Facility Design-Week 9 Computerized Layout Planning By Anastasia L. Maukar Created by Lorna StJohn For Operations Management 345 Professor Tom Foster Wednesday, May 08, 2002

Computerized Layout Planning Focus on how computers can aid the facility layout process. Designer must interact with multiple design databases and provide the integration between them to translate information and ensure consistency.

Computerized Layout Planning Concentrate on decision aids for block layout planning. Information required Common elements “Classical” layout programs Craft, Corelap, Aldep, and Planet “Newer” layout programs M-Craft, LayOpt, FactoryPlan

Computerized Layout Planning Information in layout planning Numeric information Space required for an activity Total flow between two activities Logic information Preferences of the designer, i.e., activity relationship chart Graphical information Drawing of the block plan Numeric and logic information is relatively easy to manipulate. The largest difficulty is obtaining the logic information in the first place. The graphical information poses the largest challenge.

Computerized Layout Planning Key element of computerized layout planning is the representation and manipulation of these three types of information. Graphical representation is most challenging. A method suitable for display is not suitable for manipulation and vice-versa. Numeric and logic information is relatively easy to manipulate. The largest difficulty is obtaining the logic information in the first place. The graphical information poses the largest challenge.

Computerized Layout Tech’ Computerized Layout Technique A Layout Construction Procedure: ALDEP, CORELAP A Layout Improvement Procedure, CRAFT Distance Between Two Departments Total Distance Traveled Savings and a Sample Computation Improvement Procedure Exact Centroids

Computerized Layout Technique Suppose that we are given some space for some departments. How shall we arrange the departments within the given space? We shall assume that the given space is rectangular shaped and every department is either rectangular shaped or composed of rectangular pieces. We shall discuss a layout improvement procedure, CRAFT, that attempts to find a better layout by pair-wise interchanges when a layout is given and a layout construction procedure, ALDEP/CORELAP, that constructs a layout when there is no layout given.

ALDEP Automated Layout Design Program ALDEP is a construction procedure. ALDEP does not need any initial layout. ALDEP constructs a layout when there is none. Given Size of the facility The departments Size of the departments Proximity relationships (activity relationship chart) and A sweep width (defined later)

ALDEP Use: vertical scanning pattern 2 disadvantages: scoring method and the fixed values assigned to the closeness ratings. The size of the facility and the size of the departments are expressed in terms of blocks. Score is determined using the numerical values assigned to the closeness rating). A = 43 = 64 I = 41 = 4 U = 0 E = 42 = 16 O = 40 = 1 X = –45 = –1.024

ALDEP Production area Office rooms Storage Dock area Locker room Tool room A O U E X I A: absolutely necessary E: especially important I: important O: ordinarily important U: unimportant X: undesirable Figure 1. ARC

ALDEP The procedure will be explained with an example. Suppose that the facility is 8 blocks (horizontal)  6 block (vertical). The departments and the required number of blocks are: Production area (P) 14 blocks Office rooms (O) 10 Storage area (S) 8 Dock area (D) 8 Locker room (L) 4 Tool room (T) 4

ALDEP The proximity relationships are shown as figure 1. ALDEP starts to allocate the departments from the upper left corner of the facility. The first department is chosen at random. By starting with a different department, ALDEP can find a different layout for the same problem.

ALDEP Let’s start with dock rooms (D). On the upper left corner 8 blocks must be allocated for the dock area. The sweep width defines the width in number of blocks. Let sweep width = 2. Then, dock area will be allocated 2  4 = 8 blocks.

ALDEP To find the next department to allocate, find the department that has the highest proximity rating with the dock area (D). Storage area (S) has the highest proximity rating A with the dock area. So, the storage area will be allocated next. The storage area also needs 8 blocks.

ALDEP There are only 2 2 = 4 blocks, remaining below dock area (D). After allocating 4 blocks, the down wall is hit after which further allocation will be made on the adjacent 2 (=sweep width) columns and moving upwards.

ALDEP See carefully that the allocation started from the upper left corner and started to move downward with an width of 2 (=sweep width) blocks. After the down wall is hit, the allocation continues on the adjacent 2 (=sweep width) columns on the right side and starts moving up. This zig-zag pattern will continue. Next time, when the top wall will be hit, the allocation will continue on the adjacent 2 (=sweep width) columns on the right side and starts moving down.

ALDEP To find the next department to allocate, find the department that has the highest proximity rating with storage area. Production area (P) has the highest proximity rating A with the storage area. The production area (P) needs 14 blocks. After allocating 8 blocks, the top wall is hit and the remaining 6 blocks are allocated on the adjacent 2 (=sweep width) columns moving downward.

ALDEP To find the next department to allocate, find the department that has the highest proximity rating with production area.Tool room (T) has the highest proximity rating A with the production area. The tool room needs 4 blocks. Next, there is a tie, both locker room (L) and office room (O) has the same proximity rating of U with the tool room. Ties are broken at random. So, any of the locker room or the office room can be allocated next.

