can’t be switched on while you are working on it.

o   If you get oil or grease into an open wound, get medical treatment immediately or the wound may become infected.

o   Drums containing oil and grease are very heavy. Get someone to help you move it in the workshop. If you drop a drum it can crack or burst, spilling oil or grease all over the floor. People may slip on the oil or grease and hurt themselves.

o   Never add lubricants in a machine that is still running.

o   Never reach over, under, through or around moving parts of machinery.

o   Don’t remove any protective guards from moving parts of the machine, like open gears or couplings, until the machine is isolated and disconnected. Make sure you replace the guards as soon as you have finished the job.

o   Wear rubber gloves while working with grease and solvents to prevent yor skin from becoming irritated.

o   Never smoke around any petroleum products, and handle them with care as they can catch fire.

o   Dispose of any leftover solvents and waste rags soaked with this liquid in the special hazardous waste material containers provided in the workshop.

o   Dispose of the lubricants that you removed from during maintenance in the special hazardous waste material containers in the worksite, as they are harmful to people, animals and the environment.

Planning Maintenance.

Obtain the following documents to investigate the service history and obtain details about lubricants.

o   The job card

o   The maintenance schedule

o   The manufacturer’s manuals for the machine

o   The reports on all work done to the machine

o   The engineering drawings

The job card: You will get the job card from your supervisor. The job card will tell you if it’s a scheduled maintenance job or if there is a problem on the machine that needs repairing. It will also include information like the name and number of the machine. 

The maintenance schedule: this is a schedule that describes all the inspections, tests, service details and repair or replacement work that needs to be done on the specific machine or specific parts of the machine. This will help you to plan the work. You need to complete all the tasks on the schedule and your supervisor will sign the schedule after the work is complete.

 The manufacturer’s manual: This will give you specific information on the type of lubrication to use, as well as any important maintenance you need to know about the lubrication system. It will also contain technical specifications about settings, tolerances and performance requirements you need to know.

The reports on all work done to the machine: This is a complete history of all work done on the machine. This will tell you how often the system has been serviced and when the filters have been replaced. Other problems related to the lubrication system like;

§  Bearings overheating

§  Leaking seals

§  Couplings changing color

can all indicate problems with the lubrication system. It will also tell you about all the lubricants used in the past and problems experienced with specific lubricants.

The engineering drawings: These detailed drawings show all the parts, their sizes, as well as how they fit together. It will also indicate all the lubrication points on the machine. Find the position of the lubrication system and you will see which parts you must remove to get to the lubrication system.

Additional information on the nameplate (also called a data plate) of a machine: The following information are required for nameplates and will help you choose the correct lubricant. Lubricants are designed to work under specific conditions like pressure, load and temperatures and you need to confirm the details on the nameplate with the information of the manufacturer’s manual, as the manufacturer will specify the lubricant to use on the machine.

Ø  The manufacturers name, model and serial number

Ø  The rated voltage and full load amperage

Ø  The rated electrical frequency

Ø  The phase

Ø  The rated full load speed

Ø  The rated temperature rise or insulation class and ambient temperature

Ø  The duty rating

Ø  The rated horsepower

Ø  The design code letter.

Different types of lubricants:

We will look at oil, grease and a material called self-lubricating thermoplastics.

Oil – The four categories of oil are

Animal oil: - examples- lard, sperm oil and tallow. Animal oils are much better than mineral oils with regard to the pressure they can stand but unfortunately they are expensive and turn to sludge easily.

Vegetable oil: - examples- castor oil, palm oil, olive oil and linseed oil.

Mineral oil: - found under the earth’s service in the form of crude petroleum. It keeps its properties well in air and if it is pure, it do not get sticky or dry up. This properties makes mineral oil an ideal, all-purpose lubricant to use in all systems.

Synthetic oil: - made using a chemical process to change carbon dioxide, carbon monoxide and methane into oil. Synthetic oil is always a better option than conventional oil in the following situations: 

·         In high temperatures, conventional oil becomes thin and tents to leak, while synthetic oil remains at the right grade of viscosity.

