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Case Study for Plant Layout :: A modern analysis

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Information about Case Study for Plant Layout :: A modern analysis

Published on January 22, 2009

Author: sarangbhutada

Source: slideshare.net

Description

A studied analysis into a case calling for optimized plant layouts.
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For Slideshare Case: http://books.google.co.in/books?id=Dh19GaFCzrIC&printsec=frontcover&source=gbs_summary_r&cad=0#PPA63,M1

Established in 1949 Core business being manufacturing of rotating machinery Acquired general engineering plant in 1989 New products to be manufactured Mr. Lamba appointed to develop a new layout

Established in 1949

Core business being manufacturing of rotating machinery

Acquired general engineering plant in 1989

New products to be manufactured

Mr. Lamba appointed to develop a new layout

Mr.Lamba found out that 6000 components were required in final products out of which 5000 components were to be fabricated on Indus facilities The approach followed was Gathering reasonably accurate forecast figures Using stratified random sample (4%) for the purpose of evaluation Using Schnieder’s method for developing alternate layout Getting the proposal checked by production department Used data to create routing table, a load matrix and a distance matrix chart

Mr.Lamba found out that 6000 components were required in final products out of which 5000 components were to be fabricated on Indus facilities

The approach followed was

Gathering reasonably accurate forecast figures

Using stratified random sample (4%) for the purpose of evaluation

Using Schnieder’s method for developing alternate layout

Getting the proposal checked by production department

Used data to create routing table, a load matrix and a

distance matrix chart

 

 

Using Table 2 and Table 3, a load distance matrix was developed and Schnieder’s method was applied to it.

Using Table 2 and Table 3, a load distance matrix was developed and

Schnieder’s method was applied to it.

All the primary operation centers (handling maximum load) are placed as close to raw material stores as possible Similarly, the secondary operation departments are placed close to primary operation departments Using this method, the existing layout was transformed into a new layout

All the primary operation centers (handling maximum load) are placed as close to raw material stores as possible

Similarly, the secondary operation departments are placed close to primary operation departments

Using this method, the existing layout was transformed into a new layout

 

 

The plant’s efficiency improved from 43% to 85.4% The moves distance per time period for path reduced from 2803.8 to 1403.09 Material handling efficiency reduced from 1023005 unit-load move feet to 517210 unit-load move feet Cost of material handling came down by 50% The factory plant and production personnel pointed out that the location of the mechanical assembly and assembly erection departments didn’t allow smooth movement of painted products.

The plant’s efficiency improved from 43% to 85.4%

The moves distance per time period for path reduced from 2803.8 to 1403.09

Material handling efficiency reduced from 1023005 unit-load move feet to 517210 unit-load move feet

Cost of material handling came down by 50%

The factory plant and production personnel pointed out

that the location of the mechanical assembly and

assembly erection departments didn’t allow smooth

movement of painted products.

 

Time constraint : Only six weeks for making the decision Information constraint : Lack of information from Product division and Process planning departments Sampling : Stratified data was assumed to be correct

Time constraint : Only six weeks for making the decision

Information constraint : Lack of information from Product division and Process planning departments

Sampling : Stratified data was assumed to be correct

Factors Considered: Load and Cubic space utilization Distance Factors not Considered: Safety factors Working condition for workers   Cost Flexibility  Concern of other departments  Customized orders Optimum usage of floor space

Factors Considered:

Load and Cubic space utilization

Distance

Factors not Considered:

Safety factors

Working condition for workers  

Cost

Flexibility 

Concern of other departments 

Customized orders

Optimum usage of floor space

 

Schnieder’s Method has both pros and cons Pros: Ensures smooth flow of materials through different operations The high preference given to proximity between primary operations and raw materials reduced the to-fro movement Cons: Approach focused at minimizing material handling alone Does not account the costs for shifting from the existing layout

Schnieder’s Method has both pros and cons

Pros:

Ensures smooth flow of materials through different operations

The high preference given to proximity between primary operations and raw materials reduced the to-fro movement

Cons:

Approach focused at minimizing material handling alone

Does not account the costs for shifting from the existing layout

 

Total material handling effort (TMHE) - single most important and frequently used criterion for layout planning We look at an alternate layout that is based on a heuristic method that could reduce the time required to bring out a product Tried to create a “hybrid” layout which looks to introduce a hint of assembly line in a process-based layout Reason: Continuous lines are usually preferred when time is a factor, since they act to reduce the time spent on a particular WIP when compared to process layouts

Total material handling effort (TMHE) - single most important and frequently used criterion for layout planning

We look at an alternate layout that is based on a heuristic method that could reduce the time required to bring out a product

Tried to create a “hybrid” layout which looks to introduce a hint of assembly line in a process-based layout

Reason: Continuous lines are usually preferred when time is a factor, since they act to reduce the time spent on a particular WIP when compared to process layouts

