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Introducing one man to many machine strategy in Mesfin industrial engineering machine shop.

Chapter one 1.1 Back ground of Mesfin industrial engineering

Mesfin Industrial Engineering's history goes back to 1982. Its foundation was laid during the

armed struggle -waged by the TPLF against the Dictator Dergue Regime of Ethiopia. The

TPLF had established a workshop, which could support its movements in the bushes The

workshop was established with few professionals in electricity, electronics, metal works,

chemistry, etc., who were educated and trained in colleges and universities in the Diaspora

and inside the country. Few high school students who were interested in working in the

workshop were also trained by those professionals to work in the workshop. The workshop

was helping the armed struggle by maintaining electronic apparatus like wireless

communications radios which were important to the army. Broken down generators and

engine were also being maintained at the workshop. All the machines used at the workshop

were either captured from the Dergue army or (few) bought from outside.

In1991 the Dergue Regime was toppled down. EPRDF, a national front in which the TPLF was

the significant arm, came to power in Ethiopia. During this time situations had changed and

TPLF had to change its activities to fit to the situations. The war time had ended, and

everybody had to think of democracy and development in the country. The TPLF had a

significant capital in cash and in kind collected during the 17 years of armed struggle. It had

two choices, at that time, of what to do with the money and other resources.

One choice was to divide the resources to all its members. This choice was not acceptable at

that time, because it meant completely wasting all the resources collected in 17 years for

nothing, distributing it in hundreds of birr in to the pockets of individual members. The second

choice was to donate it to an endowment fund so that it could be invested in different business

entities and contribute to the development endeavor of the country at large and the Tigray

Region in particular. This second choice was accepted. Therefore, based on the accepted

choice MIE was founded in 1993 as one of the EFFORT owned company with a total initial

investment capital of 7 million Ethiopian birr. And its name Mesfin was derived from a former

fighter technician who graduated from a Poly technique College in Ethiopia and was manager

of the workshop in the bushes during the armed struggle and who died on duty.

MIE is the Leading Engineering Company in Ethiopia has got -ISO 9001:2008 Quality

Management System certificate No, FM 512406 from BSI for the following scope: MIE currently is mainly engaged in the manufacture of liquid and dry cargo bodies, trailers, semi-trailers, low beds and in the fabrication of fuel storage tanks and various equipments for the construction and energy sectors such as cement components, and hydropower elements. It is also engaged in electromechanical erection and installation works, and includes erection of machineries.


1.2 Problem statement

In Mesfin industrial engineering machine shop there are around 16 machines, so for each

machine there is at least one operator which means the company is applying one man to

one machine strategy. But one man can operate more than one machine (one man to many

machine strategy) without affecting the quality of the product. Therefore the strategy of the

company has the following main problems.

� Unnecessary cost of labor force. � High idle time of workers.

1.3 Scope of the study

In Mesfin industrial engineering there are many workshops. But the scope of this

study is focused only on the machine shop of the company. In addition to this scope,

since the workers are not familiar to operate more than one machine at a time, so this

study is focused on two or three machines.

1.4 Limitation of the study

� Some limitations of this study are:

� Lack of facility like computer.

� Lack full information.

� Variety of the machine function.


1.5Objective of the study

1.5.1 General objective

� To minimize high idle time of labor force in machine shop.

1.5.2 Specific objective

� To reduce unnecessary labor cost. � To increase labor utilization.


1.6 Research Methodology

1.6.1 Data collection methodology

� In order to do this research both primary and secondary data collection methodology

are used.

1.6.1.1 Primary sources from:-

� Direct observation

� Informal interview with the concerned body

1.6.1.2 Secondary from:-

� Internet

� Reference book

� Literature review

1.6.2 Data analysis tools

� Work study (using multi activity chart)


Chapter two

Literature review

2.1 Optimization

Optimization is Finding an alternative with the most cost effective or highest achievable performance under the given constraints, by maximizing desired factors and minimizing undesired ones. In comparison, maximization means trying to attain the highest or maximum result or outcome without regard to cost or expense. Practice of optimization is restricted by the lack of full information, and the lack of time to evaluate what information is available. In computer simulation (modeling) of business problems, optimization is achieved usually by using linear programming techniques of operations research.

It is also a mathematical discipline that concerns the finding of minima and maxima of functions, subject to so-called constraints. Optimization originated in the 1940s, when George Danzig used mathematical techniques for generating "programs" (training timetables and schedules) for military application. Since then, his "linear programming" techniques and their descendants were applied to a wide variety of problems, from the scheduling of production facilities, to yield management in airlines. Today, optimization comprises a wide variety of techniques from Operations Research, artificial intelligence and computer science, and is used to improve business processes in practically all industries.

