Solution of Assignment 1

Step 1: What is the takt time?
Takt time =

Available working time
Customer demand

=

28,800 – 2×15×60
7200 / 20

= 75 sec.

This means that the company needs to produce one refrigerator every 75 seconds in order to meet the customer demand.

Step 2: Should the company build heaters to a finished goods supermarket or deliver directly to shipping? Assuming that the demand is volatile and having only two product varieties, we recommend the company to build a finished product supermarket.

Step 3: Where can the company introduce continuous flow?
The operator-balance chart below summarizes the current cycle time for each operation.
Operator Balance Chart

55
1

60
2

60
1

ACCESSORY INSERTION

120
1

DOOR ASSEMBLY

70
1

TESTING

45
2

FINAL ASSEMBLY

operators

INSULATION FOAMING

Cycle Time
(seconds)
Number of

BASE ASSEMBLY

BENDING & CUTTING

Ta kt Ti me: 75 s econds

62
1






The first two operations can be merged together in one cell (1st cell) and performed with 2 workers. We set the cycle time to 70 sec (93% o Takt). In this case total work content should be decreased from 160
(2x45+70) to 140. C/O needs to be eliminated as well.
Since the changeover time of the insulation foaming process cannot be reduced, it is not a candidate for a continuous flow. Nevertheless, its cycle time needs to be reduced below Takt. There are several options to reduce its cycle time. o Option 1: Add another operator to work in parallel (easiest option especially if there is no expensive machinery to be duplicated). o Option 2: Introduce a second shift in insulation foaming (this option is more viable if there is expensive machinery that cannot be easily duplicated).
We choose Option 1. Now the cell with two operators has a C/T =120/2=60 seconds. With daily demand of 360 units, we will accumulate 360 x (75-60) = 90 minutes for C/Os. See Step 6 for more.
A continuous flow that combines all the remaining processes is recommended. Number of workers=
(55+60x2+60+62) / 75 = 3.96 workers. The required number of workers for this cell (2nd cell) is four.
Four workers with C/T=70 requires the TWC to be reduced from 297 to below 280 seconds. C/Os should also be eliminated as well. A kaizen target might be to reduce the total work content to be less than or equal to 280 seconds (equivalent to 70 sec. of work content for each operator, as shown on the FSM).

Step 4: Where will the company need to use supermarket pull systems?
We already decided to produce heaters to a finished goods supermarket. . There should be two additional supermarkets. One between insulation foaming operation and 2nd work cell, and one for raw materials.
See Step 6 below for sizing the first supermarket.
Even though Heath Company’s supplier is not ready to receive kanban and produce according to them,
Heath Company still can attach an interval withdrawal Kanban to every raw sheet and send those kanban to its own production control department whenever another raw sheet is used. Production control can then order raw sheets based on actual usage instead of MRP’s best guess of what future usage will be. Once production control has made the day’s order for raw sheets, the corresponding Kanban can be placed in
Kanban slots at the receiving dock. These indicate that the day that raw sheets arrive. Currently the supplier is shipping coils once in every two weeks. By lining up other customers along a milk run delivery and motivating the supplier it may be possible to get the necessary amount of raw sheets on a daily basis. For now, we will reduce raw sheets inventory to 2 days (Additional 1 day of inventory is kept for the possible problems in shipment).

Step 5: What is the pacemaker process?
We are planning to use a supermarket pull system between the insulation foaming process and the second cell that contains the last four processes. This pull