Layout Planning Models, Algorithms and computerized l h d d Layout Planning
References
1. Tompikins et al., Facility Planning, 3rd edition, John Wiley & Sons Ltd., Singapore,2003. i 2003 2. Richard L.Francis et al., Facility Layout and Location: an analytical d diti approch, 2nd edition, P ti H ll of I di Ltd 2002 h Prentice Hall f India Ltd., 2002.

3. Dr-Ing. Daniel Kitaw, Industrial Management and Engineering Economy
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Introduction
• The generation of layout alternatives is a critical step in the facilities planning process, since th l i th f iliti l i i the layout t selected will serve to establish the physical relationships between activities.

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CONT’D
• Which comes first, the material handling system or the facility layout?  Centralized versus decentralized storage of work in i process(WIP), t li (WIP) tooling, and supplies d li  Fixed path versus variable path handling  The degree of automation used in handling  The type of level of inventory control physical control, control, and computer control of materials.
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Layout procedures
• A number of different procedures have been developed to id the facilities l t aid th f iliti planner i d i i l in designing layouts. t  Construction type  Improvement type

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Apples plant layout procedure
• • • • • • • • • • Procure th b si d t P the basic data Analyze the basic data Design the productive process Plan the material flow pattern Consider the handling l h dli plan general material • • • • • • • • • • Determine storage requirements Plan service activities and auxiliary

Determine space requirements Allocate activities to total space Consider building type Construct master layout Evaluate, adjust, and check the , j , layout with appropriate persons Obtain approvals Install the layout Follow up on implementation of the layout. 4-5

Calculate equipment requirement Plan individual workstations nd v dual workstat ons Select specific material handling equipment Coordinate C din t operations groups ps of f related l t d

Design activity interrelationships

Reeds plant layout procedure
• Analyze the product or products to be produced • Determine the process required to manufacture the product • Prepare layout planning charts • Determine workstations • Analyze storage area requirements l • Establish minimum aisle widths • E t bli h office requirement Establish ffi i t • Consider personnel facilities and services • Survey plant services • Provide for future expansion
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Cont’d
• Layout planning chart is the most important single phase of the entire layout process, it incorporates the following: f ll i  Flow process, including operations, transportation, storage and i d inspection i  Standard time for each operation  Machine selection and balance  Material handling equipment
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Cont’d

Layout planning chart

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Systematic Layout Planning(SLP) procedure
• Systematic Layout Planning (SLP) methodology was developed by Richard Muther Muther. • The framework is uses activity relationship diagram as y p g a foundation activity.

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SLP cont’d
• Based on the input data and an understanding of the roles and relationships b t l ti hi between activities, a ti iti

material flow analysis(from-to-chart ) and an activity relationship analysis(activity relationship chart) are performed. y p , analysis performed, relationship diagram is developed. the a

• From

SLP procedure

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Cont’d
• The relationship diagram positions activities spatially. p y • Proximities are typically used to reflect the th relationship l ti shi between b t pairs i s of f activities.

Activity relationship chart

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Cont’d

Relationship diagram

Space relationship diagram

Alternative block layouts

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Algorithmic approaches
• Algorithmic approach is a formal procedure that can help the layout analyst t d h l th l t l t to develop or i l improve a l layout, t and it provide objective criteria to facilitate the evaluation of various layout alternatives that emerge in the i th process. ss

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Algorithm classification
• Most layout al orithms can be classified accordin to algorithms according the type of input data they requires.  Qualitative flow data(such as relationship chart)  Quantitative flow data(such as flow matrix

expressed as a from to chart) from-to-chart)  Some algorithms accepts both relationship chart m g m p p and from-to-chart
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Cont’d
• Layout algorithms can also be classified according to their objective functions.  Minimizing the sum of flows times distances  Maximizing an adjacency score