Data regarding sub-divisions of factors (like product mix, market accessibility, etc) is not available, hence ignored Main factory has not been included in calculations Assumed portability of units, in line with Lamba’s approach

Data regarding sub-divisions of factors (like product mix, market accessibility, etc) is not available, hence ignored

Main factory has not been included in calculations

Assumed portability of units, in line with Lamba’s approach

Looked at the most frequent and repetitive sequences of departments in the material flow Arrived at an arrangement that makes the WIP flow between most of them akin to an assembly line, without much back-and-forth between departments

Looked at the most frequent and repetitive sequences of departments in the material flow

Arrived at an arrangement that makes the WIP flow between most of them akin to an assembly line, without much back-and-forth between departments

To -> From ↓ RMS M/c HT Process Shop Project Stores Welding Total RMS 0 7 0 0 0 1 8 M/c 0 0 2 2 3 0 7 HT 0 0 0 7 0 0 7 Process Shop 0 0 0 0 12 0 12 Project Stores 0 0 0 0 0 0 0 Welding 0 0 0 1 0 0 1 Total 0 7 2 10 15 1

Preceding table based on Table 5.1 in given sample data A pattern is seen along the diagonal (in red), that enables us to make an arrangement that is in a continuous chain Important to keep in mind not only the frequencies, but also the loads that are transferred between the departments Keeping this in mind, arrived at an alternate layout that is continuous and yet would not involve carrying heavy loads too far Had to resort to some trial-and-error to get there

Preceding table based on Table 5.1 in given sample data

A pattern is seen along the diagonal (in red), that enables us to make an arrangement that is in a continuous chain

Important to keep in mind not only the frequencies, but also the loads that are transferred between the departments

Keeping this in mind, arrived at an alternate layout that is continuous and yet would not involve carrying heavy loads too far

Had to resort to some trial-and-error to get there

The pseudo “line”

Pro: Objection raised by production personnel about Mechanical Assembly and Assembly Erection departments may be mitigated to a large extent Con: Load-distance efficiency is less (64%) as compared to Lamba’s method (85%)

Pro:

Objection raised by production personnel about Mechanical Assembly and Assembly Erection departments may be mitigated to a large extent

Con:

Load-distance efficiency is less (64%) as compared to Lamba’s method (85%)

Minimization of total space occupied, by area (square footage) If area is considered, problem is analogous to sheet-cutting problem (pieces of different shapes and sizes need to be cut from a single sheet while minimizing the sheet area used)

Minimization of total space occupied, by area (square footage)

If area is considered, problem is analogous to sheet-cutting problem (pieces of different shapes and sizes need to be cut from a single sheet while minimizing the sheet area used)

Qualitative method that considers five key factors: Product (P): What is to be produced? Quantity (Q): How much of each item will be made? Routing (R): How will each item be produced? Supporting services (S): What support will be required for production? Time (T): When will each item be produced?

Qualitative method that considers five key factors:

Product (P): What is to be produced?

Quantity (Q): How much of each item will be made?

Routing (R): How will each item be produced?

Supporting services (S): What support will be required for production?

Time (T): When will each item be produced?

SLP procedures

Some well known computer programs that use algorithms based on heuristic/qualitative data to optimize layouts are ALDEP (Automated Layout Design Program) and CORELAP (Computerized Relationship Layout Planning).

Some well known computer programs that use algorithms based on heuristic/qualitative data to optimize layouts are ALDEP (Automated Layout Design Program) and CORELAP (Computerized Relationship Layout Planning).

Gives a ‘relative importance’ of parameters with each other Based on the premise that not all factors are equally important, while designing a layout Factors can be divided into sub-factors and relative weights can be calculated, however not performed here due to lack of data

Gives a ‘relative importance’ of parameters with each other

Based on the premise that not all factors are equally important, while designing a layout

Factors can be divided into sub-factors and relative weights can be calculated, however not performed here due to lack of data

Step 1: Formation of AHP initial matrix, based on investigator’s judgment Step 2: Calculation of proportionate worth of criteria. This is the result Step 3 : Verify result. Multiply initial matrix by average worth Step 4: Divide final matrix of step 4 by average worth to get l Consistency Index (CI) = (lavg – n) / (n – 1), where n is the order of the matrix. Consistency Ratio (CR) = CI/RI (Random Index) If CR << 0.1, then results can be held valid

Step 1: Formation of AHP initial matrix, based on investigator’s judgment

Step 2: Calculation of proportionate worth of criteria. This is the result

Step 3 : Verify result. Multiply initial matrix by average worth

Step 4: Divide final matrix of step 4 by average worth to get l

Consistency Index (CI) = (lavg – n) / (n – 1), where n is the order of the matrix.

