Chapter 14 – JIT and Lean Operations
5. Given:
Processing order = A-B-C-D-E.
Service
Operation
Number of
Daily Reps
A
22
B
12
C
4
D
18
E
8
b. Determine the number of repetitions for each service if four cycles are used.
Note: Dividing each quantity by 4 does not yield integers for all services.
Service
Operation
Number of
Daily Reps
Reps per
Cycle
A
22
22/4 = 5.5
B
12
12/4 = 3
C
4
4/4 = 1
D
18
18/4 = 4.5
E
8
8/4 = 2
Cycle
2
3
4
A
6
5
5
B
3
3
3
C
1
1
1
D
4
5
5
E
2
2
2
Operation
A
22
B
12
12/2 = 6
B
6
6
D
9
9
Chapter 14 – JIT and Lean Operations
6. Given:
Processing order = F-G-H-K.
Product
Daily
Quantity
F
9
G
8
H
5
K
6
The smallest daily quantity is 5. However, none of the other daily quantities are divisible by 5.
Using 5 cycles and producing 1 unit of each product per cycle would leave some products, as
shown in the following table. Hence, if 5 cycles are used, some extra units will have to be made in
some cycles.
Product
Daily
quantity
Units per
Cycle
F
9
9/5 = 1.8
G
8
8/5 = 1.6
H
5
5/5 = 1
K
6
6/5 = 1.2
One possibility would be:
Cycle
1
2
3
4
5
Pattern
F(2)–G–H–K(2)
F(2)-G(2)-H-K
F(2)-G(2)-H-K
F(2)-G-H-K
F-G(2)-H-K
Extra units(s)
F, K
F, G
F, G
F
G
7. Given:
Total time per shift = 480 minutes.
There is 1 shift and workers are given two 15-minute breaks and 45 minutes for lunch.
Daily demand is 300 units.
Chapter 14 – JIT and Lean Operations
14–10
Education.
Case: Level Operations
Given:
The department operates 5 days a week. Partially completed safes are not permitted; each cycle must turn
out finished units.
Projected demand for the next 5 weeks:
Model
S1
S2
S7
S8
S9
Weekly
Quantity
120
102
48
90
25
Stephanie determined that the best production quantity per cycle is S7-S8–S9–S1-S2.
What might Stephanie determine as the best production quantity per cycle for each day of the week?
Step 1:
Divide the weekly demand for each model by 5 to determine daily demand for each model.
Model
S1
S2
S7
S8
S9
Daily
Quantity
120/5 =
24
102/5 =
20.4
48/5 =
9.6
90/5 =
18
25/5 =
5
Step 2:
Divide each value by 5 to determine the number of units per cycle for each model:
Model
S1
S2
S7
S8
S9
Quantity
per Cycle
24/5 =
4.8
20.4/5 =
4.08
9.6/5 =
1.92
18/5 =
3.6
5/5 =
1
Chapter 14 – JIT and Lean Operations
14-11
Step 3:
Determine the production quantity per cycle for each day (there will be 5 cycles per day). This is
somewhat subjective. Production cycle must be S7-S8–S9–S1-S2 in each cycle. We tried to produce the
same total number of units per cycle. If this was not possible, we tried to schedule fewer units on the last
cycle of a day to allow for catching up each day. The schedules for Monday – Thursday are identical.
Friday’s schedule calls for slightly less production to allow for catching up at the end of each week.
Day
Cycle
S7
S8
S9
S1
S2
Total per
Cycle
Monday
1
2
4
1
5
4
16
2
2
3
1
5
5
16
3
2
4
1
5
4
16
4
2
3
1
5
4
15
5
2
4
1
4
4
15
Total
10
18
5
24
21
78
Tuesday
1
2
4
1
5
4
16
2
2
3
1
5
5
16
3
2
4
1
5
4
16
4
2
3
1
5
4
15
5
2
4
1
4
4
15
Total
10
18
5
24
21
78
Wednesday
1
2
4
1
5
4
16
2
2
3
1
5
5
16
3
2
4
1
5
4
16
4
2
3
1
5
4
15
5
2
4
1
4
4
15
Total
10
18
5
24
21
78
Thursday
1
2
4
1
5
4
16
2
2
3
1
5
5
16
3
2
4
1
5
4
16
4
2
3
1
5
4
15
5
2
4
1
4
4
15
Total
10
18
5
24
21
78