Discrete optimization problems arise, when the variables occurring in the optimization function can take only a finite number of discrete values. For example, the staff scheduler of a hospital unit has a finite set of staff members available, and thus staff scheduling consists of taking discrete decisions, one for each slot of the resulting schedule. Discrete optimization aims at taking these decisions such that a given function is maximized (for example revenue) or minimized (for example cost), subject to constraints, which express regulations or rules, such as required numbers of rest days for the staff in a schedule.

Perhaps surprisingly, discrete optimization is more difficult than its "continuous" counterpart, where variables are allowed to take fractional values or even "real numbers". In fact, there is no general solution known for optimization problems that reliably and speedily computes solutions to discrete optimization problems. A variety of computation techniques compete for the best solution. In recent years, it has become clear that different application domains lend themselves to different solution techniques. Linear programming has been applied to discrete optimization using so-called "branch-and-bound" techniques, for example to solve facility location problems. Heuristic search aims at finding good but not necessarily optimal solutions quickly. This technique is successfully used in a wide variety of applications; for example the Lin Kernighan heuristic for the Traveling Salesman problem finds solutions that are extremely close to the optimal solution for very large problem instances. Constraint programming is a solution technique that developed out of programming language research and artificial intelligence. It employs specialized algorithms in the general framework of tree search, and has been successfully applied to production scheduling problems.


Another recent trend is the combination of optimization techniques for problems that do not lend themselves easily to one technique alone. Today, these techniques prove to deliver robust engines that provide very high quality solutions for even very large problem instances. 2.2 Work study Work study is a body of knowledge designed to increase the productivity of an organization. It has an objective of elimination of unnecessary work for the objective of finding better and simpler methods of getting the job done and determining the time required by a qualified and a properly trained person working at normal place to do the specific task or operation. This is divided to time study and method study. 2.2.1 Work measurement (time study)

� Work measurement is the technique of observing and recording the time required to do

each detailed element of an industrial operation. � Work measurement is used to determine the required time by qualified and well trained

person working at a normal place or temperature to do a specific task.

Objective of time measurement is:- � Comparing alternative methods � Assessing the initial manning � Planning and controlling � Realistic costing � Financial incentive schemes � Delivery date of goods � Cost reduction and cost control � Identifying substandard workers

2.2.2 Techniques of time measurement Time can measure in different way such as:-

a. Time study: – recording times and rates of a job and analyzing the data to determine the time for carrying out the job.

b. Synthetic data:- building up the time for a job by totaling element times obtained

previously on other similar jobs or from synthetic data . c. Work sampling:- recording a number of observations made over a period of time of

machines ,processes of workers as activities, or delay at the instant, and considering the percentage of activities/delay time occurrence

d. Predetermined motion time study (pmts):- times established for basic human motions are used to build up the time for a job.

e. Analytical Estimating:- to estimate time partly from knowledge and practical experience of the elements concerned and partly from synthetic data.


2.2.3 Multi activity chart

• It is a chart where activities of more than subject (equipment) are each recorded on a common time scale to show their inter relationship.

• It is made to:

� Study idle time of the man and machines. � Determine number of machines handled by one operator. � Determine number of operators required in teamwork to perform the given task.

Construction of the chart

A multiple activity chart consists of a series of bars hatched for working and for blank for the columns) placed against a common time scale. Each subject is allocated with one bar and the activities related to the subjects are represented in this bar.

Operator machine 0 description T(min) S T(min) S 0.2 Load job 0.20 Idle .28 Switch ‘on; 0.08 .36 min Idle .36 Switch ‘on’ 0.08 Idle 1.86 Idle Machining

of part’ auto cycle’

1.5 1.5 min

1.91 Pick up part 0.05 1.96 Keep in tray 0.05 .4 min

subject Cycle time Time worked per cycle %age of utilization

Operator 1.96 .46 23.4

machine 1.96 1.5 76.6


Chapter three

3.1 Data analysis Table1. Recorded data S No.

Machine name

Function of machine

Size of the part

Speed (rpm)

Time spend by operator (min)

