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Sem 5 Prep
← OperationsProcess layout and CRAFT

Formulas for this chapter

Process-layout cost

Minimise SUM(i) SUM(j) Xij x Cij

Scoring any process layout. Cij is normally the handling rate times the centroid-to-centroid distance.

Xij
Number of loads moved from department i to department j
Cij
Cost to move one load between departments i and j
n
Total number of work centres or departments

Rectilinear centroid distance

d(i,j) = |xi - xj| + |yi - yj|

Building the distance matrix in a layout problem, exactly as the class CRAFT spreadsheet does with ABS formulas.

(xi, yi)
Centroid of department i in the layout
(xj, yj)
Centroid of department j

Adjacency cost rule

Cost of a flow = loads x rate, rate = 1 unit if departments are adjacent, 2 units if they are more than one apart

The simplified rule the class uses for the six-department factory, when only adjacency is given rather than distances.

loads
Number of moves between the two departments per period
rate
1 for adjacent, 2 for non-adjacent, in the units the question gives
Step 1 of 20
The ideaTheory

Put the noisy neighbours far apart

Six departments, six rooms. Some pairs send trolleys back and forth all day. Some pairs never speak.

Put the chatty pairs next to each other and the silent pairs at opposite ends. That is the whole of process layout design.

The only difficulty is that with six departments there are 720 ways to arrange them, so you need a rule for searching rather than a picture.

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