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Cont’d
• Distance based objective

m = the number of departments fij = the flow from department i to department j(unit load/unit time) cij = the cost of moving a unit l d one d h f load distance unit from department i to j dij = th di t the distance f from d department i t j t t to
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Cont’d
• Adjacency based objective

m = the number of departments fij = the flow from department i to department j(unit load/unit time) xij = the adjacent of d h d f department i and j in the l d h layout • The adjacency score is helpful in comparing two or more alternative l lt ti layouts t
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Cont’d
• According to the primary functions layout algorithms can be classified as:  Improvement type: start with an initial layout and p yp y seek to improve the objective function through incremental change. i t l h  Construction type: develop a layout from scratch
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Modeling techniques/methods • The overall modeling techniques and/or methods used in various layout algorithms;
 P i i exchange method Pairwise h th d  A graph based method  CRAFT  BLOCPLAN  MIP  LOGIC  MULTIPLE
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Graph-based method • The graph-based method is a constructiontype layout algorithm algorithm. objective. • Uses the adjacency based objective

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Graph-based method-Considerations
• The adjacency score does not account for distance distance, nor does it account for relationships other than those between adjacent departments. • Dimensional specifications of departments are not considered; the length of common boundaries between adjacent department are also not considered. • The arcs do not intersect; this property of graphs is called planarity. • The score is very sensitive to the assignment of numerical weights in the relationship chart.
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Graph-based method • Consider a company want to develop layout for its new five departments of equal sizes. p q
1

0 9 8
12 10 13 20

2 3

1

9 12

2

7 13
5

8 0
3

10 20
4

7

2 0

4

0 2

5

Relationship chart

Relationship diagram

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Graph-based method Procedure
Step 1: from the relationship chart select a department pair with the largest weight weight.
1

9 2
12

8
10 13 20

3
4

0
7

0 2

5

• Departments 3 and 4 are selected to enter the graph.
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Graph-based method Procedure
Step 2: Select the third department to enter, the third department is selected based on the sum of the weights with respect to departments 3 and 4.
3 1 2 5 8 12 0 4 10 13 2 Total 18 25(best) 2
3
20 12

2
13

4

Department 2 i chosen with a value of 25 D t t is h ith l f 25.
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Graph-based method Procedure
Step 3: Pick the fourth department to enter by evaluating the value of adding one of the unassigned departments represented by a node g p on a face of the graph 2
2 1 9 5 7 3 8 0 4 10 2 Total 27(Best) 9
8 12 9 13

1
10 20

3

4

Department 1 is chosen with a value of 27.
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Graph-based method Procedure
Step 4: Determine on which face to insert the last department. department 2
1 5 0
Faces 1-2-3 1-2-4 1-3-4 2-3-4

2 7

3 0
Total 7 9(best) 2 9(best)

4 2
12 7 9 13

5
0

1
8

2 10 20
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3

4

Graph-based method Procedure
Step 5: Construct a corresponding block layout.
13

2
12 8 9 7

1
10

0 2

5

3
20

4
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Computerized Relative Allocation of Facility Technique(CRAFT)

• Introduced in 1963 by Armour, Buffa, and Vollman. • CRAFT is a tool used to help improve the existing layout of the facilities. • The f cilit is impr ved b s itchin t facility improved by switching two or three r departments to help arrange the facility in an optimal floor plan plan.

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Computerized Relative Allocation of Facility Technique(CRAFT)

• This procedure requires the following inputs: o From-To Chart, o Cost Matrix, o Distances (determined for a given layout) and an ( g y ) Initial layout. • Craft is used when the number of departments is so large that the computation by hand would be very intensive and make the improvement not worth the time for many companies.
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Computerized Relative Allocation of Facility Technique(CRAFT)

• The major features of CRAFT are: o Attempts to minimize transportation cost,

Transportation cost=flow*distance*unit cost T i fl *di * i o CRAFT is a path-oriented method, the final layout is dependent on the initial layout. o Requires an assumption that: q p i. Move costs are independent of the equipment utilization and

ii. Move costs are linearly related to the length of 4 - 30 the move

Computerized Relative Allocation of Facility Technique(CRAFT)

• CRAFT requirements: i t o Initial layout o Flow data o Cost per unit distance o Total number of departments o F dd Fixed departments and their l d h location o Area of departments
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Computerized Relative Allocation of Facility Technique(CRAFT)

• Th procedures adopted f using CRAFT are: The d d t d for i o Determine department centroids. o Calculate rectilinear distance between centroids. o Calculate transportation cost for the layout layout. o Consider department exchanges of either equal area departments or of departments sharing a common boarder.

