Consider any two departments, say, A and B:

Transcription

1 December, 0 valuation Criteria Consider any two departments, say, and B: Distance from to B Cost of traveling one unit of distance from to B Number of trips (say, per day) from to B Multiply all three Total material handling cost (per day) from to B lternatively: Importance of having and B close to (far away) from each other captured by the ctivity Relationship Chart Departments with high importance relationship should be close to each other From-To-Chart: Number of trips per day (flow) to from X X 0-0 X X X sing the distance between any pair of departments, and the flow, we can compute the total distance traveled per day

2 December, 0 From-To-Chart: Cost of traveling one unit of distance between the departments to from X X - X X - X sing the total distance traveled per day and the cost of traveling one unit of distance, we can compute the daily total cost of traveling (material handling) between the departments 6 ctivity relationship chart The activity relationship chart is constructed/modified by considering qualitative information - absolutely necessary (< %) - especially important (< 0%) I - important (<%) - ordinary importance (<0%) - unimportant (> 0%) X - not desirable (< %) I X 7

3 December, 0 xample Relationships Dept. Space (sqft) 0,000 0,000 0,000 0,000 I X ssume: facility is square, is 90,000 sq.ft., departments must be -connected, rectilinear metric, =6, =, I=, =, =0, X=-0 (e.g., Rel(,)=6, Rel(,)=) xample continued Potential layout 9

4 December, 0 Centroid Method Compute the centroid for each department. Compute distance between each pair of departments (D(i,j)). Compute SCR as SCR = 0; for i = to # of departments do for j = (i+) to # of departments do SCR = SCR + D(i,j)*Rel(i,j); In this case we want to minimize SCR. 0 xample continued Potential layout Centroids: Dept. C X C Y...

5 December, 0 Centroid evaluation Relationships Rectilinear Distances SCR = 6(.)+(.7)+(.)+(.)+()-0(.) = 8.7 Graph Method Construct a graph where each node corresponds to a department Draw an edge between two nodes if they are adjacent in the layout. Weight each edge by the number of (or 8) adjacencies times the relationship for that edge. SCR = sum of the edge weights. We want to maximize SCR

6 December, 0 Graph evaluation Potential layout 6() () () () Relationships () 6-0 SCR= Creating a Layout From Scratch 6

7 December, 0 Creating a Layout from Scratch Determine importance levels Prepare activity relationship chart Create a layout using LDP or CRLP (or other approach) Determine a score for the layout Repeat several times to generate alternative layouts and pick the one with the highest score 6 Burger Queen - ctivity Relationship Chart.Cooking burgers.cooking fries.packing/storing.drink dispensers. Counter service - absolutely necessary (< %) 6 - especially important (< 0%) I - important (<%) - ordinary importance (<0%) - unimportant (> 0%) X - not desirable (< %) X I I Rel chart 7 7

8 December, 0 Creating a layout from scratch: LDP (utomated layout design program) Select a department at random and place it to the upper-left corner of the layout Place a department with a high closeness rating next to the first department Continue the process every time selecting a department with the highest closest rating to an already placed department Compute the score for the layout using a numeric scale attached to the closeness ratings Repeat the process several times and choose the layout with the highest score 8 Creating a layout from scratch: CRLP (Computerized relationship layout program) Similar to LDP, but does not select the initial placement at random Compute the Total closeness rating (TCR) for each department (sum of the absolute values of the relations): Cooking fries: X, I,, = 9 Packaging and storing: I, I,, = 6 Drink dispensers:,,, = Counter service:,,, = 7 Select the department with the highest TCR in the center of the facility. In case of a tie, give priority to the department with the largest area or with the highest number of s. 9 8

9 December, 0 CRLP (Cont.) The second department is the one with an relationship with the first one. If a tie exists, choose the one with the greatest TCR value. The third department picked should have the highest combined relationships with the two already placed. gain use tie-breaking rule if needed. Continue until all departments placed. 0 Procedure to Place Departments Consider the figure on the right. ssume that a department is placed in the middle (position 0). Then, if another department is placed in position,, or 7, it is fully adjacent with the first one. If it is placed in position,, 6 or 8, it is partially adjacent 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:. The first department selected is placed in the middle.. The placement of a department is determined by evaluating all possible locations around the current layout in counterclockwise order beginning at the western edge.. The new department is located based on the greatest WP value. 9

10 December, 0 xample. Receiving. Shipping. Raw Materials Storage. Finished Goods Storage. Manufacturing 6. Work-In-Process Storage 7. ssembly 8. ffices 9. Maintenance X X = = I = = = 0 X = - Partial adjacency: = 0. Table of Total Closeness Rating (TCR) Values Dept Department Summary I X X X - X X TCR rder () (7) () (6) () (8) () (9) () = = I = = = 0 X = - For Dept. : ()+()+()+(0)=0 0

11 December, 0 xample (cont.) Relationship between 7 and is, and is ranked () Remember: The second department is the one with an relationship with the first one. If a tie exists, choose the one with the greatest TCR value.,, 6, and 9 have an relationship with 7. mong these, has the highest TCR. place next xample (cont.) Relationship between 7 and is, and is ranked () Relationship between 9 and (and 7) is, and 9 is ranked () Relationship between and (and 9) is, and is ranked ()

12 December, 0 xample (cont.) xample (cont.)

13 December, 0 Improving an xisting Layout Improving an xisting Layout. valuate the layout.. Generate a new layout satisfying connectedness by - opting or -opting.. valuate the new layout based on from-to chart for total material handling cost. If the interchange results in an improvement, keep the change. therwise don t keep the change.. Repeat steps and until no further improvement is possible. 9

14 December, 0 Improving an existing layout by pairwise interchange: -opt -opting involves the switching of two departments. It is performed by: If department i and j are the same size, then the tiles in i and exchanged for the tiles in j. If they are different sizes, then the departments must be adjacent in the layout for the interchange (though the interchange is performed the same way). Keep the change if it improves the objective function In both cases, (or 8) - connectedness must be preserved 60 xample -way interchange of and B Note: This is discussed under CRFT in your book 6

15 December, 0 Improving an existing layout by -opt -opting involves the switching of three departments. It is performed by: For departments i, j and k: i is switched with j, j is switched with k and k is switched with i. Size and or adjacency must be maintained (as in the case of - opting) gain, the departments must maintain (or 8) connectedness 6 xample: -opt C C D D C C B B C D D C D B B C D C D D D D B B B B -way interchange of, B and D B D 6

16 December, 0 Summary Layout is complicated by multiple often competing objectives such as minimize investment in equipment minimize overall production time provide for employee/customer convenience maintain flexibility of arrangement/operation minimize material handling cost utilize existing space most efficiently Can have a significant effect on productivity and cost 6 6