Record 1 Record 2

Average time

1 power hack saw

cutting 100mm - 4 4 4

2 Lathe machine

turning (25-1)mm

228 2.2 &3 respectively

1.4& 3respctively

2 &3 respectively

3 Lath machine

Turning two steps

From 50-30 mm And 50 to 10 mm

355 2 and 3 respectively

2 and 3 respectively


4 Shaper machine

Draw bar pin 20mm 280 4 6 5

5 Shaper machine

Draw bar pin 20mm 300 4.4 5.2 5

6 Drilling machine

Drilling of sheet metal

8 sheet metals

- 1 1 1

7 Hydraulic press machine

Small hinge (bending)

8mm - 1 1 1

8 Lath machine

boring 260mm 2 step

250 7 5.4 6.2

9 Lath machine

Boring 200 2 step

250 6 5 5.3

10 Lath machine

Turning operation


320 1.3 and3 respectively

2. 3 and 3 respectively

2and3 respectively

11 Lath machine

tread manufacturing

_ _ irregular - irregular

12 Lath machine

Tread manufacturing

_ _ irregular - irregular


There for using the average time shown above the following analysis Can be develop.

13 Milling machine

Not functional

- - - - -

14 Milling machine

Gear manufacturing

irregular - irregular

1’ power hack saw

cutting 50mm - 4.2 3.4 4


S No.

Machine name

code Function of machine

Size of the part

Speed (rpm)

Time spend by operator (min)

Time spend by machine(min)

Activities done by operator

1 power hack saw

50013 cutting 100mm - 4 65 Adjusting &loading the machine

2 Lathe machine

50005 turning (25-1)mm

228 2 &3 9 Adjusting &loading the machine

3 Lath machine

50055 Turning two steps


355 2 and 3 respectively


Adjusting &loading the machine

4 Shaper machine

50049 Draw bar pin 20mm 280 5 12 Adjusting &loading the machine.

5 Shaper machine

50036 Draw bar pin 20mm 300 5 12 Adjusting &loading the machine.

6 Drilling machine

50017 Drilling of sheet metal

8 sheet metals

- 1 4 Adjusting &loading the machine.

7 Hydraulic press machine

50009 Small hinge (bending)

8mm - 1 1 Adjusting &loading the machine

8 Lath machine

5006 boring 260mm 2 step

250 6.2 32 Adjusting &loading the machine

9 Lath machine

500012

Boring 200 2 step

250 5.3 20 Adjusting &loading the machine

10 Lath machine

50015 Turning operation


320 2and3 respectively


Adjusting &loading the machine


11 Lath machine

50011 tread manufacturing

_ _ irregular irregular Adjusting &loading the machine

12 Lath machine

50018 Tread manufacturing

_ _ irregular irregular Adjusting &loading the machine

13 Milling machine

50010 Not functional

- - - -

14 Milling machine

50056 Gear manufacturing

irregular irregular Adjusting &loading the machine

� One power hack saw is occurred in material preparation shop with the following data.

S No. Machine

name code Function of

machine Size of the part

speed Time spend by operator (min)

Time spend by machine(min)

Activities done by operator

1’ power hack saw

50024 cutting 50mm - 4 32 Adjusting &loading the machine

The existing rearrangement of the machines is as follows One power hack saw is occurred in material preparation shop but for the other machines it is drawn as shown below. The dimension of the work shop is Length-60 meter Wedith-24meter and the average distance between machines is 3 meter.


� Existing rearrangement of machines in Mesfin industrial engineering machine shop

Entrance

Exit

Store

Machine 8

CNC machine

Machine 1

CNC machine

Machine 9

Machine 10

Machine 11

Machine 12

Welding area

Machine 13

Machine 14

Machine 7

Machine 6

Machine 5

Machine 4

Machine 3

Machine 2

8 m gap


The following diagram shows how many machines can handle by one operator at a time and after how many time is the worker shits from one machine to machine anther machine.

Multi activity chart for two cutting machines (hack saws) Macine1’ is the machine found in material preparation shop Tt (min)

operator Machine 1’

Machine 1

0 description T(min) s T(min) s t s 3.8 Load job 3.8 idle idle 4 switch on .2 idle idle 5 T time 1 9min cutting 1 32 min idle 8.8 Load job 3.8 Cutting 3.8 Idle 9 switch on .2 cutting .2 idle 36 idle 27 cutting 27 cutting 27 36.2 Switch off .2 idle cutting .2 39.2 Unload

job 3 7.2 min idle cutting 3 65

min 43 Load job 3.8 Idle cutting 3.8 43.2 switch on .2 idle cutting .2 74 idle cutting 30.8 cutting 30.8 74.2 Switch off .2 1.4 min cutting .2 32 min finish 75.2 T time 1 cutting 1 idle 75.4 Switch off .2 finish idle From the above chart it is possible to determine the utilization of the operator and the machines as follows. subject Cycle time(min) Time worked

