Stoneheaven

1. Cutting

During cutting process 3 machines are working on 4 diff. pieces each parallelly

And next batch is taken in only after the first one goes out. So the slowest of the three machines will give the capacity of the department. All the time shown is in minutes & x is size of batch (Given 100). Therefore:

Cutting

Operation Set Up Time / Per die change Run Time / piece Total time per Batch

(5.25 *4+.05*100*x) Capacity/hr. (Batch)

60/max. time reqd. in the deptt.

M/c 1 5.25 0.05 41 1.46

M/c 2 5 0.05 40

M/c 3 4 0.04 32

2. Kitting

Here kits are being manufactured out of pieces from cutting process & diff materials reqd. for assy.

Kitting

Operation Run time / batch Capacity/hr. (Batch)

=60/Run time per batch

Kit making 10 6.00

3. Stitching

In the stitching process every worker is working on one full kit (which is our batch). Since the no. of workers are more than one so it is a parallel line & the capacities of each process can be summed up. After that the least capacity process will be the bottleneck of the dept. & hence the capacity of the process.

Stitching

Operation No. of workers Run time / pair Total time per Batch per worker Individual Capacity/hr. (Batch)

=60*no. of workers/total time per batch per worker Capacity of stitching/ hr. (Batches)

Prefit 4 5 500 0.48 0.48

Join 3 3 300 0.60

Ornament 2 2.5 250 0.48

4. Steaming

Here the shoe uppers are steamed. Since it is mentioned that the oven capacity is not a bottleneck so we are assuming that the capacity is more than whatever is slowest capacity of the sytem.

Steaming

Operation Run time Total time per Batch Capacity of stitching/ hr. (Batches)

Steaming in an oven 360 360 Excess Capacity so not a bottleneck

5. Lasting

Here the process breaks from batch to sequential Production & hence the total capacity of the line will be the because of the slowest process in the deptt.

Lasting

Operation Run Time / pair Total time per Batch Capacity/hr. (Batch)

=60/Max. total time per batch

St.1 -Staple Insole 0.7 70 0.60

St.2 - Toe & heel Seat Lasts 0.6 60

St. 3- Rough Sole Pound 1 100

St. 4- Cement Sole, Pull Last 0.9 90

St.5- Inspect, Pack 0.3 30

a) Factory's Daily Capacity:

From the above tables we choose the lowest capacity across the system which is going to be the capacity of the plant.

So we see the bottleneck process is stitching with a capacity of .48 batches/ hour.

So the capacity of the system is .48 batches/ hour or 3.84 batches / day or 384 pairs per day.

b) Minimum Manufacturing Lead Time:

In minimum manufacturing lead time we assume that no time was consumed during storage of the WIP & material handling time was negligible.

In the cutting process the total time for a batch will be the time taken by the bottleneck m/'c as all the machines are working parallelly

. So 41 mins will be reqd.

In the stitching process since one worker is working on a complete kit. So the time taken by the batch to finish that process will be sum of time taken by each worker in each process (500+300+250= 1050)

In the lasting process Since the production is in pairs. So the first pair goes in & will require time (.7+.6+1+.9+.3 = 3.5 min) Now since the line is running continuously so every one minute a pair comes out. For a full batch of 100 pairs (1 done + 99 following) it will take time = 3.5 +99 min. = 102.5 min

Operations Time reqd. at each dept. (min.)/ Batch

Cutting 41

kitting 10

Stitching 1050

Steaming 360

lasting 102.5

Min. MLT (Sum of time consumed in all the processes) 1563.5

Adding all the times the minimum MLT comes out to be 1563.5 min or 26.06 hrs.

c) Improvements:

First we calculate the average MLT (including Material Storage time)

Since the capacity of plant is .48 per hour so it takes 2.083 hrs for every batch to come out. So to maintain the avg. inventory level the Batches move every 2.083 hours. Now like kitting has 2 batches as inventory before it. So time consumed in storage is 2.083 * 2 hrs. Similarly for other processes. Within the stitching the batch has to wait 3 times . So total no of storage areas (21=2+6+3+6+4)

Hence extra Lead time is 21* 2.083*60 mins = 2625 mins.

Total MLT = 1563.5 + 2625 = 4188.5 mins

Ð'* Now if we arrange our Stitching process such that the each batch is divided among the group of workers & all of them simultaneously work on each batch. Then Time reqd. for each process will be distributed among the no. of workers Hence the MLT will reduce while the capacity of the plant remains the same. The calculationa as per the new MLT follows

Stitching

Operation No. of