Method Study For Process Flow Of Cement Packing

Method study for process flow of cement packing and dispatch

Done in Chettinad Cements Corporation Ltd By, K.Ramesh Kumar (06M640)

About the industry Ø T h e C H E TT IN A D C E M E N T C O R P O R A T IO N LT D ( C C C L ) e sta b lish e d in 1 9 6 2 is lo ca te d a t a d ista n ce o f 2 5 km fro m ka ru r. Ø T h e p la n t p ro d u ctio n ca p a city – 2 0 0 0 to n s p e r d a y. Products Ø Chettinad Royal Grade – 53 Ø Chettinad Grade – 43 Ø Chettinad Super Grade – 53 Ø Sulphate Resistant Portland cement Ø Chettinad Super Steel cement

Ø

Outline of the manufacturing process

Outline of the manufacturing process

Packing and dispatch unit

Roto packer

Method study Ø Method Study is the systematic recording and critical examination of existing and proposed ways of doing work as a means of developing and applying easier and more effective methods and reducing cost. Ø Method study is mainly concerned with finding better ways of doing work. • •

Objectives of method study Ø To improve work methods and procedure. Ø Develop the best sequence of doing work to have smooth flow of work with minimum back tracking. Ø Improve plant utilisation and material utilisation Ø Elimination of waste and unproductive operations. Ø Reduce the total manufacturing cost and the total cycle time.

Steps involved in method study SELECT: the job to be analyzed. RECORD: all relevant facts about present method. EXAMINE: the recorded facts critically. DEVELOP: the most efficient and economic method. DEFINE: the new method. INSTALL: the defined method. MAINTAIN: the newly installed method.

Selection of job The process selected for the method study analysis was the cement packing and dispatch in packer unit 1 of Chettinad Cements Corporation Ltd. The reasons for selecting the job are: Ø The packing unit was not part of the plants central control unit, so any changes done had no effect on the operation of the plant. Ø The packing unit was the major contributor to the high inventory carrying cost of the plant. Ø The layout of the unit lacked smooth work flow. Ø There was frequent complaints from the worker regarding the tiring work.

Recording the flow of work The selected job is recorded using flow process chart using the following symbols: OPERATION

INSPECTION

TRANSPORTATION

DELAY STORAGE

Flow process chart (Material type)

Time chart for material flow Symbol

Frequency

Time

3

60min per truck

8

15min

2

12min

26min 2

1

2min

Flow process chart (Man type)

Time chart for worker Symbol

Frequency

Time

8

25 min

7

12 min

Critical Examination The inference taken from both charts : Ø The delay time in the form of temporary cement storage was found to be high. Ø The time consumed in worker movement were non productive. Ø Idle time of machine was high. Ø Lot of stress on worker due to repetitive movements.

Critical Examination By careful examination it was found that the manual opening and closing of the diverting head was the main cause for machine idle time, delay in process and high worker movement. Suggestions: Instead of having a manually operated diverting head, automate the system by developing a pneumatic mechanism for opening and closing of the diverting head and coupling it with the main operation of the packing unit.

Development of a new method The process flow was altered by redesigning the diverting head assembly. The elements of change in the new design are: Ø   The material of the diverting head was selected as structural steel ASTM- A36. Ø The opening and closing of the diverting head was done using a pneumatic cylinder. Ø A new electromagnetic locking design was made

Development of a new method Existing Design

Development of a new method New design

The new process sequence Ø The electromagnet near the closing side gets deenergized, the diverting head gets unlocked. Ø As soon as the lock is released the pneumatic cylinder gets actuated and plunges the diverting head. Ø The diverting head is opened . Ø The electromagnet on the other side (i.e opening side) gets energized thereby it attracts the armature present in the diverting head and hence locking it. Ø Once the electromagnet in the opening side gets deenergized, the lock is released. Ø The pneumatic cylinder gets actuated and plunges the diverting head. Ø The diverting head is closed. Ø The closing side electromagnet gets energized and hence locks the diverting head. •

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Magnetic lock Ø A magnetic lock is a simple locking device that consists of an electromagnet attached to the side frame and an armature to the diverting head. Ø The current passing through the electromagnet attracts the armature plate holding the diverting head shut. •The reasons for choosing an electromagnetic lock is: 1. Easy to install 2. Quick operation 3. Ability to withstand high loads.