Per cycle

%of utilization

Operator 36 4 11.1 Machine 1’ 36 32 88.9

subject Cycle time(min) Time worked

Per cycle

%of utilization

Operator 69 4 5.7 Machine1 69 65 94.2


After one worker is assigned to operate two machines subject Cycle time(min) Time worked per cycle %of utilization Operator 146.6 17.6 12.1 Machine1’ 146.6 64 43.6 Machine1 146.6 65 44.3

� Multi activity chart for machine 2 &3 Tt in (min)

operator Machine 2(M2)

Machine 3(M3)

0 description T(min) s T(min) s T(min) s 2 Load job

and switch on machine

2 5 min

idle Idle

3 Go to M 3 1 turning 1 Idle 5 Load and

switch on machine

2 turning 2 9 min Idle

11 idle turning 6 turning 6 14 Unloading

then loading

3 3 min Finish 1 round

turning 3

23 idle turning 9 9 min turning 9 22 min 26 Unloading

then loading

3

idle turning 3

24 Go to M3 1 7 min turning 1 turning 1 27 Unloading

then loading

3 turning 3 9min Finished 1 round

32 idle turning 5 turning 5 35 Unloading

then loading

3 idle turning 3 9 min

36 Go to M3 1 9 min idle turning 1 39 Unloading

M3 3 idle finished


subject Cycle time(min) Time worked per cycle %of utilization Operator 26 8 30.7 Machine 2 26 18 69.3

subject Cycle time(min) Time worked per cycle %of utilization Operator 39 8 20.5 Machine3 39 31 79.5

After one worker is assigned to operate two machines subject Cycle time(min) Time worked

Per cycle

%of utilization

Operator 82 24 29.3 Machine 2 82 27 32.9 Machine 3 82 31 37.8

� Multi activity chart for machine 4 &5

Tt (min)


Machine 5(M5)

0 description T(min) s T(min) s T(min) s 4.8 Load a job 4.8 idle idle 5 Switch on .2 11 min idle idle 6 Go to M4 1 operate 1 idle 10.8 Load job 4.8 operate 4.8 12 min idle 11 Switch on .2 operate .2 idle 17 idle operate 6 operate 6 22 Switch off

& load job 5 5 min Finish

(idle) operate 5 12 min

23 idle operate 1 operate 1 23.2 Switch off .2 .2 min operate .2 finished


Per cycle

%of utilization

Operator 17 5 29.4 Machine 4 17 12 70.6


Per cycle

%of utilization



After one worker is assigned to operate two machines subject Cycle time(min) Time worked per cycle %of utilization Operator 40.2 16.2 40.3 Machine 4 40.2 12 29.85 Machine 5 40.2 12 29.85

� Machine 7 (Hydraulic press machine) is used for bending of 8mm thickness of plate

metals. So the machine and the operator time is 1 minute for both. Which means the operator cannot operate more one machine at a time.

� Multi activity chart for machine 6 & 8.

Note be: The operator should start with machine 8 rather than with machine 6

Tt (min)


Machine 6(M6)


& switch on

6 idle idle

7 Go to M6 1 8 min boring 1 idle 8 Load job

& switch on

1 boring 1 idle

12 idle boring 4 drill 4 4 min 13 Switch of

& unloading M6

1 2 min boring 1 idle

14 Loading & switch on M6

1 boring 1 idle


& unloading M6

1 boring 1 32 min idle




& 1 1 min boring 1 idle


unloading M6



30 idle boring 4 drill 4 4min 31 Switch of

& unloading M6

1 1min boring 1 idle

32 idle boring 1 idle 38 Switch of

& unloading M8

6 finish idle

44 Load job & switch on

6 14 min idle idle

45 Go to M6 1 boring 1 idle 46 Load job

& switch on

1 boring 1 idle


& unloading M6



1 boring 1 idle


& unloading M6

1 boring 1 32 min idle




& unloading M6



1 boring 1 idle

68 idle boring 4 drill 4 4min 69 Switch of

& 1 1min boring 1 idle


unloading M6

70 idle boring 1 idle

76 Switch of & unloading M8

6 6 min finish idle

Subject Cycle time(min) Time worked Per

cycle %of utilization


subject Cycle time(min) Time worked per cycle %of utilization Operator 88 24 27.2 Machine 8 88 64 72.8

After one worker is assigned to operate two machines subject Cycle time(min) Time worked per cycle %of utilization Operator 138 42 30.4 Machine 6 138 64 46.3 Machine 8 138 32 23.3

� Multi activity chart for machine 9&10.

