Layout Planning Models, Algorithms l h and d computerized 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
approch, h 2ndd edition, diti P Prentice ti H ll of Hall f India I di Ltd., Ltd 2002. 2002 3. Dr-Ing. Daniel Kitaw, Industrial Management and Engineering Economy 4-1
Introduction • The generation of layout alternatives is a critical step i the in th facilities f iliti planning l i process, since i th layout the l 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 i process(WIP), in (WIP) tooling, t li and d supplies li Fixed path versus variable path handling The degree of automation used in handling The type of level of inventory control, control physical control, and computer control of materials. 4-3
Layout procedures • A number of different procedures have been developed t aid to id the th facilities f iliti planner l i designing in d i i layouts. l t Construction type Improvement type
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Apples plant layout procedure •
P Procure th basic the b si data d t
•
Determine storage requirements
•
Analyze the basic data
•
•
Design the productive process
Plan service activities
•
Plan the material flow pattern
•
Determine space requirements
•
Consider the h dli plan handling l
•
Allocate activities to total space
•
Consider building type
•
Calculate equipment requirement
•
Construct master layout
•
Plan individual nd v dual workstat workstations ons
•
•
Select specific material handling equipment
Evaluate,, adjust, j , and check the layout with appropriate persons
•
Obtain approvals
•
Coordinate C din t operations
•
Install the layout
•
Follow up on implementation of the layout. 4-5
•
general
groups ps
of f
material
related l t d
Design activity interrelationships
and
auxiliary
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 l storage area requirements • Establish minimum aisle widths • Establish E t bli h office ffi requirement i t • Consider personnel facilities and services • Survey plant services • Provide for future expansion 4-6
Cont’d • Layout planning chart is the most important single phase of the entire layout process, it incorporates the f ll i following: Flow process, including operations, transportation, storage and d inspection i i Standard time for each operation Machine selection and balance Material handling equipment 4-7
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 y relationship p diagram g as a foundation activity.
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SLP cont’d • Based on the input data and an understanding of the roles and relationships l ti hi b t between activities, ti iti a
material flow analysis(from-to-chart ) and an activity relationship analysis(activity relationship chart) are performed.
y performed,, p analysis relationship diagram is developed.
• From
SLP procedure
the
a
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Cont’d • The
relationship
diagram
positions
activities spatially. p y • Proximities are typically used to reflect th the
relationship l ti shi
b t between
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 h l the help th layout l t analyst l t to t develop d l or improve i a layout, l t and it provide objective criteria to facilitate the evaluation of various layout alternatives that emerge i the in th process. ss
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Algorithm classification • Most layout algorithms al orithms can be classified according accordin to 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 m algorithms g m accepts p both relationship p chart and from-to-chart 4 - 14
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 h cost of f moving a unit load l d one distance d unit from department i to j dij = the th distance di t f from d department t t i to t j 4 - 16
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 h adjacent d of f department d i and d j in the h layout l • The adjacency score is helpful in comparing two or more alternative lt ti layouts l t 4 - 17
Cont’d • According to the primary functions layout algorithms can be classified as: Improvement p type: yp start with an initial layout y and seek to improve the objective function through i incremental t l change. h Construction type: develop a layout from scratch 4 - 18
Modeling techniques/methods • The overall modeling techniques and/or methods used in various layout algorithms; Pairwise P i i exchange h method th d A graph based method CRAFT BLOCPLAN MIP LOGIC MULTIPLE 4 - 19
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. 4 - 21
Graph-based method • Consider a company want to develop layout for its new five departments p of equal q sizes. 1
0 9 1
8
2 3
13
4
0 2
8
7
3
20
5
13
10
0 7
20
2
12
10
12
9
2
4
0
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 8
2
10
12
3
13
7
20
4
0
0 2
5
• Departments 3 and 4 are selected to enter the graph. 4 - 23
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
4
Total
1
8
10
18
2
12
13
25(best)
5
0
2
2
2 13
12
3
4 20
D Department t t 2 is i chosen h with ith a value l off 25. 25 4 - 24
