You decide that before \"traditional\" lean techniques are implemented in your c

Question

You decide that before "traditional" lean techniques are implemented in your current "push" process, some Factory Physics improvements must be made to reduce variability and lower lot sizes in order to reduce current WIP inventory between stations. After these improvements have been made, then you can do an internal benchmark using the "basics" of Factory Physics on the revised production process to find out what is theoretically "physically" possible in terms of critical work in process (W_o) and throughput (TH_PWC). You obtained the following data after greatly reducing the in-process inventory (lowered CT from many days to a few days): The bottleneck rate (r_b,) of the line is 60 units/hour The average time for a unit to be processed from input to the first station to exit at the last station is now 50 hours (CT) The raw processing time (T_o) is measured by stopwatch to be 2 hours. Customer demand is 7200 units per month (assume 20 work days per month with 7 hours per day work time available). You measured the average production throughput (TH) at 40 jph. Calculate (and, enter only the number into the first 3 boxes that follow): The critical work in process, W_o; and, using Little's Law determine the average WIP; and, then determine TH_PWC (round your answer to the nearest jph). Compare with Customer Demand to see if the Factory Physics "lean" techniques will allow the current line to be "lean" and make production (enter, either yes or no into the 4th box).

Explanation / Answer

Solving the exercise:

1) The critical work in process Wo:

W0 = rb * T0

Remember, the Critical WIP (W0) illustrates the amount of WIP that is needed to have the maximal throughput in stabilized environment with no variability.

rb: Bottleneck speed (rb) is in parts/time -unit and it is the workstation that has the worst throughput in the long run. It is the mean value after all outages.

Raw process time, T0
Raw process time (T0) is the sum of all workstations mean process time. This is only the process time and does not include queuing time.

Now, Wo= (60 units/hour). 2 hours = 120 units (amount of WIP that is needed to have the maximal throughput)

2) The work in process WIP:

WIP= TH.CT   where:

WIP: Work in Process illustrates the parts in production line.

TH: Throughput (TH) means the production that comes out of the line. Usually products/hour.

CT: Production time, cycle time or throughput time illustrates the time that product spends in the production line. It is the time that parts are in WIP condition. From the time they are taken into the production all the way until they are ready.

Now, TH= (7200 units/month).(1 month/20 work days).(1 work day/ 7hour)= 51.43 units/hour=52 units/hour

Then, WIP= (52 units/hour). 50 hours= 2600 units

3) the production throughput at 40 jobs per hour:

THPWC = [ w / ( W0 + w -1)] * rb

THPWC = [ 2600 units/ ( 120 units + 2600 units -1)]. 60 units/hour = 57.37 units/hour= 58 units/hour

The production that comes out of the line is 58 units/hour

(Yes to the comparison)

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