Tt (min)


Machine10 (M10)


& switch on

5 idle idle

6 Go to M10 1 8 min boring 1 idle 8 Load job

& switch on

2 boring 2 20 min

idle

25 idle boring 17 turning 17 25.2 Switch off

M9 .2 .2min finish turning .2 20min

28 idle idle turning 2.8 30 Switch off

M10& un load it.

2 2min idle idle


After one worker is assigned to operate two machines subject Cycle time(min) Time worked per cycle %of utilization Operator 50.2 10.2 19.42 Machine 9 50.2 20 38.84 Machine 10 50.2 20 38.84

Subject Cycle time(min) Time worked Per cycle

%of utilization

Operator 25 5 20 Machine9 25 20 80

Subject Cycle time(min) Time worked Per cycle

%of utilization

Operator 22.2 2.2 9.9 Machine10 22.2 20 91.1


3.2 Results of the study

� As the input data indicates machine 11, 12 and 14 cannot operate by one worker because their product (gear and tread) needs more accuracy so the operator is not idle most of his time is spend on operating the machines. Machine 13 is also not functional at this time. There for each machine 11, 12 & 14 needs one worker. But

� Machine 1&1’ can operate with one operator. � Machine 3 & 2 can operate with one operator. � Machine 4 & 5 can operate with one operator. � Machine 6 & 8 can operate with one operator. � Machine 9&10 can operate with one operator

� Existing and To-Be utilization of worker becomes as follows:

Operator of Existing utilization To be utilization Machine 1’&1 11.1&5.5 respectively 12.1 Machine 2&3 30.7&20.5 respectively 29.3 Machine 4&5 29.4&29.4 respectively 40.3 Machine 6&8 33.33&27.2 respectively 30.4 Machine 9&10 20&9.9 respectively 19.42

� Existing and To-Be cost of labor force becomes as follows: .

In Mesfin industrial engineering machine shop there are 16 machines which have at least one operator for each machine. Since there are 3 shift per day 3*16=48 workers As I have gathered information from the company the average monthly payment of one worker is 2700 birr. There for the total monthly cost of labor is 48*2700= 129,600birr (existing cost of labor force) But, according to this study 5 workers per shift can be minimized without affecting the quality of the product. There for 5*3=15 workers can be minimizing. (48-15)*2700birr=89,100 birr (To-be cost of labor force) Then the difference is 129,600-89,100= 40,500 birr per month. This unnecessary cost is only from one machine shop so if the companies apply this strategy to the other shops it can gain additional profit. There for to reduce longest transfer time of labor force, it is better to change the existing rearrangement of the machines as follows.


� Recommended rearrangement of machines in Mesfin industrial engineering machine shop.

Entrance

Exit

Store

Machine 7

Machine 2

Machine 4

Machine 3

Machine 10

Machine 9

Machine 8

CNC machine

CNC machine

Machine 1’

Machine 1

Machine 6

Machine 5

Machine 11

Machine 12

Machine 13

Machine 14

Welding area


Chapter four 4. Conclusion and recommendation 4.1 Conclusion

• In Mesfin industrial engineering there many workshops but this study is focused only on the machine shop of the company. According this study in the machine shop of the company 40,500 birr cost of labor force can be minimize if the company applies this study strategy.

• According this study the utilization of five workers is increased as follows.

Operator of Existing utilization To be utilization Machine 1’&1 11.1&5.5 respectively 12.1 Machine 2&3 30.7&20.5 respectively 29.3 Machine 4&5 29.4&29.4 respectively 40.3 Machine 6&8 33.33&27.2 respectively 30.4 Machine 9&10 20&9.9 respectively 19.42


4.2 Recommendation

� Using this study as reference the company should apply to other workshops of the company.

� When the company tries to do this it should consider on the load of the workers and quality of the product.

� Since this is new strategy to the company, so rather than fairing the worker it is better to shift to other shops.

� Before applying this, the worker should train how to operate the machines that are assigned to operate simultaneously.

� One power hack saw is found in preparation shop so it must be take to machine shop.


References

1. Work study hand out (un published) 2. http://www.scienceofbetter.org accessed on 26 /05 /2012 3. George kanawaty 3rd ed.introduction to work study, Geneva: ILO, 1979 4. Schroder, R.Goperation management 4th edition New Jersey: pearso educationITD, 2007

heat excanger

Documents

years of armed struggle

accepted choice mie

machine strategy

time situations

dergue army

war time

leading engineering

significant capital