ALDEP Let’s choose locker room (L) room at random. Then, the last department must be office room (O). The resulting layout is shown below. Note that since the ALDEP chooses the first department at random and since the ties are broken at random, ALDEP can give many solutions to the same problem. Using the layout, the adjacency relationships and the proximity ratings, we can find an overall rating of each layout. Then, the layout with the highest overall rating is selected.

ALDEP After a layout is obtained, a score for the layout is computed with the following conversion of proximity relationships: A = 43 = 64, E = 42 = 16 I = 41 = 4, O = 40 = 1 U = 0, X = -45 = -1024 If two departments are adjacent in the layout then the weight corresponding to the rating between the two departments is added to the score.

ALDEP Let’s compute the overall rating of the layout constructed. Make a list every pair of adjacent departments. For each pair, a letter rating will be obtained from the activity relationship chart (see figure 1) Convert the score into a numeric score using the conversion scheme on the previous slide.

ALDEP Adjacent departments: (D,S) (D,P) (S,P) (S,T) (S,L) (P,T) (P,O) (T,L) (T,O) (L,O)

ALDEP Adjacents Dept Proximity Ratings Value Score (D,S) A 64 128 (D,P) I 4 8 (S,P) (S,T) O 1 2 (S,L) U (P,T) (P,O) (T,L) (T,O) (L,O) X -1024 -2048 -763 -1526

ALDEP The process is repeated several times and the layout with the highest score is chosen. Notice the large negative weight associated with X ratings. If the departments which cannot be next to each other, are adjacent in a layout, then the layout score reduces significantly. This is important because ALDEP also uses a cut-off score (if not specified by the user this cut-off is zero) to eliminate any layout which has a layout score less than the cut-off score.

CORELAP Uses Relationship Chart as input (REL) Requires users to assign weights to the alphabetic ratings in the REL chart . (Closeness Ratings) Computes the total closeness ratings (TCR) for each department by summing all the CR associated with that department. Values selected for ratings are important

CORELAP Importance of Closeness Value A E I O U X Closeness Line code Numerical weights Absolutely necessary Especially important Important Ordinary closeness OK Unimportant Undesirable 32 26 8 4 2 -32

CORELAP - STEPS Selection Procedure Placement and Evaluation Procedure

CORELAP – STEP 1 First department: Where: Second department: X-relation  “last placed department” A-relation with first. If none E-relation with first, etcetera

CORELAP – Tie Breaker Rules Highest TCR Largest Area Lowest Dept. Number (random)

CORELAP – STEP 2 Department areas are converted into grid squares. CORELAP does not take the building shape into account. The final shape of the facility created by CORELAP depends on the placement of departments it has selected.

CORELAP – STEP 2 Place the first department in the center of the layout Subsequent department is placed abutting already placed departments in the position that gives the best placement rating After the layout is completed CORELAP calculates a numerical score for the layout

CORELAP – STEP 2 1st 8 1 2 3 7 6 5 4 2nd

Example of Dept Placements Contoh: Dept. 1, 2, 3 sudah diletakkan di layout dan dept. 4 akan diletakkan. Weighted Rating: (assigned by the user) A = 600 E = 200 I = 50 O = 10 U = 0 X = –200 2 4 1 3 (b) 650 2 4 1 3 (a) 800 2 4 1 3 (c) 850 1 - 4: A 2 – 4: E 3 – 4: I

Procedure to Place Departments Assume that a department is placed in the middle (position 0). Then, if another department is placed in position 1, 3, 5 or 7, it is “fully adjacent” with the first one. It is placed in position 2, 4, 6 or 8, it is “partially adjacent”. 8 7 6 5 4 3 2 1 8 7 6 1 Pusat 5 2 3 4

Procedure to Place Departments For each position, Weighted Placement (WP) is the sum of the numerical values for all pairs of adjacent departments. The placement of departments is based on the following steps: 1. The first department selected is placed in the middle. 2. The placement of a department is determined by evaluating all possible locations around the current layout in counterclockwise order beginning at the “western edge”. 3. The new department is located based on the greatest WP value. 8 7 6 5 4 3 2 1

Example - CORELAP 1. Receiving 2. Shipping 3. Raw Materials Storage CV values: V(A) = 125 V(E) = 25 V(I) = 5 V(O) = 1 V(U) = 0 V(X) = -125 Partial adjacency:  = 0.5 1. Receiving 2. Shipping 3. Raw Materials Storage 4. Finished Goods Storage 5. Manufacturing 6. Work-In-Process Storage 7. Assembly 8. Offices 9. Maintenance A E O U X

Table of TCR Values

Example (cont.) 7 125 62.5 187.5 5 7 125 62.5 7 125.5 5 1.5 9 126.5 0.5 1 63.5 3 125 62.5 7 62.5 5 187.5 9 125

Example (cont.) 7 125 5 137.5 9 25 100 3 37.5 12.5 1 62.5 3 1 7 125 5 9 12.5 87.5 137.5 62.5 25 4 7 5 9 1 125 3 1.5 188 4 0.5 2 63.5 62.5

Example (cont.) 7 5 9 75 -60.5 3 112.5 1 87.5 -62.5 -112 4 -37.5 12.5 2 25 -61.5 25.5 6 0.5 7 5 9 3 1 4 2 6 8