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 graph p on a face of the g 2 2
3
4
Total
1 9
8
10
27(Best)
5 7
0
2
9
9
12
13
1 8
3
10 20
4
Department 1 is chosen with a value of 27. 4 - 25
Graph-based method Procedure Step 4: Determine on which face to insert the last department. department 2 1
2
3
4
5 0
7
0
2
Faces
7
12
9
13
Total
1-2-3
7
1-2-4
9(best)
1-3-4
2
2-3-4
9(best)
5 0
1
2
8
10
3
4
20 4 - 26
Graph-based method Procedure Step 5: Construct a corresponding block layout. 13
2 7
9
12 8
3
0
1
2
10 20
5
4 4 - 27
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 facility f cilit is improved impr ved by b switching s itchin two t orr three 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 g given layout) y ) and an 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. 4 - 29
Computerized Relative Allocation of Facility Technique(CRAFT)
• The major features of CRAFT are: o Attempts to minimize transportation cost,
T Transportation i cost=flow*distance*unit fl *di * i cost o CRAFT is a path-oriented method, the final layout is dependent on the initial layout. o Requires q an assumption p that: 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 Fixed F d departments d and d their h l location o Area of departments 4 - 31
Computerized Relative Allocation of Facility Technique(CRAFT)
• The Th procedures d adopted d t d for f using i CRAFT are: 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 Determine t i transportation t t ti costt of f each h departmental d t t l interchange. o Select l and d implement l the h departmental d l interchange h that offers the greatest reduction in transportation cost. cost o Repeat the procedure for the new layout until no int interchange h n is able bl to t reduce d th ttransportation the nsp t ti n cost.
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Computerized Relative Allocation of Facility Technique(CRAFT)
• Major M j disadvantages di d t of f using i CRAFT o Because the basis is the cost of material handling, only l production d d departments are considered. d d No N service departments are considered. o An initial idea of the layout is required. Therefore the technique is only applies to the modification of an n existing xistin layout. l t o The distances between the departments is taken as straight t i ht lines li whereas h i practice in ti movementt is i 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 4 - 35
COmputerized RElationship LAyout Planning (CORELAP) •D Developed l d for f main i frame f computers t • Adjacency‐based method o CORELAP uses A=4, A=4 E=3, E=3 I=2, I=2 O=1, O=1 U=0 and X=‐1 values • Selection of the departments p to enter the layout y is based on Total Closeness Rating. • Total Closeness Rating (TCR) for a department is the sum of f the h numericall values l assigned d to the h closeness l relationships between the department and all other departments departments. 4 - 36
COmputerized RElationship LAyout Planning (CORELAP) Department D t t selection l ti 1. The first department placed in the layout is the one with the greatest TCR value. value If there is a tie, tie then choose the one with more A’s (E’s, etc.). 2. If a department p has an X relationship p with the first one, it is placed last in the layout. If a tie exists, choose the one with the smallest TCR value. 3. The h second d department d is the h one with h an A relationship with the first one (or E, I, etc.). If a tie exists choose the one with the greatest TCR value. exists, value 4 - 37
COmputerized RElationship LAyout Planning (CORELAP) 4 If a department 4. d t t has h an X relationship l ti hi with ith the th second d one, it is placed next‐to‐the‐last or last in the layout. If a tie exists, exists choose the one with the smallest TCR value. 5. The third department p is the one with most A ((E,, I,, 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 4 - 38
COmputerized RElationship LAyout Planning (CORELAP) D Department t t placement l t • Placing rating(PR) is the sum of the weighted closeness ratings between b the h department d to enter the h layout l and its neighbors. •
, where k-{departments already placed}
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COmputerized RElationship LAyout Planning (CORELAP) • Th The placement l t of f departments d t t is i based b d on the th following steps: 1 The 1. h first f d department selected l d is placed l d in the h middle. 2. The placement of a department is determined by evaluating PR for all possible locations around the current nt layout l t in counterclockwise nt l k is order d beginning b innin at the “western edge”. 3 The 3. Th new department d t t is i located l t d based b d on the th 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 n completely c mpl t l randomly r nd ml o The selection procedure is repeated until all the departments are selected 4 - 48
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, met it prints out the layout and the scores • Repeats p the p procedure (m (max 20 layouts y per run)) p • User evaluation 4 - 49
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