figure 5.1: milling machine (left) and steer support parts (right)
TRANSCRIPT
Figure 5.1: Milling machine (left) and steer support parts (right)
Figure 5.2: The impact of Set-up times on Capacity
Batch of 12
Batch of 60
Batch of 120
Batch of 300
Time [minutes]60 120 180 240 300
Set-up from Ribs to Steer support
Set-up from steer support to ribs
Produce ribs (1 box corresponds to 24 units = 12 scooters)
Produce steer supports (1 box corresponds to 12 units = 12 scooters)
Production cycle
Production cycle
Capacity
1/p
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
10
50
90
13
0
17
0
21
0
25
0
29
0
33
0
37
0
41
0
45
0
49
0
53
0
57
0
61
0
65
0 Batch Size
Figure 5.3.: Capacity as a function of the batch size
Production with large batches Production with small batches
CycleInventory
End ofMonth
Beginning ofMonth
CycleInventory
End ofMonth
Beginning ofMonth
Produce Sedan
Produce Station wagon
Production with large batches Production with small batches
CycleInventory
End ofMonth
Beginning ofMonth
CycleInventory
End ofMonth
Beginning ofMonth
Produce Sedan
Produce Station wagon
Production with large batches Production with small batches
CycleInventory
End ofMonth
Beginning ofMonth
CycleInventory
End ofMonth
Beginning ofMonth
Produce Sedan
Produce Station wagon
Production with large batches Production with small batches
CycleInventory
End ofMonth
Beginning ofMonth
CycleInventory
End ofMonth
Beginning ofMonth
Produce Sedan
Produce Station wagon
Figure 5.4: The impact of batch sizes on inventory
Figure 5.5: The impact of Set-up times on Capacity
Inventory[in units of xootrs]
Time [minutes]200 260 600
Set-up from Ribs to Steer support Set-up from steer support to ribs
Produce ribs Produce steer supports
Production cycle
460 520 800 860 12001060 1120 1400 1460
Idle time
133
Rib inventory
Steer support inventory
Figure 5.6: Data from the scooter case about set-up times and batching
Set-up time, S
Milling Machine Assembly process
120 minutes -
Per unit time, p 2 minutes/unit 3 minutes/unit
Capacity (B=12) 0.0833 units/minute 0.33 units/minute
Capacity (B=300) 0.4166 units/minute 0.33 units/minute
Figure 5.7: Choosing a “good” batch size
Batch size is too small, process capacity could be increased (set-up step is at the bottleneck)
Batch size is too large, could be reduced with no negative impact on process capacity (set-up is not at the bottleneck)
Capacity
1/p
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
10
50
90
13
0
17
0
21
0
25
0
29
0
33
0
37
0
41
0
45
0
49
0
53
0
57
0
61
0
65
0 Batch Size
Capacity of sloweststep other than the onerequiring set-up
Figure 5.8: Different patterns of inventory levels
Time
Inventory
Production cycle
PeakInventory
Production Deplete inventory
Time
Order cycle
Shipmentarrives
Inventory
Inventory
Figure 5.9: Inventory and ordering costs for different order sizes
0
10
20
30
40
50
60
70
80
90
3000
4000
5000
6000
7000
8000
9000
1000
0
1100
0
1200
0
1300
0
1400
0
1500
0
1600
0
1700
0
Cost per weekC(Q)
Cost per weekC(Q)
Inventory cost
Ordering fees
Order quantity
Time
Inventory
T
Imax
T1 T2
Slope:1/p-R
Slope:-R
Figure 4.10: Inventory trajectory for the case of internal production
Figure 5.10: Data for the production of orange juice
Set-up time, S
Extraction Bottling
Requires a 30 min. down-time followingevery 4h of production
-
Capacity (while operating)
Filtering
80 barrels/h 100 barrels/h 120 barrels/h
-
Reduce the need for batches• Set-up time reduction, SMED• Process lay-out
Analyze Set-up timesand Set-upcosts
ComputeCapacity as function ofbatch size
Compute cycletime (CT) of the rest of the process
Solve for batchsize:Cap(B)=1/CT
Compute set-upcosts and inventory costs
Use EOQmodel or oneof its variants
Set-up timesdominate
Set-up costsdominate
Figure 5.11.: Summary of batching
Figure 5.12.: Choosing a batch size and reducing set-up costs / time
Responsiveness
Costs
High
Low
High perunit costs
Low perunit costs
Now
Set-up occurs atnon-bottleneck=> use smaller batches
Set-up occurs At bottleneck=> use larger batches
Reduce set-up times
Higherfrontier