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Computerized Relative Allocation of Facility Technique(CRAFT)

o D t Determine t i transportation cost of each d t ti t f h departmental t t l interchange. o Select and implement the d l d l h departmental interchange l h that offers the greatest reduction in transportation cost. cost o Repeat the procedure for the new layout until no interchange is able t reduce th t nsp t ti n int h n bl to d the transportation cost.

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Computerized Relative Allocation of Facility Technique(CRAFT)

• M j di d Major disadvantages of using CRAFT t f i o Because the basis is the cost of material handling, only production d l d departments are considered. N d d No service departments are considered. o An initial idea of the layout is required. Therefore the technique is only applies to the modification of an existing l n xistin layout. t o The distances between the departments is taken as straight li t i ht lines whereas i practice movement i h in ti t is usually rectangular along ortagonal lines.

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Computerized Relative Allocation of Facility Technique(CRAFT)

Example: consider the following layout problem with unit cost matrix. Use Craft algorithm to obtain layout. The initial layout and the flow matrix is shown below

Initial layout

Flow matrix
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COmputerized RElationship LAyout Planning (CORELAP) •D Developed f main f l d for i frame computers t • Adjacency‐based method o CORELAP uses A=4 E=3 I=2 O=1 U=0 and X=‐1 A=4, E=3, I=2, O=1, values • Selection of the departments to enter the layout is p y based on Total Closeness Rating. • Total Closeness Rating (TCR) for a department is the sum of the numerical values assigned to the closeness f h l l d h l relationships between the department and all other departments. departments
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COmputerized RElationship LAyout Planning (CORELAP) Department selection D t t l ti 1. The first department placed in the layout is the one with the greatest TCR value If there is a tie then value. tie, choose the one with more A’s (E’s, etc.). 2. If a department has an X relationship with the first p p one, it is placed last in the layout. If a tie exists, choose the one with the smallest TCR value. 3. The second d h d department is the one with an A h h relationship with the first one (or E, I, etc.). If a tie exists, exists choose the one with the greatest TCR value value.
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COmputerized RElationship LAyout Planning (CORELAP) 4. 4 If a d department h an X relationship with th second t t has l ti hi ith the d one, it is placed next‐to‐the‐last or last in the layout. If a tie exists choose the one with the smallest TCR exists, value. 5. The third department is the one with most A (E, I, p ( , , etc.) relationships with the already placed departments. If a tie exists, choose the one with the greatest TCR value. l 6. The procedure continues until all departments have been placed placed.
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COmputerized RElationship LAyout Planning (CORELAP) Department placement D t t l t • Placing rating(PR) is the sum of the weighted closeness ratings b between the d h department to enter the l h layout and its neighbors. • , where k-{departments already placed}

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COmputerized RElationship LAyout Planning (CORELAP) • Th placement of d The l t f departments i b t t is based on th d the following steps: 1. h first d 1 The f department selected is placed in the l d l d h middle. 2. The placement of a department is determined by evaluating PR for all possible locations around the current l nt layout in counterclockwise order b innin t nt l k is d beginning at the “western edge”. 3. The 3 Th new d department i l t t is located b t d based on th d the greatest PR value.

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Example

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ALDEP ‐ Procedure • Department selection o Randomly selects the first department o Out of those departments which have “A” A relationship with the first one (or “E”, “I”, etc. – min level of importance is determined by the user) it selects randomly the second department. o If no such department exists it selects the second one c mpl t l r nd ml n completely randomly o The selection procedure is repeated until all the departments are selected
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Department placement • Starts from upper left corner and extends it downward • Vertical sweep pattern • Sweep width is determined by the user Adjacency‐based evaluation • If minimum requirements met it prints out the layout met, and the scores • Repeats the procedure (max 20 layouts per run) p p (m y p ) • User evaluation
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