·         In low temperatures, conventional oil becomes thick while synthetic oil remains at the right grade of viscosity.

·         For engines and machines that run at high revolutions, synthetic oil causes them to run more quietly at all speeds than conventional oil does.

·         In outdoor conditions, synthetic oil is the better choice because of its stability over a wide temperature range.

A thin, light lubricant like oil is chiefly used in in machines that operate at high speeds and with light loads.

Grease – A common lubricant used on slow-moving machinery parts such as bearings, bushes and hinges. It consist of a combination of a lubricating agent, and additives like graphite and a thickener (made of substance like copper or non-metallic substance like graphite, lithium or Teflon.)

Conventional greases use a petroleum-based product like mineral oil as base.

Synthetic greases use a synthetic lubricant made of plant oils. This ingredients mean that synthetic greases can cope with much wider temperature extremes than conventional greases. Synthetic greases is a better choice than conventional greases in the following applications:

·         In high temperatures, conventional grease soften and leaks, while synthetic grease remains more stable.

·         In low temperatures, conventional grease becomes thick while synthetic grease remains more pliable.

·         For high speeds, synthetic grease is quieter at high speeds than conventional grease.

·         In outdoor conditions, synthetic grease is the better choice because of its stability over a wide temperature range.

Self-lubricating thermoplastics – This is a type of plastic material that has a lubricant already build into it. This has been developed to overcome the problem of oil and grease building up dirt and grit over time which is what a lubricant actually try to prevent. Parts made from thermoplastic are not affected by this problem because they don’t need oil or grease lubricant, they are able to resist friction and, therefore, wear extremely well.

Self-lubricating thermoplastics components are starting to replace metal and ceramics parts because they have the following advantages:

·         The parts can be assembled easily

·         The parts are easy to manufacture

·         The parts are flexible with regard to design

·         The parts are very reliable because they do not deteriorate quickly

·         The parts can operate at very high performance levels at high or low speeds, and with high and low fixed loads.

However, thermoplastic material has the following disadvantages:

·         They are expensive

·         Thermoplastics bushes or bearings cannot carry heavy axial loads.

Identify the filtration components to be used:

The lubrication system will have a filter to prevent dirt from getting into the pumped oil. This filter will be accessible from the outside of the machine for easy replacement and will come with a seal to prevent leakage of lubricant, and damp from entering the system. You will need to identify the component so you can order a replacement part before you remove the used filter. The manufacturers manual will provide you with the information to order the correct part.

Identify the correct tools and equipment for the job:

Once you identified the machine you can draw up a list of tool and equipment that you are going to use. Don’t forget to include the safety equipment you may need. Some of the common tools and equipment you may need for maintenance on a lubrication system may include:

·         A complete set of ring and flat spanners

·         An oil filter wrench

·         A complete set of screwdrivers

·         A complete set of Allan keys

·         Cleaning materials like waste rags

·         A container into which you can drain the used oil.

Prepare the site for maintenance.

Make sure the worksite is safe to work in, taking into account the type of machine you are going to work on. (Heavy, electrical, hydraulic, etc.)

Identify the type of lubricating system.

If the machine has a filter and a sump, then it uses an oil lubrication system. (high speed machine)

If the machine has a grease nipple, then it uses a grease lubrication system. (slow speed machine)

Prepare the work site so that it is safe:

Make sure the work site is clean and there is no water or oil on the floor. Check that all the necessary safety signs are visible and the personal protective gear needed for the job is checked and ready for use.

Select the correct tools and equipment and make sure you know how to operate them safely.

Use the right lubricants and fluids or solvents for each part making sure you wear protective gloves.

Isolate the system:

·         Switch off the machine and install a lock-out device

·         Put up a safety sign to show that you are working on the machine.

·         Isolate the machine you work on mechanically according to the machine type.