Selection of material The material selected was structural steel ASTM- A36 with yield strength of 250MPA and ultimate strength of 400MPA. •The material was chosen due to the following reasons: Ø Good strength against impact loads. Ø The endurance limit to ultimate strength ratio is high(0.5) so better resistance to fatigue failure. Ø •

Finite Element Analysis(FEA) Ø Transient structural analysis is done using Ansys to find the maximum stress developed. Ø The structure subjected to a dynamic load of 490.5N for 1000 cycles. Ø The element type is selected as solid45. Ø The material properties for structural steel ASTM- A36 is given as young's modulas = 200 GPA and Poisson ratio = 0.32. Ø Tetrahedral volume mesh with 5 nodes per element is generated.

Finite Element Analysis(FEA) •

After meshing and applying loads •

Finite Element Analysis(FEA) •

Nodal solution for displacement •

Finite Element Analysis(FEA) •

Nodal solution for stress •

Finite Element Analysis(FEA) •

•

From the finite element analysis Ø The maximum stress is found to be 31.4MPA and it is said to be below the yield strength of material (250 MPA). Ø So the material will not undergo permanent deformation when subjected to dynamic loading thereby justifying its selection.

Design of pneumatic system Ø A pneumatic system is developed for the automatic opening and closing of the diverting head. • • • • • •

A - Compressor B - Check valve •C – Accumulator D - Directional control valve •E – Actuator(cylinder) •

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Design of pneumatic system •

Calculation of system parameters   Theoretical force applied by the pneumatic piston (Ft) 

The actual force required (Fr)

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Load Ratio Acceleration force (Fa)

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Design of pneumatic system Ft = π * D2/4 * P (for forward stroke)  Ft = π * (D2 – d2)/4 * P (for return stroke)  Fr = weight of the diverting head (w)  Load ratio = (Fr / Ft) * 100 % •In practical load ratio must be 85% or lower.  Acceleration Force (Fa) = (Ft) – (Fr) 

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Design of pneumatic system Given: volume of diverting head = 9.75 *10^-3 m3  Density of material of steel = 7800 kg/m3  Weight of material = 746N  Assuming pneumatic pressure of 5bar and load ratio of 80%. •Load ratio = (Fr / Ft) * 100 % •0.8 = (746/Ft); Ft = 933N •Diameter of piston  Ft = π * D2/4 * P  933 = π * D2/4*5*10^5 ; D = 50 mm  Acceleration Force (Fa) = (Ft) – (Fr)  Fa = 933 – 746 = 187 N. 

•

The pneumatic system is designed by using a pneumatic cylinder with piston diameter of 50 mm.

Time chart for material flow after re-design:

Symbol

Frequency

Time

3

60min per truck

0min

8

15min

0 min

2

12min

0 min

5min

21 min

2min

0 min

Time reduced

2 1

Time chart for worker after redesign: 

Symbol

Time reduced

Frequency

Time

8

20 min

5 min

7

3 min

9 min

        

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From both charts Delay time reduced by 80% Operation time of worker reduced by 20%, Transportation time of worker reduced by 75%.

Conclusion 

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The project has successfully presented a method study for the process flow of cement packing and dispatch. For doing the method study packing unit 1 was chosen and all facts related to it were recorded using a flow process chart both material type and man type. The recorded data were critically examined and suggestions were made to re-design the diverting head assembly. After the re-design it was found that the delay time in material flow reduced from 26 minutes to 5 minutes. In the worker chart the time of operation of the worker reduced from 25 minutes to 20 minutes and time of movement of the worker reduced from 12 minutes to 3 minutes.

ACKNOWLEDGMENT Ø I would like to express my sincere thanks to Mr. S. Ponnusamy, Personnel Manager and Mr V. Annadurai Chief General Manager Chettinad Cement Corporation Ltd, for granting me the permission to do my project. Ø I also would like to express my gratitude to Mr. Natrajan, General Manager of Instrumentation CCL, for guiding me throughout the project. Ø My sincere thanks to my project guides Mr. Giri chief engineer, and Mr Mathi Arasan assistant engineer. 

REFERENCES Ø Mayal W H, “Industrial Design for Engineers” Ø Gavriel Salvendy, “Handbook of industrial engineering: technology and operations” Ø www.wikipedia.com Ø Roto packer manual by Haver and Boecker Ø www.chettinad.com Ø www.team116.org Ø Punmia and Jain A K, “Strength of Materials and Theory of Structures” 