Consistency Ratio (CR) = CI/RI (Random Index)

If CR << 0.1, then results can be held valid

Initial Matrix:   No. of items Volume Distance Weight No. if items 1 0.5 0.5 0.5 Volume 5 1 0.5 0.8 Distance 7 5 1 1 Weight 7 3 1 1

  No. of items Volume Distance Weight Avg Worth No. if items 0.05 0.05 0.15 0.15 0.10 Volume 0.25 0.10 0.15 0.25 0.19 Distance 0.35 0.50 0.35 0.30 0.37 Weight 0.35 0.35 0.35 0.30 0.33

  No. of items Volume Distance Weight Avg Worth No. if items 0.05 0.05 0.15 0.15 0.10   0.1195 Volume 0.25 0.10 0.15 0.25 x 0.19 =   0.1820 Distance 0.35 0.50 0.35 0.30 0.37   0.3585 Weight 0.35 0.35 0.35 0.30 0.33   0.3300

l avg = (2.295+0.95+0.96+1) / 4 = 1.026 Consistency Index (CI) = (lavg – n) / (n – 1), where n is the order of the matrix. CI = (1.026 – 4)/3 = -0.9913 Consistency Ratio CR = CI / RI = -0.9913 / 0.90 = -1.101 Since -1.101 << + 0.10, the results are acceptable. Calculation of l

 

 

Possible Implications Since buildings cannot be altered, no extra construction or demolishing costs involved Size of the buildings is immaterial for location of the departments The process of developing a new layout can still be complicated if we have length and breadth constraints for the blocks TMHE is the only criteria under consideration in the current method while other factors like minimization of moves,etc. can also be considered

Possible Implications

Since buildings cannot be altered, no extra construction or demolishing costs involved

Size of the buildings is immaterial for location of the departments

The process of developing a new layout can still be complicated if we have length and breadth constraints for the blocks

TMHE is the only criteria under consideration in the current method while other factors like minimization of moves,etc. can also be considered

 

‘ Not properly located to allow painted products to move out smoothly’ can signify that movement is obstructed due to space constraint or due to narrow exit entrances The Mechanical and Assembly erection departments which are farther away from the road and aisle can be located much closer Also check if the material handling equipment is proper and allows smooth flow

‘ Not properly located to allow painted products to move out smoothly’ can signify that movement is obstructed due to space constraint or due to narrow exit entrances

The Mechanical and Assembly erection departments which are farther away from the road and aisle can be located much closer

Also check if the material handling equipment is proper and allows smooth flow

 

Assumption No volume restriction, only weight restriction (2000 kg per truck) Trucks are considered as the only material movement equipment Load is considered in tons Main Factory is situated as per layout given below The j th department has N j machines which work simultaneously and take T j time to finish one product Speed of a truck is considered to be constant at “v” feet / minute Dedicated trucks are provided between the nodes and the number of trucks moving between node i and node j are represented by X i The main criteria for deciding the number of trucks is the total cost of acquiring the trucks, which is calculated by multiplying the total number of trucks in to the cost of one truck (K). The total cost is to be minimized

Assumption

No volume restriction, only weight restriction (2000 kg per truck)

Trucks are considered as the only material movement equipment

Load is considered in tons

Main Factory is situated as per layout given below

The j th department has N j machines which work simultaneously and take T j time to finish one product

Speed of a truck is considered to be constant at “v” feet / minute

Dedicated trucks are provided between the nodes and the number of trucks moving between node i and node j are represented by X i

The main criteria for deciding the number of trucks is the total cost of acquiring the trucks, which is calculated by multiplying the total number of trucks in to the cost of one truck (K). The total cost is to be minimized

Machine Assembly Machine Shop Welding Shop Process Shop Project Store Assembly Errection HT Plant RMS Blade Plastic Main Factory

Fig 2 Load – Hop Distance Map

Objective Function: Minimize Z = (X 12 +X 13 +X 14 +X 15 +X 16 +X 17 +X 24 +X 26 +X 27 +X 29 +X 32 +X 36 +X 37 +X 39 +X 46 +X 47 +X 49 +X 48 +X 52 +X 59 +X 63 +X 67 +X 78 +X 79 +X 73 +X 76 +X 98 +X 9,10 +X 10,8 ) * K, it should be minimized   K = Cost of a power vehicle Constraints   Number of vehicles running from i th node to j th node >= (( Time of round trip from i th node to j th node / Time of operation of machine at j th node ) * number of machines at j th node)   Example:  X 12 >= ((4d/v)/T 2 )*N 2   Where X 12 = Number of vehicles running from 1 st node to 2nd node d = 1 hop distance v = speed of power trucks T 2 = Time of operation of a machine at 2 nd node N 2 = Number of machines at 2 nd node

NOTE: Also we need to consider the recurring cost of truck operations over a long period of time. X 12 trucks are moving in between node 1 and 2 which will cost us P= X 12 *K for acquiring the trucks. Now for example say cost of moving a truck for 1 hop costs C. So total cost for X 12 trucks will be (2*(73/X 12 )*C). So if we consider M period as the life time of the truck, then total recurring cost for X 12 will be R= (2*(73/X 12 )*C)*M. So after M period   R <= P

Thank you! Questions at [email_address] please

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