Inspect and assess the system.

·         Hold a screwdriver against the machine near the bearings and listen for any strange noises or vibrations

·         Hold a thermometer against the machine to see if the temperature runs to high

·         Check to see if the coupling have changed colour or if the seals are leaking

·         Check through the sight glass if the lubricant changed colour and if so take some oil samples

·          Test the oil to see if it contains any water. Do so by pouring some in a glass container and wait for a while. The water will sink to the bottom.

·         Put a couple of drops of oil on blotting paper. If a star pattern or rings appear, the oil is contaminated or dirty

·         Check for thickness changes and service deposits on the oil

·         Check the filters to see if they are blocked

System faults and possible causes:

Symptom	Possible causes
The machine produces strange noises or vibrations.	Damage parts, for example the bearings or couplings, or loose parts
The temperature of the machine is to high.	Incorrect lubricants
	Lubricants that have broken down chemically
	Dirty lubricants
	Abnormal friction or wear
The coupling change colour to blue or the seals leak.	Problems with the lubrication, causing a coupling to overheat
The colour of the oil has become darker	Oil has overheated
	Dirt and impurities in the oil
	Wrong lubricant has been used
Ongoing foam forms at the top of the oil.	Oil is dirty or contaminated
The oil separates.	The oil is contaminated with water
The oil shows the star burst or rigs during the blotting paper test.	Oil is dirty or contaminated. (clean oil forms a uniform oil colour on the paper)
The viscosity or thickness changes in the oil, and service deposits.	May indicate an oil pressure problem
Filters are blocked.	May indicate the presence of soft contaminants like sludge and organic material

Fix the faults.

Identify parts to be serviced or replaced:

Based on the results of your research you are now ready to draw up a list of parts that need to be replaced and serviced. For instance: you need to replace the seals, the filter and the oil. If the couplings changed colour you need to replace them as well and depending on the condition of the bearings you need to either replace or service them.

Remove, service and replace serviceable and new parts:

You should drain the oil at operating temperature because it will flow more quickly. Replace any seals that are worn or damaged. Look for loose clamps, worn or cracked pipes and leaking seals and replace any damaged parts. Remove the old oil filter. Make sure that you do not burn your hands with too hot oil. Replace the old filter with a new one. Put some oil on the filter seal before you replace it to make sure of a good fit. Fit the drain plug with a new washer and replace the plug. Once the plug is in place you can fill up the reservoir with the right grade and quantity oil through the filler hole.

If the lubrication system has an oil pressure sensor, check the oil pressure when you restart the engine. If the oil pressure is too low, make sure that you used the correct grade and amount of oil. If the type and amount of oil is correct, check the lubrication system or the oil pump system for possible leaks.

Check that system operates correctly.

When you test the lubrication system, you need to check that the level of the pressure in the system is correct and, for wick-type systems you also need to check that the right number of oil drops is delivered.

Check the pressure level in a lubrication system:

Step 1.      Check the manufacturer’s manual to find out the correct pressure at which the lubricating system must operate.

Step 2.      Connect the pressure gauge to the pipes in the lubrication system that you are about to test.

Step 3.      Start the engine and let it run until it reach the right operating temperature, as stated in the manufacturer’s manual.

Step 4.      Take a reading on the pressure gauge that you have connected.

Step 5.      Check the fluctuations in pressure because any fluctuations greater than specified in the manufacturer’s manual mean that the lubrication system is faulty.

Record information on work completed.

After the maintenance work on the lubrication system is finished you must write a report on the work you have carried out. You need to include the following information in your report:

·         The date you serviced the lubrication system

·         The procedure that you followed

·         The type of lubrication system you worked on

·         The different parts that you replaced

·         Your opinion about why these parts failed, for example operator’s negligence

·         The type and amount of fluids and lubricants that you used

·         Any defects relating to the specific machine

·         The results of all the tests you carried out.

Store the information in a safe place.